共混改性和微层共挤制备聚甲基乙撑碳酸酯基复合材料及其结构与性能研究

发布时间：2018-05-11 03:13

本文选题：聚甲基乙撑碳酸酯 + 熔融共混　；参考：《华南理工大学》2016年硕士论文

【摘要】：聚甲基乙撑碳酸酯(PPC)是由二氧化碳和环氧丙烷合成的一种脂肪族聚碳酸酯,具有完全生物降解特性和较好的气体阻隔性能,然而PPC的热力学性能较差,氧气阻隔性能仍低于传统阻隔材料EVOH,因此应用受到限制。本文采用熔融共混和微层共挤的方法制备PPC复合材料,旨在通过复合材料的结构调控增强PPC热力学性能的同时,仍能保持甚至提高材料的阻隔性能,为PPC在包装材料的进一步应用提供新方法和理论指导。基于氢键作用有利于增强多组分聚合物之间的相互作用,并进而提高复合材料的热力学性能,采用熔融共混的方法制备PPC/热塑性淀粉(TPS)、PPC/热塑性氧化淀粉(TPOS)和PPC/铝酸酯预处理的TPOS(AL-TPOS)复合材料。红外光谱分析表明PPC和三种淀粉均形成了氢键作用,淀粉的氧化改性将淀粉的部分羟基转化成羰基,增强PPC和淀粉的氢键作用,SEM证实了淀粉的氧化改善了淀粉和PPC的界面粘结力。因此与PPC/TPS复合材料相比,PPC/TPOS复合材料的复数粘度、储能模量、损耗模量、拉伸强度、玻璃化转变温度(Tg)和热分解温度更高。对于PPC/AL-TPOS复合材料体系,铝酸酯对氧化淀粉的包覆改善了淀粉在PPC基体中的分散并对淀粉的热分解起到减缓效果,从而使PPC/AL-TPOS复合材料的拉伸强度和热分解温度均高于PPC/TPOS;随着AL-TPOS含量的增加,PPC/AL-TPOS复合材料的拉伸强度和Tg均表现出先上升后下降的趋势。然而,亲水性淀粉的加入提高了PPC吸附水蒸气分子的能力,降低了其水蒸气阻隔性能。从增强PPC的力学强度和阻隔性能出发,将具有优异力学强度和阻氧性能的聚乙烯醇(PVA)引入PPC基复合材料中。首先采用熔融共混制备PPC/PVA共混材料,分析PVA含量对PPC/PVA共混物的微观形态、动态流变行为、力学性能和阻隔性能的影响规律;然后以PPC/PVA共混物为增强层、PPC为基体层,采用微层共挤技术制备PPC/(PPC/PVA)微层复合材料,研究微层结构对复合材料力学和阻隔性能的影响机制。对于PPC/PVA共混体系,SEM和动态流变结果均表明PVA与PPC的相容性较好,两相之间有良好的相互作用力,PPC/PVA共混物的拉伸强度随PVA含量的增加而提高,并能保持高于400%的断裂伸长率;PVA在共混物中的均匀分布延长了氧气分子在PPC中的渗透路径,增强了PPC基复合材料的氧气阻隔性能,但亲水性的PVA使复合材料的水蒸气阻隔性能略有降低。对于PPC/(PPC/PVA)微层复合材料体系,稳定的微层结构和良好的层间粘结力使微层复合材料保持良好的拉伸强度和断裂伸长率;PPC作为微层复合材料的外层,有效减弱了PVA对水蒸气分子的吸附,使微层复合材料表现出较高的水蒸气阻隔能力。基于微层结构对复合材料力学和阻隔性能的有效增强,将PLA作为力学性能增强层、PPC作为阻隔性能增强层,采用微层共挤的方法制备PPC/PLA微层复合材料,并与PPC/PLA共混材料进行对比,研究微层复合材料的相形态、动态流变性能、力学性能和阻隔性能。力学性能结果表明交替分布的层状PLA使微层复合材料的拉伸强度高于共混材料;增加层数可以提高PPC/PLA微层复合材料的断裂伸长率,这是因为层数增加时,界面分层吸收了更多的拉伸能量且遭到破坏的PLA层状结构使PLA对复合材料的脆性破坏减少。阻隔性能结果表明PPC/PLA微层复合材料的氧气和水蒸气透过系数均远低于共混材料,提高层数可进一步提高阻隔性能。此外,PLA的加入能减少温度升高对PPC/PLA微层复合材料阻隔性能的破坏,提高层数可进一步增强这种效果,原因是PLA作为刚性层限制了温度升高时PPC链段的运动和自由体积的增加,导致气体分子在PPC中的渗透变得困难。
[Abstract]:Polymethylethylene carbonate (PPC) is a kind of aliphatic polycarbonate synthesized from carbon dioxide and propylene oxide. It has complete biodegradation and better gas barrier properties. However, the thermodynamic properties of PPC are poor and the oxygen barrier performance is still lower than that of the traditional barrier material EVOH. Therefore, the application is limited. The preparation of PPC composites by layer coextrusion is designed to maintain or even improve the barrier properties of the materials by controlling the structure of the composite by the structure and control of the composite materials. It provides a new method and theoretical guidance for the further application of PPC in the packaging materials. The interaction between the multi component polymers is beneficial to the enhancement of the interaction between the multi component polymers. PPC/ thermoplastic starch (TPS), PPC/ thermoplastic starch (TPOS) and PPC/ aluminate pretreated TPOS (AL-TPOS) composites were prepared by melt blending. The IR analysis showed that both PPC and three kinds of starch formed hydrogen bond, and the oxidized starch of starch was the part of starch. The hydroxyl group is converted into carbonyl group to enhance the hydrogen bonding effect of PPC and starch. SEM confirms that the oxidation of starch improves the interfacial bonding force between the starch and PPC. Therefore, compared with the PPC/TPS composite, the complex viscosity, energy storage modulus, loss modulus, tensile strength, glass transition temperature (Tg) and thermal decomposition temperature of PPC/TPOS composites are higher. For PPC/AL-TPO In the S composite system, the coating of the oxidized starch by Aluminate improves the dispersion of starch in the PPC matrix and slows the thermal decomposition of the starch. Thus the tensile strength and the thermal decomposition temperature of the PPC/AL-TPOS composites are all higher than that of the PPC/TPOS. With the increase of AL-TPOS content, the tensile strength and the Tg performance of the PPC/AL-TPOS composites are all shown. However, the addition of hydrophilic starch increases the ability of PPC to adsorb water vapor molecules and reduces the performance of water vapor barrier. Starting from the mechanical strength and barrier properties of the PPC, the polyvinyl alcohol (PVA) with excellent mechanical strength and oxygen resistance is introduced into the PPC matrix composites. The effects of PVA content on the micromorphology, dynamic rheological behavior, mechanical properties and barrier properties of PPC/PVA blends were mixed, and the PPC/ (PPC/PVA) microlayer composite was prepared by microlayer coextrusion with PPC/PVA blends as reinforcement and PPC as the matrix layer, and the microstructure of the PPC/PVA was studied on the mechanics of the composite materials and the mechanics of the composite materials. For PPC/PVA blends, SEM and dynamic rheological results show that the compatibility of PVA and PPC is better, and there is good interaction between the two phases. The tensile strength of PPC/PVA blends increases with the increase of PVA content, and can keep the breaking elongation higher than 400%, and the uniform distribution of PVA in the blends is prolonged. The permeation path of oxygen molecules in PPC enhances the oxygen barrier properties of the PPC based composites, but the hydrophilic PVA makes the water vapor barrier property of the composite slightly lower. For the PPC/ (PPC/PVA) microlayer composite system, the stable microlayer structure and the good interlayer bonding force make the micro layer composite maintain good tensile strength. And the elongation at break, PPC, as the outer layer of the microlayer composite material, effectively weakened the adsorption of PVA to the water vapor molecules, and made the microlayer composite exhibit high water vapor barrier capability. Based on the microlayer structure, the mechanical and barrier properties of the composites were enhanced effectively, and PLA was used as a mechanical property enhancement layer, and PPC was used as a barrier property enhancement layer. PPC/PLA microlayer composites were prepared by microlayer coextrusion, and compared with PPC/PLA blends, the phase morphology, dynamic rheological properties, mechanical properties and barrier properties of the microlayer composites were studied. The mechanical properties showed that the tensile strength of the microlayer composite material was higher than that of the blends; the number of layers was increased. In order to improve the elongation at break of PPC/PLA micro layer composites, this is because the interface layer absorbs more tensile energy and is destroyed by the damaged PLA layer when the number of layers increases, and the brittle failure of the composite is reduced by PLA. The barrier performance results show that the oxygen and water vapor transmission coefficient of the PPC/PLA micro layer composites are far below the blend. In addition, increasing the number of layers can further improve the barrier performance. In addition, the addition of PLA can reduce the damage to the barrier properties of PPC/PLA micro layer composites by increasing the temperature. The increase of the number of layers can further enhance this effect. The reason is that PLA as a rigid layer restricts the movement of the PPC chain and the increase of free volume when the temperature rises, resulting in the gas molecule in P. The penetration in PC becomes difficult.

【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB33

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