【作者】 王宁；

【导师】 王经武；

【作者基本信息】 郑州大学 ， 材料学， 2010， 硕士

【摘要】 工程塑料聚已二酰已二胺(polyamide 66, PA66),俗称尼龙66,具有较高的刚性、耐磨性、耐化学介质等优良的性能,在交通、机械制造、电子电器等领域已大量应用。为了降低成本、适应多样化使用性能的要求,PA66的共混、填充改性已是工程塑料高性能化和实用化研究的重点领域之一。近年来,随着聚对苯二甲酸乙二醇酯(Poly(ethylene terephthalate), PET)在包装领域中用量的迅速增长,每年就要产生大量的废旧PET(rPET). PET主要作为饮料等食品的包装,货架期短,又是一次性使用,废弃PET瓶等包装制品依然较好的保持着PET的性能,选用废旧PET瓶片作为改性材料,若技术方法得当,既可以制备出性/价比高的PA66基工程塑料(PA66/rPET),又使废弃物资源化,更具有重要的经济、社会意义和学术价值。然而,一般的PA66/rPET复合材料的综合力学性能往往达不到预期要求。究其原因主要在于PA66和rPET的界面结构问题和rPET的结晶问题。因此将rPET与PA66共混,要制备出综合性能优于PA66的新型PA66基工程塑料,PA66和rPET形成何种界面结构并加快rPET的结晶速率成为亟待解决的科学技术问题。为了在大幅度提高PA66/rPET复合材料的韧性的同时保持或者尽量少降低其刚性(拉伸屈服应力、弯曲弹性模量),本工作设计出PA66/rPET复合材料应具有如下结构特征：在PA66中加入rPET时,引入既能与PA66反应、又能与rPET反应,同时具有增韧作用的反应性增容增韧剂(reactive compatibilizing toughener, RCT),在PA66和rPET之间有化学键连接；再采取合适的反应性共混工艺,使RCT在能效应、熵效应的作用下,能自组装于PA66与rPET之间,形成结合力强的适度柔性界面区。这种结构特征使材料在受到外力作用时,能保证在PA66和rPET之间很好的传递应力,强韧的界面区能有效地终止剪切形变和银纹化,具有较高的吸收冲击能的能力。此外,通过加入高效、适量的rPET成核剂,加工成型过程中改变rPET的结晶行为,加快rPET的结晶速率,有效提高复合材料的刚性或者尽量减少刚性的降低。基于此,本工作以聚丙烯、弹性体、含有环氧官能团的单体及辅助单体等为主要原料,采用低粘度反应体系,利用“聚合桥连接、反应性混配”的原理和技术研制出了反应性增容增韧剂,将PA66、RCT、rPET和成核剂(滑石粉,记为Ta)按一定配比、采取不同的反应性共混工艺,经双螺杆挤出机熔融反应共混,制备出了PA66/RCT/rPET/Ta复合材料。采用分级提取、红外分析(IR)法、透射电镜(TEM)、扫描电镜(SEM)、偏光显微镜(PLM)、热分析(DSC)、力学性能测定等手段,对RCT和PA66/RCT/rPET/Ta复合材料的结构和性能进行了表征,得出了如下主要结果和结论：(1)RCT是由两种单体的均聚物和共聚物,未参加反应的PP和弹性体,PP和弹性体分别与单体的接枝共聚物,单体桥链连接的PP与弹性体接枝共聚物,单体桥链连接的PP和弹性体及两种弹性体之间的交联物组成的。(2)综合考虑苯甲酸钠、滑石粉、有机膨润土和钛白粉四种成核剂对rPET结晶行为和力学性能的影响,优选出滑石粉作为rPET的成核剂。滑石粉使rPET的TPcc下降了13.6℃,Scc提高到15.4,TPmc提高了25℃,Smc提高到6.1。rPET/滑石粉复合材料的拉伸强度、弯曲模量分别比原料rPET提高了24%、22%,热变形温度提高了3.1℃。(3) PA66/RCT/rPET/Ta复合材料中,RCT中的环氧官能团与PA66和rPET分子链上的反应性官能团发生了化学反应,组分间形成了化学键连接；PA66基体与rPET之间形成了结合力强的适度柔性界面。(4)RCT与rPET的反应程度大于与PA66的反应程度。PA66/RCT/rPET/Ta复合材料的力学性能与反应性共混工艺密切相关：PA66预先与部分RCT反应性共混,再与其他物料反应性共混挤出的“二次共混”工艺最优。(5)采用最优工艺,随着RCT含量的增加,PA66/RCT/rPET/Ta复合材料的拉伸屈服应力、弯曲模量逐渐降低,冲击韧性逐渐提高。当PA66/RCT/rPET/Ta组成为66.5/5/28.5/5时,复合材料的综合力学性能最佳,拉伸屈服应力、弯曲弹性模量、悬臂梁缺口冲击强度分别是原料PA66的96%、122%和141%,热变形温度提高了4.8℃。(6)采用最优工艺,随着RCT含量的增加,PA66/RCT/rPET/Ta复合材料中PA66的Tg均高于原料PA66的Tg,提高的幅度先增大后降低；Tmcp提高了11.1～13.3℃,提高的幅度逐渐减小。复合材料中rPET的Tg稍低于原料rPET的Tg,降低的幅度逐渐增大；Tccp降低了26.1～28.1℃,降低的幅度逐渐增大；Tmcp提高了11.7～18.9℃,提高的幅度逐渐减小。更多还原

【Abstract】 Engineering plastics poly(hexamethylene adipamide) (polyamide 66, PA66) exhibits excellent properties, such as a high rigidity (tensile yield stress, flexural modulus), excellent abrasion resistance, heat resistance, chemical resistance etc. It has been widely applied in machinery, electronic equipment, automobiles, and other fields. In order to reduce the cost,enlarge the using ranges and satisfy the more requirements for performance, blending and filling modification for PA66 has become a focus of researching high performance and practicality of engineering plastics.At present, polyethylene terephthalate (PET) in the packaging area is a rapid growth in consumption, due to the short shelf life of PET bottles, but also a one-time use, the consumption of waste PET that still maintain good performance was also increasing at the roughly same rate. If technical methods used properly, using rPET chips as a filling material, it can be prepared PA66-based engineering plastics(PA66/rPET) with high performance/cost, but recyced PET bottles. So it has the important economic, social significance and academic value. But generally speakig, the properties of PA66/rPET blends falls short of expections due to the interface structure of PA66 and PET and crystallization of PET based on the analysis of literature. Therefore, it is urgent to form a proper interface structure and accelerate the crystallization of rPET for preparing PA66/rPET blends with better properties than that of PA66.In order to significantly improve the toughness and maintain the rigidity or reduce the rigidity as little as possible(Tensile Yield Stress, Flexural Modulus), PA66/rPET blends of this work should have the following structural characteristics: adding rPET to PA66, reactive compatibilizing toughener(RCT) we prepared is also added at the same time. RCT has chemical reactions and chemical bonds connection with PA66 and rPET. RCT also can significantly improve the toughness and maintain the rigidity of PA66/rPET. Using a suitable reactive blending technology, RCT can concentrate in the interlayer between PA66 and rPET and form the moderate flexible interlayer with high interfacial adhesion by the effects of energy and entropy. The emergence of such structure can avoid that rigid interface induce the formation of micro-cracks of resin matrix in the interface area, transfer stress between the matrix resin and rPET. The resin matrix mainly exhibits shear yield deformation under the external forces, the good interface adhesion can effectively terminate shear deformation, crazing and absorb impact energy. In addition, in order to change the crystallization behavior and accelerate the crystallization rate of rPET in the processing, it is necessary to add a high-performance, appropriate amount of rPET nucleating agent to improving the rigidity of materials effectively.Based on the above designs, the reactive compatibilizing toughener was synthesized in the low-viscosity reaction system through the technique "grafting copolymerization, reactive blending" using PP, elastomer, containing epoxy functional groups of bridge agents and so on. PA66/RCT/rPET/Ta blends was prepared using PA66, RCT, rPET and talcum by different thermal mechanical reactive blending technology. The structure and properties of RCT and PA66/RCT/rPET/Ta composites were investigated by means of fraction extraction, IR, TEM, SEM, PLM, DSC and mechanical properties measuring. The main results and conclusions are as follows:(1) The compositions of RCT are composed of unreacted PP and elastomers, graft polymers of PP and elastomers with bridge agents, cross-linked copolymer of PP and elastomers, elastomers and elastomers by polymer bridge conjuction using bridge agents, homopolymer and copolymers of bridge agents.(2) Considering sodium benzoate, talcum, bentonite and titanium on crystallization behavior and mechanical properties of rPET, Talcum powder is the optimal nucleating agent for rPET. Talcum makes Tpcc reduce 13.6℃, Scc increases to 15.4, Tpmc increases 25℃,Smc increases to 6.1.The tensile yield stress(TYS), flexural modulus(FM) of rPET/Ta blends increases 0.24 times,0.22 times as high as those of the pure rPET respectively while thermal deformation temperature increased 3.1℃.(3) RCT, rPET and PA66 have chemical bonds through the chemical reaction between the epoxy functional group in RCT, the bottom amide groups and carboxyl groups of PA66 chains and the bottom hydroxyl groups and carboxyl groups of rPET. The moderate flexible interplay with high interfacial adhesion has been formed between the PA66 and rPET.(4) RCT has the greater degree of response with rPET than that with PA66. The mechanical properties of PA66/RCT/rPET/Ta and reactive blending technology are closely related. The blending technology of PA66 in advance reactive extrusion with some of RCT, and then with rPET,talcum powder and the remaining RCT shows the best.(5) When using the best blending process, along with the increase in RCT content, The tensile yield stress, flexural modulus of PA66/RCT/rPET/Ta blends reduce gradually while the notchod Izod impact strength increases gradually. The mechanical properties of PA66/RCT/rPET/Ta blends with ratio 66.5/5/28.5/5 of PA66/RCT/rPET/Ta shows the best. The tensile stress, flexural modulus and notchod Izod impact strength of PA66/RCT/rPET/Ta are 0.96 times,1.22 times and 1.41 times as high as those of pure PA66 respectively.(6) When using the best blending process, with the increase of RCT added, Tg of PA66 in PA66/RCT/rPET/Ta is higher than pure PA66 and the extent of increase first increases and then reduces; Tmcp increases 11.1～13.3℃and the extent of increase reduces gradually. Tg of rPET in PA66/RCT/rPET/Ta is lower than pure rPET and the extent of decrease increases gradually; Tccp reduces 26.1～28.1℃and the extent of decrease increases gradually; Tmcp increases 11.7～18.9℃and the extent of increase reduces gradually.更多还原