Poly(aryl ether ketone)s containing dibenzoylbiphenyl groups: dynamic mechanical and physical ageing behaviour

✍ Scribed by Goodwin, A A; Campbell, J A; Wang, Z Y

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 118 KB
• Volume: 48
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199905)48:5<353::aid-pi138>3.0.co;2-j

✦ Synopsis

The dynamic mechanical and physical ageing behaviour of a series of isomeric poly(aryl ether ketone)s containing 2,2'-and 3,3'-dibenzoylbiphenyl groups has been determined. A secondary g-process, which was detected in all polymers by dynamic mechanical analysis, was both broader and located at higher temperatures in the 3,3' polymers; this was attributed to greater intermolecular cooperativity and a higher effective relaxation time, arising from the more densely packed chains. The enthalpy relaxation of a pair of isomers was analysed using a common multi-parameter model for structural relaxation. The equilibrium enthalpy lost by the aged glass showed good agreement with the value extrapolated from the liquid state. Although the enthalpy lost by the equilibrium glass was identical for each isomer, the 3,3' substituted polymer required a longer time to reach equilibrium and showed a greater dependence of physical ageing on structure. The higher density of the 3,3 isomer resulted in a slowing of both the physical ageing and the mechanical relaxation process.