The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition o...The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition of tensile failure.The rate-dependent behaviors originate from intrinsic relaxations,ranging from perturbation of molecular bonds between polymer segments to reptation of polymer chains.In this work,we develop a constitutive model that incorporates segmental and chain dynamics into the deformation of bond and polymer networks,respectively.The dynamic scission of polymer chains is also incorporated into the theoretical framework to describe the damage evolution and ultimate failure of polymers.A comparison between theoretical predictions and experiments shows that the present model is able to simultaneously capture the observed rate-dependent features,including the transition from glassy state to rubbery state,strain hardening,and failure threshold.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12022204,12002302 and 12072316)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21A020008)the Fundamental Research Funds of Zhejiang Sci-Tech University(Grant No.2021Q039).
文摘The stress response of amorphous polymers in the glass transition region shows apparent temperature and rate dependence.With increasing loading rate,amorphous polymers also exhibit a clear ductile-brittle transition of tensile failure.The rate-dependent behaviors originate from intrinsic relaxations,ranging from perturbation of molecular bonds between polymer segments to reptation of polymer chains.In this work,we develop a constitutive model that incorporates segmental and chain dynamics into the deformation of bond and polymer networks,respectively.The dynamic scission of polymer chains is also incorporated into the theoretical framework to describe the damage evolution and ultimate failure of polymers.A comparison between theoretical predictions and experiments shows that the present model is able to simultaneously capture the observed rate-dependent features,including the transition from glassy state to rubbery state,strain hardening,and failure threshold.
