Microhardness as a thermally activated process: Indentation time dependence for an amorphous copolyester

Abstract

Vickers microharness, MH, measurements have been performed on samples of a plasticized amorphous copolyterephthalate with different diluent contents. The dependence of MH on contact time is explained in terms of the Eyring equation and it has been found that the activation volume increases abruptly in the vicinity of the glass transition. © 1993 John Wiley & Sons, Inc.

On the Glass Transition Temperature of Polyethylene as Revealed by Microhardness Measurements

“…They used five commercial samples of PE, three LD and two HD (high-density) type. It should be mentioned here that the temperature dependence of H was studied again by Pereña et al for completely amorphous condensation homo-and copolymers of terephthalic type in the range between −20°C and 25°C [20,21]. The β-relaxation was recorded by DMTA only for LD samples, in accordance with previous reports of Popli et al [19] and in contrast to the observations of Lam and Geil [9].…”

Persistent interactions between hydroxylated nanoballs and atactic poly(2-hydroxyethyl methacrylate)(PHEMA)

“…When a load is applied to the surface, as in microindentation experiments, the polymer chains are able to slide past each other more easily, resulting in a decrease in the surface hardness number. 10 Dielectric analysis (DEA) of the nanocomposites further confirmed this behaviour. Dielectric analysis was used to determine the molecular motions and structural relaxations present in the composites; it also revealed the mobility of ions, or ionic conductivity, through the polymer matrix.…”

Nanostructure reorganization in a thermotropic copolyester. A simultaneous WAXS and SAXS study

“…Here, we further investigated the consequences of heat treatment by carrying out microindentation testing to determine the microhardness, H , of B–N copolyester. Hardness has been effective to determine thermally activated processes, aging in thermotropic copolyesters, and mechanical anisotropy in engineering polymers . The method uses a diamond pyramid indenter that penetrates the surface of the specimen upon application of a given load at a constant rate.…”