the effect of strain rate on the tensile properties of pmma/hydroxyapatite composite

To investigate the effect of the different content of hydroxyapatite (ha) (5, 10, and 15 wt.%) on the tensile properties and deformation mechanism of the poly methylmethacrylate (pmma), tensile test at different strain rate (4.1×10^-4 , 8.3×10^-4 ,1.66×10^-3 , 3.31×10^-3, 8.275×10^-3, and 16.6×10^-3 s^-1), microscopic evaluations were performed on the standard samples. the results of the tensile test showed that by adding ha to the pmma, its strain rate sensitivity increased. the activation energy (δh) for chain fluctuation decreased from 56.42 to 37.81 j/mol as ha content increased from 0 to 15 wt.%. in addition, the active volume (𝑉 ∗ ) of the chain during the tensile test was measured indicating that its value decreased from 3.02 to 2.35 as ha content promoted from 0 to 15 wt.%. the results of microscopic evaluation showed that the deformation mechanism of pmma during the tensile test was crazing and dispersity of craze depended strongly on the ha content.