CN114075373B - Modified polyglycolic acid composition, preparation method and application thereof - Google Patents

Abstract

The invention relates to the field of polymer materials, and discloses a modified polyglycolic acid composition, a preparation method and an application thereof. The modified polyglycolic acid composition includes polyglycolic acid, a modifying agent and an antioxidant; relative to 100 parts by weight of polyglycolic acid, the amount of the modifying agent is 0.5-5 parts by weight, and the antioxidant The consumption of agent is 0.1-1.5 weight part; Described modifying agent has the structure shown in formula I:

Wherein, R is H, C1-C6 alkyl, phenyl or C1-C6 alkoxy, and n is an integer greater than 2. The modified polyglycolic acid composition has a high thermal decomposition temperature, the stability at high temperature is significantly improved, and the melt viscosity is increased at the same time, which is beneficial to processing and molding.

Description

Modified polyglycolic acid composition and its preparation method and application

technical field

The invention relates to the field of polymer materials, in particular to a modified polyglycolic acid composition and its preparation method and application.

Background technique

Due to the serious environmental problems caused by the extensive use of traditional polymer materials, biodegradable polymer materials have received more and more attention. Polyglycolic acid (PGA) has excellent biodegradability, and the final degradation products are carbon dioxide and water. It is regarded as an environmentally friendly green polymer material. PGA has good prospects in medical applications such as medical sutures, tissue engineering, and drug sustained release systems, and is an important medical biodegradable polymer material. In addition, PGA can also be used in agricultural biodegradable films, degradable packaging materials and other fields.

Polymer materials are generally molded and processed into products at a temperature higher than the melting point. The melting point of PGA is about 220°C, and its molding processing temperature is very high, and PGA is prone to thermal degradation under high temperature conditions, resulting in a decrease in relative molecular weight and poor performance. Therefore, how to improve the relative molecular mass and viscosity of PGA has received more and more attention.

CN106566216A discloses a method for improving the secondary processing stability of polyhydroxy acid. Mix polyhydroxyacids (such as PGA, PLA) and bishydrazides (0.05-1%) uniformly; add the obtained mixture to a twin-screw extruder under the protection of an inert gas for melt mixing, and extrude out. The method enables the secondary processed polyhydroxy acid to also have higher molecular weight and higher mechanical properties. However, this technology only makes the catalyst inert by adding bishydrazides and improves the processing thermal stability, and does not solve the problem of low melt viscosity of polyhydroxy acid. That is, in the above-mentioned prior art, polyglycolic acid has poor processing thermal stability, is easily thermally degraded, and has low melt viscosity, which cannot meet actual needs.

Contents of the invention

The object of the present invention is to provide a modified polyglycolic acid composition and its preparation method and application in order to overcome the problems of poor thermal stability of polyglycolic acid during processing and easy degradation at high temperature in the prior art. The composition has a high thermal decomposition temperature, the stability at high temperature is significantly improved, and the melt viscosity is increased at the same time, which is beneficial to processing and molding.

In order to achieve the above object, the first aspect of the present invention provides a modified polyglycolic acid composition, wherein the modified polyglycolic acid composition includes polyglycolic acid, a modifier and an antioxidant;

Relative to 100 parts by weight of polyglycolic acid, the amount of the modifying agent is 0.5-5 parts by weight, and the amount of the antioxidant is 0.1-1.5 parts by weight;

Described modifying agent has the structure shown in formula I:

Wherein, R is H, C1-C6 alkyl, phenyl or C1-C6 alkoxy, and n is an integer greater than 2.

The second aspect of the present invention provides a method for preparing a modified polyglycolic acid composition, wherein the method comprises the following steps:

(1) After drying the polyglycolic acid, modifier and antioxidant respectively, mix them uniformly to obtain a mixture;

(2) Melting, blending and extruding the mixture obtained in step (1) through a twin-screw extruder to obtain the modified polyglycolic acid composition;

Described modifying agent has the structure shown in formula I:

Wherein, R is H, C1-C6 alkyl, phenyl or C1-C6 alkoxy, and n is an integer greater than 2.

The third aspect of the present invention provides the modified polyglycolic acid composition prepared by the above preparation method.

The fourth aspect of the present invention provides an application of the above-mentioned modified polyglycolic acid composition in degradable materials or barrier packaging materials.

The fifth aspect of the present invention provides an application of the above-mentioned modified polyglycolic acid composition in the preparation of at least one of film, fiber and board.

Through the above technical scheme, the modified polyglycolic acid composition provided by the present invention and its preparation method and application obtain the following beneficial effects:

In the present invention, the modified polyglycolic acid composition contains a modifier with a specific structure, and the modifier can modify the polyglycolic acid, so that the melt viscosity of the polyglycolic acid is significantly improved. At the same time, the thermal degradation rate is effectively reduced.

Further, in the present invention, the modified polyglycolic acid composition also includes an antioxidant, and the thermal decomposition temperature of the modified polyglycolic acid composition can be further increased by selecting the antioxidant to cooperate with the modifier, The thermal degradation during melt extrusion is reduced, thereby improving the thermal stability of the composition.

Description of drawings

FIG. 1 is an infrared comparison chart of the modified polyglycolic acid composition of Example 1 and the polyglycolic acid of Comparative Example 1.

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

The first aspect of the present invention provides a modified polyglycolic acid composition, wherein the modified polyglycolic acid composition includes polyglycolic acid, an antioxidant and a modifier;

Relative to 100 parts by weight of polyglycolic acid, the amount of the modifying agent is 0.5-5 parts by weight, and the amount of the antioxidant is 0.1-1.5 parts by weight;

Described modifying agent has the structure shown in formula I:

Wherein, R is H, C1-C6 alkyl, phenyl or C1-C6 alkoxy, and n is an integer greater than 2.

In the present invention, the modified polyglycolic acid composition contains a modifier having a structure shown in formula I and an antioxidant, and the combination of the two can significantly improve the thermal stability of polyglycolic acid during processing. Specifically, the modifier can modify the polyglycolic acid, and the modified polyglycolic acid composition thus obtained has the characteristics of high thermal decomposition temperature and high melt viscosity. Further, in formula I, R is methyl, ethyl, phenyl or methoxy, and n is an integer of 3-30.

In the present invention, in the modified polyglycolic acid composition, when the amount of polyglycolic acid, modifying agent and antioxidant satisfies the above-mentioned limitation, the modified polyglycolic acid composition has high thermal stability, melt viscosity high merit. Further, relative to 100 parts by weight of polyglycolic acid, the amount of the modifying agent is 1-3 parts by weight, the amount of the antioxidant is 0.5-1 parts by weight, the modified polyglycolic acid composition has more for excellent performance.

According to the present invention, the weight average molecular weight of the polyglycolic acid is 50,000-300,000, preferably 100,000-150,000.

According to the present invention, the antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants, preferably phosphite antioxidants.

More preferably, the antioxidant is selected from at least one of antioxidant 168, antioxidant 626 and antioxidant 9228.

According to the present invention, the 5% weight loss temperature of the polyglycolic acid and the 5% weight loss temperature of the modified polyglycolic acid composition are T1 and T2 respectively;

Wherein, T2-T1≥20°C, preferably, T2-T1 is 20-40°C.

In the present invention, the weight loss temperature of 5% by weight refers to the temperature corresponding to the weight loss of 5% by weight of polyglycolic acid, which is measured by the TG thermal weight loss method.

According to the present invention, at 240°C and a load of 2.16kg, the melt flow rates of the polyglycolic acid and the modified polyglycolic acid composition are MFR1 and MFR2, respectively;

Wherein, MFR2≤40%×MFR1, preferably, MFR2 is (10-25%)×MFR1.

In the present invention, the melt flow rate is measured according to the GB/T 3682-2000 method.

According to the present invention, at 230°C, 2% strain and 0.1rad/s frequency, the melt viscosities of the polyglycolic acid and the modified polyglycolic acid composition are η1 and η2 respectively, wherein η2≥4η1.

In the present invention, the melt viscosity of the polyglycolic acid composition is measured by rotational rheological frequency scanning.

The second aspect of the present invention provides a method for preparing a modified polyglycolic acid composition, wherein the method comprises the following steps:

(1) After drying the polyglycolic acid, modifier and antioxidant respectively, mix them uniformly to obtain a mixture;

(2) Melting, blending and extruding the mixture obtained in step (1) through a twin-screw extruder to obtain the modified polyglycolic acid composition;

Described modifying agent has the structure shown in formula I:

Wherein, R is H, C1-C6 alkyl, phenyl or C1-C6 alkoxy, and n is an integer greater than 2.

In the present invention, polyglycolic acid, a modifier having a structure shown in formula I and an antioxidant are melt-blended and extruded in a twin-screw extruder, so that the modifier containing maleic anhydride structure Realize the reactive extrusion modification of polyglycolic acid (PGA), and use the modifier to undergo a nucleophilic substitution reaction with the PGA end group -OH. The esterification reaction conditions are mild and the reaction rate is fast. At the same time, the modified polyglycolic acid composition obtained by adding an antioxidant has both high molecular weight, good processability and thermal stability.

According to the present invention, relative to 100 parts by weight of polyglycolic acid, the amount of the antioxidant is 0.1-1.5 parts by weight, preferably 0.5-1 parts by weight; the amount of the modifier is 0.5-5 parts by weight, Preferably it is 1-3 parts by weight.

According to the present invention, the weight average molecular weight of the polyglycolic acid is 50,000-300,000, preferably 100,000-150,000.

According to the present invention, in formula I, R is methyl, ethyl, phenyl or methoxy, and n is an integer of 3-30.

According to the present invention, the drying conditions include: the drying temperature is 50-80° C., preferably 60-80° C.; the drying time is 5-10 hours, preferably 5-8 hours.

In the present invention, the inventors found that when the polyglycolic acid and the antioxidant are dried under the above conditions, the moisture in the raw material can avoid the hydrolysis of the mixture containing the polyglycolic acid and the antioxidant during extrusion.

In the present invention, the inventors have studied the conditions of melt blending, and found that when the melt blending is extruded, the temperature is 220-250°C, and the screw speed is 80-110r/min, the extrusion process can be reduced. The degradation of polyglycolic acid avoids deterioration of the properties of the prepared polyglycolic acid composition. Furthermore, when the melt blending is extruded, the temperature is 230-240° C., and the screw speed is 90-100 r/min. The polyglycolic acid composition thus prepared has more excellent comprehensive properties.

The third aspect of the present invention provides a modified polyglycolic acid composition prepared by the above method.

In the present invention, the 5% weight loss temperature of the polyglycolic acid and the 5% weight loss temperature of the modified polyglycolic acid composition are T1 and T2 respectively;

Wherein, T2-T1≥20°C, preferably, T2-T1 is 20-40°C.

In the present invention, the 5% weight loss temperature refers to the temperature corresponding to 5% weight loss of polyglycolic acid, which is measured by TG thermal weight loss method.

In the present invention, at 240°C and a load of 2.16kg, the melt flow rates of the polyglycolic acid and the modified polyglycolic acid composition are MFR1 and MFR2, respectively;

Wherein, MFR2≤40%×MFR1, preferably, MFR2 is (10-25%)×MFR1.

In the present invention, the melt flow rate is measured according to the GB/T 3682-2000 method.

In the present invention, at 230°C, 2% strain and 0.1rad/s frequency, the melt viscosities of the polyglycolic acid and the modified polyglycolic acid composition are η1 and η2 respectively, wherein η2≥4η1.

In the present invention, the melt viscosity of the polyglycolic acid composition is measured by rotational rheological frequency scanning.

The fourth aspect of the present invention provides the application of the above-mentioned modified polyglycolic acid composition in degradable materials or barrier packaging materials.

The fifth aspect of the present invention provides the application of the above-mentioned modified polyglycolic acid composition in the preparation of at least one of film, fiber and plate.

The present invention will be described in detail below by way of examples. In the following examples,

The 5% by weight weight loss temperature of polyglycolic acid is measured by the TG thermogravimetric method;

The melt flow rate of polyglycolic acid is measured by GB/T 3682-2000 method;

The melt viscosity of polyglycolic acid was measured by rotational rheological frequency sweep (230°C, strain 2%, frequency 0.1-100rad/s);

The infrared spectrum of the modified polyglycolic acid composition and polyglycolic acid was measured by Fourier transform infrared spectrometer IRPrestige-21 of Japan Shimadzu Company, and the specific test conditions were: scanning range 4000-400cm ^-1 , scanning times 32 times;

Polyglycolic acid A, with a weight average molecular weight of 140,000, commercially available;

Polyglycolic acid B, with a weight average molecular weight of 90,000, commercially available;

Polyglycolic acid C, with a weight average molecular weight of 40,000, commercially available;

Modifier I, SMA1000, wherein, R is phenyl, n is 27, and the weight average molecular weight Mw is 5500, purchased from Yushuo New Material Technology Co., Ltd.;

Modifier II, CAS number: 9006-26-2, wherein, R is H, n is 3, and the weight average molecular weight Mw is 378, purchased from Shanghai Dingfen Chemical Technology Co., Ltd.;

Other raw materials used in Examples and Comparative Examples are commercially available.

Example 1

100 parts by weight of polyglycolic acid A, 3 parts by weight of modifier A and 1 part by weight of antioxidant (antioxidant 168) were dried for subsequent use, the drying temperature was 80°C, and the drying time was 6 hours; The acid, the modifier and the antioxidant were mixed evenly, and then the twin-screw extruder was used for melt blending, extrusion and granulation under the conditions of 240° C. and 90 r/min, to obtain the modified polyglycolic acid composition A1.

After testing, the melt flow rate MFR2 of the modified polyglycolic acid composition is 14g/10min (down to 32% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 349° C. (compared to that of Comparative Example 1 5% weight loss temperature T1 increased by 27°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 1500 Pa·s (increased to 5.7 times the melt viscosity η1 of Comparative Example 1).

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说明聚乙醇酸的端羟基由于发生化学反应而被消耗。The infrared spectrogram of the modified polyglycolic acid composition is as shown in Figure 1. In Figure 1, 3512cm ^-1 is the characteristic peak of -OH, and 720cm ^-1 is the CH vibration peak of saturated hydrocarbon group _CH , and the characteristic peak at 720cm ^-1 is Internal standard, to investigate the change of the 3512cm ^-1 peak, by calculating the infrared absorption peak area ratio to obtain the

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It shows that the terminal hydroxyl groups of polyglycolic acid are consumed due to chemical reactions.

Example 2

100 parts by weight of polyglycolic acid A, 3 parts by weight of modifier B and 1 part by weight of antioxidant (antioxidant 168) were dried for subsequent use, the drying temperature was 80°C, and the drying time was 6 hours; The acid, the modifier and the antioxidant were mixed evenly, and then the twin-screw extruder was used to perform melt blending, extrusion and granulation under the conditions of 240° C. and 90 r/min, to obtain the modified polyglycolic acid composition A2.

After testing, the melt flow rate MFR2 of the composition is 11g/10min (down to 25% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 351° C. (compared with the 5% weight loss temperature of Comparative Example 1 T1 increased by 29°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 1610 Pa·s (increased to 6.2 times the melt viscosity η1 of Comparative Example 1).

Example 3

100 parts by weight of polyglycolic acid A, 5 parts by weight of modifier B and 0.1 part by weight of antioxidant (antioxidant 168) were dried for subsequent use, the drying temperature was 80° C., and the drying time was 6 hours; The acid, the modifier and the antioxidant were mixed evenly, and then the twin-screw extruder was used for melt blending, extrusion and granulation under the conditions of 240° C. and 90 r/min, to obtain the modified polyglycolic acid composition A3.

After testing, the melt flow rate MFR2 of the composition is 10g/10min (down to 23% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 342°C (compared with the 5% weight loss temperature of Comparative Example 1 T1 increased by 20°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 1690Pa·s (increased to 6.5 times the melt viscosity η1 of Comparative Example 1).

Example 4

100 parts by weight of polyglycolic acid A, 0.5 parts by weight of modifier A and 1.5 parts by weight of antioxidant (antioxidant 168) were dried for subsequent use, the drying temperature was 80° C., and the drying time was 6 hours; The acid, the modifier and the antioxidant are mixed evenly, and then the twin-screw extruder is used for melt blending, extrusion and granulation under the conditions of 240° C. and 90 r/min, to obtain the modified polyglycolic acid composition.

After testing, the melt flow rate MFR2 of the composition is 17g/10min (down to 38% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 355°C (compared with the 5% weight loss temperature of Comparative Example 1 T1 increased by 33°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 1050 Pa·s (increased to 4 times the melt viscosity η1 of Comparative Example 1).

Example 5

The modified polyglycolic acid composition was prepared according to the method of Example 1, except that polyglycolic acid B was used instead of polyglycolic acid A.

After testing, the melt flow rate MFR2 of the composition is 23g/10min (down to 35% of the melt flow rate MFR1 ^* of Comparative Example 2), and the 5% weight loss temperature T2 is 344°C (compared with the 5% weight loss of Comparative Example 2 The temperature T1 ^* increases by 29°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 800 Pa·s (increased to 4.2 times the melt viscosity η1 ^* of Comparative Example 2).

Example 6

The modified polyglycolic acid composition was prepared according to the method of Example 1, except that the temperature for melt blending and extrusion was 230°C.

After testing, the melt flow rate MFR2 of the composition is 12.5g/10min (down to 28% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 347 ° C (compared with the 5% weight loss of Comparative Example 1 The temperature T1 is increased by 25° C.). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 1560 Pa·s (increased to 6 times the melt viscosity η1 of Comparative Example 1).

Comparative example 1

Dry 100 parts by weight of polyglycolic acid A for later use, the drying temperature is 80°C, and the drying time is 6 hours; the dried polyglycolic acid is melt-extruded with a twin-screw extruder at 240°C and a speed of 90r/min. out of granulation.

After testing, the melt flow rate MFR1 of polyglycolic acid is 44g/10min, and the 5% weight loss temperature T1 is 322°C. The melt viscosity η1 (230°C, strain 2%, 0.1rad/s) is 260Pa·s.

Comparative example 2

Polyglycolic acid was prepared according to the method of Comparative Example 1, except that polyglycolic acid B was used instead of polyglycolic acid A.

After testing, the melt flow rate MFR1 ^* of polyglycolic acid is 65g/10min, the temperature T1 ^* of 5% weight loss is 315°C, and the melt viscosity η1 ^* (230°C, strain 2%, 0.1rad/s) is 190Pa· s.

Comparative example 3

100 parts by weight of polyglycolic acid A and 1 part by weight of antioxidant (antioxidant 168) were dried for later use, the drying temperature was 80°C, and the drying time was 6 hours; the dried polyglycolic acid and antioxidant were mixed evenly, Then, a twin-screw extruder was used to carry out melt blending, extrusion and granulation under the conditions of 240° C. and 90 r/min, to obtain a modified polyglycolic acid composition.

After testing, the melt flow rate MFR2 of the composition is 27g/10min (down to 61% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 357° C. (compared with the 5% weight loss temperature of Comparative Example 1 T1 increased by 35°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 500 Pa·s (increased to 1.9 times the melt viscosity η1 of Comparative Example 1).

Comparative example 4

The modified polyglycolic acid composition was prepared according to the method of Example 1, except that no antioxidant was added.

After testing, the melt flow rate MFR2 of the composition is 19g/10min (down to 43% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 339 ° C (compared with the 5% weight loss temperature of Comparative Example 1 T1 increased by 17°C). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 900 Pa·s (increased to 3.5 times the melt viscosity η1 of Comparative Example 1).

Comparative example 5

The modified polyglycolic acid composition was prepared according to the method of Example 1, except that the amount of antioxidant and modifier was different from that of Example 1.

After testing, the melt flow rate MFR2 of the composition is 30.8g/10min (down to 70% of the melt flow rate MFR1 of Comparative Example 1), and the 5% weight loss temperature T2 is 332°C (compared with the 5% weight loss of Comparative Example 1 The temperature T1 is increased by 10° C.). The melt viscosity η2 (230°C, 2% strain, 0.1rad/s) was 540 Pa·s (increased to twice the melt viscosity η1 of Comparative Example 1).

Table 1 (parts by weight)

Example polyglycolic acid Modifier I Modifier II antioxidant melt blending extrusion Example 1 A/100 3 0 1 240℃/90r/min Example 2 A/100 0 3 1 240℃/90r/min Example 3 A/100 0 5 0.1 240℃/90r/min Example 4 A/100 0 0.5 1.5 240℃/90r/min Example 5 B/100 3 0 1 240℃/90r/min Example 6 A/100 3 0 1 230℃/90r/min Comparative example 1 A/100 0 0 0 240℃/90r/min Comparative example 2 B/100 0 0 0 240℃/90r/min Comparative example 3 A/100 0 0 1 240℃/90r/min Comparative example 4 A/100 3 0 0 240℃/90r/min Comparative example 5 A/100 0.2 0 0.3 240℃/90r/min

As can be seen from the results in Table 1, polyglycolic acid is modified by using the modifying agent with a specific structure of the present invention in conjunction with an antioxidant, and the thermal stability of polyglycolic acid after modification is significantly improved, and its Melt viscosity, the overall performance of the obtained polyglycolic acid composition is more excellent.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (20)

1. A modified polyglycolic acid composition, wherein the modified polyglycolic acid composition comprises polyglycolic acid, a modifier, and an antioxidant;

the modifier is used in an amount of 0.5 to 5 parts by weight and the antioxidant is used in an amount of 0.1 to 1.5 parts by weight relative to 100 parts by weight of polyglycolic acid;

the modifier has a structure shown in a formula I:

wherein R is H, C alkyl of 1-C6, phenyl or C1-C6 alkoxy, and n is an integer greater than 2.

2. The modified polyglycolic acid composition of claim 1, wherein in formula I, R is methyl, ethyl, phenyl, or methoxy, and n is an integer from 3 to 30.

3. The modified polyglycolic acid composition of claim 1 or 2, having a weight average molecular weight of 5-30 ten thousand.

4. The modified polyglycolic acid composition of claim 1 or 2, having a weight average molecular weight of 10-15 ten thousand.

5. The modified polyglycolic acid composition of claim 1 or 2, wherein the modifier is used in an amount of 1-3 parts by weight and the antioxidant is used in an amount of 0.5-1 parts by weight, relative to 100 parts by weight of polyglycolic acid;

and/or the antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants.

6. The modified polyglycolic acid composition of claim 1 or 2, wherein the antioxidant is selected from phosphite antioxidants.

7. The modified polyglycolic acid composition of claim 1 or 2, wherein the antioxidant is selected from at least one of antioxidant 168, antioxidant 626, and antioxidant 9228.

8. The modified polyglycolic acid composition of claim 1 or 2, wherein the polyglycolic acid has a 5 weight percent weight loss temperature and the modified polyglycolic acid composition has a 5 weight percent weight loss temperature of T1 and T2, respectively;

wherein T2-T1 is more than or equal to 20 ℃;

and/or, at 240 ℃ and under a load of 2.16kg, the melt flow rates of the polyglycolic acid and the modified polyglycolic acid composition are MFR1 and MFR2, respectively;

wherein MFR2 is less than or equal to 40% by MFR1;

and/or, the melt viscosity of the polyglycolic acid and modified polyglycolic acid compositions are η1 and η2, respectively, wherein η2 is greater than or equal to 4 η1, at 230 ℃, 2% strain and a frequency of 0.1 rad/s.

9. The modified polyglycolic acid composition of claim 8, wherein T2-T1 is 20-40 ℃;

and/or MFR2 is (10-25%). Times.MFR1.

10. A process for preparing a modified polyglycolic acid composition, wherein the process comprises the steps of:

(1) Respectively drying polyglycolic acid, a modifier and an antioxidant, and uniformly mixing to obtain a mixture;

(2) Carrying out melt blending extrusion on the mixture obtained in the step (1) through a double-screw extruder to obtain the modified polyglycolic acid composition;

the modifier has a structure shown in a formula I:

wherein R is H, C alkyl of 1-C6, phenyl or C1-C6 alkoxy, n is an integer greater than 2;

the antioxidant is used in an amount of 0.1 to 1.5 parts by weight relative to 100 parts by weight of polyglycolic acid; the modifier is used in an amount of 0.5 to 5 parts by weight.

11. The method of claim 10, wherein the polyglycolic acid has a weight average molecular weight of 5-30 ten thousand.

12. The method according to claim 10 or 11, wherein the antioxidant is used in an amount of 0.5 to 1 part by weight relative to 100 parts by weight of polyglycolic acid; the modifier is used in an amount of 1-3 parts by weight;

and/or, the polyglycolic acid has a weight average molecular weight of 10 to 15 ten thousand.

13. The method according to claim 10 or 11, wherein in formula I, R is methyl, ethyl, phenyl or methoxy, and n is an integer from 3 to 30.

14. The production method according to claim 10 or 11, wherein the drying conditions include: the drying temperature is 50-80 ℃; the drying time is 5-10h.

15. The production method according to claim 10 or 11, wherein the drying conditions include: the drying temperature is 60-80 ℃; the drying time is 5-8h.

16. The production method according to claim 10 or 11, wherein the conditions of melt blending extrusion include: the temperature is 220-250 ℃; the rotating speed of the screw is 80-110r/min.

17. The production method according to claim 10 or 11, wherein the conditions of melt blending extrusion include: the temperature is 230-240 ℃; the rotating speed of the screw is 90-100r/min.

18. A modified polyglycolic acid composition produced by the process of any one of claims 10-17.

19. Use of a modified polyglycolic acid composition of any one of claims 1-9 and claim 18 in a degradable material or barrier packaging material.

20. Use of the modified polyglycolic acid composition of any one of claims 1-9 and claim 18 in the preparation of at least one of a film, a fiber, and a sheet.

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