硅橡胶网络结构调控及其对填充硫化胶非线性黏弹性的影响

Nanoparticles can significantly reinforce rubber materials, but also enhance the strain softening behaviors (Payne effect/Mullins effect under dynamic/static loading conditions) of vulcanizates. In the past researches of about 70 years, breakdowns of filler-rubber interfacial interaction and "filler network" are widely accepted as reasons initiating strain softening of the filled vulcanizates. However, the applicant's preliminary study indicates that the strain softening of filled vulcanizates is determined by the same event of the nonideally crosslinked network structure of the rubber matrix promoted by the filler via a strain amplification effect. This proposal is aimed at the relationship between the molecular network structure and nonlinear viscoelasticity of crosslinked matrix and strain softening of filled vulcanizates. Crosslinked network with clearly defined molecular structures will be created by using poly(dimethyl siloxane) (PDMS) via the method of thiol-ene click chemistry. The contributions of elastically effective network and mobile entanglement network to entropy elasticity and viscoelasticity of the crosslinked matrix will be revealed. The strain softening mechanism of the crosslinked matrix with nonideally crosslinked network will be clarified. Furthermore, the influences of silica loading and filler-rubber interaction on the molecular relaxation, strain amplification effect, entropic elasticity and viscoelasticity of the crosslinked matrix will be accounted for. In-depth and systematic explorations in the aforementioned aspects will be pronouncedly helpful for providing experimental foundations for establishing theoretical models of strain softening and for optimizing the network structure of crosslinked matrix for designing highly reinforced vulcanizates.

纳米粒子可显著补强橡胶材料，但同时也增强硫化胶的应变软化行为(动态/静态加载条件下的Payne效应/Mullins效应)。在近70年的研究历史中，粒子-橡胶界面破坏、“粒子网络”破坏是广为接受的填充硫化胶应变软化的原因。然而，申请人前期研究表明，填充硫化胶的应变软化是由非理想交联网络结构橡胶基体所决定的，填料通过应变放大效应而促进基体应变软化。本项目针对基体分子网络结构-非线性黏弹性-填充硫化胶应变软化关系这一主题，拟采用巯-烯点击化学法构建结构清楚的聚二甲基硅氧烷(PDMS)交联网络，揭示弹性有效网络、能动性缠结网络对基体熵弹性、黏弹性的贡献，阐明非理想网络结构橡胶基体的应变软化机制；进一步研究白炭黑含量及其与PDMS界面相互作用对橡胶基体分子弛豫、应变放大效应、熵弹性和黏弹性的影响，为建立填充硫化胶应变软化理论模型提供实验依据，为高补强低损耗型填充硫化胶的基体网络结构调控提供理论基础。

橡胶纳米复合材料的微观结构、补强机理与非线性黏弹性机理长期以来备受关注。针对多层级微观结构和非线性黏弹性研究难度大且主要结论分歧大等问题，项目以橡胶基体黏弹性为基础开展纳米复合材料微观结构-补强效应-非线性黏弹行为关系，通过建立以硫化胶基体为基础的Payne效应叠加曲线，揭示了基体对该效应的决定性贡献，发现网络链非线性Rouse动力学是该效应的主要机理；建立了橡胶纳米复合材料非线性流变应变-浓度等效原理，发现合成橡胶的弱应力过程行为由非理想交联结构的基体所决定，而天然橡胶的弱应力过程行为由非橡胶缔合组分所决定；提出橡胶基体硫化动力学调控新方法和低锌高效硫化体系应变软化调控新机制。研究结果排除了长期以来有关“粒子团簇软化”、“粒子表面吸附链脱吸附-滑移”、“粒子表面玻璃层屈服”、“粒子网络破坏”等应变软化原因的错误假设，为研究橡胶纳米复合材料补强效应和应变软化行为的分子机制奠定了理论基础，发展应用绿色助剂、填料，调控基体交联结构与纳米复合材料非线性黏弹性提供了实验和理论基础。指导4名硕士研究生、9名博士研究生、2名博士后从事项目研究，发表学术论文33篇，参加国内外学术会议12人次，因在“Polymeric Nanocomposites: Synthesis and Characterization”方面的贡献，获国际先进材料学会（International Association of Advanced Materials）颁发的IAAM Scientist Award。部分研究结论已在合作企业高性能胶料生产和硫化工艺调控中实施应用，企校合作项目“低滚阻、高抗湿滑轿车子午线轮胎的关键技术与装置及产业化”获浙江省2021科学技术进步奖二等奖。