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Stereo-complex polylactic acid material or product with excellent melt stability and melt processability and preparation method thereof

A melt-stabilized and composite polylactic acid technology, applied in the field of stereocomposite polylactic acid materials or products and their preparation, can solve the problems of SC-PLA melt viscosity, low melt strength, difficulty in melt processing and interchain interaction Weaken and other problems, to achieve excellent melt processing performance, excellent melt stability, and the effect of inhibiting separation

Active Publication Date: 2020-08-18
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the melt processing method is used to prepare the weight average molecular weight greater than 1 × 10 5 The high molecular weight of g / mol (high molecular weight is an important prerequisite to ensure the high performance of PLA) SC-PLA faces huge difficulties and challenges: on the one hand, the melt stability of high molecular weight SC-PLA is very poor (PLLA and PLA in the molten state PDLA chain pairs are easy to separate, and the interaction between chains will be greatly weakened, and even cause microphase separation between PLLA and PDLA, so it is easy to form HC crystals in their respective microdomains during the crystallization process), that is to say, even if 100% SC SC-PLA composed of crystals is used as a raw material, but it is still difficult to obtain SC-PLA products composed of 100% SC crystals after melt processing and molding. The obtained products often have SC and HC crystals at the same time, and the existence of HC crystals will seriously reduce the quality of the product. Various properties, such as heat resistance, mechanical strength and hydrolysis resistance, etc.; on the other hand, the melt processing of SC-PLA needs to be carried out at a temperature higher than the melting point of SC crystal (higher than 230 ° C), at this time SC -The melt viscosity and melt strength of PLA are low, which makes the melt processing of SC-PLA difficult, especially in blown film, foaming and other molding processes that require high melt viscosity and melt strength middle

Method used

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  • Stereo-complex polylactic acid material or product with excellent melt stability and melt processability and preparation method thereof
  • Stereo-complex polylactic acid material or product with excellent melt stability and melt processability and preparation method thereof
  • Stereo-complex polylactic acid material or product with excellent melt stability and melt processability and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The weight average molecular weight was 5.0×10 5 g / mol and 3.7×10 5 PLLA and PDLA with g / mol and optical purity of 90% and 95% respectively were vacuum-dried at 60°C until the water content was lower than 200ppm under a vacuum degree of less than 900Pa; 0.1 part of ADR4300 grafting agent, 0.1 part of 14DMA catalyst, 50 1 part of PLLA and 50 parts of PDLA were stirred and mixed evenly; the mixed material was added to a torque rheometer, melted and blended at a temperature of 170 ° C for 3 minutes, and granulated to obtain SC-PLA pellets. The crystallinity of the obtained pellets was 30.7%, and the melting temperature was 210°C; at 240°C, the viscosity of the SC-PLA melt in the high-frequency region was 56Pa·s, and the melt index was 55.1g / 10min.

[0040] The Vicat softening temperature and heat distortion temperature of the product obtained by melting the above pellets at 240°C were 180°C and 166°C, respectively.

Embodiment 2

[0042] The weight average molecular weight was 3.2×10 5 g / mol and 1.0×10 5 PLLA and PDLA with g / mol and optical purity of 92% and 99% respectively were vacuum-dried at 60°C until the moisture content was lower than 200ppm under a vacuum degree of less than 900Pa; 0.2 parts of TTI grafting agent, 0.2 parts of 12DMA catalyst, 50 1 part of PLLA and 50 parts of PDLA were stirred and mixed evenly; the mixed material was added to a torque rheometer, melted and blended at a temperature of 210 ° C for 4 minutes, and granulated to obtain SC-PLA pellets. The crystallinity of the obtained pellets was 55.2%, and the melting temperature was 227°C; at 240°C, the viscosity of the SC-PLA melt in the high-frequency region was 116Pa·s, and the melt index was 26.3g / 10min.

[0043] The Vicat softening temperature and heat distortion temperature of the product obtained by melting the above pellets at 240°C were 205°C and 190°C, respectively.

Embodiment 3

[0045] The weight average molecular weight was 2.6×10 5 g / mol and 5.0×10 5 PLLA and PDLA with g / mol and optical purity of 95% and 99.5% respectively are vacuum-dried at 60°C until the water content is lower than 200ppm under a vacuum degree of less than 900Pa; 0.3 parts of L-lysine triisocyanate grafting agent, 0.3 parts of 18DMA catalyst, 50 parts of PLLA and 50 parts of PDLA were stirred and mixed evenly; the mixture was added to a torque rheometer, melted and blended at a temperature of 200°C for 7 minutes, and granulated to obtain SC-PLA pellets. The crystallinity of the obtained pellets was 53.1%, and the melting temperature was 222°C; at 240°C, the viscosity of the SC-PLA melt in the high-frequency region was 188Pa·s, and the melt index was 3.6g / 10min.

[0046] The Vicat softening temperature and heat distortion temperature of the product obtained by melting the above pellets at 240°C were 202°C and 189°C, respectively.

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Abstract

The invention discloses a stereo-complex polylactic acid material or product with excellent melt stability and melt processability and a preparation method thereof. A grafting agent, a catalyst, L-polylactic acid and D-polylactic acid are mixed uniformly, then the mixed materials are added into a melting mixer, the mixed materials are blended and granulated, and the granules are melted, processed,and molded to obtain the SC-PLA material or product with excellent melt stability and melt processability. Part of PLA molecular chains are grafted to molecular chains of the grafting agent in-situ by virtue of a reactive blending technology, so that a grafted copolymer with a long branch chain structure is obtained, the melt stability of SC-PLA is effectively improved, and the obtained SC-PLA also has good melt processability. The preparation method is simple, feasible, green and efficient, and large-scale industrial production is easy to realize.

Description

technical field [0001] The invention belongs to the technical field of polylactic acid materials and their preparation, and in particular relates to a stereocomposite polylactic acid material or product with excellent melt stability and melt processability prepared by reactive melt blending technology and a preparation method thereof. Background technique [0002] Since the last century, the polymer industry has developed rapidly. With its advantages of light weight, low price, and good flexibility, polymer materials have gradually replaced wood, metal, etc. in various fields such as construction, industrial packaging, and consumer goods. Traditional materials such as glass and ceramics. In 2017, my country's domestic production of plastic products has reached as high as 70 million tons. However, while traditional petroleum-based synthetic polymers bring great convenience to human production and life, they also bring two serious problems. On the one hand, the synthesis of ...

Claims

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Application Information

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IPC IPC(8): C08G81/02C08G63/91
CPCC08G63/912C08G81/027
Inventor 白红伟傅强邓世豪张琴
Owner SICHUAN UNIV
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