Micromechanical model for hydroxyapatite whisker reinforced polymer biocomposites

Abstract

A micromechanical model was developed to predict the elastic moduli of hydroxyapatite (HA) whisker reinforced polymer biocomposites based upon the elastic properties of each phase and the reinforcement volume fraction, morphology, and preferred orientation. The effects of the HA whisker volume fraction, morphology, and orientation distribution were investigated by comparing model predictions with experimentally measured elastic moduli for HA whisker reinforced high-density polyethylene composites. Predictions using experimental measurements of the HA whisker aspect ratio distribution and orientation distribution were also compared to common idealized assumptions. The best model predictions were obtained using the experimentally measured HA whisker aspect ratio distribution and orientation distribution.

Processing and tensile properties of hydroxyapatite-whisker-reinforced polyetheretherketone

“…The degree of the preferred orientation in HA-whisker-reinforced PEEK was similar to that of apatite crystals in human cortical bone tissue. The maximum degree of apatite crystal c-axis preferred orientation in the longitudinal anatomic axis was also on the order of 2.5 MRD for tissue from the mid-diaphysis of a human femur [5]. The preferred orientation of apatite in bone is thought to be determined by guided nucleation and growth of crystals within collagen fibrils, and a hypothesized mechanosensory mechanism for crystals residing outside collagen fibrils [6].…”

“…The apatite crystals are plate-like and elongated with a c-axis preferred orientation in directions of principal stress, such as the longitudinal anatomic axis of long bones [1,[3][4][5]. Therefore, bone tissue exhibits corresponding anisotropic mechanical properties [6,7].…”

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…Besides, general knowledge on composite mechanics suggests that any high aspect ratio particles, such as whiskers or fibers, significantly improve the modulus at a lower loading. 179 Thus, some attempts have already been made to prepare biocomposites containing whisker-like [225][226][227][228][229] or needle-like [230][231][232] calcium orthophosphates as well as calcium orthophosphate fibers. 49,233 The history of implantable polymer-calcium orthophosphate biocomposites and hybrid biomaterials started in 1981 234 with ©2 0 1 1 L a n d e s B i o s c i e n c e .…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…Besides, general knowledge on composite mechanics suggests that any high-aspect-ratio particles, such as whiskers or fibers, significantly improve the modulus at a lower loading [147]. Thus, some attempts have been already performed to prepare biocomposites containing whiskerlike [177][178][179][180] or needle-like [181][182][183] calcium orthophosphates, as well as calcium orthophosphate fibers [45,184]. [186,187].…”