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

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.

Chemically expanded graphite-based ultra-high molecular weight polyethylene nanocomposites with enhanced mechanical properties

“…The storage modulus at room temperature decreases by 14% from 737.2 MPa to 630.9 MPa when introducing 1 wt% CEG with respect to pure UHMWPE. The initial decrease in storage modulus has previously also been found for expanded graphite and graphite oxide by Rocha et al at a reinforcement content of 0.5 wt% [42]. An identical decrease was also observed for lower percentages of rGO in polyethylene [43][44][45].…”

The Structure and Mechanical Properties of the UHMWPE Films Modified by the Mixture of Graphene Nanoplates with Polyaniline

“…The α-relaxation of the UHMWPE is the result of deformation or movements within the interfacial regions (folds or tie molecules), which were activated because of chain mobility in the crystalline region [41]. The α-relaxation temperature of the UHMWPE is very wide, ranging between 30 and 120 °C [42], depending on the crystallite thickness. The thicker crystals (lamellae) have led to an increase to the α-relaxation temperature values [43].…”

“…The values of T α are very close to each other, so the lowest temperature of α-relaxation was observed for the film of 2 wt % GNP/PANI. The α-relaxation of polyethylene had decreased with a lower crystallite size [42].…”

“…As shown in Figure 9 and Table 4, the highest storage modulus at room temperature was observed for the UHMWPE/GNP film of 2.0 wt % GNP/PANI, showing a significant increase in stiffness. Good uniform distribution [31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46] and a strong interfacial interaction between a polymer matrix and a filler lead to an increase in the storage modulus of polymers. Also, in Figure 9, it can be seen that above the temperature of 100 °C, an increase in the storage modulus can be observed in all films (Figure 9, discontinuous lines).…”

Extrusion Processing of Ultra-High Molecular Weight Polyethylene

“…At present, two types of twin-screw extruder are usually used to extrude UHMWPE in industrial production [20,37,38]. However, the difficult realities of low extrusion output, high energy consumption, and large driving load are still troubling people and hindering the development of UHMWPE processing.…”