分子鎖の挙動に基づく結晶性高分子材料の非弾性変形のモデル化に関する研究

抄録

Semi-crystalline polymer (SCP) has very complex hierarchical structure consisting of a laminar structure of crystalline and amorphous phases in nm scale and a spherulite structure in μm scale. The inelastic mechanical behavior of SCP is usually explained by the slip deformation in crystalline phase. However, the folded molecular chain in crystal phase changes to the highly oriented structure in a large strain range. This change cannot be explain using only the slip deformation and a rigid rotation accompanied by the slip. In the present study, the inelastic deformation behavior of SCP is modeled by introducing the separation and recombination of the physical bonding of molecular chain into the rubber elasticity model. In-situ observation of elongation process of the spherulite of polypropylene revealed that the prominently localized deformation occurred in the equator area of spherulite. The softening due to the separation of the physical bonding may cause such a microscopic local deformation in the spherulite. The mechanical model was then constructed based on the separation and recombination of the physical bounding. The relationship of the stress and strain under the uniaxial tensile test predicted by the proposed model represented the softening followed by the hardening due to the orientation of molecular chain. Furthermore, the propagation of the local deformation zone, which is often seen in the tensile test of polymeric material, was also predicted by FEM simulation with the proposed constitutive equation.