一軸延伸により熱成形したポリメタクリル酸メチルの構造と静的破壊特性
Structure of Uniaxially Thermoformed Poly (methyl methacrylate) and its Fracture
塚本晃久・南斎征夫
Tsukamoto, Akihisa / Nanzai, Yukuo
In order to examine the effect of thermoforming process on the fracture behavior of thermoplastics, uniaxial tensile tests and deformation recovery measurements at heating were carried out for uniaxially stretched poly(methyl methacrylate)(PMMA). In spite of the development of tensile stress during rapid cooling processes, stretched specimens were much more ductile than undeformed ones. Plastic strain frozen in the thermoformed specimens was recovered at heating only in the glass transition range. Thus, the molecular structure of the stretched PMMA was supposedly free from the localization of strain energy which is probably a key factor reducing the static strength of thermoplastics. The smoothness of the specimen surface probably improved by stretching was also likely to contribute to the increase of ductility for the PMMA.
Key words: Poly (methyl methacrylate) (PMMA) / Thermoforming / Fracture behavior / Deformation recovery at heating / Strain energy