【作者】 张久礼；

【导师】 戚嵘嵘；

【作者基本信息】 上海交通大学 ， 材料学， 2010， 硕士

【摘要】 聚乳酸(PLA)是一种以可再生的植物资源为原料经化学合成制备的生物降解高分子,制备的各种薄膜、纤维等产品可以广泛应用在服装、纺织、无纺布、包装、农业、林业、医疗卫生用品、日常生活用品等领域。PLA具有优良的生物相容性、生物可降解性,最终降解产物是二氧化碳和水,不会对环境造成污染。可由于PLA分子链中长支链少,熔体粘度很小,导致熔体强度低,应变硬化不足,使其加工成型方法受到限制,尤其是发泡成型十分困难,很难得到高倍率的发泡成型体。高分子链的支化,与另一种共聚物接枝,或共混支化聚合物和线性聚合物是增加其粘度的基本方法,以使其能够发泡。本论文首先通过端羧基聚酯(CP)与固体环氧(SE)的原位交联反应,采用熔融挤出及模压方法制备PLA/SE与PLA/CP/SE复合材料,并系统研究了其流变性能、热性能、形态结构、机械性能。我们发现对于PLA/SE复合材料,随着SE含量的增加,平行板流变仪表明其粘度先增加后基本不变;DSC及偏光显微镜表明结晶度表现为先降低后增加;SEM与DSC表明二者相容性较好,但仍为不相容的体系;拉伸测试表明断裂伸长率有一定程度的增加,拉伸强度略有下降。而对于PLA/CP/SE复合材料,随着CP/SE含量的增加,平行板流变仪表明粘度有显著地增加;DSC及偏光显微镜表明结晶度明显降低;SEM与DSC表明复合材料为不相容体系;拉伸测试表明拉伸强度明显增加,断裂伸长率变化不明显。我们成功制备了具有高粘度的PLA/CP/SE复合材料。其次本论文采用传统的模压化学发泡方法来制备聚乳酸发泡材料,力图使现有传统发泡企业就能进行聚乳酸发泡材料的制备与生产。本论文详细研究了发泡剂偶氮二甲酰胺用量,发泡助剂氧化锌用量,CP/SE用量以及发泡工艺等因素对聚乳酸发泡过程及泡沫材料的性能影响。找到了较合适的成功发泡配方和工艺条件,可以成功地制备聚乳酸发泡材料,并且聚乳酸发泡材料的密度可以在0.155-0.546g/cm3可控,同时该发泡材料具有良好的吸水性,最高吸水率可达到11%。更多还原

【Abstract】 Polylactide (PLA) is a kind of biodegradable polymer prepared by chemical synthesis through renewable plant as raw materials, which can be processed into a variety of film, sheet, fibers and other products widely used in garment, textile, non-woven fabrics, packaging, agriculture, forestry, medical and health supplies, daily necessities and other fields. PLA has excellent biocompatibility, biodegradability, and the ultimate degradated products are carbon dioxide and water, which have no pollution to the environment. However, due to the molecular chain of PLA lacks of long-branched, the melt viscosity is very small, leading to particularly low melt strength, lacking of strain hardening makes it difficult for foaming, and it’s difficult to get high magnification of the foaming material. Branching polymer chains, copolymerizing with another monomer, and blending branched or cross-linked polymers are the basic methods to increase its viscosity so that it can be suitable for foaming.In this paper, first through the in situ cross-linking reaction of terminal carboxyl polyester (CP) and epoxy (SE), using melt extrusion and molding method to prepare PLA/SE and PLA/CP/SE composites materials. The effect of the various factors on their rheological properties, thermal properties, morphological structure and mechanical properties has been studied in detail. The results show that the viscosity of the PLA/SE composite materials firstly increases and reaches a level with the increase of SE concentration; DSC and polarized optical microscopy show that the crystallinity firstly reduced and then increasd; SEM and DSC indicate that the PLA/SE system is immiscible; their elongation at break increase, while tensile strength decreased slightly compare to pure PLA. As for the PLA/CP/SE composite materials, with the CP/SE content increasing, their viscosity has a significant increase; DSC and polarized optical microscopy show that the crystallinity obviously decreased; SEM indicates that there exists reaction-induced phase separation in binary polymer; tensile tests show a marked increase in tensile strength, elongation at break did not change significantly. We have successfully prepared high viscosity PLA/CP/SE composite.Secondly, PLA foam can be successfully prepared through traditional compression molding chemical foaming method. The effect of the different factors such as foaming agent content, CP/SE content and process conditions on the properties of PLA foam material has been discussed. Optimal process conditions and appropriate formulas have been found. The density of PLA foam can be controlled from 0.546-0.155g/cm3.更多还原