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double bubble tubular film extrusion of polybutylene terephthalate--polyethylene terephthalate blends.

by:Top-In     2020-07-31
A technique has been developed for the production of a two-way oriented mixture of polybenzene-diester (PBT)
And Polyethylene (PET)
Extruded with double-bubble tubular film.
The mechanism of mechanical instability and its origin is described.
The stability of bubbles varies with deformation and composition.
The structural features of these films are the wide angle X-
X-ray diffraction and optical technology.
The directions of each stage in the mixture are different.
We present a model of the crystal morphology of a two-way orientation tb/PET hybrid film.
The structure of the film is related to the processing conditions.
Introduction The Double bubble tubular film process for the production of two-way oriented films has been used commercially for half a century, and its first application was made by Stephenson and other Dow Chemical companies [1, 2].
The patent literature of the following years describes its application in many polymers [3-13]
Including polyethylene ester3, 4, 8, 11, 12]
, Polypropylene [3-7, 9, 10]andpolyamide-6 [3, 13].
Few studies or discussions published in scientific literature14-19].
In the process of double bubble tube film, the coaxial orientation is usually produced by two-stage process.
In the first phase, a screw extruder with a ring mold is used to produce a film that is basically non-oriented.
In the second stage, the film collapses and reexpands in a circular high greenhouse located above the first bubble stage.
The second phase of the film is under two-way stretching, in which the state of two-way orientation is fixed.
It is impossible to apply the double bubble process to all thermoplastic plastics equally easily.
The first phase is usually possible, but the second phase requires the film to have strain hardening properties.
Otherwise, the second bubble is often unstable.
In fact, this means that the film produced in the first phase should be deformed and glass-like, and this strain
Induced crystals should occur in the second stage.
Stephenson [knows the slow crystalline properties of polyethylene zinc chloride]1]
It was the foundation of his invention.
This also explains why it can be easily applied to [polyethylene ester]
3, 4, 8, 11, 12, 14, 16]
Poly-benzene support [15],polyantlde-6 [13, 17, 18]
And polypropylene [3-7, 9, 10]
It can form glass, slowly crystallize, and can also be quenched into a more stable state.
It is often difficult to apply a double-bubble tubular film extrusion to a glass transition polymer or a fast-crystalline polymer because there is no natural \"strain hardening\" property of the material in the second bubble.
People have been trying to introduce strain hardening into this material so that they can demonstrate this property.
Patent byBaird, etc. [20]
A radiation continuous cross-linked polyethylene film is described between the first and second steps of the double-bubble tubular membrane process.
This allows the second stable bubble to produce a two-way orientation.
Subsequent patent applications by Benning and others. [21]
Introduction of peroxide in polyethylene.
After the first bubble, the bubbles degrade in the hot water bath and free radioactivity results in cross-linked polyethylene.
In our lab, we have developed another method to introduce the second bubble strain hardening into a thermoplastic plastic with natural rapid crystals.
This includes the production of two-way directional tubular films with multi-vinyl-based fluorine dene (PVF2)
By adding different amounts of polypropylene (PMMA)
Can be mixed in poly vinyl fluoride [22].
The existence of organic glass slows down the crystal [PVF. sub. 2]
Turn the first bubble into a glass-like natural crystal.
The purpose of this paper is to describe the process of the double bubble tube membrane of Poly diester (PBT).
This polymer quickly crystallizes in the process of double bubbles, and the second bubble is unstable [23].
We are trying to overcome this problem by mixing polyethylene ester (PET)into the PBT.
PET has a slow crystal and has been successfully made into a film by double bubble method [
3, 4, 8, 11, 12, 14, 15].
The polymer used in this study is polydinyl (PBT)
Ultradur KR4036-
Q692 and polyethylene ketone ester of BASF Company (PET)
Tenite, Eastman Chemical 7352
Among them, in the viscosity range of 1,24 and 0. 8 d[ell]
/G, respectively.
A series of pbx/PET blends were prepared using 30 mmWerner & Pfleiderer co-by melting mixing
Rotary screw extruder (ZSK-30).
By weight, the mixing ratio of PET/PET was 95/5, 90/10, 80/20, 70/30 and 50/50, respectively.
These particles are mechanically mixed and dry on the evening [10]degrees]
In the vacuum furnace of the laboratory, it is then fed into the extruder.
The screw speed is set to 100 rpm and the barrel temperature is 285 [degrees]C.
The mixed particles are also 100 [dry]degrees]
C at least 24 hours before processing in the extruder.
The film forming tubular film is prepared with a Killion tubular film extrusion device with a size ring mold;
Inside diameter of 30.
4mm, outer diameter 33. 4 mm.
A pure pbx was squeezed out at a temperature of [260]degrees]
280 C and tb/PET mixing and pure PET under [degrees]C.
The extrusion speed is fixed at 1500 [cm. sup. 3]/hr.
In the first phase, the froman ring mold appears a thin specification extrusion that expands into a film.
The movies are vertical and rolled out.
The cooling air volume and temperature are 680 respectively [m. sup. 3]/m and 22[degrees]
C, carefully controlled through experiments to observe the processing performance of the polymer.
In the second stage, the first bubble burstup ratio (FBR)x draw-down ratio (FDR)= 1.
25x25 is inflated again by air.
At the deformation temperature of [90], the film passes vertically through a hot air ringdegrees]C.
Then, a double-bubble tubular membrane was produced under different plane strain. e . , second draw-down ratio (SDR)X second blow-up ratio (SBR).
Fixed annealing of selected films in [at200]degrees]
C use a square frame for 10 minutes in a forced convection oven.
Figure 1 shows the double-bubble tubular film process. Wide Angle X-
X-ray diffraction WAXS diffraction measurements were performed using ge x-raygenerator.
The instrument operates at 30kv and 30 mA. The X-
Monochrome the light with a nickel foil filter to obtain CuK [alpha]radiation.
The film is stacked with epoxy resin and cut into a size of 1. 2 x 15 x 1. 2 mm.
Take tablet photos in three orthogonal directions of the sample :(i)through view; theX-
The beam is parallel to the normal direction (ND), (ii)edge view; theX-
Parallel to the horizontal beam (TD), (iii)end view; the X-
The beam is parallel to the direction of the machine (MD).
The exposure time of each sample varies depending on the degree of crystal. The sample-to-
The film distance is kept at 5. 4 cm.
The pole number (100)and (010)
The plane is constructed to quantify the crystal orientation. Several off-
The noon reflection is also a polar map to characterize c-axis.
PBTtriclinic cells in Hall and Pass [24]
Close to aspseudo-orthorhombic [25, 26].
In this unit, c-
Axis along the axis,-
Axis parallel to benzene normal, B-
The axis is orthogonal to the \"ac\" plane.
Secondary moments of chain axis orientation distribution (c)
Normal to benzene ring (a)
Determined by applying wilchinsky\'s streatment [27]to the pseudo-
Oblique Square unit. [overline{[cos. sup. 2][[phi]. sub. j]}]= [frac{[[[integralof]. sup. 2[pi]]. sub. 0][[[integral of]. sup. 2[pi]]. sub. 0][I. sub. hkl]([[phi]. sub. 1], [[chi]. sub. 1])[cos. sup. 2][[phi]. sub. 1]sin[[phi]. sub. 1]d[[phi]. sub. 1]d[[chi]. sub. 1]}{[[[integralof]. sup. 2[pi]]. sub. 0][[[integral of]. sup. 2[pi]]. sub. 0][I. sub. hkl]([[phi]. sub. 1], [[chi]. sub. 1])sin[[phi]. sub. 1]d[[phi]. sub. 1]d[[chi]. sub. 1]}](1)[overline{[cos. sup. 2][[phi]. sub. i,c]}]= [frac{([[f. sup. 2]. sub. 1]-[[e. sup. 2]. sub. 1])[overline{[cos. sup. 2][[phi]. sub. i,010]}]-([[f. sup. 2]. sub. 2]-[[e. sup. 2]. sub. 2])[overline{[cos. sup. 2][[phi]. sub. i,100]}]+ [[e. sup. 2]. sub. 1][[f. sup. 2]. sub. 2]-[[e. sup. 2]. sub. 2][[f. sup. 2]. sub. 1]}{[[e. sup. 2]. sub. 1]([[f. sup. 2]. sub. 2]-[[e. sup. 2]. sub. 2])-[[e. sup. 2]. sub. 2]([[f. sup. 2]. sub. 1]-[[e. sup. 2]. sub. 1])}](2)[overline{[cos. sup. 2][[phi]. sub. i,a]}]= [frac{[[f. sup. 2]. sub. 2][overline{[cos. sup. 2][[phi]. sub. i,100]}]-[[f. sup. 2]. sub. 1][overline{[cos. sup. 2][[phi]. sub. i,010]}]}{[[f. sup. 2]. sub. 2]([[e. sup. 2]. sub. 1]-[[f. sup. 2]. sub. 1])-[[f. sup. 2]. sub. 1]([[e. sup. 2]. sub. 2]-[[f. sup. 2]. sub. 2])}](3)where [I. sub. hkl]([[phi]. sub. 1], [[chi]. sub. 1])
The distribution of diffraction intensity in the pole graph, I is the direction of the film (1: MD, 2:TD).
E and f are (100)and (010)planes.
Reflection overlap is a major difficulty in calculating two-way orientation factors in mixed films.
For each sample of the polar graph, the orientation pattern with interval [chi]of 5[degrees]
It was taken from the Prague angle of the aircraft, and then
Solving the real strength of a single peak using linear curve fitting [28, 29].
The two-way crystal orientation factor is then calculated using the redistributed strength.
To confirm this, the orientation factor of thec
The axis is also calculated from the pole distribution of tb ([bar{1}]04)[alpha]and PET ([bar{1}]05)planes.
The two measurements are usually consistent. White-
Two-way crystal orientation factor [30]are: [[f. sup. B]. sub. 1,j]= 2[overline{[cos. sup. 2][[phi]. sub. 1,j]}]+[overline{[cos. sup. 2][[phi]. sub. 2,j]}]-1 (4a)[[f. sup. B]. sub. 2,j]= 2[overline{[cos. sup. 2][[phi]. sub. 2,j]}]+[overline{[cos. sup. 2][[phi]. sub. 1,j]}]-1 (4b)where [[phi]. sub. i,j]
Is the angle between the film direction I and the crystal axis j. Small Angle X-
X-ray scattering angle XRay scattering (SAXS)
The pattern is made by a GEX
X-ray diffraction with furnace Xray camera.
The instrument operates at 30 kV and 30 mA.
Nickel foil filter for obtaining [alpha]
Radiation and vacuum are applied on the camera.
The size of the sample is 1.
2mm X 15mm X 1. 2 mm.
The exposure time for each sample is usually maintained at 24 hours. The sample-to-
Movie distance 50. 25 cm.
The optical properties, refraction index and refractive index of the film were obtained using the Bellingham Stanley Abbe 60/HR refraction instrument with a bias lens.
Single color sodium lamp with wavelength of 589.
Sulfur with asa light source and diiodine ([n. sub. D]= 1. 75)
Like liquid.
Samples of a size of 40mm X 40mm are placed on a prism whose MD is parallel or perpendicular to the long axis of the measuring prism.
Two refractive indices were then read separately.
From the refractive index, the refractive index ([Delta][n. sub. 13], [Delta][n. sub. 23])
Determined: [Delta][n. sub. 13]= [n. sub. 1]-[n. sub. 3](5a)[Delta][n. sub. 23]= [n. sub. 2]-[n. sub. 3](5b)
Results the instability of the tube membrane extrusion process the stability of the tube membrane extrusion process is manifested under a wide range of operating conditions, following the procedures of kanai and White [1]31].
Two kinds of instability were observed (Figure2); (a)
The bubble is unstable, the symmetric periodic fluctuation of the bubble diameter, and (b)
The second is that the spiral is unstable, as described by Mingdao and Bai [32].
The region of the first bubble\'s stable and unstable behavior is shown in figure 2. down ratio, [V. sub. L]/[V. sub. O](FDR)and first blow-up ratio, [D. sub. L]/[D. sub. O](FBR).
Here V is the speed of the film, D is the diameter of the bubble.
Subscript L refers-
That\'s how it died.
Under all processing conditions below [1], instability occurs in the first bubbleV. sub. L]/[V. sub. O]= 20.
Symmetric bubble instability occurred at low [D. sub. L]/[D. sub. O]
When the spiral is unstable [D. sub. L]/[D. sub. O].
Bubble instability occurring at a low FDR of FER = 1.
0, with the increase of FBR, it becomes spiral instability.
In all processing conditions, an increase in the FDR causes the first bubble to stabilize while increasing the FBR unstable bubble.
Pet supplies]leq]
10wt %, there is a serious instability.
The bubble stability increases with the increase of PET content.
Mix with pet classgeq]
30wt % reveals a wide stable region similar to that of pure PET polymers.
The PET/PET tube membrane with double bubbles only exhibits unrotational instability (Figure 3).
However, the stable operation of the simple pbx second bubble method is very limited.
Only under single axis can the double bubble film of pure pbx be produced (SBR = 1. 0)
Stretching conditions.
It is striking to mix the pet with the pet, greatly improving the stability of the second bubble.
The bubble stability increases with the addition of PETcontent in the mixture.
Under the condition that the PET content is 20% or higher, the second bubble of the two kinds of PET has a stable working window.
These mixed polymers are processed into double bubbles in a very stable way.
WAXS diffraction photos of the first bubble.
Figure 4 shows the reflection of tb and PETcrystals in the mixed film. At low draw-down ratios (FDR)[leq]
40, the first bubble with a PET content lower than 10wt % usually exhibits a concentrated Debye ring reflected by the crystal.
With the improvement of PET level, reflection becomes diffuse amorphous halo.
With the further increase of the FDR, the diffraction ring evolves into a fairly wide arc around the equator (Figure 5).
The first bubble generated in FDR [geq]
60 revealeddiffuse (010)
Debye arc on the equatorDouble Bubble.
A double-bubble film produced at SDR = 4 usually exhibits a diffusion Debye arc (Figure 5).
Individual phases cannot be distinguished due to crystal defects.
In a single-axis double bubble ,(010)
Arc through the thin film and edge direction of tb and PET phase (100)
There are arcs on the equator.
The end mode reveals (010)
The arc on the meridian and (100)
Reflection on the equator
With the addition of PET, the Crystal arc weakened.
With biaxialblow-up, the (010)
When the arc of the two stages turns into a circle (100)
There is almost no change in reflection outside the plane.
Double-bubble annealing
Double bubble film of At200 [annealingdegrees]
C exhibits Crystal features of different phases in 10 minutes (Figure 6). The PBT [alpha]-
Stage dominance of PETcontents [leq]30 wt%.
When sdr x br = 4x1 ,(010)
The movie arc through the PET and PET stages completely overlap. However, the(100)
An arc perpendicular to the \"13\" plane shows a discrete Braggmaxima for a single phase.
The crystal reflection of a component continues to enhance as its content in the mixture increases.
50/50 of the double bubbles show the mixing properties of the two crystals, but still have different PET (001)[alpha]
Debye passes through the plane of \"13.
The diffraction pattern perpendicular to the \"23\" plane shows reflection overlap and does not change much with the composition. Biaxial blow-
Up causes the dabyne arc to become blurred and overlapping.
For example, in an unannealing pioneer ,(010)
The arc of the film through citrix and PET phases becomes a circular, Edge View (100)
The rising Ding benzene softens the pattern.
PET in The Edge direction of 50/50 double bubble diffusion (001)[alpha]reflections.
The two-bubble hybrid film of SAXS scattering mode annealing is usually similar to the pupet film with two stripes on the meridian (Figure 7).
In the uniaxialdouble bubble, with the addition of the PET, the stripe through the direction becomes wide, while the Edge pattern changes very little.
The end view mode contains a diffuse aura.
The pure pet double bubble shows four-
The maximum stripe value in the edge pattern.
With the increase of coaxiality, it becomes circular and double angles by directional scattering-
The normal stripes of the \"23\" aircraft appear in PETlevels [geq]30 wt%.
Pure pet double foam also contains 4-
The maximum value of the stripes in the edge pattern is quite scattered and round.
The WAXS pole diagram of the unannealing film.
PET/PET mixed film usually has similar properties to pure PET film.
The first bubble film shows an isopolar graph consisting of a randomly distributed plane normal.
The pole diagram of SDR = 4 double-bubble films with different SER is shown in figure 8. The (010)
The polar map contains reflection overlap;
PET and PET (010)
The plane happened at 20 [approx]17[degrees].
The increase in PET content and br tends to be distributed (010)Electrical pole of NDTD plane. The (010)
The pole diagram of the 50/50 hybrid film contains a rather weak Prague maximum. The PBT (100)[alpha]
Usually concentrated at the poles of ND and off-
Noon reflection, concentrated in MD, spreads on the plane of the membrane as time increases.
The increase in pet content often increases pets ([bar{1}]05)poles.
Figure 9 shows a polar diagram of a double-bubble hybrid film with various SDR at br = 2.
A single mixed film with different components is similar to SDR deformation.
When sdr x ser = 2x2, the polar graph shows the random distribution of tb/PET (010)and PET ([bar{1}]05)poles. The PBT (100)[alpha]
However, the Poles are concentrated in ND and spread to MD and TD.
The increased SDRintroduced introduced a concentration (010)and PET ([bar{1}]05)
When it spreads pets, the pole (100)[alpha]
Electrical pole of NDTD plane.
It was also observed that the double bubbles showed a strong td orientation at br = 3. At SDR [leq]
2 and br = 3 ,(010)and PET ([bar{1}]05)
The two poles are concentrated in MD and TD, PET (l00)[alpha]
Two poles in ND-MD plane.
However, the increased SDR atSER = 3 tends to be allocated at the same time (010)and PET ([bar{1}]05)
Pauline on the film plane. The PET (100)[alpha]
With the increase of SDR, the two poles spread to td.
Double-bubble film of annealing.
Two-bubble mixed film with annealing has good performance
A polar graph defined and highly symmetrical (Figure 10).
Pole position number ()100)
The plane of each component is from (100)
Reflection shows the Prague maximum for two different crystals.
In a single-axis double bubble (Figure 10a)
With the addition of PET, the poles of PET components weaken and distribute, while the Poles of PET components enhance. The PBT([bar{1}]04)[alpha]
The pole diagram includes a strong double peak maximum that is tilted towards ND.
The two-way double bubbles of sdr x br = 4x3 show the same trend as the decrease in extreme strength (Figure10b).
Annealing greatly reduces the distribution of polarization.
The Poles (010)and PET ([bar{1}]05)
Planes tend to be in MD-
TD landline with (100)
Polesnarrowly focuses on ND.
The refractive index of the first bubble film.
When drawn according to PET content, the primary refractive index of the first bubble mixed film is the lowest (Figure 11).
Increase attraction at higher pet levelsdown ratio (FDR)increased [n. sub. MD]
And reduced [n. sub. TD]and [n. sub. ND]. The[n. sub. TD]
Appears with the increase of FBR, [n. sub. MD]and [n. sub. ND]decreased.
The dielectric constant of the mixed film with a PET content of 30wt % is low.
At lower PET levels, the development of polarization states is different.
They tend to decrease as pet content increases.
The increase in FDR and FBR has a similar effect on birefringence. The[Delta][n. sub. 13]
Increased with the increase of FDR and [Delta][n. sub. 23]
With the increase of FBR.
The 70/30 hybrid film of fbrx fdr = 2x60 shows [Delta][n. sub. 13]of 0. 0128 and a[Delta][n. sub. 23]of 0. 0101.
Double bubble movie
Figure 12 summarizes the results of the two-bubble hybrid film.
The second deformation has greatly increased [n. sub. MD]and [n. sub. TD]
And reduce [n. sub. ND]. The [n. sub. MD]and[n. sub. TD]
Down, and [n. sub. ND]
Increased with the addition of PETcontent.
A mixed film with a PET content of less than 10wt % is a similar topure PET film.
70/30 double bubbles with sdr x br = 2x2 have [n. sub. MD][approx][n. sub. TD]= 1. 6071 and [n. sub. ND]= 1. 5249.
Separate mixtures of different components have similar reactions to SDRand br.
Rapid increase in SDR at br = 1 [n. sub. MD]And reduced [n. sub. TD]and [n. sub. ND].
[Increase]n. sub. MD]
More profound. Biaxial blow-up decreased [n. sub. MD]and [n. sub. ND]
Although it has increased [n. sub. TD].
The double bubble film of SDR = 2 is-
The plane of Ding benzene and [is] homophobicn. sub. TD]
Continued to increase with further strikesup.
70/30 double bubbles appear when sdr x br = 2x3n. sub. TD]= 1. 6398 and [n. sub. ND]= 1. 5020.
Show double bubbles with pets 【leq]
30wt % has a similar level of refraction.
However, with the further increase of PET content over 30wt %, the value of birefringence decreased.
Double foam with equal axis [Delta][n. sub. 13][approx][Delta][n. sub. 23]. A maximum[Delta][n. sub. 13]= 0.
138 occurs in 80/20 double bubbles of SDR xbr = 2x3.
Double-bubble film of annealing.
Further increase in annealing [n. sub. MD]and [n. sub. TD]
And reduce [n. sub. ND](Figure 13).
Blendfilms with pet rating [leq]
10wt % is similar to the pure pet film with a high content [n. sub. ND]at SDR [leq]3.
70/30 double bubbles annealing with sdr x br = 4x2 have [n. sub. MD]= 1. 6720 and a [n. sub. ND]=1. 4851.
The polarization behavior is similar to that of the unannealing precursor.
Annealing double bubbles with pet grade [leq]10 wt% had[Delta][n. sub. 13][approx]0.
Sdr x br = 152 at 4x1, below [Delta][n. sub. 13]= 0.
1829 of the corresponding 70/30 annealing double bubbles. A maximum [Delta][n. sub. 23]= 0.
Under sdr x br = 2x3, 1792 was obtained in 70/30 double bubbles of annealing.
The two-axis double bubbles after annealing also appeared [Delta][n. sub. 13][approx][Delta][n. sub. 23].
Discussion on the stability of single bubble extrusion in tube membrane extrusion.
It was found that the stable operating area in the first bubble extrusion varies depending on the stretch level of the film represented by FDR and FBR and blendcomposition.
It is stable to increase the FDR while increasing the unstable foam.
Bubble instability occurs at a low FDR of FBR = 1.
With the increase of FBR, 0 becomes spiral instability.
These generally agree with observations by Kang et al. [14-17]
For pet, PPS and PC.
They pointed out that stability can only be achieved through FDR.
With the increase of PETcontent in the mixture, the stability of the first bubble increases.
The bubble instability that occurs at low FBR = 1 may have a great relationship with the viscosity I. e. , a self-
Supporting properties of polymer melts.
At a higher FDR, the material develops hardening due to an increase in cooling rate or an increase in the film
Line stress, resulting in stable bubbles.
This stable behavior is certainly related to an increase in the viscosity of the extrusion. At PET content[geq]
20 wt %, the Crystal degree of the first bubble determined from the measurement of the mean refractive index changed from 3% to 10%, where the crystal degree increased with the increase of FDR.
However, these changes are insignificant, but may play a role in the stability of the bubble.
The instability of bubbles may also be related to process variables. g.
Temperature fluctuation 【14-17]
Throughput wave from die Region [33]
High inflation pressure for low FBR [34].
The spiral instability only occurs at the higher FBR [geq]1.
With the increase of PET content and the hardening of bubbles, itstendence decreased.
This suggests that the source of the spiral instability seems to involve factors such as the flow properties of the polymer, aerodynamics, temperature fluctuations, and heterosexual HD deformation during solidification.
Double bubble extrusion
In the second stage, bubble deformation occurs in a rubber-like solid
State, which results in a much higher axial and loop-to-loop stress ratio when melting
The extended state of the first bubble. This cold-
Compared to the first phase, the drawing process appears to have narrowed down the operation window for the second phase.
Antenna in rubber
The viscosity of the state is significantly higher than that of ina melting-state.
Therefore, compared to the first bubble, there is no bubble instability in the second bubble at br = 1.
With the increase of PET content, the processing window of stable operation has expanded dramatically.
The stability of the second bubble must be derived from strain
Hardening behavior of bubbles.
A tb/PET mixture with a PET content of 20wt % or larger produces transparent primary first bubbles that are mostly non-crystalline and glass-like.
The first bubble
The second stage induced crystals.
It is believed that the second bubble stability of the mixing system is related to the blending of the mixing system, which reduces the crystal rate of PET.
Deformation with PET content and crystalline features of the first bubble film [geq]
The 20 wt % produced at less than 50 of the FDR is mostly amorphous, probably because tb crystals are suppressed under mild processing conditions.
An increase in FDR over 60 results in an orderly structure in the bubbles.
Since the stress in the second phase is much higher, the two-bubble hybrid film develops an orderly texture, although it is still not perfect.
The deformation of a single film of different composition is basically the same as that of the homogeneous film.
Presumably, their similarity in chemical structure in these mixtures can provide a local deformation environment similar to that of pure polymers.
In a binary mixture that is not mixed, it is found that the deformation of a single phase depends largely on the phase morphology [35].
It was found that the crystal integrity of a single component decreased as the content of other components in the mixture increased.
This can be explained by dilution effect and mixing.
It may have a double effect on the crystal of PET components.
During the crystalline process of PET, there may be a central position, while a large part of PET non-crystals may be a highly viscous polymer dilution, resulting in a delay in the crystalline of PET.
Content of AtPET [leq]
30. the pet crystal cannot be identified;
Because of its rapid crystal properties, it has become the mainstream product in the market. Stein et al. [36]
WAXS measurements did not detect PET crystals in PET/PET mixtures at PET levels up to 20 wt %, reported.
A mixture with a high component content mainly exhibits the crystal of the component.
This is usually consistent with our results for unannealing films.
However, changes were introduced in annealing.
Annealing film of PET grade [geq]
10wt % presents different PET crystals, which indicates the presence of disordered PETtextures in unannealing pioneers.
The results showed that no co-crystal was found in PET/PET ble nd film regardless of the composition.
Due to the difference in its crystal parameters [it is considered not possible to crystal with this system]36].
Crystal form double bubble tubular film with PET content up to 50wt % showed long
The range is similar to the periodic superstructures of pure TE 2 films with alternating crystal and amorphous regions on MD.
This shows that the structural development of PETphase has been hindered.
The increase in PET content in the mixture increases the overall pressure generated during the extension process;
Therefore, it is easier to produce the superstructure.
In order to develop a basic ordered texture, a higher stress may be required for the PET assembly.
As suggested by the WAXS film photos, the main components are no longer included during the Crystal process, followed by the crystal at that location.
This exclusion process is clearly related to factors such as melting mixing, diffusion rate and crystal rate [1]36].
Based on observations, we present a schematic model of the crystal morphology in a two-way orientation tb/PET hybrid film in Figure 14, where the superstructure has a separation membrane of two species, without any co-occurrence
Crystal orientation of unannealing film.
The first bubble mixed film has a very low or very small crystal orientation. The values of [[f. sup. B]. sub. 1,c](
Direction factor of C-axes)and [[f. sup. B]. sub. 2,c](
Factors of TDorientation)
Was found close to zero.
Figure l5a figure White-
Spruiell two-way orientation factor Eqs 4a, B, in the double-bubble tubular film of pbx/PET mixture.
Interestingly, the orientation of PET phase usually decreases as the level of PET increases.
This behavior seems to be related to the crystal properties in the film.
It was found that with the addition of PET, the number and perfection of PET crystals decreased, which may reduce the crystal orientation of the BES phase.
SDR increase for a given benzene [[f. sup. B]. sub. 1,c]
Although it has decreased [[f. sup. B]. sub. 2,c]
, Representing the arrangement of crystals along the stretching direction. Both [[f. sup. B]. sub. 1,a]and[[f. sup. B]. sub. 2,a]
With the increase of SDR, the orientation factor of benzene on the molecular skeleton increases. Biaxial blow-up incr eased[[f. sup. B]. sub. 2,c]
At the expense [[f. sup. B]. sub. 1,c].
With the increase of br, the benzene ring is further oriented.
It seems that the individual benzene ring in the mixture is similar to the deformation behavior of the homogeneous film.
Due to its large volume and plane geometry, the benzene ring is aligned parallel to the surface of the film during deformation.
This parallelism can be accelerated by the strong tendency of molecular accumulation and the significant van der Waals interaction between the chemical parts [37]. Annealed Film.
Figure 15b describes the crystal orientation of each component in the annealing double-bubble hybrid film.
Surprisingly, the orientation of individual chains is different: the orientation of PET components decreases with the increase of PET content, while the orientation of PET components increases.
50/50 mixed film annealing with sdr x br = 4x1 has a lower [orientation][f. sup. B]. sub. 1,c]= 0.
64 is for pbx components and 【[f. sup. B]. sub. 1,c]= 0.
69 pet chains.
Annealing significantly increases the orientation of the PET phase.
80/20 double bubbles annealing with SDR xbr = 4x3 have [[f. sup. B]. sub. 2,c]= 0. 53 and [[f. sup. B]. sub. 2,a]=-0.
59 and the corresponding pure pet double bubble 【[f. sup. B]. sub. 2,c]=0. 49 and [[f. sup. B]. sub. 2,a]= -0. 60.
Studies have shown the orientation in each phase of the polymer mixture.
King and Potter [38]
Through the study of infrared spectrum, it is found that the orientation of polystyrene (PS)
Chain in mixed PS/poly (2,6-dimethyl-1,4-Benzene-supported oxide(PPO)
The mixture decreases with the increase of po concentration.
They believe that the interaction between PS and po chains leads to a delay in the orientation of PS chains. Min et. al. [39]
It was found that the addition of polystyrene topoly ethylene reduced the development of crystal orientation in polyethylene, while the rattan and so on. [40]
Found in the study of polyethylene tubular film (PE)/Polyester (PC)
Two-way directional factor [[f. sup. B]. sub. 1j]and[[f. sup. B]. sub. 2j]
By introducing PC, the number of PE is reduced.
They claim that the mechanism of this behavior is that when the melt is cooled on the fiber or film line, the stress is redistributed to focus on the glass transition stage where the viscosity increases more than PE. Next village, etc. [41]
According to the study of WAXS diffraction, it is shown that the Tube film of incompatible crystals
Crystalline PE/polypropylene (PP)
In the hybrid system, the molecular orientation in a single phase is lower than that in the homogeneous membrane.
This reduction in orientation is due to a reduction in tensile stress caused by a decrease in the melting viscosity of the mixture. Liang et al. [42]
Reported that in incompatible crystals
Crystalline PP/nylon 6 mixture, the presence of PP hinders the orientation development of nylon 6 in the melt spinning process, while the orientation in PP is determined by stress.
The authors explain that the delay in the orientation of nylon 6 is due to the stress concentration of the PP phase due to its higher crystalline temperature.
In this study, it was observed that the crystal is in a mixture-
Within the composite range studied, the orientation of one phase increases with the presence of the other phase in the crystalline tb/PET mixture, which is often consistent with the orientation of shimomura et. al. [41].
This seems to indicate that, to a large extent, the crystalline capacity of an alloy, whatever composition, changes.
The presence of PET inhibits the crystals of PET components, which may lead to stress reduction and redistribution in the tb phase during deformation.
The PET phase is usually slow due to its slow crystalline properties and dilution effects.
With the addition of other phase contents, the crystal structure of a single phase becomes less perfect.
Therefore, it is considered that the orientation delay in a single phase in a pbx/PET mixture can be attributed to the reduced crystalline capacity of the component polymer, which stems from the presence of another polymer.
The overall orientation of the molecular-oriented polymer chain, such as the refraction ([Delta][n. sub. 13], [Delta][n. sub. 23])
As the PET content increases, the content in the mixed film decreases.
This trend is more evident at a lower level of deformation.
As mentioned earlier, the mechanism of this behavior will involve a change in the crystalline capacity of a single polymer in the mixture.
The presence of PET inhibits the crystals of PET in the mixture, resulting in strain delays
Crystals are induced during deformation.
At a lower level of deformation, the pbx chain is more prone to directional crystals, and the orientation increases with the decrease of PETlevel.
It was found that the double-bubble tubular membrane of pure PETpolymer has a lower birefringence value than the corresponding blendfilms [23].
This may be due to the high tensile temperature ([T. sub. g]+ 60[degrees]C)
And non-uniformity in secondary foam.
Double foam for processing-
The pbx film has a considerable distribution in the specification.
Annealing leads to a significant increase in bire-fringences.
With the decrease of MD stretching and the increase of PET content, the degree of this increase will increase.
The mechanism of this behavior seems to involve non-oriented amorphous parts in the pre-annealing.
Fixed annealing results in a contraction force, which may result in further molecular build-up and stretching.
When annealing, due to the large internal rearrangement of the microstructure, the film with a higher amorphous content seems to be oriented.
The optical properties of the material can be associated with the overall benzene ring orientation distribution function.
Assuming orthogonal symmetry of PET unitcell, Ward [43]
Use Lorenzo-
The Lorenzo equation presents the relationship between the second moment of orientation distribution and the index of refraction. [frac{2[[phi]. sub. 3]-[[phi]. sub. 2]-[[phi]. sub. 1]}{[[phi]. sub. 1]+ [[phi]. sub. 2]+ [[phi]. sub. 3]}]=[frac{2[[alpha]. sub. ac]}{3[bar{[alpha]}]}][[f. sup. H]. sub. 3,a]+2[frac{[[alpha]. sub. cb]}{[bar{[alpha]}]}][[f. sup. H\']. sub. 3,a](6)where [[phi]. sub. i]= [frac{[[n. sup. 2]. sub. i]-1}{[[n. sup. 2]. sub. i]+2}](7)[[f. sup. H]. sub. a,3]= [frac{1}{2}](3[overline{[cos. sup. 2][[theta]. sub. 3,a]}]-1)(8)[[f. sup. H\']. sub. 3,a]= [frac{1}{6}](2[[f. sup. H]. sub. c,3]+[[f. sup. H]. sub. a,3](9)[bar{[alpha]}]= [frac{[[alpha]. sub. c]+ [[alpha]. sub. b]+[[alpha]. sub. a]}{3}], [[alpha]. sub. ac]= [[alpha]. sub. a]-[frac{[[alpha]. sub. b]+ [[alpha]. sub. c]}{2}], [[alpha]. sub. cb]=[[alpha]. sub. c]-[[alpha]. sub. b](10)
Here, the quantity 【[phi]. sub. i]
Related to the nature and direction of the susceptibility tensor [[alpha]. sub. i],[[f. sup. H]. sub. 3,a]
It is the orientation factor of the Hermann people; [[theta]. sub. 3,a]
Is the angle between normal ND and benzene ring;
Efficient [[f. sup. H]. sub. 3,a]
If the chain does not have a preference direction around its own axis, it is zero.
We have calculated the direction of the benzene normal relative to ND using Equation 8. The [[f. sup. H\']. sub. 3,a]
Terms in Eq 6 have been ignored since [[f. sup. H]. sub. 3,a][ll][[f. sup. H\']. sub. 3,a][44, 45].
The value of the three main deviations is [[alpha]. sub. c]=2. 49, [[alpha]. sub. b]= 2. 45, and [[alpha]. sub. a]= 1. 63 X [10. sup. -23][cm. sup. 3]for PBT [46]and [[alpha]. sub. c]= 2. 25, [[alpha]. sub. b]=2. 18, and [[alpha]. sub. a]= 1. 18 X [10. sup. -23][cm. sup. 3]for PET [45].
Based on the performance of the two components, the polarization capability of the mixture is estimated.
Figure 16 shows the calculated [[f. sup. H]. sub. 3,a]
As a function of the history of composition and deformation.
Unannealing film.
Mixed film manifested as [reduced][f. sup. H]. sub. 3,a]
With the increase in pet rating
This behavior is consistent with the orientation in the crystal phase.
[Reduction][f. sup. H]. sub. 3,a]
However, it is relatively sharp due to the increased contribution of the amorphous phase.
The orientation of the first bubble is very low. The a-
For the second bubble film, the axis is quickly aligned parallel to ND.
The mixed film of different composition is similar to SDR and br in the orientation of benzene ring.
Rapid increase of single axis deformation [[f. sup. H]. sub. 3,a]
But the two-way stretch is quite slow at br = 3. A maximum[[f. sup. H]. sub. 3,a]= 0.
43 was obtained in sdr x br = 4x3. Annealed Film.
Annealing caused a significant increase in [[f. sup. H]. sub. 3,a]. The levels of [[f. sup. H]. sub. 3,a]
The film for annealing is much higher than the unannealing pioneer.
Consistent with the refraction results, the incremental range [[f. sup. H]. sub. 3,a]
With the decrease of SDR and the increase of PETcontent, it becomes larger.
Again, this can be attributed to a large number of phase transitions during annealing.
This shows that the behavior of the benzene ring in the mixture is similar to that in the homophane.
The benzene ring on a single chain is stacked vertically with the deformation of the surface of the film.
The amount of this arrangement may depend on the crystalline capacity of a single component.
Fixed annealing enhances the fluidity of the chain, which enables the molecule to be packaged further.
Conclusion the double bubble tube membrane extrusion of PET/PET blends has been widely studied.
The first bubble shows a bubble and a swirling instability.
Bubbles that appear in low strikes are unstable
Upratios is primarily associated with role I. e.
, Melting rigidity of polymer, while spiral instability occurs during high blow
Upratios is mainly due to changes in processing.
With the increase of PET level, the stability of bubbles increases.
Double bubbles with Petlevel of 10wt % or lower are largely unstable.
With the further increase of PETcontent, the instability of the second bubble decreases sharply.
At a PET level of 20 weight % or higher, the second bubble shows operating stability similar to the pure PET double bubble.
The mechanism of this behavior is clearly related to the compatibility of the PET/PET mixture.
The first bubble generated when the FDR is less than 50 is mainly the amorphous atPET contents above 10wt %.
With the increase of FDR over 50, the disordered structure has developed.
The orientation of the first bubble is very low or small.
In the second stage, the crystal structure and orientation are constantly improved with deformation.
With the increase of PET content, the orientation of PET stage decreased, while the orientation of PET stage increased.
With the addition of PET, the overall orientation of the benzene ring of the two phases is reduced.
However, with the increase of SDR x br, the orientation of benzene ring continues to increase.
The upper structure of the film contains separate flakes of two species that tend to be arranged along the stretching direction.
The deformation mechanism of PET/PET mixture mainly includes components-
The crystalline capacity of a single polymer.
The author would like to thank BASF.
And Eastman Chemical
Used to provide the polymer resin studied.
They are particularly grateful to Mr. M. D. Crist, Dr. K. M[ddot{u}]hlbach, and Mr. J. J.
Ocampo BASFCo. , and Dr. M. Knight and Mr. J.
Shadden of Eastman Chemical
Useful discussion on polymer processing. (*. )
Current Address: Yale University, Department of Mechanical Engineering, 9 Hillhouse Avenue, New Haven, CT 06520. (+. )
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