Abstract
Optical and transmission electron microscopy have been used to investigate the microdeformation mechanisms in thin films of amorphous semi-aromatic polyamides with different chemical structures and chain lengths. In the chosen range of test temperatures (between −120 °C and the principal mechanical relaxation temperature, T α), three successive microdeformation mechanisms were identified: chain scission crazing (CSC) at the lowest temperatures, shear deformation zones (SDZs) at intermediate temperatures and chain disentanglement crazing (CDC) at the highest temperatures. The critical stress for SDZ formation was identified with the experimental yield stress, whereas the critical stresses for CSC and CDC were derived from model expressions, using experimental data for the molecular mass between entanglements, the monomeric friction coefficient and the plastic flow stress. Variations in the transition temperatures among the different polymers were attributed to differences in the temperature dependence of the yield stress, and hence to variations in chain mobility, which could be accounted for in terms of the chemical structure.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
