Effect of Carbon Fillers in Ultrahigh Molecular Weight Polyethylene Matrix Prepared by Twin-Screw Extrusion

Luiz Felipe M Rocha,Maria De Fátima Marques,Suellem B Cordeiro,Leonardo C Ferreira,Flávio James H Ramos

doi:10.4236/msa.2016.712066

Abstract

Oxidized (GO) and expanded (G-Exp) graphite were employed to prepare composites with ultrahigh molecular weight polyethylene (UHMWPE) matrix using masterbatches of polyethylene with different compositions. The materials and a blend of UHMWPE/HDPE were prepared by extrusion and their properties were evaluated. The effect of carbon fillers on the crystalline structure, thermo dynamic-mechanical (DMTA) and thermal properties (melting and crystallization temperatures) of the composites were discussed. The thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements showed that the addition of masterbatch with GO and G-Exp significantly increased the crystallite size of composites, increasing the temperatures of melting, degradation, glass transition and the degree of crystallinity of polyethylene. DMTA analysis indicated the storage and loss moduli of composites in relation to neat UHMWPE, the blend and UHMWPE/composites. SEM micrographs showed a flatter, continuous and uniform surface meaning a compact lamellar structure. The present work resulted in interesting findings on the effects of GO on the crystalline structures, mechanical and thermal properties of UHMWPE, which can lead to generalizations useful for future work.

Highlights

Ultra high molecular weight polyethylene (UHMWPE) possesses numerous excellent material characteristics, including outstanding chemical, abrasion, wear and impact resistance, and it is biocompatible
The thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements showed that the addition of masterbatch with graphite oxide (GO) and G-Exp significantly increased the crystallite size of composites, increasing the temperatures of melting, degradation, glass transition and the degree of crystallinity of polyethylene
BATCH2, which was prepared with the compatibilizer HDPE-g-MA, presented broader reflection peak of graphite centered at 27.24 ̊ in comparison with BATCH1, which means that the crystallite size of the carbon filler is lower and more imperfect due to the higher interaction between the polar HDPE-g-MA with the graphite structure

Summary

Introduction

Ultra high molecular weight polyethylene (UHMWPE) possesses numerous excellent material characteristics, including outstanding chemical, abrasion, wear and impact resistance, and it is biocompatible. It has extremely long chains, with a molar mass usually between 3.5 and 7.5 million g/mol. Polymer composites and nanocomposites with improved mechanical, electrical or thermal properties have been investigated intensively, and they have become one of the important classes of materials [3] [4]. The change in their properties is intimately related to the filler aspect ratio, microscopic arrangement of the disperse phase, polymer chain-filler interaction, as well as the formation of filler-filler networks. Suñer and co-workers suggested graphene oxide as an interesting filler for polymers due to its superior mechanical properties, such as excellent in-plane strength and high surface area, but little attention has been paid to the possibilities of using graphene oxide as a reinforcement material for UHMWPE matrices [5]

Methods

Results

Conclusion