Mechanical, Rheological, and Bioactivity Properties of Ultra High-Molecular-Weight Polyethylene Bioactive Composites Containing Polyethylene Glycol and Hydroxyapatite

Mazatusziha Ahmad,Mat Uzir Wahit,Khairul Zaman Mohd Dahlan,Mohammed Rafiq Abdul Kadir

doi:10.1100/2012/474851

Mazatusziha Ahmad, Mat Uzir Wahit + Show 2 more

Open Access

https://doi.org/10.1100/2012/474851

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Abstract

Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis.

Highlights

Biomaterials in the form of implant are widely used to replace and/or restore the function of traumatized tissues or organs, to assist in healing, to improve function, and to correct abnormalities [1]
Shear viscosity of the Ultrahigh-molecular-weight polyethylene (UHMWPE)/HDPE/polyethylene glycol (PEG)/HA composites is a decreasing function of shear rate and increasing function with HA loading which are in agreement with the findings reported by Wang et al [16]; it is valid at shear rate below 100 s−1 only
The apatite layer continuously spreads and covers the bioinert polymer area of the composites. This is in agreement with the findings reported by Fang [35] who concluded that the bioactivity properties were controlled by the surface area of HA particles exposed to the physiological environment

Summary

Introduction

Biomaterials in the form of implant are widely used to replace and/or restore the function of traumatized tissues or organs, to assist in healing, to improve function, and to correct abnormalities [1]. The mechanical properties of UHMWPE/HDPE blend are well documented [12, 13], its processability using polyethylene glycol (PEG) as processing aid has not been investigated and explored. Our recent preliminary study found that HDPE with small amounts of poly(ethylene glycol) (PEG) as processing aids reduced viscosity of UHMWPE and effectively improved the processability of UHMWPE without compensating mechanical properties [14]. HA-reinforced UHMWPE/HDPE/PEG composites were processed using single screw extruder Nanomixer. The unique geometry of the Nanomixer with multiple inlets and outlets can divide, reorient, and recombine the melt stream The ability of this compounding method allows filler agglomerates to break up into fine particles and disperse thoroughly throughout the polymer melt

Experimental

Testing

Results and Discussion

Rheological Study

C K P K CaK C Total

Conclusions