聚氨酯/环氧树脂互穿网络硬泡静态压缩塑性变形模式

采用同步法合成聚氨酯/环氧树脂互穿网络硬泡,通过FTIR和SEM研究其化学结构及微观结构形态,为研究其压缩响应及变形模式,对其进行静态压缩试验。结果表明:IPN硬泡的压缩行为表现出各向异性。平行发泡方向的压缩应力-应变曲线表现出三个变形阶段,其中平台阶段的显著特征是应变软化和局部变形。垂直发泡方向的压缩曲线则单调增加,平台阶段没有产生应变软化,整个压缩过程中试样变形均匀分布。IPN硬泡的静态压缩存在明显的应变率效应,环氧树脂含量对压缩性能影响显著。描述IPN硬泡压缩局部变形理论模型,变形带厚度和变形带前沿传播速度的理论值与试验值吻合较好,采用该模型分析研究IPN硬泡的压缩变形机理。

Plastic Deformation Modes of Rigid PU/ER Interpenetrating Polymer Networks Foams Under Static Loading

A series of rigid polyurethane/epoxy resin interpenetrating polymer networks (PU/ER IPN) foams were prepared by a simultaneous polymerization technique.The chemical structure and morphology of these foams were investigated by fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).The compression responses of the IPN foams are anisotropic.Compression in the rising direction yields a typical three-stage stress-strain response of foams, and the prominent features are strain-softening and deformation localization.Compression in the transversal direction gives rise to a monotonously increasing stress-strain curve without strain-softening and always produces uniformly distributed deformation.The results show that the compression behaviors of the IPN foams are sensitive to the strain rates and ER contents.A theoretical model, which could describe deformation localization of the foams, is referenced to calculate the deformation band parameters, and correlates well with experiments.The compression deformation mechanism of the IPN foams is analyzed by this model.