Starch and polylactic acid composite material and preparation method thereof

Abstract

The invention relates to a starch and polylactic acid composite material and a preparation method thereof. The composite material comprises, by weight, 20 to 75 parts of modified starch, 10 to 65 parts of polylactic resins, 2 to 10 parts of hydroxy-terminated lactic acid oligomer with molecular weight of 800 to 2000, 1 to 10 parts of plasticizers, 0.1 to 1.0 part of aliphatic chain extenders, 0.5 to 2 parts of talcum powders and 0.1 to 3 parts of auxiliaries. The preparation method includes that firstly the modified starch, the polylactic acids, the hydroxy-terminated lactic acid oligomer, the plasticizers, the talcum powders, lubricating agents and coupling agents are blended together in a homogenizer to obtain a blend, and then a mixed material of the blend and the chain extenders is added in a twin-screw extruder to be subjected to melt extrusion, cooling and granulation to obtain the starch and polylactic acid composite material. The starch and polylactic acid composite material has the advantages that the compatibility, toughness and heat resistance are good, the cost is low, the biodegradation can be completely achieved, the preparation technique process is simple, the 'three wastes' emission is absent, and the mass production can be achieved.

Description

technical field [0001] The invention belongs to the technical field of biodegradable polymer materials, and in particular relates to a composite material of starch and polylactic acid and a preparation method thereof. Background technique [0002] At present, with the increasing shortage of petroleum resources, environmental pollution has become one of the most important problems for human survival, and the fully degradable non-petroleum-based polymer materials have attracted more and more attention. Polylactic acid is a polymer material obtained from corn fermentation and repolymerization. It is an environmentally friendly and biodegradable material. At the same time, polylactic acid has good biocompatibility, thermoplastic processing performance and mechanical properties, and can be used in various high-grade materials. field of molecular materials. However, the high price of polylactic acid has greatly restricted its application. As a natural polymer compound, plant sta...

AI Technical Summary

Problems solved by technology

So far, there have been many researches and reports on polylactic acid and starch blend materials at home and abroad, but there are still problems such as poor compatibility, poor toughness, low heat distortion temperature, less starch addition and a large amount of non-degradable Sexual additives etc.

[0003] For example, Chinese patent CN 102408690 A discloses a thermoplastic starch-modified polylactic acid material, which forms a blend system of starch and polylactic acid through simple direct blending, but the starch and polylactic acid are incompatible, and the interface of the blend system sticks Poor performance, resulting in low mechanical properties of the product

[0004] Chinese patent CN 101831155 A discloses a method for preparing a starch / polylactic acid blend, and the chain extender used is a toxic diisocyanate compound, which limits its application in disposable food packaging and tableware

[0005] Chinese patent CN 102311562A discloses a blend of thermoplastic starch and polylactic acid and its preparation method. The solubilizer used is polyhydroxyester ether, which is beneficial to the mechanical properties of the starch / polylactic acid blend system. A certain improvement, but the degree of performance improvement is limited

[0006] Chinese patent CN 101781448A discloses a preparation method of a fully biodegradable reinforced polylactic acid / starch blend, which improves the mechanical and thermal properties of the blend by adding a thermoplastic elastic toughening agent, but the used Thermoplastic elastic tougheners are liquid rubber or thermoplastic elastomers, which are non-biodegradable components that affect the complete degradability of the blend

[0007] Chinese patent CN 101948613A discloses a fully biodegradable high-toughness polylactic acid resin and its preparation method, in which the solvent toluene is used for reflux and water separation during the starch modification process, and the final modified starch contains residual solvent toluene, which is highly volatile , it is easy to spread when exposed to the air, which is not conducive to environmental protection

[0008] Chinese patent CN 101343406A discloses a temperature-resistant polylactic acid-starch alloy system biodegradable material and its preparation method. Although the heat distortion temperature of polylactic acid is increased to above 85°C, the content of grafted modified starch is only 10 ~20, the filler component in polylactic acid does not exceed 40, the manufacturing cost is high

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