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multilayer method as a tool for depth dependent polymer film photodegradation studies.
by：Top-In
2020-07-28
In order to analyze the photos, a new depth profile protocol for destruction of polymer films was proposed.
Thermal degradation film in a depth range of less than 100 microns.
The method is gathering (vinyl chloride)(PVC)
, Provides a preparation by many ([greater than]20)
A thin layer with a single thickness of less than 15 microns.
At the appropriate pressure, temperature and time treatment, the constituent layers are fused together to produce a thin film assembly with a high optical quality, which behaves as a uniform single layer under light,
Compared with previous technologies, this new method is relatively simple,Labor intensive.
The adhesion performance of the film is controlled within the scope [+ or -]
By using UV-analysis of each of these decomposition layers, the concentration depth distribution of 5% aggregated photo decomposition products was reconstructed
Visible spectrum.
The continuity of these film assemblies in terms of mechanical properties, adhesion properties, and the depth distribution of key photofinishing reagents and products was confirmed by light and reference microscopy techniques.
Optical absorption depth distribution examined in UV
Light degradation Poly (vinyl chloride)(PVC)
In the presence of nitrogen and oxygen atmosphere, the film exhibits the expected classical dependence.
In the study of Degradation and Stability Mechanisms in film polymer films and coatings, it is critical to describe the depth-dependent changes in composition on the micron length scale [1-10].
In addition, deep contour analysis can reveal the effects of many external variables on the degradation process.
These variables include the intensity and spectral distribution of visible and ultraviolet radiation, temperature, humidity, oxygen and ozone concentrations, and other factors that affect material reactivity.
Classic examples of photos
Non-induced depth
Uniformity, is the formation of the center of the color group in many materials, and as the radiation progresses, these centers gradually limit the deeper propagation of the light decomposition radiation in the sample.
Then, there may be material disintegration in the shallow underground area.
Some previous works have been devoted to the study of the deep variation in the composition of polymer films, which is the result of [photo] degradation2-8].
A clear obstacle to these investigations is the lack of a convenient and reliable approach to range 1-100 [micro]m.
Previous deep sampling methods typically include cutting or scraping thin layers from the surface of the sample and then analyzing the removed thin layers (
Or sometimes the rest. material.
Analytical methods include infrared spectra in which the removed substance is pre-deposited into particles with potassium bromide [5]
, Microtiter of sampled dust [8].
Labor intensity, potential low repeatability, and the complexity of calibration are serious limitations of this destructive approach.
Therefore, a convenient, reliable and repeatable depth profile analysis method is needed.
In the present work, we present a new strategy for the in-depth study of the degradation mechanism in polymer films.
In principle, this method is to prepare materials under testas, as components of many very thin layers that blend together under unknown processing conditions.
Maintain the adhesion force between layers under compromise conditions: the adhesion force must remain high enough to ensure that the performance of the assembly is as close as possible to the performance of a continuous single layer medium, but low enough, it can be separated by mechanical stripping after degradation.
This work will provide a new method for the preparation of multi-layer thin film assemblies with high optical quality and repeatable components under known adhesion conditions.
This method is more convenient, reliable and labor-intensive than previously reported.
The thin film components prepared by this method are inspected through a variety of optical and thermal technologies to confirm the continuity of the material in terms of transmission performance.
Our research will use unstable Poly (vinyichioride)(PVC)
As a test material with good performance.
Its degradation mechanism is accompanied by the depth pattern of the photo.
[Extensively studied oxidation and photodehydrogen oxidation2, 5-8,10].
Experiment section.
Unstable gathering of materials (vinyl chloride)(PVC)
The author of the communication, AldrichChem. Co. (No 9002-86-
2. Relative viscosity 2.
Average molecular weight [M. sub. n]= 55,000;
Average molecular weight]M. sub. w]= 97,000).
Removal of traces of catalyst and other impurities by three precipitation of Methanol (HPLC grade)
From the solution of sifluoride ether (HPLC, HPLC grade)
Vacuum drying followed. II.
Film preparation method of 5-PVC film15 [micro]
The M thickness is used as a single blade in a multi-layer assembly.
These films are prepared by spraying and casting on the surface of the glass through the following techniques.
Spray casting is carried out by connecting the spray gun supplied with compressed nitrogen to feed 4% w/w solution of PVC inTHF.
The spraying operation was carried out in a tent enclosure, which was built in a nitrogen atmosphere saturated with THF.
The program is used to prevent the formation of bubbles in the film by quickly releasing solvent steam.
The drying of the film is carried out in the Shell under the condition of slow reduction of the evaporation concentration of THF in the nitrogen carrier, starting from the saturation of THF and eventually reducing to zero concentration.
The exact time period required for this procedure depends on the thickness of the film, but at 3-5 hours.
The spray of the film is deposited on the glass and the air brush is kept 500mm away from the surface of the glass.
A film is prepared by deposition on a microscope slide that is pre-cleaned by a mixture of chromium and sulfuric acid.
Then treated in an ultrasonic bath with deionized water, and finally treated with HPLC graded methanol as a cleaning medium.
As mentioned above, by gradually removing the solvent from the airflow, the film is dried in the tent.
The final drying operation was carried out in a dry nitrogen atmosphere of 70 [degrees]
C. After 30 minutes in the vacuum (0. 001 mm Hg)at 100[degrees]C, 2 hr.
After drying, the prepared pvc film can be easily released from the surface of the glass. III.
The procedure outlined below for multi-layer membrane assemblies is used to prepare multi-layer membrane assemblies for photo degradation testing.
Multi-layer assemblies for these purposes must be highly optical free of defects, bubbles and folds.
Usually, when preparing multi-layer films with traditional methods, it is difficult to avoid the formation of these defects, which adopt the method of combining coverage and pressure.
However, the method described below Introduces New program elements that are capable of manufacturing multi-layer components consisting of many thin layers (15-20 layers and)
, Maintenance with high overall optical quality.
A single film in a multi-layer assembly must be bonded together during manufacturing, but must be separated after processing.
In order to ensure the final separation of the layer, the circular cardboard spacing is prepared (70-100 [micro]
Thickness m, diameter 30mm)
Each of the Andattached (5-15 [micro]m thickness)
Before the film is released from the glass backing (
See the preparation stage above).
These rings are attached to the film with an acrylic adhesive.
After the adhesive is cured, trim each sample of the film into a circle (
Diameter is only 30mm on the outer edge of the cardboard spacer ring)
It is then released from the surface of the glass. About 15-
20 films were assembled in a typical multi-layer film.
The number and thickness of the film are not limited, depending on the depth resolution required.
The lower limit of the individual film thickness has not been determined, but the thickness is 1 [micro]
M should be feasible. We have used 5-15 [micro]
For easy processing, m film meets the acceptable depth resolution standard for current applications.
The selected number of films supported with a cardboard spacer ring is covered in a vacuum mold assembly of a proprietary design (O.
Nepotchatykh, who is applying for a patent in the United States).
The mold chamber is immersed in a constant temperature oil bath and then evacuated to [pressure]10. sup. -4]
Mm Hg that releases the mezzanine gas within 20 minutes.
The external clamping of the mold element is near the top of the stroke to prevent mechanical pressure on the film during the initial evacuation phase.
After completely removing the mezzanine gas from the chamber, the mold is released and the mechanical pressure is equivalent to 1 kg /[cm. sup. 2]
For movies.
The degree of adhesion between the layers in the assembly is characterized by stripping force tests.
A force meter with an aircraft
The scale resolution of 1 kg is used to measure peelstrength in [range]+ or -]
Repeatability of 5%.
During the drying and manufacturing of multi-layer components, PVC polymer must be exposed to 100-120[degrees]
Under nitrogen atmosphere and vacuum.
The possible contribution of degradation to PVC assembly during preparation was considered.
Research on low temperature degradation of PVC based on past [11]
, We estimate that the degree of degradation of unstable PVC under these conditions is called 2x [10. sup. -6]to 5 X [10. sup. -5]
Moore HC1/Moore pvc corresponding to % wt.
Degradation is less than 0.
002% preparation materials.
It is known that this degree of degradation contributes little to the experimental error in the photo degradation test. IV.
The film representation method uses an optical microscope to perform an optical microscope analysis of the preparation cross-section of a multi-layer assembly with the aim of detecting the presence (or absence)
Interface between sticky layers.
By setting the sample in the Epon 812 resin matrix, a thin cross-section of the multi-layer film was prepared (J. B.
Montreal, Canada)at60[degrees]
C, then cured at room temperature. 5 [micro]
Cutting m cross sections using Reichart over speed (Austria)
Slicer.
Under Nomarski Differential interference contrast, thin sections were examined using Zeiss Ultra-thermal optical microscope (
First order red delay).
Photo thermal analysis provides another possible way to test the continuity of materials through photo-thermal representation.
In some recent works, the technique of thermal depth contour is used [12-17]
The optical and thermal properties of the film materials are characterized by changes in depth.
The optical depth profile method is generated based on laser induction of heat sources in the material [17]
, By observing the temperature changes that occur in the time or frequency domain due to the generation of the response heat source.
Analysis of thermal transient or modulation signals allows detection of non-continuity in the thermal properties of the interface [of the burial subsurface]13].
In the preliminary work of this laboratory, a thermal depth contour technique for detecting deep-resolved optical absorption in thin film materials was developed, and also used to detect the interface properties of layer components containing a small number of discrete interfaces [12-16].
These work includes demonstrating the depth distribution of light and heat in the photo of light absorption
Degradation of PVC film by laser light silver electric effect [14].
Recently, based on the laser mirage effect, a more quantitative method of photo-thermal depth imaging, a method of deflection of the photo-thermal beam, has been developed, used to measure the thermal conductivity from the surface of the optical heated sample to the adjacent fluid medium.
This method is described in detail in reference [16]and[18-19]
, The optical and thermal continuity confirmation method as a photo-degradation film is included in this work.
When the optical absorption in the sample is relatively weak, it has a special advantage of good immunity to the background signal, which is also a requirement encountered in the current work.
The film preparation technology for mirage effect analysis is simple, involving pressing the rolling cutting part of the photo-degradation material on the back of the plexiglass. using a thin (1-5 [micro]m)
Adhesive layer.
After the adhesive is cured, the installed sample is assembled into an amirage effect battery for photothermal analysis. V.
The photo-degradation program performs the photo-degradation of PVC film samples in the self-designed and constructed aphotodevalidation chamber.
The degradation device contains a light source that can be used to simulate the solar spectrum, which is composed of 1000 W xenon arclamp (
Hanovia 98 2c0011)
Installed in a housing with a quartz lens and a spherical concave mirror system (Oriel Corp. Model 66023).
The quartz water battery, which acts as a broadband infrared filter, is placed between the lamp shell and the optical solution battery.
An adjustable aperture is placed between the water battery and the optical solution battery to select an area with a uniform height space of the beam for optical decomposition.
Under typical operating conditions, the device provides an irradiated beam of 45mm in diameter to the sample, and the irradiance is uniform in the [range]+ or -]3. 5%.
The light solution cell is made up of an organic glass enclosed battery body.
The battery is equipped with quartz entrance and exit windows for gas supply (
Oxygen)
And there is an internal micro-fan that is used to cool the photodynamics of the sample.
Designed by means of a radiometer for measuring the radiation of the beam-
A house based on Apollo (
Partial fluorine)
Film detectors (28[micro]
M thickness, material provided by North American Company
Part I: TO28NA).
The detector film is covered with a black body absorption layer and installed in a previously reported [Shell]20].
Due to the known frequency response limit of the detector circuit at low frequency, at the frequency of 15Hz, the light on the thermoelectric element is modulated by a mechanical cutter.
Detector signals modulated using lock recordinginamplifier (
Princeton applied research, model 5101)
, Monitor chopperfrequence using a frequency counter and read the locked output channel using a digital voltmeter-in amplifier.
In the wavelength range of 400-, the thermoelectric force meter is calibrated through the Newport model 835 optical energy meter1000 nm.
However, this measuring instrument does not cover the ultraviolet rays, so it is a thermal device that has a flat spectrum over the entire ultraviolet rays.
Visiblerange is used for the actual calibration measurement on the lamp system.
Under the power of 900 W provided to the lamp, the total irradiance of the light decomposition beam on the sample is 8400 W /[m. sup. 2](1580 W/[m. sup. 2]for [lambda][less than]350 nm).
The Oriel model 77250 monometer equipped with aset quartz lens is used to regularly monitor the spectral irradiance of the light decomposition beam to improve the throughput of the input beam.
The thermoelectric force meter is immediately aligned to the exit slit plane of the monochrome.
The spectral irradiance distribution in the light decomposition beam gives an additional approximation
Solar spectrum on the ground]21]
, When the beam passes through the near UV absorption filter.
However, for the purposes of this study, the aim is not to simulate solarexposure, but to repeatedly cause depth-dependent changes in the composition of the film on the accelerated time scale through known photodynamics mechanisms.
To achieve this, no mechanism will filter the lamp output except for the use of water batteries.
The contribution of the spectral radiation distribution of our lamp system to ultraviolet rays is greatly enhanced.
Our measurements show that our light decomposition beam has an integrated UV irradiance (in the range [lambda]= 200 nm-350 nm)whichis 27.
It is 8 times the estimated value of the planet outside the Sun. The UV-
The visible absorption spectra of all films were made on the HPModel 8452A photoelectric diode array spectrometer.
Results and discussion in the photo degradation test, the successful use of multi-layer thin film components to replace the amonolithic single layer depends on twopremisses.
First, the model film should be mechanically decomposed into separate layers (
Although there is enough adhesion between layers)
, Which is necessary for convenient deep-resolution sampling of materials.
Second, in the depth-related study of light degradation, a single-layer test sample was replaced by a multi-layer test sample
Layer Assembly works only if the multi-layer material shows good depth continuity in the following properties.
The second IST (i)
Optical properties; (ii)
Heat transfer properties; and (iii)
Mass transport properties, especially the molecular diffusion coefficient of atmospheric gases and species such as HC1, which is the basic degradation product [2, 5, 9, 22].
Given the need to determine the validity of these assumptions, a series of characterizing tests were conducted to determine the degree of material continuity of the multi-layer components prepared under known conditions. I.
Film preparation variables in order to avoid the change of polymer chain orientation, so with the change of preparation conditions, adhesion between individual films is induced at relatively low mechanical pressure and temperature.
To ensure that the film assembly was prepared under known and repeatable conditions, in order to apply mechanical pressure, the adhesive existing between layers as a function of the preparation temperature and time duration was studied.
Table 1 summarizes the results of this study.
The measurement of the adhesive is repeatable in the [range]+ or -]
For all entries in this table, an error 5% occurred while copying the preparation of the component under changing conditions.
In addition, the adhesion force between layers has nothing to do with the number of layers that make up the assembly.
We determined that for PVC, there is an accessible working range for the temperature and duration of the mechanical pressure, which can be used to produce films with useful mechanical properties.
In particular, within 30 of the anadhesive force-150 g/[cm. sup. 2]
Between the layers of the sample, the mechanical separation can be easily made into separate layers. Above 400 g/[cm. sup. 2]
The adhesion force is comparable to the tensile strength of a single material layer and the tear of the film layer before separation. Below 30 g/[cm. sup. 2]
The adhesion force is too weak to withstand minimum treatment without separating a single layer.
Preparation temperature higher than the glass deposition temperature ([T. sub. g][sim]85[degrees]
C is presentmaterial)
Good adhesion is promoted due to enhanced fluidity (
Thus increases the probability of entanglement)
Polymer chain.
The temperature is too low to promote adhesion, while the temperature is basically higher [T. sub. g]
And close to the aggregation point ([T. sub. m][sim]170[degrees]C)
Promote the fusion of twoph when it is impossible to separate individual layers.
As shown in Table 1, successful preparation of multiple projects
The layer components of our test materials, whose performance is within the working range of the required adhesive, at 110-120[degrees]
C and finishing for mechanical pressure application in 10-range30minutes.
The nature of these preparations is repeatable with [error]+ or -]5%. II.
As mentioned earlier, the continuity of optical properties, the optical quality of the film prepared by our Assembly program is high and comparable to the quality of the separate cast layer.
Figure I shows a photo of a typical multi-layer membrane assembly before photo degradation.
It should be noted that adhesion (
Eventually, light)
Occurs effectively in a1 [cm. sup. 2]
The circular center area of the conference (
Corresponding to the size of the mold element used to press the film together).
Before the decomposition of light, we measured the transparency (
Optical Transmission)
Center attachment area of single layer film and film
Layer Assembly with wavelength range 200-820 nm.
These requirements indicate that there is no significant difference in the ability of a single or assembled film to transmit light.
In order to observe the structure of the possible interface in the undegraded PVC assembly, we conducted a microscopic study of the multi-layer films along the depth cross-sections of these samples and prepared them under different levels of sandwich adhesives.
Method of differential interference comparison (Nomarski-
Quartz red delay)
Selected due to its high sensitivity reflection index and thickness-related non-uniformity in the transparent medium [23].
Microscope checks were performed on multiple devices
Layer cross section with sandwich adhesive in 5-limit range1000 g/[cm. sup. 2].
Here, however, we have encountered some difficulties in the sample preparation process.
Due to the process of cutting micro-cutting from the embedded sample matrix (
Experimental part)
Many layers of material have been eaten.
We usually observe
Just like separating one or more people from these cross-sectional cuts, fold di splacedmaterial on the full part of the cut.
Even in the relatively large value of the adhesion force of the sandwich ([great than]50 g/[cm. sup. 2])
As the number of interfaces in the sample increases, this is an increasingly common problem.
Because of this problem, our microscopic examination is limited to only 1-
3 layers of composition.
Another feature of these preparatory work is the presence of a regular pattern of fractional markers in the cross-sectional area and sample matrix images.
These human factors are caused by the process of image processing, which may make image interpretation more complicated.
Nevertheless, for the microscope drawing obtained on the complete sheet of these multi-layer samples, it can be clearly pointed out that
A typical example is shown in 2a.
This method cannot observe any interface that can be detected.
The sandwich interface is only seen on damaged flakes where the material is either clearly separated or on the verge of breaking (Fig. 2b).
Based on these images, there is therefore no evidence of a significant deviation from the properties of the multi-layer components with optical and structural continuum.
Recent research on these components using the newly developed light profile microscope technology [24].
This is a cross-beam microscope method based on elastic scattering (
Other mechanisms).
The light profile microscope is able to detect the interface in complete samples of these materials with very high sensitivity.
However, since the unusual contrast of this new method is still under study, the significance of this observation is still unclear from the transport continuity model of multi-layer materials.
Further investigations are under way and will be reported in future work. III.
Continuity of thermal physical properties of the interface the heat interface that is not detectable in the multi-layer components prepared by our experimental method is confirmed using the recently developed laser mirage effect spectrum technology [1]18, 19].
Double-layer components prepared at a temperature of 110 [degrees]
C. As a material for testing adhesion between interfaces, bear mechanical pressure within 20 minutes.
The schematic diagram of the test sample is shown in the figure. 3.
The surface of the film assembly is deposited on the front (F)and rear (R)
A surface with a thin black body index mark for absorbing excitation light from a modulated beam.
The sample is glued to the Flat Poly (
Mma)(PMMA)
Backing blocks are then sealed into an optical cell containing a water medium for thermal beam deflection analysis.
In this measurement, the sample is heated by the optical adsorption of the broadband modulated beam, in this way, athermo-
Extraction of light pulse response from measurement [15].
The measured pulse response is used to reconstruct the depth profile of the heat flow induced by light absorption at t = 0 in the material, by (
Math though)impulse.
When a hot continuous sample is excited by a pulse on the front surface, all light absorption (
And generate heat source density)
Is limited to the front surface of the sample.
The depth distribution of the heat source density generated by pulses reconstructed in this method in the sample should be approximate to the spatial Dirac deltafunction function corresponding to the heat source density confined to the front surface.
In the practical application, even for the theoretical continuous material, the reconstruction algorithm can be very good.
Features of expanding [12, 13, 16, 17]
, This is the typical case seen in the observed profile.
Similarly, when the back of the sample is irradiated by a thelaser pulse, in a hot continuous material, the heat source structure should accurately contain the peak at the depth of the back (
Measured from the front surface position of the sample).
Irradiation of the rear interface (R)
Reconstruction of wide peak results located at depth 140 [micro]
M from the front.
Similarly, in the presence of hot continuous materials, it is found as the depth expands to be a feature of the reconstruction algorithm.
In materials with detectable thermal non-continuity at the internal interface, reconstruction of heat source density in the case of positive absorption would obviously contain a large surface thermal source peak, significant satellite peaks at Numerical [depth position]2n1. sub. 1](n = 1, 2,. . . )(where[l. sub. 1]= 70 [micro]m).
These contributions come from the reflection of thermal energy at the interface where the interface adhesion is poor [13].
In the case of optical excitation of the rear interface, the effect of poor interface adhesion will delay the arrival of thermal energy on the front surface.
The reconstruction depth of the rear surface absorber will then be greater than the physical distance between the rear surface and the front of the sample.
Since both effects are clearly absent, the test confirms a good first-order approximation of the thermal uniformity of the two materials. IV.
Continuity of Pphotoproduct distribution in photo-degradation films from the study process of dehydrochloride [the polyene sequence formed in PVC]2, 9, 10].
Due to the multiple Coole olefin structures formed on many repeated steps of the dehydrochloride reaction, polyene photoproducts have significant visible wavelength absorption [2, 5, 9, 10].
This process is effective and only in the absence of oxygen will there be competition for photooxidation.
When oxygen is present, the well-known bleachingeffect occurs due to the oxidation of the olefinic boundary, which interferes with the binding of polyene and forms transparent over the visible wavelength range2)
And use the infrared effect spectrum to exclude from the analysis.
Results shown in Figure 1
4 demonstrate the level of accuracy of the absorption coefficient depth profile using our mirageeffect method.
In this case, the sample is made up of multi-layer components that are degraded in an oxygen atmosphere.
After the central area of multi-layer assembly is decomposed (see Fig. 1)
Divided into two halves: half was analyzed by mirage effect, the other half was mechanically separated, and Peel force test and absorption spectrum test were performed on the separated layer.
Depth Distribution of absorption coefficient ,[beta](x)
At 476 nm, recovered by microwave effect spectrum as described by reference [18, 19]
, Is integrated into the average thickness of the layers used in multi-layer components.
This block integrated profile is superimposed with the profile recovered by the absorption luminosity method and measured directly on a single layer.
The consistency between the depth profiles is measured as root mean square (rms)
The difference between P. rofiles and the peak absorption coefficient value of the contour (s).
This protocol is always better than 12% rms for both technologies.
Inherent uncertainty (random error)
At present, the luminosity error is limited in the depth profile of destrucemultimilayer.
These profiles follow the well
It is known that the optical absorption depth mode of the degradation PVC film in the presence of oxygen.
In the photodegraded film, photooxidation occurs effectively within an oxygen diffusion depth from the surface (10-40 [micro]m)
, Gives a product distribution that is almost transparent in the visible wavelength range.
Deep film ([great than]30-40 [micro]m)
The oxygen concentration is effective at zero, dehydrogen-based is effective, and the long chain long polyene sequence accumulates rapidly during the photodecomposition process.
However, as the sequence length increases, the UV absorption of the light product also increases dramatically, by absorbing the attenuation light before reaching a greater depth.
Far greater than the depth [sim]100 [micro]
M, the film becomes transparent again.
A test was designed to evaluate the continuity of the transmission properties of these multi-layer components, including comparing the depth distribution of absorption coefficients ,[beta](x)
, Obtained in a separated multi-layer component, obtained in Fusion (non-separable)assembly.
Two identical material components were prepared for this test, but the heat treatment was different, as shown in Table 1.
The detachable assembly has adhesion in the range of 100 [+ or-]20 gm/[cm. sup. 2]
When the molten material is heat treated at [50 ℃]degrees]
C 15 minutes, give non
The adhesion force is larger than the detachable layer of 600 gm/[cm. sup. 2].
Depth Analysis of laser Phantom effect for recovery [beta](x)
For these components, due to their special sensitivity to interface non-continuity in heat flow. Theprofiles, [beta](x)
In the figure, we compare the results obtained for two components.
5, and there is no significant difference in the depth profile feature, which is better than 10% rms with full scale.
This finding is consistent with the fact that there is no significant degradation product transport barrier in the detachable assembly.
Absorption depth profile and single layer based on mirage effect obtained in separated multi-layer components (200 [micro]m)
PVC spray plastic film, exposed under parallel conditions.
This is more difficult here because single-layer casting contains different solvent loads (THF)
From multi-layer components.
This solvent has several effects on photodynamics, so the depth distribution of the photo
Products in PVC have been identified in past work.
Stabilizer and peroxide are common impurities in reagent level THF.
A large concentration of peroxide, especially [alpha]-
The peroxide of THF has a direct effect on the rate of photooxidation by its tendency to form free radicals.
Through light shielding or other mechanisms, there is also a problem with the effect of the stabilizer.
In the absence of these impurities, the THF itself has been shown to have a slight inhibitory effect on the extent of the photo
Dechlorine in PVC [25].
In the current work, all film preparation is carried out using a plc-grade solvent in which this impurity does not exist in trace amounts or more.
We have experimentally determined that the presence of the THFin PVC film reduces the polyene formation rate during the photo-degradation of PVC [presence]O. sub. 2]or [N. sub. 2]
Consistent with past work25].
This is consistent with the very good repeatability of the depth distribution determined in photodynamics of our multi-layer components.
In the case of multi-layer components, a single layer ([less than]15 [micro]m thickness)
Thoroughly dry in a vacuum oven before assembly, and thick (200 [micro]m)
It takes a long time for a single casting to dry under vacuum to remove the casting.
In addition, we found evidence of differences in particle morphology based on differences in spray casting procedures [24]
Therefore, when comparing the light degradation in a very thin assembly layer, an additional variable is generated ([less than]15 [micro]m)and thick ([greaterthan]200 [micro]m)layers.
Still, when [Lieutenant Colonel] is peakabsorptionbeta](x)
Through the depth distribution recovered by mirageeffect, a close agreement was found between the polyene absorbance distribution found in the separated multi-layer assembly and the single-layer cast layer.
Another test on the photo-degradation samples of this material is to measure the adhesion between layers as a depth function.
The interlayer adhesion observed in the material sample was not deeply dependent prior to the decomposition.
After light decomposition, the sample shows the depth mode of the adhesive, which usually changes according to the profile shown in Figure 16.
In this case, the samples examined had adhesion prior to the degradation of 30 gm/[cm. sup. 2]
, But in the most extensive areas of light degradation, [an adhesive has been added]sim]100 g/[cm. sup. 2].
For samples exposed under nitrogen, similar adhesion enhancement was also observed, with peak non-adhesion force near the surface of the sample, where the photoelectric concentration was the largest.
The most direct explanation of this effect is the increase in the internal temperature of the sample, which may be produced by the combination of high-gloss source radiation with the strong enhanced UV and visible absorption of the product, relative to the starting material.
In order to produce a very large absorption change, a relatively small total degree of chemical transformation of the starting material is required.
However, processes initiated by other light, such as polyene cross-linking [can also enhance adhesion2](
This will be most effective without oxygen)
, Or the interaction of polarized structures caused by photographsoxidation (
In the near-surface area of the oxygen light material).
However, further research is needed to distinguish the relative contribution of these processes.
This enhanced adhesion seems to promote the continuity of the mezzanine, and in fact, from the polyene absorption curve, there is no evidence that the increased adhesion forces can undermine the continuity of transport performance.
As a further note, we can also extend the results of the recovery of multi-layer and non-destructive depth profile methods to the comparison of light degradation of PVC Films in nitrogen atmosphere (Fig. 7).
Based on these results, we observed another typical pattern of the depth dependence of the absorption coefficient of PVC at visible wavelengths.
After degradation in an oxygen atmosphere, the maximum concentration of the polymer occurs at 30-60[micro]
M, decreases with monotony of polymer depth.
In an inert atmosphere such as nitrogen, we observed 5-10 [micro]
The m surface layer of the sample, the peak light absorption degree is enhanced.
This model is known in the literature. 26, 27].
It should be noted that an important advantage of the multi-layer method is that it is not limited by the spectral range or even by the optical analysis of the separation layer.
The depth profile method has many attractive features, especially its non-
It is destructive and can only work at the available laser wavelength.
In principle, multi-layer methods can be extended to the analysis of more chemical species than optical methods.
Finally, while the results of these studies show a huge application prospect for multi-layer membrane testing methods, we must also keep in mind the limitations it brings.
In extreme conditions, such as at the extreme of high temperature, presence of solvents, or degradation, the layered model may fail in several directions.
For example, the component can be pre-configured to be layered, in which case the boundary effect is enhanced.
Alternatively, a single layer may fuse together at high temperatures, so it is inseparable after the light breaks down.
Nevertheless, under controlled experimental conditions, and under conditions of weak to moderate light degradation, we have established that this method has many in advanced technologies for obtaining depth-related information in film PVC
Extending these results to other polymer materials requires a clear adjustment of our experimental procedures.
However, the current work laid the foundation of the methodological principles and procedures for the completion of this extension.
Conclusion under specific conditions, mechanical separated PVC film components with high optical quality and predictable adhesive properties can be prepared.
Our preparation method is reliable and unambiguous. Labor intensive.
The results of thermal and conventional optical microscopy tests failed to detect any evidence of significant interface inconsistency between assembly layers.
Consistency between multi-layer destructive analysis and deep distribution of dehydrogen chloride in non-degraded filmsdestructive(mirage effect)
Absorption depth distribution was observed in the early quantitative range.
The results of the optical absorption depth distribution test give a picture consistent with the continuity of the mass transmission properties of oxygen and hydrogen chloride.
This shows that multi-layer components give a good approximation of continuous single layers under light decomposition, but can still be analyzed separately after that.
The author wants to thank the doctor. S. W.
Fu contributed the mirage effect depth profile data to support this approach.
The author would also like to thank the Canadian commission for Natural Science and Engineering Research (NSERC)
Thanks for their continued support for the work. REFERENCES (1. )G. C. Marks and G. Butters, J. MacromoL Sci-Chern. A12, 569(1978). (2. )K. S. Minsker, S. V. Kolesov, and G. E.
Aging and stability of Zaikov, Moscow Noka Vinylchloride polymer (1982). (3. )G. E.
Schoolenberg and P.
Polymer, 32,432 (1991). (4. )G. E.
Schoolenberg and H. D. F. Meijer.
32, 438 (polymer)1991). (5. )A. P. Alexandrov, V. N. Genkin, and V. V.
Institute of aggregation science of the Soviet Union, 1188 (1985). (6. )J. Gardette and J. Lemaire, Polym. Degr. Stab. , 25, 293(1989). (7. )J. Gardette and J. Lemaire, Polym. Degr. Stab. , 33, 77 (1991). (8. )N. M. Biturin, V. N. Genkin, V. P. Lebedev, A. V. Nikitin, V. V. Sokolov, L. D.
Strelkova, T. G.
Fedoseyeva, Soviet polymer science, 25,1, 91 (1983). (9. )K. Maruyama, Y. Kuramoto, M. Yagi, and Y.
Polymer Valley Kawasaki. 29, 24 (1988). (10. )D. Braun and E.
Encyclopedia of PVC, Second Edition. ch. 8, pp. 397-433, L. I. Nass and C. A. Heiberger, eds.
Marcel Decker, New York (1986). (11. )O. V. Nepotchakyh, M. I. Adullin, K. S. Minsker, G. E. Zaikov, and C. R. H. I.
Pauline de JongDegrad. Stab. , 18, 349 (1987). (12. )J. F. Power and M. C. Prystay, Appl. Spec. , 49, 709 (1995). (13. )J. F. Power and M. C. Prystay, Appl. Spec. , 49, 725 (1995). (14. )M. C. Prystay and J. F. Power, Polym. Eng. Sci. , 36, 685(1996). (15. )M. A.
Schweitzer and J. F. Power, Appl. Spec. , 48, 1076-1087(1993). (16. )J. F. Power and M. A. Schweitzer.
Light-light and heat phenomenon: 10 th International Conference
Bertolotiang F. Scudieri, eds.
Page 463 of the AIP meeting record. 190-94,Woodbury, N. Y. (1999). (17. )J. F.
Volume 3 International Seminar-electricity-
Progress in signal processing of material NDE, page57-63, X. P.
Maldague, technical editor, non-destructive assessment series
Destructive Testing (1998). (18. )J. F. Power, S. W. Fu, and M. A.
Schweitzer, ApplSpec. , 54,110 (2000). (19. )S. W. Fu and J. F. Power, Appl. Spec. , 54, 127 (2000). (20. )J. F. Power, App. Spec. , 45, 1252 (1991). (21. )M. Iqbal.
Introduction to solar radiation, academic paper. , Toronto (1983). (22. )K. Patel, A. Velazquez, H. S.
Calderon and G. R. Brown, J. Appl. Polym, Sci. , 46, 179 (1992). (23. )L. C. Sawyer and D. C.
Grubb, polymer microscope, p. 21,Chapman-Hall London (1987). (24. )J. F. Power and S. W. Fu. Appl. Spec, 52, 1507(1999). (25. )K. S. Minsker, M. I. Abdullin. and V. A.
Krajkin, 3 years old, 31 years old (1980). (26. )L. D. Strelkova, G. T.
Fedoseyeva, K. S.
Minsker, vysokomocular. Soed. , 18. No. 9, 2064 (1976). (27. )N. M. Biturin, V. N. Genkin, and V. V.
Sokolov, vissocomo
Soed, short report, 23. No. 3, 221 (1981).
Thermal degradation film in a depth range of less than 100 microns.
The method is gathering (vinyl chloride)(PVC)
, Provides a preparation by many ([greater than]20)
A thin layer with a single thickness of less than 15 microns.
At the appropriate pressure, temperature and time treatment, the constituent layers are fused together to produce a thin film assembly with a high optical quality, which behaves as a uniform single layer under light,
Compared with previous technologies, this new method is relatively simple,Labor intensive.
The adhesion performance of the film is controlled within the scope [+ or -]
By using UV-analysis of each of these decomposition layers, the concentration depth distribution of 5% aggregated photo decomposition products was reconstructed
Visible spectrum.
The continuity of these film assemblies in terms of mechanical properties, adhesion properties, and the depth distribution of key photofinishing reagents and products was confirmed by light and reference microscopy techniques.
Optical absorption depth distribution examined in UV
Light degradation Poly (vinyl chloride)(PVC)
In the presence of nitrogen and oxygen atmosphere, the film exhibits the expected classical dependence.
In the study of Degradation and Stability Mechanisms in film polymer films and coatings, it is critical to describe the depth-dependent changes in composition on the micron length scale [1-10].
In addition, deep contour analysis can reveal the effects of many external variables on the degradation process.
These variables include the intensity and spectral distribution of visible and ultraviolet radiation, temperature, humidity, oxygen and ozone concentrations, and other factors that affect material reactivity.
Classic examples of photos
Non-induced depth
Uniformity, is the formation of the center of the color group in many materials, and as the radiation progresses, these centers gradually limit the deeper propagation of the light decomposition radiation in the sample.
Then, there may be material disintegration in the shallow underground area.
Some previous works have been devoted to the study of the deep variation in the composition of polymer films, which is the result of [photo] degradation2-8].
A clear obstacle to these investigations is the lack of a convenient and reliable approach to range 1-100 [micro]m.
Previous deep sampling methods typically include cutting or scraping thin layers from the surface of the sample and then analyzing the removed thin layers (
Or sometimes the rest. material.
Analytical methods include infrared spectra in which the removed substance is pre-deposited into particles with potassium bromide [5]
, Microtiter of sampled dust [8].
Labor intensity, potential low repeatability, and the complexity of calibration are serious limitations of this destructive approach.
Therefore, a convenient, reliable and repeatable depth profile analysis method is needed.
In the present work, we present a new strategy for the in-depth study of the degradation mechanism in polymer films.
In principle, this method is to prepare materials under testas, as components of many very thin layers that blend together under unknown processing conditions.
Maintain the adhesion force between layers under compromise conditions: the adhesion force must remain high enough to ensure that the performance of the assembly is as close as possible to the performance of a continuous single layer medium, but low enough, it can be separated by mechanical stripping after degradation.
This work will provide a new method for the preparation of multi-layer thin film assemblies with high optical quality and repeatable components under known adhesion conditions.
This method is more convenient, reliable and labor-intensive than previously reported.
The thin film components prepared by this method are inspected through a variety of optical and thermal technologies to confirm the continuity of the material in terms of transmission performance.
Our research will use unstable Poly (vinyichioride)(PVC)
As a test material with good performance.
Its degradation mechanism is accompanied by the depth pattern of the photo.
[Extensively studied oxidation and photodehydrogen oxidation2, 5-8,10].
Experiment section.
Unstable gathering of materials (vinyl chloride)(PVC)
The author of the communication, AldrichChem. Co. (No 9002-86-
2. Relative viscosity 2.
Average molecular weight [M. sub. n]= 55,000;
Average molecular weight]M. sub. w]= 97,000).
Removal of traces of catalyst and other impurities by three precipitation of Methanol (HPLC grade)
From the solution of sifluoride ether (HPLC, HPLC grade)
Vacuum drying followed. II.
Film preparation method of 5-PVC film15 [micro]
The M thickness is used as a single blade in a multi-layer assembly.
These films are prepared by spraying and casting on the surface of the glass through the following techniques.
Spray casting is carried out by connecting the spray gun supplied with compressed nitrogen to feed 4% w/w solution of PVC inTHF.
The spraying operation was carried out in a tent enclosure, which was built in a nitrogen atmosphere saturated with THF.
The program is used to prevent the formation of bubbles in the film by quickly releasing solvent steam.
The drying of the film is carried out in the Shell under the condition of slow reduction of the evaporation concentration of THF in the nitrogen carrier, starting from the saturation of THF and eventually reducing to zero concentration.
The exact time period required for this procedure depends on the thickness of the film, but at 3-5 hours.
The spray of the film is deposited on the glass and the air brush is kept 500mm away from the surface of the glass.
A film is prepared by deposition on a microscope slide that is pre-cleaned by a mixture of chromium and sulfuric acid.
Then treated in an ultrasonic bath with deionized water, and finally treated with HPLC graded methanol as a cleaning medium.
As mentioned above, by gradually removing the solvent from the airflow, the film is dried in the tent.
The final drying operation was carried out in a dry nitrogen atmosphere of 70 [degrees]
C. After 30 minutes in the vacuum (0. 001 mm Hg)at 100[degrees]C, 2 hr.
After drying, the prepared pvc film can be easily released from the surface of the glass. III.
The procedure outlined below for multi-layer membrane assemblies is used to prepare multi-layer membrane assemblies for photo degradation testing.
Multi-layer assemblies for these purposes must be highly optical free of defects, bubbles and folds.
Usually, when preparing multi-layer films with traditional methods, it is difficult to avoid the formation of these defects, which adopt the method of combining coverage and pressure.
However, the method described below Introduces New program elements that are capable of manufacturing multi-layer components consisting of many thin layers (15-20 layers and)
, Maintenance with high overall optical quality.
A single film in a multi-layer assembly must be bonded together during manufacturing, but must be separated after processing.
In order to ensure the final separation of the layer, the circular cardboard spacing is prepared (70-100 [micro]
Thickness m, diameter 30mm)
Each of the Andattached (5-15 [micro]m thickness)
Before the film is released from the glass backing (
See the preparation stage above).
These rings are attached to the film with an acrylic adhesive.
After the adhesive is cured, trim each sample of the film into a circle (
Diameter is only 30mm on the outer edge of the cardboard spacer ring)
It is then released from the surface of the glass. About 15-
20 films were assembled in a typical multi-layer film.
The number and thickness of the film are not limited, depending on the depth resolution required.
The lower limit of the individual film thickness has not been determined, but the thickness is 1 [micro]
M should be feasible. We have used 5-15 [micro]
For easy processing, m film meets the acceptable depth resolution standard for current applications.
The selected number of films supported with a cardboard spacer ring is covered in a vacuum mold assembly of a proprietary design (O.
Nepotchatykh, who is applying for a patent in the United States).
The mold chamber is immersed in a constant temperature oil bath and then evacuated to [pressure]10. sup. -4]
Mm Hg that releases the mezzanine gas within 20 minutes.
The external clamping of the mold element is near the top of the stroke to prevent mechanical pressure on the film during the initial evacuation phase.
After completely removing the mezzanine gas from the chamber, the mold is released and the mechanical pressure is equivalent to 1 kg /[cm. sup. 2]
For movies.
The degree of adhesion between the layers in the assembly is characterized by stripping force tests.
A force meter with an aircraft
The scale resolution of 1 kg is used to measure peelstrength in [range]+ or -]
Repeatability of 5%.
During the drying and manufacturing of multi-layer components, PVC polymer must be exposed to 100-120[degrees]
Under nitrogen atmosphere and vacuum.
The possible contribution of degradation to PVC assembly during preparation was considered.
Research on low temperature degradation of PVC based on past [11]
, We estimate that the degree of degradation of unstable PVC under these conditions is called 2x [10. sup. -6]to 5 X [10. sup. -5]
Moore HC1/Moore pvc corresponding to % wt.
Degradation is less than 0.
002% preparation materials.
It is known that this degree of degradation contributes little to the experimental error in the photo degradation test. IV.
The film representation method uses an optical microscope to perform an optical microscope analysis of the preparation cross-section of a multi-layer assembly with the aim of detecting the presence (or absence)
Interface between sticky layers.
By setting the sample in the Epon 812 resin matrix, a thin cross-section of the multi-layer film was prepared (J. B.
Montreal, Canada)at60[degrees]
C, then cured at room temperature. 5 [micro]
Cutting m cross sections using Reichart over speed (Austria)
Slicer.
Under Nomarski Differential interference contrast, thin sections were examined using Zeiss Ultra-thermal optical microscope (
First order red delay).
Photo thermal analysis provides another possible way to test the continuity of materials through photo-thermal representation.
In some recent works, the technique of thermal depth contour is used [12-17]
The optical and thermal properties of the film materials are characterized by changes in depth.
The optical depth profile method is generated based on laser induction of heat sources in the material [17]
, By observing the temperature changes that occur in the time or frequency domain due to the generation of the response heat source.
Analysis of thermal transient or modulation signals allows detection of non-continuity in the thermal properties of the interface [of the burial subsurface]13].
In the preliminary work of this laboratory, a thermal depth contour technique for detecting deep-resolved optical absorption in thin film materials was developed, and also used to detect the interface properties of layer components containing a small number of discrete interfaces [12-16].
These work includes demonstrating the depth distribution of light and heat in the photo of light absorption
Degradation of PVC film by laser light silver electric effect [14].
Recently, based on the laser mirage effect, a more quantitative method of photo-thermal depth imaging, a method of deflection of the photo-thermal beam, has been developed, used to measure the thermal conductivity from the surface of the optical heated sample to the adjacent fluid medium.
This method is described in detail in reference [16]and[18-19]
, The optical and thermal continuity confirmation method as a photo-degradation film is included in this work.
When the optical absorption in the sample is relatively weak, it has a special advantage of good immunity to the background signal, which is also a requirement encountered in the current work.
The film preparation technology for mirage effect analysis is simple, involving pressing the rolling cutting part of the photo-degradation material on the back of the plexiglass. using a thin (1-5 [micro]m)
Adhesive layer.
After the adhesive is cured, the installed sample is assembled into an amirage effect battery for photothermal analysis. V.
The photo-degradation program performs the photo-degradation of PVC film samples in the self-designed and constructed aphotodevalidation chamber.
The degradation device contains a light source that can be used to simulate the solar spectrum, which is composed of 1000 W xenon arclamp (
Hanovia 98 2c0011)
Installed in a housing with a quartz lens and a spherical concave mirror system (Oriel Corp. Model 66023).
The quartz water battery, which acts as a broadband infrared filter, is placed between the lamp shell and the optical solution battery.
An adjustable aperture is placed between the water battery and the optical solution battery to select an area with a uniform height space of the beam for optical decomposition.
Under typical operating conditions, the device provides an irradiated beam of 45mm in diameter to the sample, and the irradiance is uniform in the [range]+ or -]3. 5%.
The light solution cell is made up of an organic glass enclosed battery body.
The battery is equipped with quartz entrance and exit windows for gas supply (
Oxygen)
And there is an internal micro-fan that is used to cool the photodynamics of the sample.
Designed by means of a radiometer for measuring the radiation of the beam-
A house based on Apollo (
Partial fluorine)
Film detectors (28[micro]
M thickness, material provided by North American Company
Part I: TO28NA).
The detector film is covered with a black body absorption layer and installed in a previously reported [Shell]20].
Due to the known frequency response limit of the detector circuit at low frequency, at the frequency of 15Hz, the light on the thermoelectric element is modulated by a mechanical cutter.
Detector signals modulated using lock recordinginamplifier (
Princeton applied research, model 5101)
, Monitor chopperfrequence using a frequency counter and read the locked output channel using a digital voltmeter-in amplifier.
In the wavelength range of 400-, the thermoelectric force meter is calibrated through the Newport model 835 optical energy meter1000 nm.
However, this measuring instrument does not cover the ultraviolet rays, so it is a thermal device that has a flat spectrum over the entire ultraviolet rays.
Visiblerange is used for the actual calibration measurement on the lamp system.
Under the power of 900 W provided to the lamp, the total irradiance of the light decomposition beam on the sample is 8400 W /[m. sup. 2](1580 W/[m. sup. 2]for [lambda][less than]350 nm).
The Oriel model 77250 monometer equipped with aset quartz lens is used to regularly monitor the spectral irradiance of the light decomposition beam to improve the throughput of the input beam.
The thermoelectric force meter is immediately aligned to the exit slit plane of the monochrome.
The spectral irradiance distribution in the light decomposition beam gives an additional approximation
Solar spectrum on the ground]21]
, When the beam passes through the near UV absorption filter.
However, for the purposes of this study, the aim is not to simulate solarexposure, but to repeatedly cause depth-dependent changes in the composition of the film on the accelerated time scale through known photodynamics mechanisms.
To achieve this, no mechanism will filter the lamp output except for the use of water batteries.
The contribution of the spectral radiation distribution of our lamp system to ultraviolet rays is greatly enhanced.
Our measurements show that our light decomposition beam has an integrated UV irradiance (in the range [lambda]= 200 nm-350 nm)whichis 27.
It is 8 times the estimated value of the planet outside the Sun. The UV-
The visible absorption spectra of all films were made on the HPModel 8452A photoelectric diode array spectrometer.
Results and discussion in the photo degradation test, the successful use of multi-layer thin film components to replace the amonolithic single layer depends on twopremisses.
First, the model film should be mechanically decomposed into separate layers (
Although there is enough adhesion between layers)
, Which is necessary for convenient deep-resolution sampling of materials.
Second, in the depth-related study of light degradation, a single-layer test sample was replaced by a multi-layer test sample
Layer Assembly works only if the multi-layer material shows good depth continuity in the following properties.
The second IST (i)
Optical properties; (ii)
Heat transfer properties; and (iii)
Mass transport properties, especially the molecular diffusion coefficient of atmospheric gases and species such as HC1, which is the basic degradation product [2, 5, 9, 22].
Given the need to determine the validity of these assumptions, a series of characterizing tests were conducted to determine the degree of material continuity of the multi-layer components prepared under known conditions. I.
Film preparation variables in order to avoid the change of polymer chain orientation, so with the change of preparation conditions, adhesion between individual films is induced at relatively low mechanical pressure and temperature.
To ensure that the film assembly was prepared under known and repeatable conditions, in order to apply mechanical pressure, the adhesive existing between layers as a function of the preparation temperature and time duration was studied.
Table 1 summarizes the results of this study.
The measurement of the adhesive is repeatable in the [range]+ or -]
For all entries in this table, an error 5% occurred while copying the preparation of the component under changing conditions.
In addition, the adhesion force between layers has nothing to do with the number of layers that make up the assembly.
We determined that for PVC, there is an accessible working range for the temperature and duration of the mechanical pressure, which can be used to produce films with useful mechanical properties.
In particular, within 30 of the anadhesive force-150 g/[cm. sup. 2]
Between the layers of the sample, the mechanical separation can be easily made into separate layers. Above 400 g/[cm. sup. 2]
The adhesion force is comparable to the tensile strength of a single material layer and the tear of the film layer before separation. Below 30 g/[cm. sup. 2]
The adhesion force is too weak to withstand minimum treatment without separating a single layer.
Preparation temperature higher than the glass deposition temperature ([T. sub. g][sim]85[degrees]
C is presentmaterial)
Good adhesion is promoted due to enhanced fluidity (
Thus increases the probability of entanglement)
Polymer chain.
The temperature is too low to promote adhesion, while the temperature is basically higher [T. sub. g]
And close to the aggregation point ([T. sub. m][sim]170[degrees]C)
Promote the fusion of twoph when it is impossible to separate individual layers.
As shown in Table 1, successful preparation of multiple projects
The layer components of our test materials, whose performance is within the working range of the required adhesive, at 110-120[degrees]
C and finishing for mechanical pressure application in 10-range30minutes.
The nature of these preparations is repeatable with [error]+ or -]5%. II.
As mentioned earlier, the continuity of optical properties, the optical quality of the film prepared by our Assembly program is high and comparable to the quality of the separate cast layer.
Figure I shows a photo of a typical multi-layer membrane assembly before photo degradation.
It should be noted that adhesion (
Eventually, light)
Occurs effectively in a1 [cm. sup. 2]
The circular center area of the conference (
Corresponding to the size of the mold element used to press the film together).
Before the decomposition of light, we measured the transparency (
Optical Transmission)
Center attachment area of single layer film and film
Layer Assembly with wavelength range 200-820 nm.
These requirements indicate that there is no significant difference in the ability of a single or assembled film to transmit light.
In order to observe the structure of the possible interface in the undegraded PVC assembly, we conducted a microscopic study of the multi-layer films along the depth cross-sections of these samples and prepared them under different levels of sandwich adhesives.
Method of differential interference comparison (Nomarski-
Quartz red delay)
Selected due to its high sensitivity reflection index and thickness-related non-uniformity in the transparent medium [23].
Microscope checks were performed on multiple devices
Layer cross section with sandwich adhesive in 5-limit range1000 g/[cm. sup. 2].
Here, however, we have encountered some difficulties in the sample preparation process.
Due to the process of cutting micro-cutting from the embedded sample matrix (
Experimental part)
Many layers of material have been eaten.
We usually observe
Just like separating one or more people from these cross-sectional cuts, fold di splacedmaterial on the full part of the cut.
Even in the relatively large value of the adhesion force of the sandwich ([great than]50 g/[cm. sup. 2])
As the number of interfaces in the sample increases, this is an increasingly common problem.
Because of this problem, our microscopic examination is limited to only 1-
3 layers of composition.
Another feature of these preparatory work is the presence of a regular pattern of fractional markers in the cross-sectional area and sample matrix images.
These human factors are caused by the process of image processing, which may make image interpretation more complicated.
Nevertheless, for the microscope drawing obtained on the complete sheet of these multi-layer samples, it can be clearly pointed out that
A typical example is shown in 2a.
This method cannot observe any interface that can be detected.
The sandwich interface is only seen on damaged flakes where the material is either clearly separated or on the verge of breaking (Fig. 2b).
Based on these images, there is therefore no evidence of a significant deviation from the properties of the multi-layer components with optical and structural continuum.
Recent research on these components using the newly developed light profile microscope technology [24].
This is a cross-beam microscope method based on elastic scattering (
Other mechanisms).
The light profile microscope is able to detect the interface in complete samples of these materials with very high sensitivity.
However, since the unusual contrast of this new method is still under study, the significance of this observation is still unclear from the transport continuity model of multi-layer materials.
Further investigations are under way and will be reported in future work. III.
Continuity of thermal physical properties of the interface the heat interface that is not detectable in the multi-layer components prepared by our experimental method is confirmed using the recently developed laser mirage effect spectrum technology [1]18, 19].
Double-layer components prepared at a temperature of 110 [degrees]
C. As a material for testing adhesion between interfaces, bear mechanical pressure within 20 minutes.
The schematic diagram of the test sample is shown in the figure. 3.
The surface of the film assembly is deposited on the front (F)and rear (R)
A surface with a thin black body index mark for absorbing excitation light from a modulated beam.
The sample is glued to the Flat Poly (
Mma)(PMMA)
Backing blocks are then sealed into an optical cell containing a water medium for thermal beam deflection analysis.
In this measurement, the sample is heated by the optical adsorption of the broadband modulated beam, in this way, athermo-
Extraction of light pulse response from measurement [15].
The measured pulse response is used to reconstruct the depth profile of the heat flow induced by light absorption at t = 0 in the material, by (
Math though)impulse.
When a hot continuous sample is excited by a pulse on the front surface, all light absorption (
And generate heat source density)
Is limited to the front surface of the sample.
The depth distribution of the heat source density generated by pulses reconstructed in this method in the sample should be approximate to the spatial Dirac deltafunction function corresponding to the heat source density confined to the front surface.
In the practical application, even for the theoretical continuous material, the reconstruction algorithm can be very good.
Features of expanding [12, 13, 16, 17]
, This is the typical case seen in the observed profile.
Similarly, when the back of the sample is irradiated by a thelaser pulse, in a hot continuous material, the heat source structure should accurately contain the peak at the depth of the back (
Measured from the front surface position of the sample).
Irradiation of the rear interface (R)
Reconstruction of wide peak results located at depth 140 [micro]
M from the front.
Similarly, in the presence of hot continuous materials, it is found as the depth expands to be a feature of the reconstruction algorithm.
In materials with detectable thermal non-continuity at the internal interface, reconstruction of heat source density in the case of positive absorption would obviously contain a large surface thermal source peak, significant satellite peaks at Numerical [depth position]2n1. sub. 1](n = 1, 2,. . . )(where[l. sub. 1]= 70 [micro]m).
These contributions come from the reflection of thermal energy at the interface where the interface adhesion is poor [13].
In the case of optical excitation of the rear interface, the effect of poor interface adhesion will delay the arrival of thermal energy on the front surface.
The reconstruction depth of the rear surface absorber will then be greater than the physical distance between the rear surface and the front of the sample.
Since both effects are clearly absent, the test confirms a good first-order approximation of the thermal uniformity of the two materials. IV.
Continuity of Pphotoproduct distribution in photo-degradation films from the study process of dehydrochloride [the polyene sequence formed in PVC]2, 9, 10].
Due to the multiple Coole olefin structures formed on many repeated steps of the dehydrochloride reaction, polyene photoproducts have significant visible wavelength absorption [2, 5, 9, 10].
This process is effective and only in the absence of oxygen will there be competition for photooxidation.
When oxygen is present, the well-known bleachingeffect occurs due to the oxidation of the olefinic boundary, which interferes with the binding of polyene and forms transparent over the visible wavelength range2)
And use the infrared effect spectrum to exclude from the analysis.
Results shown in Figure 1
4 demonstrate the level of accuracy of the absorption coefficient depth profile using our mirageeffect method.
In this case, the sample is made up of multi-layer components that are degraded in an oxygen atmosphere.
After the central area of multi-layer assembly is decomposed (see Fig. 1)
Divided into two halves: half was analyzed by mirage effect, the other half was mechanically separated, and Peel force test and absorption spectrum test were performed on the separated layer.
Depth Distribution of absorption coefficient ,[beta](x)
At 476 nm, recovered by microwave effect spectrum as described by reference [18, 19]
, Is integrated into the average thickness of the layers used in multi-layer components.
This block integrated profile is superimposed with the profile recovered by the absorption luminosity method and measured directly on a single layer.
The consistency between the depth profiles is measured as root mean square (rms)
The difference between P. rofiles and the peak absorption coefficient value of the contour (s).
This protocol is always better than 12% rms for both technologies.
Inherent uncertainty (random error)
At present, the luminosity error is limited in the depth profile of destrucemultimilayer.
These profiles follow the well
It is known that the optical absorption depth mode of the degradation PVC film in the presence of oxygen.
In the photodegraded film, photooxidation occurs effectively within an oxygen diffusion depth from the surface (10-40 [micro]m)
, Gives a product distribution that is almost transparent in the visible wavelength range.
Deep film ([great than]30-40 [micro]m)
The oxygen concentration is effective at zero, dehydrogen-based is effective, and the long chain long polyene sequence accumulates rapidly during the photodecomposition process.
However, as the sequence length increases, the UV absorption of the light product also increases dramatically, by absorbing the attenuation light before reaching a greater depth.
Far greater than the depth [sim]100 [micro]
M, the film becomes transparent again.
A test was designed to evaluate the continuity of the transmission properties of these multi-layer components, including comparing the depth distribution of absorption coefficients ,[beta](x)
, Obtained in a separated multi-layer component, obtained in Fusion (non-separable)assembly.
Two identical material components were prepared for this test, but the heat treatment was different, as shown in Table 1.
The detachable assembly has adhesion in the range of 100 [+ or-]20 gm/[cm. sup. 2]
When the molten material is heat treated at [50 ℃]degrees]
C 15 minutes, give non
The adhesion force is larger than the detachable layer of 600 gm/[cm. sup. 2].
Depth Analysis of laser Phantom effect for recovery [beta](x)
For these components, due to their special sensitivity to interface non-continuity in heat flow. Theprofiles, [beta](x)
In the figure, we compare the results obtained for two components.
5, and there is no significant difference in the depth profile feature, which is better than 10% rms with full scale.
This finding is consistent with the fact that there is no significant degradation product transport barrier in the detachable assembly.
Absorption depth profile and single layer based on mirage effect obtained in separated multi-layer components (200 [micro]m)
PVC spray plastic film, exposed under parallel conditions.
This is more difficult here because single-layer casting contains different solvent loads (THF)
From multi-layer components.
This solvent has several effects on photodynamics, so the depth distribution of the photo
Products in PVC have been identified in past work.
Stabilizer and peroxide are common impurities in reagent level THF.
A large concentration of peroxide, especially [alpha]-
The peroxide of THF has a direct effect on the rate of photooxidation by its tendency to form free radicals.
Through light shielding or other mechanisms, there is also a problem with the effect of the stabilizer.
In the absence of these impurities, the THF itself has been shown to have a slight inhibitory effect on the extent of the photo
Dechlorine in PVC [25].
In the current work, all film preparation is carried out using a plc-grade solvent in which this impurity does not exist in trace amounts or more.
We have experimentally determined that the presence of the THFin PVC film reduces the polyene formation rate during the photo-degradation of PVC [presence]O. sub. 2]or [N. sub. 2]
Consistent with past work25].
This is consistent with the very good repeatability of the depth distribution determined in photodynamics of our multi-layer components.
In the case of multi-layer components, a single layer ([less than]15 [micro]m thickness)
Thoroughly dry in a vacuum oven before assembly, and thick (200 [micro]m)
It takes a long time for a single casting to dry under vacuum to remove the casting.
In addition, we found evidence of differences in particle morphology based on differences in spray casting procedures [24]
Therefore, when comparing the light degradation in a very thin assembly layer, an additional variable is generated ([less than]15 [micro]m)and thick ([greaterthan]200 [micro]m)layers.
Still, when [Lieutenant Colonel] is peakabsorptionbeta](x)
Through the depth distribution recovered by mirageeffect, a close agreement was found between the polyene absorbance distribution found in the separated multi-layer assembly and the single-layer cast layer.
Another test on the photo-degradation samples of this material is to measure the adhesion between layers as a depth function.
The interlayer adhesion observed in the material sample was not deeply dependent prior to the decomposition.
After light decomposition, the sample shows the depth mode of the adhesive, which usually changes according to the profile shown in Figure 16.
In this case, the samples examined had adhesion prior to the degradation of 30 gm/[cm. sup. 2]
, But in the most extensive areas of light degradation, [an adhesive has been added]sim]100 g/[cm. sup. 2].
For samples exposed under nitrogen, similar adhesion enhancement was also observed, with peak non-adhesion force near the surface of the sample, where the photoelectric concentration was the largest.
The most direct explanation of this effect is the increase in the internal temperature of the sample, which may be produced by the combination of high-gloss source radiation with the strong enhanced UV and visible absorption of the product, relative to the starting material.
In order to produce a very large absorption change, a relatively small total degree of chemical transformation of the starting material is required.
However, processes initiated by other light, such as polyene cross-linking [can also enhance adhesion2](
This will be most effective without oxygen)
, Or the interaction of polarized structures caused by photographsoxidation (
In the near-surface area of the oxygen light material).
However, further research is needed to distinguish the relative contribution of these processes.
This enhanced adhesion seems to promote the continuity of the mezzanine, and in fact, from the polyene absorption curve, there is no evidence that the increased adhesion forces can undermine the continuity of transport performance.
As a further note, we can also extend the results of the recovery of multi-layer and non-destructive depth profile methods to the comparison of light degradation of PVC Films in nitrogen atmosphere (Fig. 7).
Based on these results, we observed another typical pattern of the depth dependence of the absorption coefficient of PVC at visible wavelengths.
After degradation in an oxygen atmosphere, the maximum concentration of the polymer occurs at 30-60[micro]
M, decreases with monotony of polymer depth.
In an inert atmosphere such as nitrogen, we observed 5-10 [micro]
The m surface layer of the sample, the peak light absorption degree is enhanced.
This model is known in the literature. 26, 27].
It should be noted that an important advantage of the multi-layer method is that it is not limited by the spectral range or even by the optical analysis of the separation layer.
The depth profile method has many attractive features, especially its non-
It is destructive and can only work at the available laser wavelength.
In principle, multi-layer methods can be extended to the analysis of more chemical species than optical methods.
Finally, while the results of these studies show a huge application prospect for multi-layer membrane testing methods, we must also keep in mind the limitations it brings.
In extreme conditions, such as at the extreme of high temperature, presence of solvents, or degradation, the layered model may fail in several directions.
For example, the component can be pre-configured to be layered, in which case the boundary effect is enhanced.
Alternatively, a single layer may fuse together at high temperatures, so it is inseparable after the light breaks down.
Nevertheless, under controlled experimental conditions, and under conditions of weak to moderate light degradation, we have established that this method has many in advanced technologies for obtaining depth-related information in film PVC
Extending these results to other polymer materials requires a clear adjustment of our experimental procedures.
However, the current work laid the foundation of the methodological principles and procedures for the completion of this extension.
Conclusion under specific conditions, mechanical separated PVC film components with high optical quality and predictable adhesive properties can be prepared.
Our preparation method is reliable and unambiguous. Labor intensive.
The results of thermal and conventional optical microscopy tests failed to detect any evidence of significant interface inconsistency between assembly layers.
Consistency between multi-layer destructive analysis and deep distribution of dehydrogen chloride in non-degraded filmsdestructive(mirage effect)
Absorption depth distribution was observed in the early quantitative range.
The results of the optical absorption depth distribution test give a picture consistent with the continuity of the mass transmission properties of oxygen and hydrogen chloride.
This shows that multi-layer components give a good approximation of continuous single layers under light decomposition, but can still be analyzed separately after that.
The author wants to thank the doctor. S. W.
Fu contributed the mirage effect depth profile data to support this approach.
The author would also like to thank the Canadian commission for Natural Science and Engineering Research (NSERC)
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