This article is concerned with the influence of several significant molecular variables on deformation modes, such as crazing and shear yielding, and on properties and behavior of glassy polymers subject to monotonic or alternating loading. The principal molecular variables to be considered are molecular weight and the extent of chain entlanglement, intra- and intermolecular interactions arising from the presence of ionic groups, and the extent of crosslinking that may be present. Existing data from the literature that bear on these variables are reviewed and collated and additional data obtained in our laboratory are presented. Primary attention is devoted to the influence of the molecular variables on craze deformation and fatigue performance, but consideration is also given to their effects on shear yielding and on properties and performance under monotonic loading conditions. It is now established that improvements in performance, such as greater resistance to craze breakdown, higher fracture toughness, and enhanced fatigue life can be realized by proper control of these molecular variables. As additional research results become available, and greater knowledge and understanding of the underlying molecular mechanisms involved in deformation and fracture are developed, significant further improvements in performance are to be anticipated.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Organic Chemistry
- Polymers and Plastics