【作者】 陈晓东；

【导师】 周南桥；

【作者基本信息】 华南理工大学 ， 机械设计及理论， 2010， 博士

【摘要】 众所周知,汽车轮胎的三大行驶性能---------低的滚动阻力、高的抗湿滑性能和耐磨性能这三者之间存在着相互制约、难以兼顾的矛盾,尤其是滚动阻力和抗湿滑性能之间的几乎不可调和的矛盾是长期困扰轮胎工业的老大难问题。而浇注性聚氨酯弹性体(CPUE)由于具有高弹性、耐磨、耐油、耐撕裂、耐化学腐蚀、耐射线辐射、黏合性好、吸震能力强等优良性能,在许多工业领域得到了广泛应用。且随着聚氨酯技术进展、应用领域不断扩大,聚氨酯已经发展成为世界上六大合成材料之一。它是一类能依据某种交联方法(链增长或交联,或者兼有两种作用)用泵计量输送(温度在100℃时,粘度为1500泊以下)注入模具来制造弹性制品的聚合物。与橡胶材料相比,PUE具有硬度可调节范围宽(邵A10～邵D85)、耐腐蚀、耐磨、耐低温、耐油等特性;又因为它的液体橡胶特性,还具有生产工艺简单、能耗小、生产自动化程度高等优点。随着国民经济的飞速发展,性能优异的CPUE材料制品倍受青睐,并在逐步替代许多特种橡胶制品,尤其是一些使用性能要求苛刻的制品,如坦克履带推进装置中的履带衬胶、负重轮挂胶、以及各种轮胎、胶轮、胶辊、减震材料和医用心血管材料等。而为了能够将具有高耐磨性的液体橡胶聚氨酯弹性体用于轮胎胎面,实现CPUE胎面三大行驶性能的优化平衡,本论文以聚己内酯(PCL)—甲苯二异氰酸酯(TDI)配方体系为模型,在研究体系中引入耐热和动态力学性能的影响因素以观察各种有关的相关关系,并综合分析和研究这些相关性,建立聚氨酯弹性体的分子组成——超分子结构——聚氨酯弹性体的性能和特性之间的相关关系。主要包括:在两种基本扩链剂体系中采用不同分子量、不同硬段含量时的力学性能、内部结构、超分子微区结构、耐热性能和动态性能的研究。然后针对聚氨酯弹性体在高温、高承载及交变应力等苛刻使用条件下的性能要求,对组成聚氨酯弹性体的三个主要成分软段多元醇、二异氰酸酯及扩链剂与材料各项性能的关系进行了系统研究,此外探索了纳米材料对聚氨酯弹性体性能的改进及其机理,在聚氨酯弹性体分子组成和内部结构与材料耐热性能和动态力学性能之间的相关关系基础上,基于胎面用高分子材料设计的思路提出“集成聚氨酯弹性体”概念。开展了集成聚氨酯弹性体的分子设计和结构设计的研究,使集成聚氨酯弹性体的动态力学性能具有良好的滚动阻力、抗湿滑性、耐磨损性和内生热性四个性能之间的综合平衡。因此“集成聚氨酯弹性体”概念的提出以及相关合成探索实验的结果验证,为高速轮胎胎面用高性能浇注型聚氨酯弹性体的分子设计和结构设计提供了应用理论基础。本论文的研究内容:①系统地研究了软段种类及分子量、异氰酸酯品种及含量、醇/胺扩链剂品种及复配比例分别对CPUE的力学性能、高温强度、动态力学性能及材料结晶性的影响作用,建立了其分子结构与应用性能之间的关系,并综合分析了其分子组成、微观结构与材料耐热性能和动态力学性能之间的相互制约机制;②通过HTPB/IPDI体系聚氨酯弹性体微相形貌和固化流变性关系的研究,提出了“聚氨酯软段和硬段的热力学不相容性、反应流变性和软硬链段的运动能力是决定嵌段聚氨酯微观结构的三个因素,而且需要结合实际情况分析其中哪一个会成为主导因素”的观点;③对纳米填料改进聚氨酯弹性体材料的性能进行了实验研究,发现其改善程度与纳米填料的表面性质及软段多元醇的种类有关联。亲水性的AEROSIL 200和疏水性的AEROSIL R972两种纳米SiO2在不同体系的CPUE中分散性和稳定性存在差异,AEROSIL 200在聚己内酯(PCL)体系中具有较好的分散性、稳定性和补强效果,而在PTMG中的分散性和稳定性均较差,甚至有超过μm级的团聚体的存在;AEROSIL R972在PCL和PTMG两种体系的CPUE中均有较好的分散性、稳定性。其中PCL体系的CPUE材料中两种纳米SiO2均有显著的增强、增韧和提高材料高温使用性能的作用,其中含AEROSIL 200的PCL体系CPUE的100℃拉伸强度和撕裂强度分别比纯PCL体系CPUE对比样提高1.84和1.13倍;而含AEROSIL R972的PCL体系CPUE的100℃拉伸强度和撕裂强度分别比纯PCL体系CPUE对比样提高1.78和2.13倍。④研究了传统硫化橡胶与CPUE液体橡胶在分子结构上的不同,同时探寻了导致传统硫化橡胶与CPUE液体橡胶在力学性能及动态性能上差异的内在因素,提出了“集成聚氨酯弹性体”的研究思路,并根据理论指导合成了多元配方体系CPU,其力学性能基本上可以满足本研究预定的设计指标要求,三元和四元多元配方体系在性能上兼备了各单元体系的优点,克服了各单元体系的缺点,使力学性能各指标之间有一个最佳的综合平衡,实现了力学性能的优化。⑤通过集成CPUE的初步探索,在材料的三大性能上取得突破,即⑴CPUE的初始模量可大幅度降低至通用硫化橡胶的水平;⑵CPUE的Tg可降低到通用硫化橡胶水平;⑶在50～100℃温度段CPUE的tanδ可低于通用橡胶,使CPUE具有低的内生热和低的滚动阻力。更多还原

【Abstract】 As it is well known that there are some unbalanced contradictions among three driving performance of tire---low roll resistance, high wet skidding resistance and abrasion resisting property. Especially, the irreconcilable conflict between rolling resistance and wet traction is the key problem in tire industry.Because of their excellent tensile strength, tear strength, load bearing ability, abrasion resistance, solvent resistance, and other physical characteristics, CPUEs have been successfully employed in a growing variety of applications and became one of the six polymeric materials. This kind of material can be delivered by metering pump and casted into mould, then formed via cross-linking reaction. Compared with rubber material, polyurethane elastomer possessed wide range of variable hardness (Shore A 10 ~ Shore D 85)、anticorrosion、tear resistance、excellent low temperature performance and oil resistance. Because of fluidity of prepolymer, the processing of polyurethane elastomer is simple, low energy consumption and highly autonomous. With the development of national economy, many CPUE materials with outstanding properties have replaced many special rubber products, especially some articles within tough requirements, such as rubber pads for tank track, road wheel, tire, rubber roller, damping materials and medical cardiovascular materials.In order to make it possible for CPUE used as tire tread, the castable polyurethane elastomers based on poly(ε-caprolactone)-toluene diisocyanate systems were carefully investigated as the model polymer materials. In order to establish the relationship between the formulas and the properties, the influence factors of thermal properties and dynamic mechanical properties were introduced and analysis. Based on the experimental research, the correlationships among the molecular architecture, supermolecular structure and the properties of castable polyurethane elastomers were constructed. The main research contents are listed below: the research on the mechanical properties, inner molecular structure, supermolecular micro domain structure, thermal properties and dynamic properties of two basic systems with two kinds of chain extenders, which were prepared with different molecular weights soft segments and various hard segment contents. And aimed at the requirement of the castable polyurethane elastomer used in the elevated temperature, high loading and harsh alternating stress application, we investigated the relationship of material properties and three main compositions of this polymer, what has been well known as the soft glycol, diisocyanate and chain extender. In addition, the improvement of nano size filler on the properties of castable polyurethane elastomer and its mechanism was studied and discussed systematically. A new concept, intergral polyurethane elastomer, was created based on the relationship between the molecular architecture & inner structure of polyurethane elastomers and thermal properties & dynamic mechanical properties of materials, also this concept stemmed from the thought of the design of polymer materials. Therefore, the study of molecular architecture and structure design of intergral polyurethane elastomer was carried out to obtain an overall balance of excellent roll resistance, wet skidding performance, wear resistance and heat build up (hysteresis). At the same time, the thermal properties of intergral polyurethane elastomer should be improved significantly. The experimental research and the theory innovation should be the theoretical basis for the molecular architecture and structure design of high performance castable polyurethane elastomer for dynamic loading application.Specific as follows:1 In order to establish the relationship between the formulas and the properties, the influence factors of thermal properties and dynamic mechanical properties, such as variety and molecular weight of glycols, content and type of isocyanates and chain-extenders, were introduced and analysis.2 Based on the study of reacting rheology and microstructure of HTPB/IPDI polyurethanes, a viewpoint was proposed like that: thermodynamics incompatibility of soft segments/hard segments of castable polyurethane elastomers, reaction rheology and mobility of soft/hard chain segment are the main factors for micro structure of the segmented polyurethane. And which one is the major should be judged from the experimental results.3 Nano size filler can be used to modify the properties of castable polyurethane elastomer and the improvement of the properties. The modification related to the surface nature of nano size filler and the type of soft polyol. The two nano size SiO2 with different properties had different dispersion and stability in different kinds of CPUE. The hydrophilic AEROSIL 200 could be dispersed in the PCL based system and the final product performed excellent. This filler was not fit for the PTMG based system, there were agglomerating phenomenon, and even some nano-agglomerates with more than 1μm diameter. The hydrophobic AEROSIL R972 could be dispersed homogeneously in both the PCL based system and the PTMG based system. Moreover, both the two types of nano size filler reinforced the PCL based system. The tensile strength and tear strength at 100℃of PCL based CPUE with 5% AEROSIL 200 were 1.84 and 1.13 times than those of the pure PCL CPUE, respectively. And the tensile strength and tear strength at 100℃of PCL based CPUE with 5% AEROSIL R972 were 1.78 and 2.13 times than those of the pure PCL CPUE, respectively.4 The molecular structure difference between traditional vulcanized rubber and CPUE liquid rubber was investigated systematically, and the inner factors resulted in the different mechanical properties & dynamic properties between traditional rubber and CPUE were analyzed. Based on these work, a new concept, integral polyurethane elastomer, was put forward. The multi-component system CPU was prepared based on theoretical and experimental analysis. The mechanical properties of tri-component/tetra-component systems meet the requirement of the designed index. The optimized properties were achieved by acquiring the integrated balance of every index of properties.5 Through the preliminary exploration in integrated CPUE, the breakthrough of polyurethane materials was obtained. That is:(1) Initial modulus of CPUE can be reduced greatly, and the value was comparable to the traditional vulcanized rubber;(2) Glass transition temperature of CPUE can be reduced to the level of the traditional vulcanized rubber;(3) The tanδin 50-100 degrees Celsius temperature range of integral CPUE is lower than that of the traditional vulcanized rubber, that mean the integral CPUE possessed lower heat build up and lower rolling resistance.更多还原