The Glass Transition Temperatures of Copolymers of N-Alkyl Substituted Maleimide and Methylacrylate

摘要

The glass transition temperatures of copolymers of N-alkylmaleimide and methylacrylate were measured by use of a glassdilatometer. The glass transition temperature (Tg) increaseswith increase in the amount of maleimide unit in copolymer,and decreases with increase in the length of N-substituents.The glass transition temperatures of N-alkyl maleimide copolymersare lower than those of N-aromatic maleimide copolymersreported previously. The relation between the glass transitiontemperature and the composition of copolymer is discussed onthe basis of the Gibbs-DiMarzio theory. The expansion coefficientsat the glassy and rubbery state decrease with increase inthe amount of maleimide unit in copolymer. However, the productTg·Δα is almost independent of the composition, where Δα is adifference in the expansion coefficients above and below theglass transition temperature.The chain stiffness seems to be a main factor for the glasstransition temperature of maleimide copolymer, although theintermolecular energy affects the glass transition temperature.