Rate‐Dependent function in the correlation between hardness and yield stress of polyethylene composites

Abstract

A study of the validity of a correlation between compressive yield stress and Vickers hardness of CaCO,/high density polyethylene composites was carried out. Composites with calcium carbonate in the range of 0-0.40 were produced by twin screw extrusion followed by compression molding. Hardness was implemented by indenting the samples with Vickers indenter and compression test were carried out at various crosshead speeds in the range of 0.2-50 mm mir-' . It was found that increasing calcium carbonate content increased both hardness and yield stress. In addition, compressive yield stress increased with increasing crosshead speed. The correlation between hardness and yield stress was observed to be independent on filler content and valid when the deformation rate employed in both tests were within the similar ranges which was in the order of lo-' mm mi^'. Tabor's equation was modified to take into account for the rate-dependent behavior of composites and was found to be applicable and yield relatively accurate results.

Correlations Between Indentation Hardness and Yield Stress in Thermoplastic Polymers

“…For a PP/PE blend system it was shown that this is not the case [13]. Considering the correlation of Vickers hardness and compressive yield stress, however, Tabor's rule may still be valid [14]. Our first attempts show a comparable strain rate dependency of yield stresses and Martens hardness in the range 10 −5 –0.1 and 0.0015–0.15 s −1 , respectively, for PVDF and PC.…”

Fabrication and properties of poly(propylene carbonate)/calcium carbonate composites

“…However, reinforcing materials such as glass fibers, carbon fibers, and aramide fibers are not biodegradable. Among the various reinforcing materials, CaCO 3 is attractive because of its low cost 12–19. Another advantage of CaCO 3 is derived from its hydrophilic behavior, that is, its water adsorption characteristics.…”

Mg2+ content control of aragonite whisker synthesised from calcium hydroxide and carbon dioxide in presence of magnesium chloride

“…[6][7][8][9][10][11][12][13][14] Calcite is the thermodynamic stable phase and generally is in rhombohedral form. Morphology and properties of CC vary with their polymorphism.…”