Correlation between interfacial interactions and internal stresses in filled high density polyethylene

Abstract

Abstract:The stress relaxation and the creep behaviour of high density polyethylene (HDPE) filled with glass fibres, clay (plate-like particles) or CaCO 3 (particles with irregular shape) were measured in uniaxial extension at room temperature. It was observed that the addition of filler increased the ir~ternal stress level, as evaluated from stress relaxation data. This increase was larger than the corresponding increase in the (short-term) elastic modulus. This behaviour may be attributed to a reduced macromolecular mobility in the matrix material close to the filler surface, i.e. to formation of an interphase region in the HDPE-matrix. From the internal stress values, the thickness of this interphase region around each filler particle was estimated, assuming a uniform coverage of the particles. It was suggested that the amount of matrix material with reduced mobility (or the thickness of the interphase region) reflected the degree of adhesion between the filler and HDPE. The change in the internal stress level due to the incorporation of different fillers, which were surface treated in some cases, was also consistent with the observed creep behaviour.

The influence of processing on fiber orientation and creep in short carbon‐fiber reinforced low density polyethylene and polycarbonate

“…The creep and stress relaxation behavior of HDPE filled with calcium carbonate, clay, and GF was measured by Ek (19) who found that the fillers had a marked influence on the long-term properties of the matrix. The effect was explained by reduced mobility of the matrix molecules adjacent to the particle surface.…”