Effect of molecular weight on rate of enthalpy relaxation of poly (methyl methacrylate) and its oligomers

Publisher Website
Google Scholar
Abstract
The enthalpy relaxation process of methyl methacrylate oligomers and poly (methyl methacrylate) was analyzed by use of the excess enthalpy (ΔHt), which was obtained from a differential scanning calorimetric measurement. The apparent relaxation time (τ½) was estimated by the assumption of the single relaxation time response. The Tg of oligomers increased with an increase of molecular weight, and approached a constant value above 1 × 104. The apparent relaxation time showed a similar molecular‐weight dependency as Tg, and approached a constant value above 1 × 104. It was expected that the molecular motion which caused the enthalpy relaxation was based on the segmental motion of main chains.