Method for preparing polylactic acid composites with high impact toughness by reactive blending of vegetable oil derivatives

Abstract

The invention discloses a vegetable oil derivative reactive blending method for preparing a high-impacting toughness polylactic acid compound. The method adopts carboxy groups or a hydroxyl group anda carboxy group at the two ends of a toughening monomer a, and the carboxy groups or the hydroxyl group and the carboxy group and a toughening monomer b isocyanate group are subjected to a high-activity condensation reaction; if the toughening monomer a further contains an unsaturated C=C double bond, a free radical cross-linking reaction is conducted again, in the PLA melt blending process, a bio-based elastomer toughening phase which has good compatibility with a PLA base body and is dispersed uniformly is generated in situ, and the required product is finally obtained. The prepared PLA compound has higher biological base content, better biodegradability and better biocompatibility, and due to the fact that the toughening monomer a (namely, a dual functional group vegetable oil derivative containing binary carboxy groups or the hydroxyl group and the carboxy group) skeleton has a hydrophobicity character, the generated PLA compound has a better water resisting property.

Description

technical field [0001] The invention belongs to the technical field of macromolecular materials, and relates to a method for preparing a polylactic acid compound with good environmental friendliness and high impact toughness by reactive blending of vegetable oil derivatives. Background technique [0002] Polylactic acid (PLA) is a thermoplastic aliphatic polyester polymerized from lactic acid or its dimer lactide. Since lactic acid monomers can be synthesized through fermentation of agricultural products such as corn or sugarcane, PLA raw materials are abundant and renewable. PLA has good biocompatibility and biodegradability, but also has the advantages of high strength and modulus, good transparency, and easy processing. It is recognized as the most promising application among many chemically synthesized biodegradable polymer plastics. "Green" material. However, the toughness of PLA is very poor, especially the notched impact strength is significantly low (only 10-20J / m)...

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Problems solved by technology

However, the toughening agent monomers used in this report mainly have the following three disadvantages: (1) Polyol toughening monomers are mostly derived from non-renewable petroleum resources, so the toughened and modified PLA materials are environmentally friendly, biologically The poor degradability and biocompatibility limit its application in fields such as biomedical materials, and the impact toughness still needs to be further improved to meet the requirements of some engineering fields; (2) the hydrophilic polyether structural unit used will Lead to poor water resistance of PLA composites (Polym.Chem., 2014, 5, 2530-2539; RSC Adv., 2014, 4, 12857-12866.), there are performance defects in the application of some engineering materials; (3 ) The toughening phase structure formed by the toughening agent monomer used is a cross-linked structure, and the melt viscosity increases significantly (improved by an order of magnitude), which is not conducive to subsequent molding processing

However, due to the lack of good interfacial compatibility or reactivity between vegetable oils and their derivatives and PLA, even after adding interfacial compatibilizers, the improvement in the impact toughness of PLA is still limited.

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