Viscoelastic Behavior of Copolymers of Methyl Methacrylate and n-Butyl Methacrylate and Glass Polishing by Use of Them

Publisher Website
Google Scholar
Abstract
In the first part of the work, shear creep compliance is measured for six kinds of copolymers of methyl methacrylate and n-butyl methacrylate above the respective glass transition temperatures. Shift factors and retardation spectra are calculated therefrom. The molecular weight between entanglement points which is obtained from the maximum of spectrum increases with the increase in n-butyl methacrylate fraction. This effect is interpreted in terms of the plasticizer effect of side chains. The maxima of the spectra of the copolymers are proportional to the square root of the corresponding retardation times if the spectra are reduced to the corresponding state in which the wedge portions of the spectra coincide with each other. In the second part, the results by Orioka who polished optical glass pieces by use of the copolymers are semi-quantitatively explained assuming that the surface of the glass polisher is heated by friction up to the temperature at which the shear creep compliance J(t) at t=polishing time is above 10-7cm2/dyn.