具有优良刚性的增韧PA66的研究

【作者】 代佳丽；

【导师】 王经武；

【作者基本信息】 郑州大学 ， 材料学， 2009， 硕士

【摘要】 聚已二酰已二胺(polyamide 66,PA66),具有较高的刚性(拉伸屈服应力、弯曲弹性模量)、耐磨性、耐热性、耐化学介质等优良的性能,被广泛应用于机械、仪器仪表、汽车和其他交通工具等领域。为了适应多样化使用性能的要求,国内外对PA66的增韧、提高刚性进行了许多富有成效的研究工作。随着对使用性能要求的提高,PA66高性能化研究的热点集中于使其韧性和刚性同时提高。在总结分析PA66增韧、提高刚性机理及影响因素的基础上,本工作设计出韧性刚性同时显著提高的改性PA66应具有如下结构特征:在PA66中引入可以提高刚性的填充剂的同时,引入既能与PA66反应、又能与刚性填充剂表面反应,还具有增韧且基本不引起刚性降低功能的多功能成分,在能效应、熵效应的“驱使”下,多功能成分既能分散于PA66中,提高基体的韧性,又能富集于PA66与刚性填充剂之间,构筑成结合强度高的适度柔性的界面区。这种结构特征,避免了刚性界面易引发界而区基体树脂微裂纹化;受到外力作用时,能在基体树脂和刚性填充剂间很好的传递应力,充分发挥刚性填充剂提高刚性和强度的作用;基体树脂将以剪切屈服形变为主,强韧的界面区能有效地终止剪切形变和银纹化,具有很高的吸收冲击能的能力。基于此,本工作以聚丙烯、乙丙弹性体、丁苯弹性体、含有环氧官能团的架桥剂(G)、辅助架桥剂(S)等为主要原料,采用“聚合桥连接和反应性混配”的原理和技术研制出了反应性增切母料(reactive toughening master batch,RTMB),将PA66、RTMB和玻璃纤维(GF)经双螺杆挤出机熔融反应共混,制备出了PA66/RTMB/GF复合材料。采用分级提取、红外分析(IR)法、扫描电镜(SEM)、偏光显微镜(PLM)、热分析、力学性能测定等手段,对RTMB及PA66/RTMB、PA66/RTMB/GF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)RTMB由未反应的PP、弹性体,PP、弹性体与架桥剂的接枝共聚物,PP、弹性体由架桥剂形成的桥链连接的接枝共聚物,通过架桥剂的聚合桥链连接的PP、弹性体的交联共聚物,架桥剂的均聚物和共聚物等组成。(2)RTMB的含量对PA66/RTMB的力学性能有影响,当PA66/RTMB组成为84/16时综合力学性能最佳,拉伸屈服应力、弯曲弹性模量和悬臂梁缺口冲击强度分别是PA66的90%、84%和308%。(3)PA66/RTMB/GF复合材料中,RTMB中的坏氧官能团与PA66分子链上的胺基、羧基以及GF表面的胺基发生了化学反应,组分间形成了化学键连接;PA66基体与GF之间形成了适度柔性强的界面结合。(4)PA66/RTMB/GF中PA66的热结晶放热峰起始温度和峰项温度比原料PA66的提高了1.1℃和1.1～5.5℃;随着RTMB含量的增加,PA66的成核和结晶速率先增大后减小。GF能诱发PA66基体沿玻璃纤维表面形成横晶。(5)PA66/RTMB/EPDM/GF复合材料的力学性能与加工工艺密切相关:和GF先与PA66复合再与RTMB、EPDM复合的两步法,PA66先与RTMB、EPDM复合再与GF复合的两步法相比,采用PA66、GF、RTMB、EPDM一步复合法制得的复合材料的综合力学性能最好;与螺杆转速为40r/min、120r/min的相比,螺杆转速为90r/min时制得的复合材料的综合力学性能最好。(6)GF含量为20%时,随着RTMB含量的增加,PA66/RTMB/GF复合材料的拉伸屈服应力、弯曲弹性模量和悬臂梁缺口冲击强度先提高后降低;RTMB含量为10%时,随着GF含量的增加,PA66/RTMB/GF复合材料的综合力学性能逐渐提高,当PA66/RTMB/GF组成为60/10/30时,拉伸屈服应力、弯曲弹性模量和悬臂梁缺口冲击强度分别提高到原料PA66的1.73倍、2.72倍、3.86倍。(7)组成为60/20/20的PA66/RTMB/GF复合材料的热变形温度为201℃,比原料PA66的热变形温度(69.8℃)显著提高。更多还原

【Abstract】 Poly(hexamethylene adipamide)(polyamide 66,PA66) exhibits excellent properties, such as high rigidity(tensile yield stress,flexural modulus),abrasion resistance,heat resistance,excellent chemical resistance etc.It has been widely used in machinery,electronic equipment,automobiles,and other fields.In order to enlarge the using ranges and satisfy the more requirements for performance,it is necessary to improve the toughness and rigidity of PA66 at the same time,a large number of fruitful researches have focused on the popular topics.Based on the analysis of mechanism of high toughness and rigidity,the works introduce the designing idea to improve toughness and rigidity of PA66 at the same time.The modified PA66 should be prepared through blending the pure PA66 with filler and multi-functional components.The filler can improve the rigidity of PA66.Multi-functional components not only react with PA66 and rigid filler surface,but also improve the toughness and maintained the rigidity simultaneously.Multi-functional components dispersing in PA66 improve the toughness of the matrix PA66,and concentrate in the interlayer between PA66 and rigid filler 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 rigid filler,play completely the role of the rigid filler to enhance rigidity and strength.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.Based on the above designs,the reactive toughening master batch(RTMB) was synthesized through the technique "grafting copolymerization,reactive blending" using PP, ethylene-propylene elastomer,styrene-butadiene rubber,containing epoxy functional groups of bridge agents(G) and auxiliary bridge agents(S).The PA66/RTMB/GF composites were prepared by thermal mechanical reactive blending.The structure and properties of RTMB, PA66/RTMB,PA66/RTMB/GF composites were investigated by means of fraction extraction, IR,SEM,PLM,DTA and mechanical properties measuring.The main results and conclusions are as follows:(1) The compositions of RTMB are composed of unreacted PP and elastomers,graft polymers of PP and elastomers with bridge agents,crosslinked copolymer of PP and elastomers,elastomers and elastomers by polymer bridge conjuction using bridge agents, homopolymer and copolymers of bridge agents.(2) The contents of RTMB have effect on the mechanical properties of PA66/RTMB.As the PA66/RTMB composition is 84/16,PA66/RTMB composite shows the excellent mechanical properties.The tensile yield stress(TYS),flexural modulus(FM) and notchod Izod impact strength(NIIS) of the PA66/RTMB composite are increased to 0.90time, 0.84times and 3.08 times as high as those of the pure PA66 respectively.(3) RTMB,GF and PA66 have chemical bonds through the chemical reaction between the epoxy functional group in RTMB,the bottom amide groups and carboxyl groups of PA66 chains and the amide groups in the GF surface.The moderate flexible interplay with high interfacial adhesion has been formed between the PA66 and GF.(4) The crystallization beginning and peak temperature of PA66 in PA66/RTMB/GF composite was increased 1.1℃and 1.1～5.5℃than those of pure PA66.With the content of RTMB increasing,PA66 nucleation and crystallization rate first increased and then decreased.GF can induce PA66 matrix to generate transcrystallization along the surface of GF.(5) The mechanical properties of PA66/RTMB/EPDM/GF composite are associated intimately with processing technology.Comparing with two-step methods of first blending GF and PA66 then RTMB and EPDM or first blending PA66,RTMB and EPDM then GF, the comprehensive mechanical properties of PA66/RTMB/EPDM/GF composite are best through one-step method;Comparing with screw speed of 40r/min,120r/min,the comprehensive mechanical properties of PA66/RTMB/EPDM/GF composite are best using screw speed of 90r/min.(6) As the GF content is 20%,with the content of RTMB increasing,the TYS,FM and NIIS of PA66/RTMB/GF composite were first increased and then decreased;As the RTMB content is 10%,with the content of GF increasing,the comprehensive mechanical properties of PA66/RTMB/GF composites increased gradually;As the PA66/RTMB/GF composition is 60/10/30,the TYS,FM and NIIS of the PA66/RTMB/GF composite are increased to 1.73 times,2.72 times and 3.86 times as high as those of the pure PA66 respectively.(7)As the PA66/RTMB/GF composition is 60/20/20,thermal deformation temperature of PA66/RTMB/GF composition is 201℃,which is obvious higher than that of the pure PA66(69.8℃).更多还原