Viscoelasticity of Poly Methacrylates

Abstract

This paper presents an intensive study of the viscous and elastic properties of the poly methacrylates. Variation of these properties is studied as a function of temperature in the range 60<T<160°C, as a function of molecular weight in the range 5×103<M<5×106, and as a function of plasticizer concentration over the range 0–100 percent. Capillary viscometers were used in the low‐viscosity systems and tensile creep and recovery measurements under very small loads were used to study the less fluid systems. Principal effort was confined to polymethyl methacrylate but enough work was done using the butyl and decyl esters to show that the whole series of these polymers fits into a relatively simple picture. Consequently, given a certain minimum amount of data, it is now possible to predict the viscoelastic behavior of these polymers in the range of variables given above. The theory of viscoelasticity previously given has been extended so as to take account of the effects of chain entanglements and distributions in molecular weight. Moderately good agreement is found between theory and experiment.