An experimental approach to the optimum strength of polyvinyl-chloride (PVC) sheet thermoformed by uniaxial stretching

摘要

Optimum strength of polyvinyl-chloride (PVC) sheet thermoformed by uniaxial stretching was studied by mechanical test, thermally stimulated deformation recovery and structural observation using polarized light. In spite of tensile stress evolution during rapid cooling of thermoformed sheets, their deformation recovery behavior at reheating showed no evidence of storage of strain energy probably lessening static strength of thermoformed sheets. Sheets thermoformed at 100℃had quite high ductility presumably due to the peculiar crystalline structure still left in PVC after thermoforming. Sheets thermoformed at 130℃ showed much less ductility and was found to have no crystalline structure.