反应包覆界面特性对丁苯橡胶/芳纶疲劳行为作用机制的研究

The fatigue life of short fiber reinforced rubber composites (SFRR) is essentially determined by the evolution of fatigue damage, which is mainly associated with the interfacial elastic modulus and interfacial bonding. However, due to the enormous challenge to construct and control the interfaces, the mechanism of the interfacial properties on fatigue behaviors is unclear yet. Therefore, it is of great significance to design and construct the controllable interfaces of SFRR, creating the chance to investigate the underlying influence of the interfacial properties on fatigue behaviors for property improvements. In this project, a kind of multi component coating agent which is composed of multi-monomer highly grafted liquid rubber and epoxy/curing agent is supposed to accomplish an effective chemical coating for the surface-treated aramid fibers. Through adjusting the component ratio and reaction kinetics, the rubber/aramid interface with controllable modulus and adhesion could be created via chemical reaction during mixing fibers with butadiene styrene rubber (SBR)/carbon black followed by vulcanization. The influence mechanisms of the interfacial properties during the fatigue testing on the microscopic and macroscopic fatigue damage evolution and fatigue performances would be investigated via combining the interfacial property regulation with the microscopic modulus characterization in various phase regions of SFRR, interfacial energy testing, microscopic structure analyses and the fiber microscopic stress analyses. The models to understanding the relationships between the interfacial properties and macroscopic fatigue performances would be established, while it would be important to study the mechanisms of altering fatigue damage process by regulating the interfacial properties. It is apparent that this project will provide a fundamental cornerstone for the fabrication and application of anti-fatigue SFRR materials, holding great potential for expanding the industrial development and applications of high-performance SFRR.

疲劳损伤的演变决定了橡胶/短纤维复合材料（SFRR）的疲劳寿命。 SFRR的界面弹性模量和界面粘接性能是疲劳损伤演变的主要影响因素，由于缺乏构建可控界面的方法，界面特性对疲劳行为的作用机制尚不清楚。本项目对SFRR进行界面设计和界面特性调控，研究其对疲劳行为的影响规律和作用机制。拟用多单体接枝液体橡胶、环氧树脂/固化剂构成包覆剂，对表面改性的芳纶进行包覆处理，调控包覆剂组份配比和反应进程，在纤维与丁苯橡胶/炭黑混炼和橡胶硫化过程中，通过化学反应构建模量和粘接可调控的橡胶/芳纶界面。将SFRR不同区域微观模量表征、界面能测定、微观结构分析及纤维微观应力分析相结合，研究疲劳试验进程中界面特性对微观和宏观疲劳损伤演变及疲劳性能的影响规律，建立界面特性参数与疲劳性能的关系模型，阐明通过对界面特性的调控来改变疲劳损伤进程的作用机制，为抗疲劳SFRR的开发提供理论依据。

本项目制备界面特性（模量和粘接）可调控的芳纶纤维（AF）增强丁苯橡胶（SBR）/炭黑（CB）复合材料，通过界面特性的调控来改变缺口试样疲劳损伤进程，提高材料的抗疲劳性能。采用聚酰胺酸修饰和POSS修饰构建了刚性界面，采用极性液体橡胶、环氧树脂/固化剂包覆AF，原位构建界面模量可调控的柔性界面，研究了界面特性及其变化对不同试验条件（应力应变、预制裂纹）下的疲劳损伤演变的影响规律，建立界面特性与宏观疲劳性能的关系模型。用原子力显微镜对界面微观模量进行测定以表征界面疲劳损伤，提出了复合材料结构表征的新方法。发现疲劳进程中纤维界面产生集中损伤，诱导裂纹向界面发展并剥离纤维，据此提出柔性界面层“吸引裂纹”的抗疲劳机制。引入纤维对裂纹扩展速率的影响因子α，提出了纤维的加入和基体橡胶材料对疲劳裂纹扩展速率影响的综合模型。发现真实应力与疲劳循环次数和裂纹扩展长度符合幂律关系，疲劳裂纹加速扩展的临界裂纹长度对应于真实应力的开始加速点，因此真实应力演变可表征纤维增强橡胶复合材料缺口试样的疲劳行为。长纤维的加入使得复合材料的动态疲劳性能显著提升，相较于短纤维增强复合材料的疲劳寿命提高了352.7%，为制备高抗疲劳橡胶复合材料提供了方法。提出了相对脱粘能（RDE）和相对改性脱粘能（RMDE）新参数，根据其随疲劳进程的衰减，判断纤维增强橡胶复合材料界面和基体的疲劳损伤的发展，利用该参数可通过改变界面特性来优化纤维增强橡胶复合材料的疲劳行为和抗疲劳性能。构建粘接良好的具有一定模量的偏柔性AF/SBR界面层，具有高的RDE和RMDE初始值，在疲劳进程中产生一定的衰减，形成界面层集中损伤，可使基体免受过度的疲劳损伤，疲劳进程中形成界面层和基体的均匀损伤，可获得最佳的抗疲劳性能，疲劳寿命提高3倍以上。发表SCI收录论文7篇(总影响因子33.6)，EI收录论文2篇，申请发明专利2项，在国内和国际学术会议作报告4次,培养博、硕士研究生5名。