No abstract

No abstract

Injection-molded samples of high-density polyethylene (HDPE) differing in the orientation pattern (with respect to the melt flow direction) and in filler content (untreated and surface-treated kaolin, respectively) were characterized by wide-angle X-ray scattering, microhardness, and stretching calorimetry techniques. The crystallinity of the polymer matrix in filled samples shows the same value as that found for the neat polymer regardless, filler content, and/or filler surface treatment. The thermoelastic behavior of all samples in the strain interval below the apparent yield point * is quantitatively discussed in terms of classical equations for elastic solids. Analysis of thermoelastic parameters of the boundary interphase (BI) reveal an unusually stiff, highly oriented structure of the matrix polymer within BI. Discrepancies of experimental values for the internal energy increment in the inelastic strain interval above * between unfilled and filled samples is explained in terms of the filler debonding process. The latter process is discussed in light of the formation of a polymer-free filler surface and of the concomitant inelastic deformation (plastic flow) of a polymer matrix in the interstitial space between filler particles.

No abstract