Jmg. Cowie et al., Stress relaxation and physical ageing in a blend of poly(styrene-co-acrylonitrile) and poly(methyl methacrylate), J CHEM S F, 94(23), 1998, pp. 3481-3486
Citations number
38
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS
The structural recovery during physical ageing of poly(styrene-co-acrylonit
rile), poly(methyl methacrylate) and of a 50/50 blend of these polymers has
been examined by determining the stress relaxation modulus, G(t), over a r
ange of temperatures below their respective glass transitions. Time-ageing
time superposition of the modulus curves is possible and this gives sets of
shift factors which reflect the changing mechanical response of the polyme
rs and their blend during isothermal ageing. The ageing rate of poly(styren
e-co-acrylonitrile) : decreases quite markedly in the region of the glass t
ransition. The rates for poly(methyl methacrylate) and for the blend also d
ecrease on approaching the glass transition, but with a lesser temperature
dependence. By scaling this behaviour to the glass transition the rate of a
geing of the blend is found not to be intermediate between that of the comp
onents but to be similar to that of poly(methyl methacrylate). This may be
explained by proposing that the two blend components respond differently to
the applied stress field.