Some polymers (e.g., bisphenol A polycarbonate) are tough and can undergo ductile large deformation while others (e.g., polystyrene) are only brittle until they are sufficiently close to their glass transition temperature. Glassy polymers brittle in extension are ductile in compression. What drives the polymers to yield and how to make them tougher? Such questions are for polymer physicists to answer. Previous theoretical treatments focused on explaining how polymer glasses yield but avoided questions such as when and why glassy polymers cease to yield upon cooling. This talk describes our efforts in the past five years, made to establish a microscopic framework for molecular mechanics of polymer glasses. The new understanding is expected to provide guiding principles for future molecular design and engineering of the next-generation polymeric materials with better mechanical properties, when combined with the latest update on the subject of polymer rheology.

Developing molecular level understanding of ductility in polymer glasses

256th National Meeting (2018)

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