The effect of photodegradation using UV radiation on the beta-relaxati
on in poly(methylmethacrylate), PMMA, was investigated dielectrically
within the temperature range 60-90 degrees C and a 20-10(5) Hz frequen
cy band. It is shown that the irradiated samples exhibit a beta-relaxa
tion process similar to that of unirradiated PMMA but with broader dis
tribution of the relaxation times. Increasing the time of UV exposure
increases the magnitude of the relaxation and displaces the peak towar
d lower temperature. The apparent activation energy decreases with irr
adiation. It is suggested that these observations can be interpreted i
n terms of the chain scissioning of the polymer chains without extensi
ve depolymerization. (C) 1996 Elsevier Science Limited