Abstract
Thermally stimulated creep recovery (TSCR) experiments have been used to study the influence of tacticity on the α retardation process in amorphous poly(methyl methacrylate) (PMMA). The α retardation process associated with the glass transition is strongly dependent on tacticity. The high-sensitivity TSCR−fractional loading (FL) method was used to extract the distributions of activation enthalpies ΔH and entropies ΔS of the α mechanical relaxation. ΔH increases with temperature and is maximum at the glass transition temperature Tg. The maximum value and the full width at half-height of the activation enthalpy distribution are tacticity-dependent. Comparing experimental activation enthalpies with Starkweather's zero entropy prediction shows that the low-temperature tail of the α retardation process extends to 30 °C independent of tacticity. This result is attributed to the presence of isotriad sequences enhancing molecular mobility in this temperature range.
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.
