Role of a small amount of comonomer on the physical aging of poly(methyl methacrylate) copolymer investigated by dynamic viscoelasticity

The physical aging of a poly(methyl methacrylate) (PMMA) copolymer having a small amount of ethyl methacrylate was investigated below its glass transi tion temperature (T-g) using dynamic viscoelastic measurements. The results were compared with those from homo-PMMAs to investigate how the comonomer in the copolymer affects the physical aging of the glass. Annealing tempera tures were classified into two categories by the glass transition temperatu re of a poly(ethyl methacrylate) (T-gPEMA; ca. 65 degreesC). The relaxation rate of the copolymer into two categories by the glass transition temperat ure of a poly(ethyl methacrylate) was faster than those of the homo-PMMAs w hen the samples were aged below T-gPEMA, but the rates were equal when aged at above T-gPEMA. The experimental results are discussed in terms of the s egmental motion. (C) 2001 Elsevier Science Ltd. All rights reserved.