A modified pultrusion process for preparing composites reinforced with continuous fibers and aligned hydroxyapatite nano needles

Abstract

Of importance to orthopedic procedures are repair materials that can carry significant loads without excessive deformation. In addition, these materials need to be biocompatible, bioabsorbable, and conducive to the replacement of the repair material with native bone. To meet these requirements, we have designed composites using two biocompatible/bioabsorbable polymers, poly(l‐lactic acid) (PLLA) in fiber form and polycaprolactone (PCL) filled in a carefully designed fashion with nano needles of hydroxyapatite (HA). Discussed in this article is a modified pultrusion process that proved useful for producing suitable composites. In this process, the feed to the pultrusion die is a stabilized suspension of the HA needles in a PCL/MEK solution, whereas the fiber “bundle” is a single yarn containing 360 PLLA fibers. The small scale is needed to maximize the content of HA in the final composite and assure uniformity. Process variables studied include the ratio of HA to PCL in the suspension, the solids content of the suspension and various geometrical variables in the die design that influence the shear‐rate profile along the fiber path. The goal of the pultrusion step is to fill all interstices between the fibers with a PCL matrix that is reinforced with highly aligned HA needles. POLYM. COMPOS., 36:931–938, 2015. © 2014 Society of Plastics Engineers

Calcium Orthophosphate-Containing Biocomposites and Hybrid Biomaterials for Biomedical Applications

“…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. Thus, some attempts have been already performed to prepare biocomposites containing whisker-like [ 167 , 168 , 169 , 170 , 171 , 172 , 173 ] or needle-like [ 174 , 175 , 176 , 177 ] CaPO 4 , as well as CaPO 4 fibers [ 178 ].…”

Effect of hydroxyapatite concentration on high‐modulus composite for biodegradable bone‐fixation devices

“…These fibers were then heated in the compression mold inside the Carver Laboratory Press and heated to 75°C, which is high enough to melt the PCL, but not high enough to melt PLLA, which has a melting temperature >160°C. Once heated to 75°C, the mold was then pressed in the same manner as practiced by Sun et al Briefly, the mold was uniaxially pressed until a pressure of 450 MPa was reached and then held for 15 min. At this point, the mold was cooled to room temperature and the samples were removed for testing.…”

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

“…General knowledge of composite mechanics also shows that particles with high aspect ratios, such as whiskers and fibers, significantly increase the modulus at low loads. Therefore, some attempts have been made to prepare biocomposites containing whisker- [226][227][228][229][230] or needle-shaped [231][232][233][234] CaPO 4 and CaPO 4 fibers [235].…”