延伸速度の急変を受けるガラス状ポリメタクリル酸メチルの動的粘弾性変化

抄録

Variation of dynamic shear modulus, G^* = G′ + iG″, was measured for glassy poly(methyl methacrylate) (PMMA) during uniaxial stretching processes where the tensile rate changed stepwise. Under the condition of constant-rate stretching, it is known that G′ and G″ gradually change to their steady values in the post-yield range of strain, and that the change occurs strongly at a higher tensile rate, indicating strain-induced changes in glassy structures. After a change of tensile rate, G′ as well as G″ varied monotonously from their values at the initial tensile rate to those at the final rate in a strain range where the uniaxial stress σ exhibited transient responses to the tensile rate change. The observed variation of G′ and G″ simply indicates that, after an abrupt change of tensile rate, structures of the glass successively change from those corresponding to initial tensile rate to final rate.