超韧PLA共混体系的相形态、界面相容性及性能研究

发布时间：2018-01-22 23:23

本文关键词： PLA超韧机械性能界面相容性相形态增韧机理　出处：《青岛科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：聚乳酸(PLA)具有优异的可生物降解性、生物相容性、高的机械强度和易加工性能,被认为是目前最具发展潜力的生物材料。但是,聚乳酸的缺口冲击强度只有2.7kJ·m-2,断裂伸长率约为3.5%,其自身的脆性大、耐热温度低和结晶速率慢等缺点严重制约着PLA材料在塑料领域的发展与应用。因此,发展超韧性聚乳酸材料具有重要的理论和应用价值。本文分别以“核壳结构共聚物”、“改性天然橡胶”、“生物弹性体”为增韧剂,通过反应性熔融共混,制备了超韧聚乳酸共混物。系统研究了不同增韧剂对聚乳酸共混物机械性能的影响规律。通过傅里叶红外光谱(FT-IR)、热分析、扫描电子显微镜(SEM)等测试方法分别研究了不同增韧剂对PLA共混体系的界面相容性和相态结构的影响规律,进一步探索超韧PLA共混物的增韧机理。主要的研究结论如下:(1)以聚丁二烯(PB)为种子乳液,苯乙烯(St)和甲基丙烯酸缩水甘油酯(GMA)为接枝单体,采用乳液聚合制备得到聚丁二烯-苯乙烯-甲基丙烯酸缩水甘油酯(PB-g-St-GMA)核壳共聚物,FT-IR和透射电镜(TEM)测试结果表明合成得到目标产物且共聚物的形貌为纺锤型核壳结构。研究了反应时间、引发剂浓度和乳化剂浓度对聚合产率及产物粒径的影响,结果表明:当引发剂浓度为0.5wt%、乳化剂浓度为0.5wt%、反应时间为4h时,聚合物产率可达到93.5%。(2)研究了PB-g-St-GMA和聚丙烯腈-丁二烯-苯乙烯(ABS)核壳共聚物对PLA共混物的力学性能和结晶行为的影响。结果表明:当PB-St-GMA含量为10wt%时,断裂伸长率达到10.1%,比纯PLA提高了约2倍。少量ABS明显改善PLA共混物的延展性。当ABS含量为6wt%时,PLA共混物的断裂伸长率达到118%,比纯PLA提高了约23倍,冲击强度提高约1倍。FT-IR和动态机械分析(DMA)测试结果表明PLA基体的酯基和ABS壳层PSAN的腈基之间产生了极性相互作用,改善了PLA与ABS之间相容性,且少量的ABS作为异相成核剂提高了PLA相的结晶速率。(3)采用自由基聚合,以GMA为改性单体,通过与天然橡胶(NR)的反应熔融共混制备得到了改性天然橡胶(NR-g-GMA),并将NR-g-GMA与PLA进行反应熔融共混制备了超韧聚乳酸热塑性弹性体。结果表明,当NR-g-GMA含量为20wt%时,超韧聚乳酸弹性体的缺口冲击强度和断裂伸长率高达73.4kJ·m-2和158.8%,比纯PLA提高了26倍和44倍。FT-IR测试结果表明NR-g-GMA与PLA基体之间发生的环氧化反应增加了PLA与改性天然橡胶之间的界面粘结力。超韧聚乳酸热塑性弹性体的冲击断面形态结果表明PLA和NR-g-GMA的界面作用很强,且发生大的屈服变形,因而可以大幅度增加PLA的冲击韧性。(4)采用生物弹性体聚己二酸对苯二甲酸丁二醇酯(PBAT)、乙烯-丙烯酸酯-甲基丙烯酸缩水甘油酯(E-AE-GMA)和PLA的反应性熔融共混制备了超韧PLA三元共混物。当E-AE-GMA含量为15wt%时,超韧PLA三元共混物的缺口冲击强度和断裂伸长率分别高达61.9kJ·m-2和265.9%,是纯PLA的22倍和78倍。采用SEM、DMA、FT-IR等测试手段对超韧PLA三元共混物的相形态进行分析,结果表明E-AE-GMA的加入有效地改善了PLA/PBAT共混体系的界面粘结力和相容性。E-AE-GMA在PLA/PBAT/E-AE-GMA三元共混体系中兼具反应性增容剂和增韧剂的双重作用。PLA共混物的SEM结果表明:PLA基体、E-AE-GMA和PBAT分散相均产生了非常大的应力屈服变形,形成了共连续的冲击断面形态结构。通过对PLA三元共混物的增韧机理分析表明:PLA基体通过E-AE-GMA的反应性增容与PBAT分散相形成强的相界面作用,以及与PBAT、E-AE-GMA之间大的剪切形变对PLA的增韧具有相互协同作用。
[Abstract]:Polylactic acid (PLA) has excellent biodegradability, biocompatibility, high mechanical strength and easy processing properties are considered to be the most potential biological materials. However, the notched impact strength of poly lactic acid only 2.7kJ - m-2, the elongation is about 3.5%, its own brittleness. Disadvantages of low heat resistance temperature and crystallization rate of slow restricts the development and application of PLA material in the plastic area. Therefore, the development of high tenacity poly lactic acid material has important theoretical and practical value. In this paper, the "core-shell structure copolymer", "modified natural rubber", "bioelastomers" as toughening agent by reactive melt blending, preparation of super toughening polylactic acid blend system. Effects of different toughening agents on the mechanical properties of the blends of poly lactic acid. Through Fourier transform infrared spectroscopy (FT-IR), thermal analysis, scanning electron microscopy (SEM) measurements Test methods of different interface toughening agent on PLA blends compatibility effect regularity and phase structure, to further explore the toughening mechanism of super toughening PLA blends. The main conclusions are as follows: (1) with polybutadiene (PB) as seed emulsion, styrene (St) and glycidyl methacrylate (GMA) as grafting monomer, polymerization preparation of polybutadiene styrene glycidyl methacrylate (PB-g-St-GMA) emulsion with core-shell copolymer, FT-IR and transmission electron microscopy (TEM) test results show that the morphology of the target compound was synthesized and the copolymer for spindle type core shell structure. The effect of reaction time, initiator concentration and the concentration of emulsifier on the polymerization rate and particle size effects, the results show that when the concentration of initiator is 0.5wt%, emulsifier concentration is 0.5wt%, the reaction time is 4h, the polymer yield can reach 93.5%. (2) of PB-g-St-GMA And polyacrylonitrile butadiene styrene (ABS) core-shell copolymer on the effect of PLA blends on the mechanical properties and crystallization behavior. The results show that when the PB-St-GMA content is 10wt%, the elongation rate was 10.1%, higher than that of pure PLA by about 2 times. A small amount of ABS can improve the ductility of PLA blends. When the content of ABS for 6wt%, the elongation of PLA blends reached 118%, higher than that of pure PLA by about 23 times, about 1 times of.FT-IR and improve the analysis of dynamic mechanical impact strength (DMA) test results show that polar interactions between nitrile ester and PLA matrix ABS shell PSAN, improved between PLA and ABS compatibility, and a small amount of ABS as nucleating agent to improve the crystallization rate of PLA. (3) by free radical polymerization, the modified monomer with GMA, with natural rubber (NR) was prepared by melt blending modified natural rubber (NR-g-GMA), and NR-g-GMA The reaction of melt blending with PLA super toughening of polylactic acid thermoplastic elastomer was prepared. The results show that when the NR-g-GMA content is 20wt%, the super tough notched impact strength and elongation at break of polylactic acid elastomer was 73.4kJ m-2 and 158.8% higher than that of pure PLA 26 times and 44 times of.FT-IR test results the epoxidation reaction between NR-g-GMA and PLA matrix increased PLA and interfacial bond strength between natural rubber. The impact section morphology of the polylactic acid thermoplastic elastomers showed that the interface effects of PLA and NR-g-GMA is very strong, and the yield of large deformation, which can greatly increase the impact toughness of PLA. (4) using bioelastomers polyethylene adipate terephthalate (PBAT), ethylene acrylate glycidyl methacrylate (E-AE-GMA) super PLA three binary blends by reactive melt blending process when E-AE-GMA and PLA. The content of 15wt%, notched impact strength and elongation at break of three yuan super toughening PLA blends were as high as 61.9kJ, m-2 and 265.9%, 22 times and 78 times of pure PLA. Using SEM, DMA, FT-IR and other testing methods to analyze the morphology of super tough PLA three blends, the results show that E-AE-GMA to effectively improve the interfacial adhesion of PLA/PBAT blends and the compatibility of.E-AE-GMA blends with the dual role of.PLA reactive compatibilizer and toughening agent in PLA/PBAT/E-AE-GMA three blends SEM results showed that the PLA matrix, E-AE-GMA and PBAT dispersed phase are all produced very big stress deformation, the formation of the morphological structure of cross section. The impact of co continuous toughening mechanism of PLA blends three yuan analysis showed that PLA matrix dispersed by PBAT Reactive Compatibilization and E-AE-GMA phase to phase interface effect, and PBAT, E-AE-GMA Large shear deformation has synergistic effect on Toughening of PLA.

【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O633.14

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