增容纳米纤维素/聚乳酸复合材料的制备与性能

采用接枝共聚法制备了马来酸酐和丙烯酸丁酯双单体接枝聚乳酸（PLA）共聚物（mPLA），然后以mPLA为增容剂，通过溶液浇铸法制备纳米纤维素（NCC）/PLA复合材料。采用SEM、DSC、TG、广角X射线衍射（WXRD）、力学和降解性能测试研究了mPLA对NCC/PLA复合材料的结构和性能的影响。结果表明:mPLA在PLA与NCC之间起到了良好的界面增容作用，促进了NCC在PLA基体中的分散。更精细分散的NCC促进了PLA的结晶成核，复合材料的结晶温度降低，结晶度提高；NCC/mPLA/PLA复合材料的力学性能随着mPLA含量增加呈先上升后下降的趋势，当mPLA含量为8%时，复合材料的拉伸强度和弹性模量与未添加mPLA的复合材料相比，分别提高了30.2%和41.4%；亲水性的NCC加速了NCC/PLA复合材料的降解，加入mPLA后，复合材料的降解速率有所减慢，但仍然快于纯PLA的降解。 

Preparation and properties of compatibilized cellulose nanocrystal/poly(lactic acid) composites

Poly (lactic acid) (PLA) graft copolymer (mPLA) was prepared by graft copolymerization using maleic anhydride and butyl acrylate as comonomers. Then the mPLA was used as compatibilizer to prepare cellulose nanocrystal (NCC)/PLA composites by solution casting method. Effects of mPLA on the structure and properties of NCC/PLA composites were investigated by SEM, DSC, TG, wide angle X-ray diffraction(WXRD), mechanical testing and degradation property test. Results show that the application of mPLA in NCC/PLA composites improves compatibilization between NCC and PLA, and promotes dispersion of NCC in the PLA matrix. More finely dispersed NCC enhances the crystallization nucleation of PLA, resulting in lower crystallization temperature and higher crystallinity. Mechanical properties of NCC/mPLA/PLA composite increase then decrease with increasing mPLA content, when the content of mPLA is 8%, the tensile strength and elastic modulus increase about 30.2% and 41.4% respectively in comparison with those of composite without mPLA. The hydrophilic NCC accelerates degradation of NCC/PLA composite, when mPLA is added, the degradation rate of NCC/PLA composite slowes down but is still higher than that of pure PLA.