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1、 聚苯乙烯论文：碳纳米管选择性分散及其诱导不相容共混聚苯乙烯论文：碳纳米管选择性分散及其诱导不相容共混物结晶的研究物结晶的研究【中文摘要】聚合物共混改性可以使单一聚合物的性能优化组合,并且获得一些特殊性能,成为开发新型高分子材料的有效途径。对于大部分的聚合物在热力学上是不相容的,不相容共混物增容改性的方法很多,添加无机纳米填料是一种实际有效的方法。碳纳米管(Carbon Nanotubes, CNTs)自从被发现以来,由于其具有优异的力学、导电、导热特性而备受关注,此外碳纳米管对结晶聚合物是很好的成核剂,少量的碳纳米管可以诱导结晶,降低结晶活化能,提高结晶速率。聚苯乙烯(Polystyrene
2、, PS).聚丙烯(Polypropylene, PP)、聚对苯二甲酸乙二醇酯(Polyethylene terephthalate, PET)在生活、工程应用上很广泛,对其进行共混改性具有现实意义。本论文以PS/PP、PS/PET 不相容共混物作为研究对象,多壁碳纳米管(Multi-Walled Nanotubes, MWCNTs)做为无机纳米填料来制备纳米复合材料。首先对碳纳米管进行化学改性,改善其与基体之间的相互作用,控制其在复合材料中的分布；研究了加工共混条件、增容剂的添加、界面条件等对碳纳米管在不相容共混物中选择性分布的影响,并进一步探讨了碳纳米管的分布对结晶相的结晶行为以及对复合材
3、料微观相形貌的影响。主要研究结果如下：(1)对碳纳米管先酸化处理,然后与马来酸酐反应,使其表面接枝上羰基、羟基、羧基等活性基团,得到改性的多壁碳纳米管(Functionalized Multi-walled Carbon Nanotubes, F-MWCNTs)。(2)把 F-MWCNTs 加入到 PS/PP 不相容共混物中,PS 与 F-MWCNTs 通过溶液法配制母料,再与其他组分挤出注塑制备复合材料。对 PP 结晶行为的研究发现,PS/PP 共混物中,PP 在低温、高温处出现两个结晶峰,有分级结晶现象,但添加 F-MWCNTs 后PP 只有一个高温结晶峰,分级结晶现象消失；同时,PS/P
4、P/F-MWCNTs复合材料中 PP 相的结晶温度比 PS/PP 共混物中 PP 相的结晶温度高,复合材料中 PP 相的结晶温度随着 PP 含量的增加而逐渐提高,表明F-MWCNTs 跟 PP 间相互作用更强,F-MWCNTs 从 PS 相迁移到了 PP 相中,F-MWCNTs 作为很好的异相成核剂诱导 PP 结晶。另外动态力学分析(Dynamic Mechanical Analysis, DMA)数据表明,复合材料中PS、PP 的玻璃化温度有所降低,说明 F-MWCNTs 充当了增塑剂的作用。扫描电子显微镜(Scanning Electron Microscope, SEM)对复合材料相形貌
5、研究表明 F-MWCNTs 的引入在一定程度上促进了 PS/PP 相形貌从“海岛”相向双连续相的转变。(3)在 80PP/20PS 不相容共混物中添加马来酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯(Maleic Anhydride Grafted Styrene-Ethylene-Butylenes-Styrene, SEBS-MA)作为增容剂,降低了两相的界面张力,增强了两相间的粘结力,分散相粒径变小,分散更均匀。同时研究了加工共混条件以及增容剂对 F-MWCNTs在复合材料中选择性分布情况的影响。以 PP/F-MWCNTs 作为母料制备的纳米复合材料,SEBS-MA 加入后 PP 的结晶温度降低
6、,表明 F-MWCNTs 与 SEBS-MA 的相互作用比较强,部分的 F-MWCNTs 被 SEBS-MA诱导而从 PP 相中迁移出来；DMA 表征发现 PS 玻璃化温度没有变化,F-MWCNTs 并没有迁移到 PS 相中。以 PS/F-MWCNTs 作为母料制备的纳米复合材料,各个组分中 PP 的结晶温度变化不大,DMA 结果发现 PP玻璃化温度也没有变化,说明 F-MWCNTs 没有迁移到 PP 相中,主要还是分布在 PS 相中,SEBS-MA 的存在可以阻止 F-MWCNTs 的迁移。以PP-MA 为基体,PS/F-MWCNTs 为母料制备的纳米复合材料,PP-MA 结晶行为的研究也说
7、明 SEBS-MA 与 F-MWCNTs 之间的相互作用力比 PP-MA与 F-MWCNTs 之间的作用力更强。(4)制备了 PS/PET/F-MWCNTs 纳米复合材料,通过热力学润湿系数计算表明 F-MWCNTs 倾向于分布在PET 相中。对复合材料中 PET 的结晶行为的研究表明 F-MWCNTs 诱导PET 结晶,起到了很好的异相成核作用,F-MWCNTs 从 PS 相往 PET 相迁移；通过 SEM 直观的反映了 F-MWCNTs 主要分布在 PET 相中及两相界面,验证了 F-MWCNTs 在复合材料中的分布情况。【英文摘要】Polymer blending is a conven
8、ient and efficient route for the development of new polymeric materials, which can combine the excellent and special properties of the constituent polymers. Many polymer blends are immiscible and their blends exhibit poor mechanical properties. Among various techniques used to compatibilize polymer
9、blends, adding inorganic nanofillers is proved to be one of the most efficient methods. Since their discovery, carbon nanotubes (CNTs) attracted tremendous attention due to their superior mechanical, electrical and thermal properties. CNTs have been proved to be a good nucleating agent for crystalli
10、zation of polymers. The addition of a few CNTs in semicrystalline polymer can efficiently promote the crystallization by decreasing the nucleation activation energy and accelerating crystallization rate. Polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET) are important engineer
11、ing polymers used in a wide variety of applications, and melt blending of them are of practical significance. In this research, nanocomposites of PS/PP and PS/PET containing Multi-walled nanotubes (MWCNTs) were mainly prepared by direct melt blending. MWCNTs were firstly functionalized to improve th
12、e adhesion with polymer matrices, so we can control the localization and dispersion of MWCNTs in immiscible polymer blends. The selective localization of MWCNTs in nanocomposites was realized by the different blending sequences, the use of compatibilizer, etc. Furthermore, the effect of selective lo
13、calization of MWCNTs on the crystallization and morphology behaviors of nanocomposites were discussed. The main results obtained in this work are listed as follows:(1)The pristine carbon nanotubes were first acidified in nitric acid and then reacted with maleic acid, to introduce carbonyl, carboxyl
14、and hydroxide groups onto the surface of carbon nanotubes and the final products are called Functionalized multi-walled carbon nanotubes (F-MWCNTs).(2)PS/PP blends containing F-MWCNTs were prepared using a twin screw extruder followed by injection molding, the F-MWCNTs was firstly dispersed in solve
15、nt to obtain PS/F-MWCNTs master batch and then the master batch was melt blended with different contents of PP and PS to obtain samples with corresponding compositions. For the PS/PP blends without F-MWCNTs, two exothermic peaks were presented in the cooling curve of PP phase, indicating fractionate
16、d crystallization of PP. The PS/PP/F-MWCNTs nannocomposites exhibited only one exothermic peak indicating that only bulk crystallization of PP phase occurred during the cooling process. Furthermore, the nanocomposite exhibited higher crystallization temperature compared with the corresponding blends without F-MWCNTs, and the crystallization temperature shifted to higher temperatures at higher content of PP. It proved that F-MWCNTs migr
