水辅混炼挤出制备聚苯乙烯纳米复合材料及其发泡行为

发布时间：2018-05-16 03:40

本文选题：水辅混炼挤出 + 螺杆结构　；参考：《华南理工大学》2016年硕士论文

【摘要】：在聚合物基纳米复合材料的制备中,如何在提高纳米复合材料性能的基础上降低能耗越来越多地得到重视。本学位论文采用水辅混炼挤出设备,制备3种氧化石墨烯(GO)含量(0.1、0.3和0.5 wt%)的聚苯乙烯(PS)/GO纳米复合材料样品和3种羧基化多壁碳纳米管(MWCNTs-COOH)含量(0.1、0.3和0.5 wt%)的PS/MWCNTs-COOH纳米复合材料样品,观察样品的微观结构,测试其拉伸强度、流变性能和热性能。在此基础上,对PS及其两类纳米复合材料进行高压釜发泡,研究发泡条件对发泡样品泡孔结构的影响。采用水辅混炼挤出将超声处理后的GO悬浮液与PS熔体混炼制备PS/GO纳米复合材料样品。结果表明,GO被较好剥离且呈网状较均匀分散在PS基体中,这主要归因于螺杆混炼流场不断细化PS熔体中的GO悬浮液以及水对熔体的塑化和溶胀效应促进PS分子链插层进入GO片层之间的共同作用。低频区PS/GO样品的储能模量、复数黏度和松弛时间均比PS样品的高,这是因为较均匀分散的网状GO片与PS之间形成较强的分子间作用力,降低了PS分子链的活动性。PS/GO样品的热稳定性比PS样品的高,这归因于GO片在PS基体中呈网状分布和GO表面存在π键。采用水辅混炼挤出将超声处理后的MWCNTs-COOH悬浮液与PS熔体混炼制备PS/MWCNTs-COOH纳米复合材料样品。结果表明,相比于PS样品,PS/MWCNTs-COOH样品的低频区储能模量和复数黏度以及热稳定性、玻璃化转变温度和拉伸强度均有提高。由于GO和MWCNTs-COOH结构及在PS基体中分散性的差异,纳米填料含量相同的情况下,PS/GO纳米复合材料的热稳定性和拉伸强度优于PS/MWCNTs-COOH纳米复合材料。采用超临界CO2作为发泡剂,研究发泡温度和发泡压力对PS及其纳米复合材料发泡样品泡孔结构的影响。相同发泡条件下,发泡样品的泡孔尺寸顺序为:PSPS/MWCNTs-COOHPS/GO。在PS中添加纳米填料可减小泡孔平均直径,提高泡孔密度。由于纳米填料的微观结构、表面含氧基团以及在PS基体中分散等方面的差异,PS/GO纳米复合材料的发泡效果更好。采用变温模式所制备的PS及其纳米复合材料发泡样品呈现双峰泡孔结构,添加纳米填料使大泡孔密度增加。
[Abstract]:In the preparation of polymer based nanocomposites, more and more attention has been paid to how to reduce energy consumption on the basis of improving the properties of nanocomposites. In this dissertation, water assisted mixing and extruding equipment was used to prepare three kinds of PS/MWCNTs-COOH nanocomposite samples with content of graphene oxide (0.1g) and 0.5 wt. respectively) and three kinds of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) contents of 0.1t0.3 and 0.5 wt. respectively. The microstructure of the sample was observed and the tensile strength, rheological and thermal properties were tested. On this basis, PS and its two kinds of nanocomposites were foamed in autoclave, and the effect of foaming conditions on the bubble structure of foamed samples was studied. PS/GO nanocomposites were prepared by water assisted extrusion of supersonic treated go suspension and PS melt. The results showed that go was well peeled off and dispersed in PS matrix in a reticular form. This is mainly attributed to the continuous refinement of go suspensions in PS melt and the plasticizing and swelling effects of water on the melt in screw mixing flow field to promote the interaction of PS molecular chain intercalation into go lamellae. The energy storage modulus, complex viscosity and relaxation time of PS/GO samples in low frequency region are higher than those of PS samples, which is due to the formation of strong intermolecular force between the more evenly dispersed reticulated go sheets and PS. The thermal stability of PS / go sample was higher than that of PS sample, which was attributed to the distribution of go sheet in PS matrix and the existence of 蟺 bond on the surface of go. The samples of PS/MWCNTs-COOH nanocomposites were prepared by mixing ultrasonic treated MWCNTs-COOH suspensions with PS melts by water assisted mixing extrusion. The results show that the glass transition temperature and tensile strength of PS / MWCNTs-COOH samples are higher than those of PS / MWCNTs-COOH samples. Because of the difference of go and MWCNTs-COOH structure and dispersion in PS matrix, the thermal stability and tensile strength of PS / go nanocomposites are superior to those of PS/MWCNTs-COOH nanocomposites with the same content of nano-filler. Supercritical CO2 was used as foaming agent to study the effect of foaming temperature and pressure on the foam structure of PS and its nanocomposites. Under the same foaming conditions, the order of foam pore size of foamed samples is: 1 / PSPS / MWCNTs-COOHPS / go. The addition of nano-filler in PS can reduce the average diameter of bubble pore and increase the density of bubble pore. Because of the difference of the microstructure of nano-filler, surface oxygen group and dispersion in PS matrix, the foaming effect of PS-go nanocomposite is better. The foaming samples of PS and its nanocomposites prepared by changing temperature mode showed bimodal bubble structure, and the density of macrobubble increased with the addition of nano-filler.
【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】：TB383.1;TB33

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