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by：Top-In
2020-02-08

Introduced the gathering (

Pet)(PET)

Therefore, the film and its practical application are directly controlled by the molecular orientation and morphology generated during the film processing.

Although the performance can be adjusted by changing the process parameters, the selection of \"balance\" or \"reverse\" processes will produce balanced or preferred orientation film shaving on the film plane respectively.

Traditional-

The so-called \"balance\" process consists of three stages.

The first one is vertical (

Machine direction)

Draw with constant force and constant width.

In the second stage, the single stretch film is stretched horizontally at a constant speed, and the third stage is basically a high temperature hot solid treatment.

In the \"inverse\" sequence, the amorphous film is first stretched horizontally at a constant speed, and then vertically at a constant stress and a constant width.

The last step is the hot-solid of the two-way stretch film.

The movement of the stretch stage during these two processes is very different.

Since the phenomenon of crystal and chain relaxation occurs during stretching, the morphology and molecular orientation of the crystalline phase may vary greatly in each case.

Structure of amorphous PET film stretched under constant forceplanar (constant width)

Several groups studied the conditions (1-7).

These films are either made by industrial processes (1)

Or on a laboratory scale (2-7).

In terms of the effect of the process parameters, it has been shown that most of the properties of the film are determined by the tensile ratio, not by temperature or applied stress.

Detailed descriptions can be found elsewhere (3-6).

Although various studies have treated the representation of deformed PET one-way stretching at a constant strain rate (8, 9)

, Or at a constant speed of drawing (10-15)

Less work is done under the condition of single-axis plane symmetry (16-20).

The purpose of this work is to accurately describe the impact of macro parameters (

Such as temperature and rabbi)

The structure and orientation of the single stretch film stretched at a given stretch speed and provides a comparison of the first stretch of the two processes.

This study is the first part of a broader project in which the three steps of the inverse process will be studied as previously done with the \"balance\" method (3-6, 22, 23).

Amorphous isogay PET film obtained by quenching the extruded melt on the cold roll by Rhone-Poulenc.

The average molecular weight is different, corresponding to the two samples of astandard viscosity (SV)

Or low viscosity polymer (LV)

Used in this study.

The melt viscosity was measured at 280 [degrees]

C. use the aRheometrics II rheostat with cone and plate geometry (

Diameter 25mm, cone angle 0. 02 rad. ).

Newton behavior was observed as high as 1000 [s. sup. -1].

Glass transition temperature of 80 [degrees]

C measured by DSC at the heating rate of 20 [degrees]

C/mm for two films.

These samples were prepared on a specially designed drawing machine at Rhone St Fons Research CenterPoulenc.

This is how the picture goes.

Amorphous film (

30x100mm)

Heat 30 s for the first time at the desired tensile temperature.

Such a heating time is sufficient to achieve the heat balance of the sample and fixture without inducing crystal.

Then, stretch the heated film in the name of 0. 75[s. sup. -1](

Near industrial process conditions)

Reach the program drawing ratio.

Typical tensile temperatures range from 85 to 115 [degrees]C.

During stretching, the film maintains a constant width through two small lateral fixtures on both sides.

Finally, the sample is blown with air at room temperature.

The quenching time is estimated at about 3 s.

Check the uniformity of the stretching process through the mesh on the sample.

At the highest temperature studied, the stretching became uneven and the sample gradually deformed towards the middle part.

In order to carry out the representation study, the part of the stretch file is cut in the uniform deformation area and the true stretch ratio is measured on the grid.

For a given temperature and program drawing ratio, LV samples obtain a higher real drawing ratio than sv samples.

Table 1 gives the properties and tensile conditions of the sample.

In this article, we chose [X. sub. 1]

As the direction of the drawing ,【X. sub. 2]

Perpendicular to the direction [X. sub. 1]

On the plane of the film and [X. sub. 3]

The direction perpendicular to the film plane.

Thereafter, the direction u of any molecular direction is relative to any macro direction [X. sub. i]

Will be quantified by means of the mean of the second order le Jean de polynomial :[

Mathematical expression omitted(1)where [[Theta]. sub. u,Xi]

Angle between U axis and [axis]X. sub. i]

Brackets represent the average of all molecular units. EXPERIMENTAL X-

Orientation measurement of wide angle X-ray diffraction

Ray diffraction has been used to characterize the crystal morphology and the orientation of the direction of the two characteristic crystals.

The two reflections of the survey are (105)

Its plane normal is close to the chain axis and (100)

Its plane is normally close to the normal of the benzene ring.

Below, we will refer to the unit cell determined by Daubeny et al. (22). The X-rays (Cu K[Alpha]radiation)

It is a generator with 39 kV and 30 mA kV and a Huber 4-

Tilt the sample using a circular angle meter.

Sample thickness of about 400 [[micro]meter]

Obtained by stacking several Stretch Films. The procedure [

Table data omitted from Table 1]

Relationship for obtaining order parameters [P. sub. 200]

Are these detailed by Faisant and others? (22).

Only a short description will be given here.

In order to determine the direction in all spaces, two rotations are required :[[Phi]. sub. o]for the out-of-

Plane rotation][Phi]. sub. p]for the in-plane rotation. [[Phi]. sub. o]

Defined as the angle between the scattering vector [

Mathematical expression omitted

And in the plane direction of the film, and [[Phi]. sub. p]

It can be changed by rotating the film around its normal direction.

The following procedure was used to collect data :(105)

Reflection: transport settings are used. The angle[[Phi]. sub. p]

Selected and [[Phi]. sub. o]

From-30 [degrees]to 30 [degrees]in steps of 2 [degrees]. [[Phi]. sub. p]

Every 2 [have value]degrees]

Drawing direction around (-20 [degrees]to 20[degrees]if [[Phi]. sub. p]

Take equal to zero when [

Mathematical expression omitted

Parallel [X. sub. 1])and every 5 [degrees]elsewhere.

The Prague corner is selected at maximum strength (105)reflection ([

Mathematical expression omittedaround 43[degrees]).

The obtained strength matrix I ([[Phi]. sub. p],[[Phi]. sub. o])

Corrected the amorphous background and the absorption changes [[Phi]. sub. o]

As described by Faisant et al. (22). (100)

Reflection: The reflection program and [[Theta]. sub. 100]

Shot at maximum intensity, the intensity is between 25. 5 [degrees]and 26 [degrees].

The data collection is as follows :[[Phi]. sub. o]

Was selected for the first time [[Phi]. sub. p]varied from-20 [degrees]to 200 [degrees]in steps of 5 [degrees]. Values of[[Phi]. sub. o]

Selected for every 2degrees]from -60 [degrees]to 60[degrees]([[Phi]. sub. o]equal to 0 [degrees]

Corresponding to Deng-plane rotation).

The experimental strength matrix was also corrected.

Order parameters ([P. sub. 200])

Calculated in three main directions in two directions (105)and (100)reflections.

Relative to the main direction of the sample, the sum of the order 3 parameters should be zero. A value of [less than]0.

04 is (100)

And zero is what you get (105).

The deviation of the second small is due to the extensive planedidistribution (100)planes normals.

Crystal size evaluation of crystal size using three crystal directions [105], [010]and [100].

The Scherrer equation is used to determine the size from the angle of the diffraction peak. [L. sub. hkl]= [Lambda]/cos [[Theta]. sub. hkl]x[Delta][[Theta]. sub. hkl](2)where [Delta][[Theta]. sub. hkl]

It\'s half-height width ,[[Theta]. sub. hkl]

The angle of maximum strength and [Lambda]

What is the wavelength of X? rays (1. 54 [Angstrom]).

There is no need to correct [Delta][[Theta]. sub. hkl]

To broaden the tools

Below ,[

Mathematical expression omitted

Will be considered as length ,[L. sub. 010]the width and [L. sub. 100]

Thickness of the crystal.

The index of refraction is measured in three main directions using the Abbe refraction device with polarized light.

Density and degree of crystal [Chi]

It is calculated from the average refractive index [

Mathematical expression omitted

Use the following formula :[

Mathematical expression omitted(3)[Chi]= d -[d. sub. a]/[d. sub. c]-[d. sub. a](4)where [d. sub. a]

The amorphous density and [d. sub. c]

Density of crystal phase.

Some people think it is 1. 335 and1. 455 g/[cm. sup. 3]respectively.

Lapersonne and others showed it. (4)

Due to the cylindrical symmetry of the polarization rate tensor, the measurement of the reflection index results in the overall orientation of the normal to benzene ring averaging on the crystal and non-crystal phases.

Calculate the mean value of the second-order Leide polynomial [

Mathematical expression omitted(5)

I, j, k, mentioned the three main directions of the film. RESULTS I -

First phase Crystal1 -

The crystalline degree maps the relationship between the crystalline degree and the tensile ratio on Figure 1. 1.

In samples of uneven deformation (

Especially at a maximum temperature of 115 [degrees]C)

The local drawing scale is estimated by the mesh drawn on the sample.

The small size sample required for Crystal Measurement allows us to obtain several crystal to tensile ratio data on the same product. At 115 [degrees]

C. The Growth of crystalline degree and [Lambda]

Shows the sigmoidal shape that has been observed elsewhere (8, 14, 19, 24).

At a lower temperature, the tensile ratio studied was too large to see the beginning of the crystals.

Figure I also shows that stress-induced crystals appear at a higher tensile ratio as the tensile temperature increases.

This behavior can be explained by the concept of the critical orientation required to induce crystals.

According to Lebourvellec and others. (8)

This critical orientation decreases as the temperature increases.

Crystal delay observed at 115 [degrees]

C shows that relaxation is common and requires a greater tensile ratio to reach the critical orientation.

At the same temperature, there is a slight difference between LV and SV samples.

With the decrease of molecular weight, getting the same crystals in both types of samples requires a higher degree of drying.

This observation can be explained again by the molecular weight dependence of chain relaxation phenomenon with relaxation time. I. 2 -

The direction chain axis diagram 2a, B, and c show (105)

The plane is normal relative to the direction [X. sub. 1], [X. sub. 2]and [X. sub. 3]

Compared with the drawing ratio, respectively.

The chain axis seems to be increasingly aligned to the drawing direction [

Diagram omitted of Figure 2A]

* As the drawing ratio increases * as the temperature decreases * as the melt viscosity increases.

However, the degree of orientation seems to be stable at the highest drawing ratio.

The chain axis shows an obvious direction in a medium drawing ratio on the film plane ([Lambda][greater than]3. 5)

It doesn\'t seem to depend on the temperature of the drawing [

Figure 2C omitted illustration].

Since the sum of the orientation functions along the three main directions of the film [

Mathematical expression omitted

Must be equal to zero and [

Mathematical expression omitted

Almost unchanged, about the direction [X. sub. 2]

Is essentially a \"mirror\" about\"X. sub. 1].

As the temperature increases, the orientation of the chain axis in the crystal phase is relaxed and clearly visible in the figure. 2a and b.

In addition, with the decrease of molecular weight, a lower orientation was observed at the same temperature and tensile ratio conditions.

This behavior again emphasizes the role of the chain relaxation process on the crystal phase orientation.

This is not obvious because, according to the Kratky model, the orientation of the crystal unit can be considered as a rotation of the rod (25)

The dominant position of deformation and relaxation processes should not play an important role.

It can be noted that in the strain rate applied for stretching, the behavior of the crystal chain axis orientation is very different from that of the constant stress deformation (3).

This will be discussed further in the discussion section.

The direction of the benzene ring shown in Figure 3a, B, and c (100)

Plane normal relative to the main direction [X. sub. 1], [X. sub. 2],[X. sub. 3]

Drawing ratio of SV samples.

As is usually observed in PET Films, the benzene ring tends to be more on the film plane as the tensile ratio increases.

As shown in the figure, the orientation mechanism is also affected by the relaxation process

3a is affected by the tensile temperature.

As the deformation progresses, as the chain axis of the Crystal stage becomes more and more oriented towards the tensile direction, the benzene normal [roughly (100)plane normals]

As shown in the figure, tend to be perpendicular to the drawing direction3b.

Better to see the evolution of normal direction of benzene ring with stretch ratio in 3-

Size map obtained by measuring the isodirectional projection of diffraction X-

The intensity of light on the plane of the film [

Diagram omitted of figure 4A and B].

With the increase in the proportion of sweepstakes, the breadth of distribution decreased more significantly [X. sub. 1]than to[X. sub. 2].

This explains the fairly constant value.

Mathematical expression omitted.

At the highest temperature (115 [degrees]C)

What double-bell-

About the shape distribution [X. sub. 3]

Observed in the drawing ratio of all surveys.

Its presence is more obvious in figure 1.

4c, where the diffraction intensity and the rotation angle of the plane ([[Phi]. sub. p])at [[Phi]. sub. 0]= 20 [degrees].

Its appearance explains the fact that there are fewer negative values [

Mathematical expression omitted

It was obtained under these conditions.

As the percentage of sweepstakes increases to 105 [degrees]

C, the twin peaks are becoming less and less obvious and may eventually merge into one peak, as shown in the figure4c.

It has been checked that the appearance of this double distribution cannot be attributed to the contribution of another Prague reflection like [1]110].

Deformation mechanism leading to this double deformationbell-

The shape distribution is not clear at present.

Low Strain and high temperature are conducive to double distribution, I . E. e.

In polymer films subjected to medium stress. I. 3 -

Shape figures 5a, B, c show the crystal size along the [direction]105],[010]and [100]versus [Lambda]

Sample SV and LV.

Regardless of the temperature, and regardless of the viscosity of the melt ,[

Mathematical expression omitted

Bigger [L. sub. 010]

Bigger [L. sub. 100]

, As has been observed in the sample stretched under constant force (3).

Along the length [

Mathematical expression omitted

As the temperature increases, the retracement rate increases but decreases.

As the molecular weight of the polymer decreases, smaller crystals can be obtained at given temperature and tensile ratio conditions.

105 and 115 [degrees]

C. The length of the Crystal seems to reach a constant value, which decreases with the increase of temperature.

The dynamics of crystal growth are determined by the shape of the curve in the figure

In our experimental conditions, 5a does not appear to be affected by temperature or molecular weight.

The slight effect of molecular weight means that stress-induced crystals basically involve short spatial scale movements of polymer chains.

The increased competition between the increase in Crystal Dynamics and the decrease in relaxation time at temperature can explain that temperature has no effect on the growth of crystal along [105]direction.

Along the length [010]

The direction shows a weak growth with deformation and is not affected by temperature.

Instead, the size of the crystal along [100]direction (

Known as thickness because the minimum size is observed along this direction)

It seems that it is basically controlled by temperature and has little effect on drawration and molecular weight.

An increase in temperature will lead to an increase in [L. sub. 100]

Observed in other studies (3).

It can be argued that growth along the [direction]100]

It does not depend on molecular orientation, but is favored due to the increase in liquidity.

The weak influence of the rabbi (

Or stretch time)

This means that orientation-induced crystals are formed at a tensile temperature corresponding to the thickness of the equilibrium state.

Crystal growth is only observed along [105]direction, i. e.

Along the electric shaft.

The knowledge of the dimensions of the crystals along three independent directions allows the estimation of their volume and their binding to the crystals, resulting in the average number of crystals per unit volume.

The two data are compared to the drawing ratio in the graph. 6a and b.

The analysis of these data shows different behaviors depending on the temperature.

At low temperatures, the size of the Crystal increases significantly as the tensile ratio increases, while the number of crystals is basically constant.

At high temperature (115 [degrees]C)

The volume of the Crystal seems to be issued to a stable value at a high tensile ratio, while the number of crystals has also increased.

This difference may indicate a slight difference in the crystalline mechanism at low and high temperatures.

At low temperatures, all crystals are formed when the orientation reaches a critical value.

Further stretching results in an increase in crystal length.

At high temperatures, some crystals are formed once the critical orientation is formed locally.

The construction of this crystal network inhibits or at least slows down the relaxation and allows the molecular orientation to reach a critical value at other locations, thus inducing further crystals.

The number of crystals observed at 105 [decreaseddegrees]

Cis within the experimental error range.

Its appearance can be attributed to a rapid increase in the length of the [Crystal]105]

This may lead to the merger of some crystals. II -

From the refraction index measurement, it is inferred that the overall orientation of the normal benzene ring is normal to the orientation of the benzene ring on average in the crystal and non-crystal phases, compared with the drawing in the figure. 7a, b, c.

The average orientation is affected by the tensile ratio and the tensile temperature.

Figure 7 shows that the normal of the benzene ring tends to be perpendicular to the tensile direction of [as the deformation progresses]X. sub. 1](as expected)

And more and more parallel [X. sub. 3]

This reflects the tendency of the benzene ring of the crystalline phase to be located on the film plane.

Weak direction parallel to the last direction [X. sub. 2]is observed.

With the rise of temperature, relaxation causes the orientation to decrease at a given stretch ratio.

Similarly, loss of orientation was observed as the molecular weight of the polymer decreased.

The corresponding data of the sample is 115 [stretch]degrees]

C shows that the appearance of crystals is reflected in the rapid orientation change relative to any macro direction, which can be attributed to the strong orientation of the crystalline block.

A small change in the average orientation was noted at 115 [degrees]

C. The highest pumping rate.

This trend is not obvious at a lower temperature, and at a lower temperature the orientation seems to be constant with the increase in the tensile ratio. III -

The non-Crystal Orientation Hypothesis two-phase model can obtain the orientation estimation of normal to benzene ring in the non-crystal phase.

The calculated amorphous orientation is :[

Mathematical expression omitted(6)where [

Mathematical expression omitted

Determined by index of refraction and [

Mathematical expression omitted

Using X-computing

Ray diffraction dataAs [

Mathematical expression omitted

Does not fully conform to the normal direction of the benzene ring in the crystal phase, because Eq 6 means the cumulative error on [Chi], [

Mathematical expression omittedand [

Mathematical expression omitted

General trends can only be discussed.

The results are given in the figure. 8a, b, c.

As expected, the data is sensitive to the drawing ratio and temperature.

The benzene normal in the amorphous phase tends to be more and more perpendicular to the tensile direction and parallel to the other two directions.

With the increase of temperature, it is basically clear to observe the relaxation of the amorphous phase orientation relative [X. sub. 1]and [X. sub. 3]. The non-

By comparing the orientation along the [direction], the single-axis features of the orientation can be observedX. sub. 3]and[X. sub. 2]on Figs. 8a and 8c.

The higher the temperature, the greater the difference [

Mathematical expression omittedam and[

Mathematical expression omittedam.

Comparison of figs.

8c and 3c reveal that the orientation behavior in the crystal and amorphous phases is very different from [X. sub. 2]direction.

Increase in the direction of the loop line relative [X. sub. 2]

It is noted in amorphouspase, while the Crystal pair is preferred perpendicular [X. sub. 2].

This effect is due only to the high orientation [100]along the [X. sub. 3]

Direction, induce preferential vertical orientation in the same crystal direction along the other two axes. IV -

Mechanical behavior during tensile nominal stress [[Sigma]. sub. 0]= F/[S. sub. 0]

F is tensile force and [S. sub. 0]

The initial part of the sample is compared to the drawing scale in the figure9.

Due to the non-uniformity of deformation, the apparent tensile ratio is different from the true tensile ratio measured in the middle of the sample and used for previous drawings. Except at 85 [degrees]

C. shape of stress-

Strain curves similar to those described by Salem (19). At 85 [degrees]

C, the maximum stress was observed at medium deformation, similar to the stress, although the stretching was carried out above the glass transition temperature.

This behavior is also reported in other deformed polymers with temperatures slightly higher [T. sub. g](26, 27).

In the low strain ,[[Sigma]. sub. o]

Almost linear growth [Lambda].

Unfortunately, there are too few data points to allow the exact calculation of Young\'s modulus.

However, as the temperature increases or the viscosity decreases, it seems to decrease, as can be foreseen from the linear viscous behavior of amorphous uncross-linked polymers.

This stress which increases strongly with deformation is followed by the plateau, and the length of the plateau increases as the temperature rises. Salem (19)

The inflection point is described as the occurrence of stress-induced crystals.

The data we collect in [degrees]

C. confirm this observation, because it is noteworthy for the crystal with a total tensile ratio of 2. 5.

The last part of stress

The strain curve corresponds to the state in which the stress increases strongly with the deformation, which can be attributed to the deformation of the network where the crystal acts as a permanent connection point (19).

According to this idea, the estimation of network density can be obtained from the last part of the stress-strain curve.

In fact, as soon as the network is formed, the additional stress required for deformation is related to the extension ratio [Lambda][prime]

Through the following relationships (28): [[Sigma]. sub. extra]= G([Lambda][prime]-1/[[Lambda][prime]. sup. 3])(7)

Where is the network modulus G ,[Lambda][prime]=[Lambda]/[[Lambda]. sub. network], and [[Lambda]. sub. network]

Is defined as the drawing ratio when the network is formed.

It is determined by assigning the corresponding overall plot score to the point where the slope change is observed under large deformation, compared with the real plot [

Diagram omitted in figure 1]. [[Lambda]. sub. network]

Indicated for SV samples at each temperature. 9 by an arrow. [[Sigma]. sub. extra]

And ([Lambda][prime]-1/[[Lambda][prime]. sup. 3])in Fig. 10.

At 95 [the network modulus is clearly the same order of magnitude]degrees]and 105 [degrees]C (8 MPa)

And significantly reduced (3. 4 MPa)at 115 [degrees]C.

As the molecular weight decreases, the deformation of the sample at a given temperature requires a lower stress.

In addition, coincidentally, the data of LV samples almost overlap with the data of sv samples with 10 [degrees]

C. temperature shift.

Difference in viscosity from melting (Table 1)

Between the relaxation time of LV and SV samples, the expected factor is 2.

The correlation of the curve allows us to check whether this factor is consistent with the WLF shift factor [a. sub. T]

Between 95 and 105 [1 [degrees]

C or 115 [1 [degrees]C.

This is obviously not the case because [a. sub. 95/105]=12 and [a. sub. 105/115]

= 6 The WLF coefficient given using Lebourvellec (29).

Therefore, it can be concluded that pressure-

The strain behavior is not only sensitive to relaxation time, but also the crystalline dynamics must be a competitive mechanism.

In this section, we will discuss and compare the main differences between constant force stretching and forced strain rate deformation.

In both stretches, the effect of the tensile ratio and the tensile temperature on the crystal phase orientation and morphology appears to be very different.

It has been shown that for samples that stretch to reach equilibrium deformation [under constant load][Lambda]. sub. p]

Direction of the chain shaft ([

Mathematical expression omitteddirection)

About the direction of stretching and the normal direction of benzene ring ([100]direction)

About [X. sub. 3]

Direction is an addition function of the balance graph [[Lambda]. sub. p]

Regardless of the tensile temperature or the applied load (3).

In the case of the sample, the deformation was stopped before [[Lambda]. sub. p](

Quenching samples)

The same behavior was observed: I. e.

Direction independent of time (

Select by temperature and applied load)

Required to achieve a given deformation (30).

The sample stretched at a given strain rate is clearly not the case.

At the given Stretch ratio, the orientation decreases with the increase of temperature, which indicates the main role of the relaxation phenomenon.

Therefore, in this latter stretch, the chain axis orientation in the crystal phase is much lower.

In fact, in constant force stretching, the orientation is controlled by the equilibrium tensile ratio, which may be due to a rough compensation for the increase in temperature between the decrease in relaxation time and the increase in deformation dynamics.

A more subtle act of distinction about [100]

Plane normal can also be recorded.

In constant force stretching, the chain axis in the crystal phase shows such a high orientation relative to the tensile direction that [100]

The direction is basically perpendicular [X. sub. 1].

The increase in the tensile ratio leads to an increase in the orientation of the benzene ring on the film plane, so [

Mathematical expression omitted

As the drawing scale decreases.

On the contrary, the deformation of the constant strain rate [

Mathematical expression omitted

Because the relaxation of the chain shaft is almost constant relative to the direction of stretching (

This leads to the less vertical direction [100]

About the direction [X. sub. 1])

And relaxation of the preferred orientation of benzene ring on the film plane.

Differences in the dynamics of the two types of tensile deformation may also result in differences in the morphology and growth of the crystal.

Whereas in constant force, the number of crystals decreases as the temperature rises, but in deformation controlled by strain rate, this seems to have nothing to do with this parameter.

In addition, in the latter case, the number of crystals per unit volume during stretching increases at high temperatures.

Never encountered such behavior in constant force stretching.

The orientation of the crystal is basically controlled by traction in constant force stretching.

This is not to say that there will be no relaxation in this stretch, because relaxation has been detected in amorphous orientation, especially between 95 [1]degrees]C and 100 [degrees]C, i. e.

Within a limited temperature range (4, 5).

In constant strain rate stretching, the same type of relaxation appears to occur.

For example, for SV samples, a strong change was found between 105 [degrees]C and 115 [degrees]

As shown in Figure C. 10.

In addition, between the two temperature ranges (

In constant strain rate stretching)

A factor of 2.

Between the slopes of figure 5. 10.

Conclusion in this study, experimental representation of molecular orientation and morphology of PET Films deformed at constant rate under single axis

The plane symmetry condition is reported.

Pay special attention to the effect of tensile temperature and tensile rate.

The relaxation phenomenon was observed to have a great influence on the orientation of crystal and non-crystal phases.

This behavior is very different from the behavior observed under constant force stretching conditions, although the general trend of orientation is the same, basically because of the same type of deformation tensor.

In both cases, a huge change in orientation was observed in a narrow temperature range.

Depending on whether the stretching is performed at low or high temperatures, the structure of the Crystal network seems to be different.

Get a more loose network at [temperature]greaterthan]110 [degrees]C.

Confirm Rhone-

The Poulenc film was appreciated for providing PhDgrant to M. V.

The author thanks Dr. F. Bouquerel (Rhone-

Industrialized)

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Polymer, 35,4092 (Lorenzo)1994). 24. D. J. Walls and J. C. Coburn, J. Polym. Sci. Part B, Polym. Phys. , 30, 887 (1992). 25. O. Kratky, Koll. Zeit. , 64, 213 (1933). 26. T. Inoue, H. Okamoto, and K.

Crab Willow and large molecule in Daqi, month, 7069 (1992). 27. H. Okamoto, T. Inoue, and K.

Crab Willow and large molecule in Daqi, month, 3413 (1992). 28. L. R. G.

Treloar, elastic physics of rubber, Clarendon Press, Oxford, UK (1975). 29. G.

Lebourvellec, PhD thesis, Sixth University, Paris (1984). 30. P. Lapersonne, J. F. Tassin, and L.

Monnerie submits toPolymer.

Pet)(PET)

Therefore, the film and its practical application are directly controlled by the molecular orientation and morphology generated during the film processing.

Although the performance can be adjusted by changing the process parameters, the selection of \"balance\" or \"reverse\" processes will produce balanced or preferred orientation film shaving on the film plane respectively.

Traditional-

The so-called \"balance\" process consists of three stages.

The first one is vertical (

Machine direction)

Draw with constant force and constant width.

In the second stage, the single stretch film is stretched horizontally at a constant speed, and the third stage is basically a high temperature hot solid treatment.

In the \"inverse\" sequence, the amorphous film is first stretched horizontally at a constant speed, and then vertically at a constant stress and a constant width.

The last step is the hot-solid of the two-way stretch film.

The movement of the stretch stage during these two processes is very different.

Since the phenomenon of crystal and chain relaxation occurs during stretching, the morphology and molecular orientation of the crystalline phase may vary greatly in each case.

Structure of amorphous PET film stretched under constant forceplanar (constant width)

Several groups studied the conditions (1-7).

These films are either made by industrial processes (1)

Or on a laboratory scale (2-7).

In terms of the effect of the process parameters, it has been shown that most of the properties of the film are determined by the tensile ratio, not by temperature or applied stress.

Detailed descriptions can be found elsewhere (3-6).

Although various studies have treated the representation of deformed PET one-way stretching at a constant strain rate (8, 9)

, Or at a constant speed of drawing (10-15)

Less work is done under the condition of single-axis plane symmetry (16-20).

The purpose of this work is to accurately describe the impact of macro parameters (

Such as temperature and rabbi)

The structure and orientation of the single stretch film stretched at a given stretch speed and provides a comparison of the first stretch of the two processes.

This study is the first part of a broader project in which the three steps of the inverse process will be studied as previously done with the \"balance\" method (3-6, 22, 23).

Amorphous isogay PET film obtained by quenching the extruded melt on the cold roll by Rhone-Poulenc.

The average molecular weight is different, corresponding to the two samples of astandard viscosity (SV)

Or low viscosity polymer (LV)

Used in this study.

The melt viscosity was measured at 280 [degrees]

C. use the aRheometrics II rheostat with cone and plate geometry (

Diameter 25mm, cone angle 0. 02 rad. ).

Newton behavior was observed as high as 1000 [s. sup. -1].

Glass transition temperature of 80 [degrees]

C measured by DSC at the heating rate of 20 [degrees]

C/mm for two films.

These samples were prepared on a specially designed drawing machine at Rhone St Fons Research CenterPoulenc.

This is how the picture goes.

Amorphous film (

30x100mm)

Heat 30 s for the first time at the desired tensile temperature.

Such a heating time is sufficient to achieve the heat balance of the sample and fixture without inducing crystal.

Then, stretch the heated film in the name of 0. 75[s. sup. -1](

Near industrial process conditions)

Reach the program drawing ratio.

Typical tensile temperatures range from 85 to 115 [degrees]C.

During stretching, the film maintains a constant width through two small lateral fixtures on both sides.

Finally, the sample is blown with air at room temperature.

The quenching time is estimated at about 3 s.

Check the uniformity of the stretching process through the mesh on the sample.

At the highest temperature studied, the stretching became uneven and the sample gradually deformed towards the middle part.

In order to carry out the representation study, the part of the stretch file is cut in the uniform deformation area and the true stretch ratio is measured on the grid.

For a given temperature and program drawing ratio, LV samples obtain a higher real drawing ratio than sv samples.

Table 1 gives the properties and tensile conditions of the sample.

In this article, we chose [X. sub. 1]

As the direction of the drawing ,【X. sub. 2]

Perpendicular to the direction [X. sub. 1]

On the plane of the film and [X. sub. 3]

The direction perpendicular to the film plane.

Thereafter, the direction u of any molecular direction is relative to any macro direction [X. sub. i]

Will be quantified by means of the mean of the second order le Jean de polynomial :[

Mathematical expression omitted(1)where [[Theta]. sub. u,Xi]

Angle between U axis and [axis]X. sub. i]

Brackets represent the average of all molecular units. EXPERIMENTAL X-

Orientation measurement of wide angle X-ray diffraction

Ray diffraction has been used to characterize the crystal morphology and the orientation of the direction of the two characteristic crystals.

The two reflections of the survey are (105)

Its plane normal is close to the chain axis and (100)

Its plane is normally close to the normal of the benzene ring.

Below, we will refer to the unit cell determined by Daubeny et al. (22). The X-rays (Cu K[Alpha]radiation)

It is a generator with 39 kV and 30 mA kV and a Huber 4-

Tilt the sample using a circular angle meter.

Sample thickness of about 400 [[micro]meter]

Obtained by stacking several Stretch Films. The procedure [

Table data omitted from Table 1]

Relationship for obtaining order parameters [P. sub. 200]

Are these detailed by Faisant and others? (22).

Only a short description will be given here.

In order to determine the direction in all spaces, two rotations are required :[[Phi]. sub. o]for the out-of-

Plane rotation][Phi]. sub. p]for the in-plane rotation. [[Phi]. sub. o]

Defined as the angle between the scattering vector [

Mathematical expression omitted

And in the plane direction of the film, and [[Phi]. sub. p]

It can be changed by rotating the film around its normal direction.

The following procedure was used to collect data :(105)

Reflection: transport settings are used. The angle[[Phi]. sub. p]

Selected and [[Phi]. sub. o]

From-30 [degrees]to 30 [degrees]in steps of 2 [degrees]. [[Phi]. sub. p]

Every 2 [have value]degrees]

Drawing direction around (-20 [degrees]to 20[degrees]if [[Phi]. sub. p]

Take equal to zero when [

Mathematical expression omitted

Parallel [X. sub. 1])and every 5 [degrees]elsewhere.

The Prague corner is selected at maximum strength (105)reflection ([

Mathematical expression omittedaround 43[degrees]).

The obtained strength matrix I ([[Phi]. sub. p],[[Phi]. sub. o])

Corrected the amorphous background and the absorption changes [[Phi]. sub. o]

As described by Faisant et al. (22). (100)

Reflection: The reflection program and [[Theta]. sub. 100]

Shot at maximum intensity, the intensity is between 25. 5 [degrees]and 26 [degrees].

The data collection is as follows :[[Phi]. sub. o]

Was selected for the first time [[Phi]. sub. p]varied from-20 [degrees]to 200 [degrees]in steps of 5 [degrees]. Values of[[Phi]. sub. o]

Selected for every 2degrees]from -60 [degrees]to 60[degrees]([[Phi]. sub. o]equal to 0 [degrees]

Corresponding to Deng-plane rotation).

The experimental strength matrix was also corrected.

Order parameters ([P. sub. 200])

Calculated in three main directions in two directions (105)and (100)reflections.

Relative to the main direction of the sample, the sum of the order 3 parameters should be zero. A value of [less than]0.

04 is (100)

And zero is what you get (105).

The deviation of the second small is due to the extensive planedidistribution (100)planes normals.

Crystal size evaluation of crystal size using three crystal directions [105], [010]and [100].

The Scherrer equation is used to determine the size from the angle of the diffraction peak. [L. sub. hkl]= [Lambda]/cos [[Theta]. sub. hkl]x[Delta][[Theta]. sub. hkl](2)where [Delta][[Theta]. sub. hkl]

It\'s half-height width ,[[Theta]. sub. hkl]

The angle of maximum strength and [Lambda]

What is the wavelength of X? rays (1. 54 [Angstrom]).

There is no need to correct [Delta][[Theta]. sub. hkl]

To broaden the tools

Below ,[

Mathematical expression omitted

Will be considered as length ,[L. sub. 010]the width and [L. sub. 100]

Thickness of the crystal.

The index of refraction is measured in three main directions using the Abbe refraction device with polarized light.

Density and degree of crystal [Chi]

It is calculated from the average refractive index [

Mathematical expression omitted

Use the following formula :[

Mathematical expression omitted(3)[Chi]= d -[d. sub. a]/[d. sub. c]-[d. sub. a](4)where [d. sub. a]

The amorphous density and [d. sub. c]

Density of crystal phase.

Some people think it is 1. 335 and1. 455 g/[cm. sup. 3]respectively.

Lapersonne and others showed it. (4)

Due to the cylindrical symmetry of the polarization rate tensor, the measurement of the reflection index results in the overall orientation of the normal to benzene ring averaging on the crystal and non-crystal phases.

Calculate the mean value of the second-order Leide polynomial [

Mathematical expression omitted(5)

I, j, k, mentioned the three main directions of the film. RESULTS I -

First phase Crystal1 -

The crystalline degree maps the relationship between the crystalline degree and the tensile ratio on Figure 1. 1.

In samples of uneven deformation (

Especially at a maximum temperature of 115 [degrees]C)

The local drawing scale is estimated by the mesh drawn on the sample.

The small size sample required for Crystal Measurement allows us to obtain several crystal to tensile ratio data on the same product. At 115 [degrees]

C. The Growth of crystalline degree and [Lambda]

Shows the sigmoidal shape that has been observed elsewhere (8, 14, 19, 24).

At a lower temperature, the tensile ratio studied was too large to see the beginning of the crystals.

Figure I also shows that stress-induced crystals appear at a higher tensile ratio as the tensile temperature increases.

This behavior can be explained by the concept of the critical orientation required to induce crystals.

According to Lebourvellec and others. (8)

This critical orientation decreases as the temperature increases.

Crystal delay observed at 115 [degrees]

C shows that relaxation is common and requires a greater tensile ratio to reach the critical orientation.

At the same temperature, there is a slight difference between LV and SV samples.

With the decrease of molecular weight, getting the same crystals in both types of samples requires a higher degree of drying.

This observation can be explained again by the molecular weight dependence of chain relaxation phenomenon with relaxation time. I. 2 -

The direction chain axis diagram 2a, B, and c show (105)

The plane is normal relative to the direction [X. sub. 1], [X. sub. 2]and [X. sub. 3]

Compared with the drawing ratio, respectively.

The chain axis seems to be increasingly aligned to the drawing direction [

Diagram omitted of Figure 2A]

* As the drawing ratio increases * as the temperature decreases * as the melt viscosity increases.

However, the degree of orientation seems to be stable at the highest drawing ratio.

The chain axis shows an obvious direction in a medium drawing ratio on the film plane ([Lambda][greater than]3. 5)

It doesn\'t seem to depend on the temperature of the drawing [

Figure 2C omitted illustration].

Since the sum of the orientation functions along the three main directions of the film [

Mathematical expression omitted

Must be equal to zero and [

Mathematical expression omitted

Almost unchanged, about the direction [X. sub. 2]

Is essentially a \"mirror\" about\"X. sub. 1].

As the temperature increases, the orientation of the chain axis in the crystal phase is relaxed and clearly visible in the figure. 2a and b.

In addition, with the decrease of molecular weight, a lower orientation was observed at the same temperature and tensile ratio conditions.

This behavior again emphasizes the role of the chain relaxation process on the crystal phase orientation.

This is not obvious because, according to the Kratky model, the orientation of the crystal unit can be considered as a rotation of the rod (25)

The dominant position of deformation and relaxation processes should not play an important role.

It can be noted that in the strain rate applied for stretching, the behavior of the crystal chain axis orientation is very different from that of the constant stress deformation (3).

This will be discussed further in the discussion section.

The direction of the benzene ring shown in Figure 3a, B, and c (100)

Plane normal relative to the main direction [X. sub. 1], [X. sub. 2],[X. sub. 3]

Drawing ratio of SV samples.

As is usually observed in PET Films, the benzene ring tends to be more on the film plane as the tensile ratio increases.

As shown in the figure, the orientation mechanism is also affected by the relaxation process

3a is affected by the tensile temperature.

As the deformation progresses, as the chain axis of the Crystal stage becomes more and more oriented towards the tensile direction, the benzene normal [roughly (100)plane normals]

As shown in the figure, tend to be perpendicular to the drawing direction3b.

Better to see the evolution of normal direction of benzene ring with stretch ratio in 3-

Size map obtained by measuring the isodirectional projection of diffraction X-

The intensity of light on the plane of the film [

Diagram omitted of figure 4A and B].

With the increase in the proportion of sweepstakes, the breadth of distribution decreased more significantly [X. sub. 1]than to[X. sub. 2].

This explains the fairly constant value.

Mathematical expression omitted.

At the highest temperature (115 [degrees]C)

What double-bell-

About the shape distribution [X. sub. 3]

Observed in the drawing ratio of all surveys.

Its presence is more obvious in figure 1.

4c, where the diffraction intensity and the rotation angle of the plane ([[Phi]. sub. p])at [[Phi]. sub. 0]= 20 [degrees].

Its appearance explains the fact that there are fewer negative values [

Mathematical expression omitted

It was obtained under these conditions.

As the percentage of sweepstakes increases to 105 [degrees]

C, the twin peaks are becoming less and less obvious and may eventually merge into one peak, as shown in the figure4c.

It has been checked that the appearance of this double distribution cannot be attributed to the contribution of another Prague reflection like [1]110].

Deformation mechanism leading to this double deformationbell-

The shape distribution is not clear at present.

Low Strain and high temperature are conducive to double distribution, I . E. e.

In polymer films subjected to medium stress. I. 3 -

Shape figures 5a, B, c show the crystal size along the [direction]105],[010]and [100]versus [Lambda]

Sample SV and LV.

Regardless of the temperature, and regardless of the viscosity of the melt ,[

Mathematical expression omitted

Bigger [L. sub. 010]

Bigger [L. sub. 100]

, As has been observed in the sample stretched under constant force (3).

Along the length [

Mathematical expression omitted

As the temperature increases, the retracement rate increases but decreases.

As the molecular weight of the polymer decreases, smaller crystals can be obtained at given temperature and tensile ratio conditions.

105 and 115 [degrees]

C. The length of the Crystal seems to reach a constant value, which decreases with the increase of temperature.

The dynamics of crystal growth are determined by the shape of the curve in the figure

In our experimental conditions, 5a does not appear to be affected by temperature or molecular weight.

The slight effect of molecular weight means that stress-induced crystals basically involve short spatial scale movements of polymer chains.

The increased competition between the increase in Crystal Dynamics and the decrease in relaxation time at temperature can explain that temperature has no effect on the growth of crystal along [105]direction.

Along the length [010]

The direction shows a weak growth with deformation and is not affected by temperature.

Instead, the size of the crystal along [100]direction (

Known as thickness because the minimum size is observed along this direction)

It seems that it is basically controlled by temperature and has little effect on drawration and molecular weight.

An increase in temperature will lead to an increase in [L. sub. 100]

Observed in other studies (3).

It can be argued that growth along the [direction]100]

It does not depend on molecular orientation, but is favored due to the increase in liquidity.

The weak influence of the rabbi (

Or stretch time)

This means that orientation-induced crystals are formed at a tensile temperature corresponding to the thickness of the equilibrium state.

Crystal growth is only observed along [105]direction, i. e.

Along the electric shaft.

The knowledge of the dimensions of the crystals along three independent directions allows the estimation of their volume and their binding to the crystals, resulting in the average number of crystals per unit volume.

The two data are compared to the drawing ratio in the graph. 6a and b.

The analysis of these data shows different behaviors depending on the temperature.

At low temperatures, the size of the Crystal increases significantly as the tensile ratio increases, while the number of crystals is basically constant.

At high temperature (115 [degrees]C)

The volume of the Crystal seems to be issued to a stable value at a high tensile ratio, while the number of crystals has also increased.

This difference may indicate a slight difference in the crystalline mechanism at low and high temperatures.

At low temperatures, all crystals are formed when the orientation reaches a critical value.

Further stretching results in an increase in crystal length.

At high temperatures, some crystals are formed once the critical orientation is formed locally.

The construction of this crystal network inhibits or at least slows down the relaxation and allows the molecular orientation to reach a critical value at other locations, thus inducing further crystals.

The number of crystals observed at 105 [decreaseddegrees]

Cis within the experimental error range.

Its appearance can be attributed to a rapid increase in the length of the [Crystal]105]

This may lead to the merger of some crystals. II -

From the refraction index measurement, it is inferred that the overall orientation of the normal benzene ring is normal to the orientation of the benzene ring on average in the crystal and non-crystal phases, compared with the drawing in the figure. 7a, b, c.

The average orientation is affected by the tensile ratio and the tensile temperature.

Figure 7 shows that the normal of the benzene ring tends to be perpendicular to the tensile direction of [as the deformation progresses]X. sub. 1](as expected)

And more and more parallel [X. sub. 3]

This reflects the tendency of the benzene ring of the crystalline phase to be located on the film plane.

Weak direction parallel to the last direction [X. sub. 2]is observed.

With the rise of temperature, relaxation causes the orientation to decrease at a given stretch ratio.

Similarly, loss of orientation was observed as the molecular weight of the polymer decreased.

The corresponding data of the sample is 115 [stretch]degrees]

C shows that the appearance of crystals is reflected in the rapid orientation change relative to any macro direction, which can be attributed to the strong orientation of the crystalline block.

A small change in the average orientation was noted at 115 [degrees]

C. The highest pumping rate.

This trend is not obvious at a lower temperature, and at a lower temperature the orientation seems to be constant with the increase in the tensile ratio. III -

The non-Crystal Orientation Hypothesis two-phase model can obtain the orientation estimation of normal to benzene ring in the non-crystal phase.

The calculated amorphous orientation is :[

Mathematical expression omitted(6)where [

Mathematical expression omitted

Determined by index of refraction and [

Mathematical expression omitted

Using X-computing

Ray diffraction dataAs [

Mathematical expression omitted

Does not fully conform to the normal direction of the benzene ring in the crystal phase, because Eq 6 means the cumulative error on [Chi], [

Mathematical expression omittedand [

Mathematical expression omitted

General trends can only be discussed.

The results are given in the figure. 8a, b, c.

As expected, the data is sensitive to the drawing ratio and temperature.

The benzene normal in the amorphous phase tends to be more and more perpendicular to the tensile direction and parallel to the other two directions.

With the increase of temperature, it is basically clear to observe the relaxation of the amorphous phase orientation relative [X. sub. 1]and [X. sub. 3]. The non-

By comparing the orientation along the [direction], the single-axis features of the orientation can be observedX. sub. 3]and[X. sub. 2]on Figs. 8a and 8c.

The higher the temperature, the greater the difference [

Mathematical expression omittedam and[

Mathematical expression omittedam.

Comparison of figs.

8c and 3c reveal that the orientation behavior in the crystal and amorphous phases is very different from [X. sub. 2]direction.

Increase in the direction of the loop line relative [X. sub. 2]

It is noted in amorphouspase, while the Crystal pair is preferred perpendicular [X. sub. 2].

This effect is due only to the high orientation [100]along the [X. sub. 3]

Direction, induce preferential vertical orientation in the same crystal direction along the other two axes. IV -

Mechanical behavior during tensile nominal stress [[Sigma]. sub. 0]= F/[S. sub. 0]

F is tensile force and [S. sub. 0]

The initial part of the sample is compared to the drawing scale in the figure9.

Due to the non-uniformity of deformation, the apparent tensile ratio is different from the true tensile ratio measured in the middle of the sample and used for previous drawings. Except at 85 [degrees]

C. shape of stress-

Strain curves similar to those described by Salem (19). At 85 [degrees]

C, the maximum stress was observed at medium deformation, similar to the stress, although the stretching was carried out above the glass transition temperature.

This behavior is also reported in other deformed polymers with temperatures slightly higher [T. sub. g](26, 27).

In the low strain ,[[Sigma]. sub. o]

Almost linear growth [Lambda].

Unfortunately, there are too few data points to allow the exact calculation of Young\'s modulus.

However, as the temperature increases or the viscosity decreases, it seems to decrease, as can be foreseen from the linear viscous behavior of amorphous uncross-linked polymers.

This stress which increases strongly with deformation is followed by the plateau, and the length of the plateau increases as the temperature rises. Salem (19)

The inflection point is described as the occurrence of stress-induced crystals.

The data we collect in [degrees]

C. confirm this observation, because it is noteworthy for the crystal with a total tensile ratio of 2. 5.

The last part of stress

The strain curve corresponds to the state in which the stress increases strongly with the deformation, which can be attributed to the deformation of the network where the crystal acts as a permanent connection point (19).

According to this idea, the estimation of network density can be obtained from the last part of the stress-strain curve.

In fact, as soon as the network is formed, the additional stress required for deformation is related to the extension ratio [Lambda][prime]

Through the following relationships (28): [[Sigma]. sub. extra]= G([Lambda][prime]-1/[[Lambda][prime]. sup. 3])(7)

Where is the network modulus G ,[Lambda][prime]=[Lambda]/[[Lambda]. sub. network], and [[Lambda]. sub. network]

Is defined as the drawing ratio when the network is formed.

It is determined by assigning the corresponding overall plot score to the point where the slope change is observed under large deformation, compared with the real plot [

Diagram omitted in figure 1]. [[Lambda]. sub. network]

Indicated for SV samples at each temperature. 9 by an arrow. [[Sigma]. sub. extra]

And ([Lambda][prime]-1/[[Lambda][prime]. sup. 3])in Fig. 10.

At 95 [the network modulus is clearly the same order of magnitude]degrees]and 105 [degrees]C (8 MPa)

And significantly reduced (3. 4 MPa)at 115 [degrees]C.

As the molecular weight decreases, the deformation of the sample at a given temperature requires a lower stress.

In addition, coincidentally, the data of LV samples almost overlap with the data of sv samples with 10 [degrees]

C. temperature shift.

Difference in viscosity from melting (Table 1)

Between the relaxation time of LV and SV samples, the expected factor is 2.

The correlation of the curve allows us to check whether this factor is consistent with the WLF shift factor [a. sub. T]

Between 95 and 105 [1 [degrees]

C or 115 [1 [degrees]C.

This is obviously not the case because [a. sub. 95/105]=12 and [a. sub. 105/115]

= 6 The WLF coefficient given using Lebourvellec (29).

Therefore, it can be concluded that pressure-

The strain behavior is not only sensitive to relaxation time, but also the crystalline dynamics must be a competitive mechanism.

In this section, we will discuss and compare the main differences between constant force stretching and forced strain rate deformation.

In both stretches, the effect of the tensile ratio and the tensile temperature on the crystal phase orientation and morphology appears to be very different.

It has been shown that for samples that stretch to reach equilibrium deformation [under constant load][Lambda]. sub. p]

Direction of the chain shaft ([

Mathematical expression omitteddirection)

About the direction of stretching and the normal direction of benzene ring ([100]direction)

About [X. sub. 3]

Direction is an addition function of the balance graph [[Lambda]. sub. p]

Regardless of the tensile temperature or the applied load (3).

In the case of the sample, the deformation was stopped before [[Lambda]. sub. p](

Quenching samples)

The same behavior was observed: I. e.

Direction independent of time (

Select by temperature and applied load)

Required to achieve a given deformation (30).

The sample stretched at a given strain rate is clearly not the case.

At the given Stretch ratio, the orientation decreases with the increase of temperature, which indicates the main role of the relaxation phenomenon.

Therefore, in this latter stretch, the chain axis orientation in the crystal phase is much lower.

In fact, in constant force stretching, the orientation is controlled by the equilibrium tensile ratio, which may be due to a rough compensation for the increase in temperature between the decrease in relaxation time and the increase in deformation dynamics.

A more subtle act of distinction about [100]

Plane normal can also be recorded.

In constant force stretching, the chain axis in the crystal phase shows such a high orientation relative to the tensile direction that [100]

The direction is basically perpendicular [X. sub. 1].

The increase in the tensile ratio leads to an increase in the orientation of the benzene ring on the film plane, so [

Mathematical expression omitted

As the drawing scale decreases.

On the contrary, the deformation of the constant strain rate [

Mathematical expression omitted

Because the relaxation of the chain shaft is almost constant relative to the direction of stretching (

This leads to the less vertical direction [100]

About the direction [X. sub. 1])

And relaxation of the preferred orientation of benzene ring on the film plane.

Differences in the dynamics of the two types of tensile deformation may also result in differences in the morphology and growth of the crystal.

Whereas in constant force, the number of crystals decreases as the temperature rises, but in deformation controlled by strain rate, this seems to have nothing to do with this parameter.

In addition, in the latter case, the number of crystals per unit volume during stretching increases at high temperatures.

Never encountered such behavior in constant force stretching.

The orientation of the crystal is basically controlled by traction in constant force stretching.

This is not to say that there will be no relaxation in this stretch, because relaxation has been detected in amorphous orientation, especially between 95 [1]degrees]C and 100 [degrees]C, i. e.

Within a limited temperature range (4, 5).

In constant strain rate stretching, the same type of relaxation appears to occur.

For example, for SV samples, a strong change was found between 105 [degrees]C and 115 [degrees]

As shown in Figure C. 10.

In addition, between the two temperature ranges (

In constant strain rate stretching)

A factor of 2.

Between the slopes of figure 5. 10.

Conclusion in this study, experimental representation of molecular orientation and morphology of PET Films deformed at constant rate under single axis

The plane symmetry condition is reported.

Pay special attention to the effect of tensile temperature and tensile rate.

The relaxation phenomenon was observed to have a great influence on the orientation of crystal and non-crystal phases.

This behavior is very different from the behavior observed under constant force stretching conditions, although the general trend of orientation is the same, basically because of the same type of deformation tensor.

In both cases, a huge change in orientation was observed in a narrow temperature range.

Depending on whether the stretching is performed at low or high temperatures, the structure of the Crystal network seems to be different.

Get a more loose network at [temperature]greaterthan]110 [degrees]C.

Confirm Rhone-

The Poulenc film was appreciated for providing PhDgrant to M. V.

The author thanks Dr. F. Bouquerel (Rhone-

Industrialized)

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Monnerie submits toPolymer.

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