形状记忆聚合物及其纳米复合材料的制备、结构与性能

IMR OpenIR

	形状记忆聚合物及其纳米复合材料的制备、结构与性能
	林国明
学位类型	博士
导师	杨锐 ; 隋国鑫
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料学
关键词	共混聚合物聚氨酯纳米碳管形状记忆效应 Polymer Blend Polyurethane Carbon Nanotubes Shape Memory Effect
摘要	"近十年来，形状记忆聚合物以其独特的性能在世界范围内引起了广泛的关注。作为一种特种功能材料，它们在医学材料领域、自修复材料领域、智能材料领域等扮演重要角色。形状记忆聚合物能够首先“记忆”自身的原始形状，再在一定条件下获得新的稳定的“暂时形状”，当受到特定刺激例如“加热”时，可以自发的回复原始形状。本文利用不同方式制备了四个系列互有异同的形状记忆材料，并对它们进行相应的测试与分析。聚合物共混为制备新型形状记忆聚合物提供了一条简便而且可控的思路。本文选用线性低密度聚乙烯及中密度聚乙烯作为可逆相，聚酰胺6作为固定相，马来酸酐接枝聚乙烯作为增容剂，首次制备这两个系列的形状记忆共混聚合物。本文首先分别分析测试马来酸酐接枝聚乙烯对聚酰胺6与两种聚乙烯相容性改善情况，再系统分析聚酰胺6含量对两个系列共混聚合物综合性能的影响。材料的机械性能通过测试材料屈服强度、杨氏模量、断裂伸长率进行衡量比较。形状记忆性能则是在温控箱中通过近似三点弯曲试验的方式进行表征。通过扫描电子显微镜与差示扫描量热法分析材料微观结构与热性能。结果显示马来酸酐接枝聚乙烯有效改善聚酰胺6与两种聚乙烯的相容性，两个系列共混聚合物的屈服强度均随着马来酸酐接枝聚乙烯的加入有所提高。对于线性低密度聚乙烯为可逆相的共混聚合物，聚酰胺6基本呈小液滴形态分布于基体中，形状记忆性能与聚酰胺6的含量密切相关。线性低密度聚乙烯、聚酰胺6、马来酸酐接枝聚乙烯的质量分数分别为60wt%、20wt%及20wt%的形状记忆共混聚合物形状固定率和回复率分别达到91.8%和98.6%。对于中密度形状记忆聚合物，30wt%的聚酰胺6在20%的马来酸酐接枝聚乙烯的帮助下，在基体中呈连续相分布，材料获得双相连续网络结构，这使材料有可能获得更好的性能。在形状固定率保持在80%以上的前提下，拥有双相连续微观结构的形状记忆共混聚合物形状回复率几乎达到100%。本文使用4,4’-二苯基甲烷二异氰酸酯、聚四亚甲基醚二醇、1,4-丁二醇合成形状记忆聚氨酯嵌段共聚物。合成路线不同于传统方式，先将依组分设计足量的聚四亚甲基醚二醇、1,4-丁二醇与80%的4,4’-二苯基甲烷二异氰酸酯加入三口瓶溶液聚合制备预聚物，在精确滴定后加入适量4,4’-二苯基甲烷二异氰酸酯完成反应。通过傅里叶变换红外光谱法与凝胶渗透色谱分析了制备的聚氨酯。使用差示扫描量热法分析聚氨酯的热性能。使用万能试验机测试样品的力学性能。样品的形状记忆性能测试则在水浴中进行。凝胶渗透色谱结果显示反应产物分子量较高，反应完全，分子量均在60000以上，红外结构显示硬段含量越高，羰基振动吸收峰由1735cm-1向1730cm-1转移硬段间相互作用力越强，微相分离越显著，这有利于聚氨酯原始形状回复。而这一变化也显著影响材料力学性能。差热扫描分析同样显示聚氨酯的热性能与硬段含量密切相关。最后，硬段质量分数为30-50wt%的聚氨酯形状固定率与回复率可以达到85-95%，且拥有良好的综合性能。形状记忆聚氨酯可以拥有优异的形状记忆性能，但其拉伸强度相对较低。纳米碳管具有优异的机械性能、导电性、磁性能，且具有纳米尺度的直径与大的长径比，是一种优秀的聚合物增强相。纳米碳管的良好分散是复合材料制备的关键，本文先将纳米碳管酸化处理和胺化处理，再加入聚氨酯的二甲基乙酰胺溶液混合，制备一系列纳米碳管与形状记忆聚氨酯复合材料。研究了纳米碳管对复合材料的力学性能，熔融结晶行为和形状记忆性能的影响，并通过扫描电子显微镜研究了纳米碳管在聚氨酯基体中的分布。结果显示纳米碳管影响了形状记忆聚氨酯软段的结晶，复合材料形状记忆机理与形状记忆聚氨酯不同，胺化纳米碳管与形状记忆聚氨酯复合材料的形状固定率与回复率均超过85%。"
其他摘要	"In recent years, shape memory polymers (SMP) have been paid intensive attention because of their potential applications as functional materials. Shape memory polymers are playing a prominent role for biomedical, self-repairing and smart materials. Shape memory polymers remember their original shape, and recover from a deformed state when exposed to a stimulus such as heat. Four types of shape memory polymers were investigated in the thesis． Polymer blending offers a simple and controllable way to fabricate novel shape memory polymers. Two serial polymer blends of polyamide (PA6) with linear low-density polyethylene (LLDPE) or medium density polyethylene (MDPE) while added maleated polyethylene (PE-G) as compatibilizer were first introduced for shape memory polymer. The effects of maleated polyethylene were studied, and polymer blends with different contents of PA6 in polyethylene matrix were obtained and investigated systematically in the thesis. The mechanical properties were studied in terms of the yield strength, Young’s modulus and elongation-to-break. The shape memory properties of the materials were characterized using a 3-point bending test in a temperature-controlled chamber. The microstructures of the blends were observed by scanning electron microscope (SEM). The thermal properties of polymer blends were determined by differential scanning calorimetry (DSC). The results showed that the incorporation of maleated polyethylene had a strong effect on the tensile properties and the morphology of all blends. PA6 phase droplet-in-matrix dispersed in linear low-density polyethylene (LLDPE) matrix and the shape memory properties of blended materials were affected by the weight fraction of PA6. Shape recovery and fixing ratio for 60wt% LLDPE, 20wt% PA6 and 20wt% PE-G were 98.6% and 91.8% respectively. Co-continuous morphology of PA6/MDPE/PE-G blend was successfully prepared by adding 30wt% PA6 in the blend with suitable amount of maleated polyethylene. The shape recovery ratios of PA6/MDPE/PE-G blends with co-continuous morphology were amazingly 100% while the shape fixing ratios of them were all over 80%. Shape memory polyurethane (SMPu) block copolymers composed of 4,4’-diphenylmethane diisocyanate (MDI), poly (tetramethylene glycol) (PTMG), and 1,4-butanediol (BD) were synthesized by a new two-step process. First, the SMPu prepolymer was prepared by reacting all PTMG and BD with 80wt% of MDI, then extended with suitable MDI. Polymer synthesis was evaluated by GPC and FT-IR. Molecular weight of SMPu block copolymers were all more than 60000. FT-IR spectra showed that carbonyl peak appearing at 1700cm-1 increased with more hard segment content, whereas another carbonyl peak at 1730cm-1 decreased. It suggested that hard segments aggregated more to form domains in the SMPu block copolymer as hard segment content increased. Such domain formation had a significant influence on the mechanical properties of SMPu in terms of tensile strength, Young’s modulus and elongation-to-break. The thermal properties of SMPus determined by differential scanning calorimetry (DSC) were also dependent on the hard segment content. Finally, 85-95% of shape recovery was obtained at 30-50wt% of hard segment content, and the hard segment content in SMPu block copolymers was very important in determining their properties. Shape memory polyurethane (SMPu) was characterized with its remarkable shape memory ability, but its mechanical properties such as strength and elastic modulus was not high enough. Carbon nanotubes (CNTs) exhibited excellent mechanical, electrical, and magnetic properties as well as nanometer scale diameter and high aspect ratio, which made them to be an ideal reinforcing agent for high strength polymer composites. The biggest issues in the preparation of CNT-reinforced composites resided in efficient dispersion of CNTs into a polymer matrix. In this thesis, CNTs were first treated with acids and diamine, and the microstructures of SMPu/CNT nanocomposites were characterized by SEM. The CNTs mostly diminished the shape memory function of SMPus which was ascribed to the interference of CNTs on the crystallization of the soft segment. The effect of CNTs on the crystallization and melting behaviors, mechanical properties, and shape memory properties of SMPu were investigated. The results indicated that the shape memory mechanism of CNT/SMPu was changed by diamine-modified CNT. Finally shape recovery and fixing ratio for CNT/SMPu obtained were all over 85%."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64487
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	林国明. 形状记忆聚合物及其纳米复合材料的制备、结构与性能[D]. 北京. 中国科学院金属研究所,2012.