Flexural and Morphological Properties of Poly(Methyl Methacrylate)/ Hydroxyapatite Composites: Effects of Planetary Ball Mill Grinding Time

Abstract

Poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) composites have potential applications in bone cement, prosthesis, and dental implant. In this study, PMMA containing 5 wt% of HA is prepared using polymerization followed by compression molding. PMMA and HA powder are ground using planetary ball milling. The grinding time takes from 30 to 120 min. The effects of the grinding time and particle size of the PMMA/HA powder on the flexural properties and morphology of the composites are investigated. The structure patterns of PMMA/5HA are characterized using X-Ray diffraction (XRD). No new phase is observed in the XRD pattern with the different sizes of PMMA/HA powder. This indicates that planetary milling solely reduces the size of PMMA/ HA powder. However, it does not modify the structure of PMMA and HA. A reduction of ~40% in the particle diameter is observed in both PMMA and PMMA/5HA powder after subjected to planetary milling for 60 min. For the planetary ball mill-ground PMMA/HA powder, the flexural modulus of the respective PMMA composites is slightly increased. Planetary milling can increase the volume of fine particles in the composites specimens, which results in a more homogeneous distribution of HA and a reduction of void contents in PMMA matrix. The reduction in void content is observed on the fractured surface of PMMA composites through field emission scanning electron microscopy.

Effect of hydroxyapatite filler concentration on mechanical properties of poly (methyl methacrylate) denture base

“…On the other hand, no significant change in the flexural strength as a function the HA incorporation into PMMA denture base material (P > 0.05). This is in agreement with the observation was reported by Tham et al [29] who studied the flexural and morphological properties of PMMA/ HA Composites. The HA filler could act as a stress concentration point.…”

“…Filler particles of large median sizes reduce the strength of the composites. During the mixing of PMMA/HA powder to the liquid components for the curing process (polymerization), agglomeration might happen and causes a reduction of flexural strength [29].…”

“…This can be attributed to the fact that spherical filler with no adhesion to polymer matrix is theoretically assumed. On the other hand, it has been proved that both good mechanical interfacing and chemical bonding between the HA and PMMA can be achieved by the physical mixing of the powder components and the silane treatment of the HA particles [29,33].…”

“…As the filler loading continued to increase from 5 to 15 wt%, the flexural modulus of the composite increased accordingly and reached a maximum value of 2.8 GPa at HA 15 wt%. The presence of HA powder in the matrix confines the movement of the matrix phases in the surrounding area of each particle, contributing to an overall increase in the modulus [29,43]. Table 4 shows the summary of statistical analysis of flexural properties.…”

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…Various apatite-containing biocomposite formulations based on PMMA [527][528][529][530][531][532][533][534][535][536][537][538][539][540] and PEMA 102,541,542 have been already developed. Such biocomposites might be prepared by dispersion of apatite powder into a PMMA viscous fluid 543 and could be used for drug delivery purposes.…”