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11	Effect of polymer matrix on the rheology of hydroxapatite filled polyethylene composites. Martyn, Michael T., Joseph, R., McGregor, W.J., Tanner, K.E., Coates, Philip D. January 2002 (has links) No / The effect of matrix polymer and filler content on the rheological behavior of hydroxyapatite-filled injection molding grade high-density polyethylene (HDPE) has been studied. Studies of the flow curves revealed that the matrix and the composite exhibit three distinct regions in the flow curve, namely, a pseudoplastic region at low to moderate shear rates, a plateau and a second pseudoplastic region at high shear rates. The shear stress corresponding to the plateau (Tc) is dependent on both the filler concentration and the melt temperature. Addition of HA in the HDPE matrix increases the value of Tc and decreases compressibility of the melt. An increase in temperature also raises the value of Tc. From the nature of flow curves it is concluded that the matrix polymer largely decides the rheology of the composite. Rheological properties Temperature effect Melting point Pseudoplastic fluid Flow curve Property composition relationship Isothermal compressibility Shear viscosity Shear stress Stress strain relation Injection molding Hydroxyapatite Dispersion reinforced material High density ethylene polymer Composite material Experimental study