阅读说明：本技术 一种聚酰胺拉伸成膜稳定性的评价方法 (Method for evaluating stability of polyamide stretch film forming ) 是由 惠志锋 于 2021-09-02 设计创作，主要内容包括：本发明提供了一种聚酰胺拉伸成膜稳定性的评价方法。其主要方法包括：(1)评价聚酰胺树脂的分子间作用力：测试聚酰胺试样在浸泡溶剂前后的压缩强度H-(0),H-(slt)；拉伸强度S-(0),S-(slt)和断裂伸长率l-(0),l-(slt)；(2)测试聚酰胺树脂的熔体强度参数S-(melt)；(3)测试聚酰胺树脂的结晶能力,得到退火后试样的相对结晶度X-(cA)；(4)按公式计算试样的成膜稳定性参数P-(stability),该指标越小,说明试样的成膜稳定性越高。本发明提供了一种聚酰胺树脂在拉伸过程中成膜稳定性的评价方法,该方法能够很好用于测定聚酰胺在拉伸时的成膜稳定性,其测试结果准确度高,与实际相符,其计算公式如下：(The invention provides a method for evaluating the tensile film forming stability of polyamide. The main method comprises the following steps: (1) evaluation of intermolecular forces of Polyamide resin: testing the compressive Strength H of Polyamide specimens before and after soaking in solvents 0 ，H slt (ii) a Tensile Strength S 0 ，S slt And elongation at break l 0 ，l slt (ii) a (2) Testing of the melt Strength parameter S of Polyamide resins melt (ii) a (3) Testing the crystallization ability of the polyamide resin to obtain the relative crystallinity X of the annealed sample cA (ii) a (4) Calculating the film forming stability parameter P of the sample according to a formula stability The smaller the index, the higher the film formation stability of the sample. The invention provides an evaluation method of film forming stability of polyamide resin in a stretching process, which can be well used for measuring the film forming stability of polyamide in the stretching process, has high accuracy of a test result, is consistent with the reality, and has the following calculation formula:)

1. A method for evaluating the stability of a polyamide stretched film, which is characterized by comprising the following steps:

(1) evaluation of intermolecular forces of Polyamide resin:

soaking a polyamide sample in a solvent to swell the sample to be detected in the solvent and absorb the solvent with a certain mass fraction; the samples before and after soaking the solvent are subjected to a compression strength test to obtain the compression strength H of the samples before and after soaking the solvent₀，H_slt(ii) a The tensile strength and the elongation at break of the sample before and after soaking the solvent are tested to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

(2) Testing of melt Strength of Polyamide resins:

testing the melt strength of the resin to obtain a parameter S reflecting the melt strength of the resin_melt；

(3) Polyamide resins were tested for their ability to crystallize:

heating the sample to a certain temperature to eliminate thermal history, and then rapidly cooling to room temperature to obtain an initial sample with low crystallinity;then placing the sample at a certain annealing temperature and staying for a certain time to enable the sample to have annealing behavior to obtain an annealed sample, and then testing the relative crystallinity of the annealed sample to obtain the relative crystallinity X of the annealed sample_cA；

(4) Calculating the film forming stability parameter of the sample according to the following formula to obtain a parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

wherein SP is the solubility parameter of the solvent.

2. The method according to claim 1, wherein the solvent in the step (1) is butadiene, diethyl ether, cyclohexane, toluene, chloroform, acetone, isopropyl alcohol, ethanol, methanol or water.

3. The evaluation method according to claim 2, wherein the mass fraction of the absorbed solvent in the step (1) is in the range of 0.01 to 60% of the mass of the polyamide itself.

4. The evaluation method according to claim 3, wherein the mass fraction of the solvent absorbed in the step (1) is in the range of 0.5 to 20% of the mass of the polyamide itself.

5. The method as claimed in claim 1, wherein the compression strength test in step (1) is carried out according to the standard "GB/T1041-2008" determination of compression Properties of plastics ".

6. The method according to claim 1, wherein the tensile strength and elongation at break in step (1) are measured according to the national standard "determination of tensile Properties of plastics" GB T1040.4-2006.

7. The method of claim 1, wherein the melt strength in step (2) is measured by a melt flow Rate tester method.

8. The evaluation method according to claim 1, wherein the annealing temperature setting step in the step (3) is as follows: firstly, measuring the melting peak temperature of a sample, namely melting point, and then setting the annealing temperature to be 5-60 ℃ lower than the melting point temperature and the annealing time to be 3-300 s.

9. The evaluation method according to claim 8, wherein the annealing temperature in the step (3) is set to 10 to 40 ℃ lower than the melting point temperature, and the annealing time is 10 to 30 seconds.

10. The evaluation method according to claim 1, wherein the crystallinity and melting point test in step (3) is performed according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: the measurement of the melting and crystallization temperatures and the enthalpy "was carried out.

Technical Field

The invention belongs to the technical field of test methods, and particularly relates to an evaluation method for polyamide stretch film forming stability.

Background

The polyamide film is an oriented film prepared from nylon resin by a flat film method (casting the resin by a T-shaped film head after being extruded by a screw extruder to obtain a cast sheet, and then performing unidirectional or bidirectional stretching) or a tubular film method. The adopted resin is a polyamide resin raw material with higher viscosity. The commercial films currently on the market are mainly films of nylon 6 and nylon 66. The polyamide film has the advantages of high strength, high toughness, acid and alkali resistance, strong gas barrier property and the like, and is widely applied to the fields of food, daily chemicals, medicines, electronics and the like.

However, the polyamide molecular chains have strong interaction force, hydrogen bonds are easily generated, and the crystallization capacity is also strong. Therefore, the film formation stability during processing is often limited by the above factors. If the conditions are not controlled well, efficient and stable stretching film formation is difficult, and problems such as film failure, poor film formation stability, film breakage, non-uniform thickness, and poor uniformity tend to occur. Therefore, how to evaluate whether a polyamide resin is suitable for stretch film forming and how to evaluate the film forming stability during the stretching process is a technical problem to be solved in the art.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for evaluating the stretch film forming stability of polyamide. Aiming at the problems, the invention innovatively provides an evaluation method for the film forming stability of the polyamide resin in the stretching process, the method can be well used for measuring the film forming stability of the polyamide resin in the stretching process, and the test result has high accuracy and accords with the reality.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the method for evaluating the stretching film forming stability of the polyamide comprises the following steps:

(1) evaluation of intermolecular forces of Polyamide resin:

soaking a polyamide sample in a solvent to swell the sample to be detected in the solvent and absorb the solvent with a certain mass fraction; the samples before and after soaking the solvent are subjected to a compression strength test to obtain the compression strength H of the samples before and after soaking the solvent₀，H_slt(ii) a The tensile strength and the elongation at break of the sample before and after soaking the solvent are tested to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

(2) Testing of melt Strength of Polyamide resins:

testing the melt strength of the resin to obtain a parameter reflecting the melt strengthNumber S_melt；

(3) Polyamide resins were tested for their ability to crystallize:

heating the sample to a certain temperature to eliminate thermal history, and then rapidly cooling to room temperature to obtain an initial sample with low crystallinity; then placing the sample at a certain annealing temperature and staying for a certain time to enable the sample to have annealing behavior to obtain an annealed sample, and then testing the relative crystallinity of the annealed sample to obtain the relative crystallinity X of the annealed sample_cA；

(4) Calculating the film forming stability parameter of the sample according to the following formula to obtain a parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

wherein SP is the solubility parameter of the solvent.

The evaluation method provided by the invention is based on several resin characteristics influencing the stability of the polyamide resin film-forming process, including molecular bond acting force, melt strength, crystallization capacity and the like. And (3) investigating the characteristics of the resin through design experiments, extracting specific indexes, and automatically refining, summarizing and verifying the accuracy of a formula. The index which accurately reflects the film forming stability of the polyamide resin can be calculated by using the formula.

The method of the invention is not only suitable for polyamide resin, but also can be used for evaluating the film forming stability of other resins with stronger intermolecular force, such as polypropylene, polyethylene, polyvinyl alcohol, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate and the like.

Further, the solvent in the step (1) is butadiene, diethyl ether, cyclohexane, toluene, chloroform, acetone, isopropanol, ethanol, methanol or water.

Further, the mass fraction of the solvent absorbed in the step (1) is in the range of 0.01 to 60% of the mass of the polyamide itself.

Further, the mass fraction of the solvent absorbed in the step (1) is in the range of 0.5 to 20% of the mass of the polyamide itself.

Further, the compression strength test in the step (1) is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard.

Further, the tensile strength and the elongation at break described in the step (1) were tested according to the national standard "determination of tensile Properties of plastics" GB T1040.4-2006 ".

Further, the melt strength described in the step (2) is measured by a melt flow rate meter method.

Further, the annealing temperature setting step in the step (3) is as follows: firstly, measuring the melting peak temperature of a sample, namely melting point, and then setting the annealing temperature to be 5-60 ℃ lower than the melting point temperature and the annealing time to be 3-300 s.

Further, the annealing temperature in the step (3) is set to be 10-40 ℃ lower than the melting point temperature, and the annealing time is 10-30 s.

Further, the crystallinity and melting point tests described in step (3) are according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: the measurement of the melting and crystallization temperatures and the enthalpy "was carried out.

The invention has the following beneficial effects:

the invention provides a method for evaluating the stability of a polyamide stretch film, which analyzes indexes such as resin molecular bond acting force, melt strength, crystallization capacity and the like, respectively inspects the resin characteristics through design experiments, extracts specific indexes, and automatically refines, summarizes and verifies the accuracy of a formula. The index which accurately reflects the film forming stability of the polyamide resin can be calculated by using the formula provided by the invention. The evaluation method is high in accuracy, simple and convenient in test and evaluation, and capable of being popularized and applied in a large scale.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following embodiments, and it should be noted that the following embodiments are only for explaining and illustrating the present invention and are not intended to limit the present invention. The invention is not limited to the embodiments described above, but rather, may be modified within the scope of the invention.

Example 1

Film production was performed using two nylon 6 resins using a tube-film method for a period of 30 days. The statistics show that the membrane breaking times of the A sample per 72h are 2.8 on average, and the membrane breaking times of the B sample per 24h are 7.0 on average.

The two nylon 6 resin samples a and B were subjected to film forming stability test according to the following method:

(1) evaluation of intermolecular forces of Polyamide resin:

firstly, a polyamide sample is soaked in a solvent (butadiene) at a certain temperature for a certain time, so that the sample to be detected is swelled in the solvent, and the solvent with a certain mass fraction (5% of the self mass of the polyamide) is absorbed;

then, the compression strength of the samples before and after soaking in the solvent is tested according to the national standard to obtain the compression strength H of the samples before and after soaking in the solvent₀，H_slt(ii) a Then testing the tensile strength and the elongation at break of the sample before and after soaking the solvent according to the national standard to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

The compression strength test is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard;

the tensile test is carried out according to the national standard GB T1040.4-2006 Plastic tensile Property determination;

(2) testing of melt Strength of Polyamide resins:

the melt strength of the resin is measured according to the method proposed in the literature, obtaining a parameter S reflecting the melt strength_melt；

The method for testing the melt strength is based on the literature "Shanglong, Zhoudong bridge and Pengzuofang". The melt strength of the polymer and the testing technology thereof are tested by the method of section 3.2 melt flow rate determinator proposed in Chinese plastics 2003, 17, 08, 79-82;

(3) polyamide resins were tested for their ability to crystallize:

using a differential calorimeter, the sample is first warmed to a temperature to eliminate the thermal history and then rapidly cooled to room temperature to obtain an initial sample of low crystallinity. Then, the sample is placed at a certain annealing temperature and stays for a certain time, so that the annealing behavior is generated, and an annealed sample is obtained. Then, the annealed sample is tested for relative crystallinity, and finally the relative crystallinity X of the annealed sample is obtained_cA；

The annealing temperature setting step is as follows: firstly, measuring the melting peak temperature (melting point) of a sample, then setting the annealing temperature to be 10 ℃ lower than the melting point temperature, and setting the annealing time to be 10 s;

crystallinity and melting point measurements according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: pdf "and literature" plastics, vol 49, No. 6, pp 13-20, 2020;

(4) then, the film forming stability parameter is calculated according to the following formula to obtain the parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

the results of the above tests are shown in Table 1, and the film formation stability parameters P of the resins A and B were calculated according to the above method_stabilityThe number of the film is 2.64 and 6.93 respectively, and the test result is consistent with the rule of the actual film breaking times according to the numerical value, so that the tensile film forming stability of different resins can be reflected.

Example 2

Two kinds of nylon 66 resins were used, and film production for 60 days was carried out by a flat film method (simultaneous biaxial stretching process). Statistics shows that the membrane breaking times of the C sample per 72h are 1 time on average, and the membrane breaking times of the D sample per 24h are 5.7 times on average.

Film stability tests were conducted on the two nylon 66 resin samples C and D as follows:

(1) evaluation of intermolecular forces of Polyamide resin:

firstly, a polyamide sample is soaked in a solvent (cyclohexane) at a certain time and a certain temperature, so that the sample to be detected is swelled in the solvent, and the solvent with a certain mass fraction (15% of the self mass of the polyamide) is absorbed;

then, the compression strength of the samples before and after soaking in the solvent is tested according to the national standard to obtain the compression strength H of the samples before and after soaking in the solvent₀，H_slt(ii) a Then testing the tensile strength and the elongation at break of the sample before and after soaking the solvent according to the national standard to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

The compression strength test is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard;

the tensile test is carried out according to the national standard GB T1040.4-2006 Plastic tensile Property determination;

(2) testing of melt Strength of Polyamide resins:

the melt strength of the resin is measured according to the method proposed in the literature, obtaining a parameter S reflecting the melt strength_melt；

The method for testing the melt strength is based on the literature "Shanglong, Zhoudong bridge and Pengzuofang". The melt strength of the polymer and the testing technology thereof are tested by the method of section 3.2 melt flow rate determinator proposed in Chinese plastics 2003, 17, 08, 79-82;

(3) polyamide resins were tested for their ability to crystallize:

using a differential calorimeter, the sample is first warmed to a temperature to eliminate the thermal history and then rapidly cooled to room temperature to obtain an initial sample of low crystallinity. Then, it is placed at a certain positionAnd (4) keeping the sample at the annealing temperature for a certain time to enable the sample to have an annealing behavior, so as to obtain an annealed sample. Then, the annealed sample is tested for relative crystallinity, and finally the relative crystallinity X of the annealed sample is obtained_cA；

The annealing temperature setting step is as follows: firstly, measuring the melting peak temperature (melting point) of a sample, and then setting the annealing temperature to be 30 ℃ lower than the melting point temperature and the annealing time to be 30 s;

crystallinity and melting point measurements according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: pdf "and literature" plastics, vol 49, No. 6, pp 13-20, 2020;

(4) then, the film forming stability parameter is calculated according to the following formula to obtain the parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

the results of the above tests are shown in Table 1, and the film formation stability parameters P of the resins C and D were calculated according to the above method_stabilityThe number of the film is 1.08 and 5.62 respectively, and the test result is consistent with the rule of the actual film breaking times and can reflect the tensile film forming stability of different resins according to the judgment of the number.

Example 3

Two nylon 6 resins were used for 45-day film production by a flat film process (step biaxial stretching process). Statistics show that the membrane breaking times of the E sample per 72h are 2.2 times on average, and the membrane breaking times of the F sample per 24h are 0.5 times on average.

Film formation stability tests were conducted on the two nylon 6 resin samples E and F described above according to the following methods:

(1) evaluation of intermolecular forces of Polyamide resin:

firstly, a polyamide sample is soaked in a solvent (acetone) at a certain temperature for a certain time, so that the sample to be detected is swelled in the solvent, and the solvent with a certain mass fraction (20% of the self mass of the polyamide) is absorbed;

then, the compression strength of the samples before and after soaking in the solvent is tested according to the national standard to obtain the compression strength H of the samples before and after soaking in the solvent₀，H_slt(ii) a Then testing the tensile strength and the elongation at break of the sample before and after soaking the solvent according to the national standard to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

The compression strength test is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard;

the tensile test is carried out according to the national standard GB T1040.4-2006 Plastic tensile Property determination;

(2) testing of melt Strength of Polyamide resins:

the melt strength of the resin is measured according to the method proposed in the literature, obtaining a parameter S reflecting the melt strength_melt；

The method for testing the melt strength is based on the literature "Shanglong, Zhoudong bridge and Pengzuofang". The melt strength of the polymer and the testing technology thereof are tested by the method of section 3.2 melt flow rate determinator proposed in Chinese plastics 2003, 17, 08, 79-82;

(3) polyamide resins were tested for their ability to crystallize:

using a differential calorimeter, the sample is first warmed to a temperature to eliminate the thermal history and then rapidly cooled to room temperature to obtain an initial sample of low crystallinity. Then, the sample is placed at a certain annealing temperature and stays for a certain time, so that the annealing behavior is generated, and an annealed sample is obtained. Then, the annealed sample is tested for relative crystallinity, and finally the relative crystallinity X of the annealed sample is obtained_cA；

The annealing temperature setting step is as follows: firstly, measuring the melting peak temperature (melting point) of a sample, and then setting the annealing temperature to be 20 ℃ lower than the melting point temperature and the annealing time to be 40 s;

crystallinity and melting point measurements according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: pdf "and literature" plastics, vol 49, No. 6, pp 13-20, 2020;

(4) then, the film forming stability parameter is calculated according to the following formula to obtain the parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

the results of the above tests are shown in Table 1, and the film formation stability parameters P of the resins E and F were calculated according to the above method_stability2.17 and 0.44 respectively, and the numerical value can be judged, the test result is consistent with the rule of the actual membrane breaking times, and the tensile membrane forming stability of different resins can be reflected.

Example 4

Film production was carried out using two nylon 1010 resins using a tube-film process for a period of 60 days. Statistics shows that the average membrane breaking times of the G sample per 72H is 1.8, and the average membrane breaking times of the H sample per 24H is 0.6.

The film forming stability tests were carried out on the above two nylon 1010 resin samples G and H according to the following methods:

(1) evaluation of intermolecular forces of Polyamide resin:

firstly, a polyamide sample is soaked in a solvent (isopropanol) at a certain temperature for a certain time, so that the sample to be detected is swelled in the solvent, and the solvent with a certain mass fraction (10% of the self mass of the polyamide) is absorbed;

then, the compression strength of the samples before and after soaking in the solvent is tested according to the national standard to obtain the compression strength H of the samples before and after soaking in the solvent₀，H_slt(ii) a Then testing the tensile strength and the elongation at break of the sample before and after soaking the solvent according to the national standard to obtain the tensile strength of the sample before and after soaking the solventS₀，S_sltAnd elongation at break l₀，l_slt；

The compression strength test is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard;

the tensile test is carried out according to the national standard GB T1040.4-2006 Plastic tensile Property determination;

(2) testing of melt Strength of Polyamide resins:

the melt strength of the resin is measured according to the method proposed in the literature, obtaining a parameter S reflecting the melt strength_melt；

The method for testing the melt strength is based on the literature "Shanglong, Zhoudong bridge and Pengzuofang". The melt strength of the polymer and the testing technology thereof are tested by the method of section 3.2 melt flow rate determinator proposed in Chinese plastics 2003, 17, 08, 79-82;

(3) polyamide resins were tested for their ability to crystallize:

using a differential calorimeter, the sample is first warmed to a temperature to eliminate the thermal history and then rapidly cooled to room temperature to obtain an initial sample of low crystallinity. Then, the sample is placed at a certain annealing temperature and stays for a certain time, so that the annealing behavior is generated, and an annealed sample is obtained. Then, the annealed sample is tested for relative crystallinity, and finally the relative crystallinity X of the annealed sample is obtained_cA；

The annealing temperature setting step is as follows: firstly, measuring the melting peak temperature (melting point) of a sample, and then setting the annealing temperature to be 40 ℃ lower than the melting point temperature and the annealing time to be 20 s;

crystallinity and melting point measurements according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: pdf "and literature" plastics, vol 49, No. 6, pp 13-20, 2020;

(4) then, the film forming stability parameter is calculated according to the following formula to obtain the parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the more stable the film formation of the sample isThe higher the character is;

the results of the above tests are shown in Table 1, and R of resins G and H was calculated according to the above method_crackThe values are 1.61 and 0.51 respectively, and the value can be judged, the test result is consistent with the rule of the actual membrane breaking times, and the tensile membrane forming stability of different resins can be reflected.

Example 5

Two kinds of nylon 6 resins were used, and film production for a period of 50 days was carried out by a flat film method (simultaneous biaxial stretching process). Statistics show that the membrane breaking times of the I sample per 72h are 16.1 times on average, and the membrane breaking times of the J sample per 24h are 3.0 times on average.

Film formation stability tests were conducted on the two nylon 6 resin samples I and J described above according to the following methods:

(1) evaluation of intermolecular forces of Polyamide resin:

firstly, a polyamide sample is soaked in a solvent (acetone) at a certain temperature for a certain time, so that the sample to be detected is swelled in the solvent, and the solvent with a certain mass fraction (20% of the self mass of the polyamide) is absorbed;

then, the compression strength of the samples before and after soaking in the solvent is tested according to the national standard to obtain the compression strength H of the samples before and after soaking in the solvent₀，H_slt(ii) a Then testing the tensile strength and the elongation at break of the sample before and after soaking the solvent according to the national standard to obtain the tensile strength S of the sample before and after soaking the solvent₀，S_sltAnd elongation at break l₀，l_slt；

The compression strength test is carried out according to the national standard GB/T1041-2008 plastic compression performance determination standard;

the tensile test is carried out according to the national standard GB T1040.4-2006 Plastic tensile Property determination;

(2) testing of melt Strength of Polyamide resins:

the melt strength of the resin is measured according to the method proposed in the literature, obtaining a parameter S reflecting the melt strength_melt；

The method for testing the melt strength is based on the literature "Shanglong, Zhoudong bridge and Pengzuofang". The melt strength of the polymer and the testing technology thereof are tested by the method of section 3.2 melt flow rate determinator proposed in Chinese plastics 2003, 17, 08, 79-82;

(3) polyamide resins were tested for their ability to crystallize:

using a differential calorimeter, the sample is first warmed to a temperature to eliminate the thermal history and then rapidly cooled to room temperature to obtain an initial sample of low crystallinity. Then, the sample is placed at a certain annealing temperature and stays for a certain time, so that the annealing behavior is generated, and an annealed sample is obtained. Then, the annealed sample is tested for relative crystallinity, and finally the relative crystallinity X of the annealed sample is obtained_cA；

The annealing temperature setting step is as follows: firstly, measuring the melting peak temperature (melting point) of a sample, and then setting the annealing temperature to be 20 ℃ lower than the melting point temperature and the annealing time to be 40 s;

crystallinity and melting point measurements according to the national standard "GB/T19466.3-2004 Differential Scanning Calorimetry (DSC) part 3: pdf "and literature" plastics, vol 49, No. 6, pp 13-20, 2020;

(4) then, the film forming stability parameter is calculated according to the following formula to obtain the parameter P reflecting the film forming stability in the stretching process_stabilityThe smaller the index is, the higher the film forming stability of the sample is;

the results of the above tests are shown in Table 1, and the film formation stability parameters P of the resins I and J were calculated according to the above method_stabilityRespectively 15.55 and 2.94, and the value can be judged, and the test result and the reality thereof can be judgedThe rule of the number of times of film rupture is consistent, and the tensile film forming stability of different resins can be reflected.

TABLE 1

SP is the Solubility Parameter (SP) of the solvent, a physical constant that measures the miscibility of liquid materials, including rubber, since rubber is liquid under processing conditions. Its physical meaning is the square of the cohesive energy density of the material.

The solvents described in this patent and their corresponding SP values are shown in Table 2 below:

TABLE 2

Name of solvent	Butadiene	Ether (A)	Cyclohexane	Toluene	Chloroform	Acetone (II)	Isopropanol (I-propanol)	Ethanol	Methanol	Water (W)
											SP	6.8	7.7	8.25	8.9	9.4	9.8	11.15	12.8	14.8	23.41