基于弹性统计理论的硅橡胶纳米复合材料本构关系的建立

基于考虑了悬垂链的橡胶弹性统计模型,通过引入应变放大因子,建立了硅橡胶纳米复合材料的基于微观机制的本构关系,其中利用硅橡胶分子信息(分子量M、乙烯基含量wt_(Vi)%)、乙烯基反应程度(q)估算获得本构方程中的交联点间链段分子量(Mc),网络链(network strands)体积分数(Φ)等参数,通过拟合确定了与纳米粒子相关的部分参数(初始应变放大因子X_0,极限应变放大因子X_∞,衰减因子z),对掺杂白炭黑的单组分及长短链配合硅橡胶拉伸应力-应变数据进行拟合,在采用相同X_∞,z值情形下,拟合曲线仍能与实测值符合较好(拟合的Adj.R-Square值分别为0.99576、0.99596)。基于微观物理机制的本构关系能够成为联系微观分子结构参数与宏观应力的桥梁,本文工作有望为更有针对性地改进和优化硅橡胶的性能提供依据。

Establishment and Application of Constitutive Model of Silicone Rubber Nanocomposite Based on Statistical Theory of Rubber Elasticity

In this article,a constitutive model based on microscopic physical mechanism was established by introducing a strain amplification factor into the statistical model of rubber elasticity,which considering the effect of dangling chains.Some parameters which relating to the polymer network,such as average molecular weight (Mc) of chain segments with both ends attached to the network (network strands) and volume fraction (Φ) of network strands,were calculated using the molecular weight (Mc),vinyl content (wtVi) of the polysiloxane and percent conversion (q) of vinyl groups.The primary strain amplification factor (X0),infinite strain limits of the amplification factor (X∞) and decay exponent (z),which relating to the nanoparticles,were obtained by fitting the stress-strain data.The resulting fitting curves were in good agreement with the experimental data of both single and bimodal silicone rubber composites.The constitutive model based on microscopic physical mechanism could become the bridge connecting the macroscopic stress-strain behavior to the microscopic molecular structure parameters and our work could promisingly provide a basis for the performance improvement and optimization of silicone rubber.