Abstract
A new method using gel-swelling state and pressure-induced flow (PIF) will be presented for obtaining high-performance materials of ultra high molecular weight polyethylene (UHMWPE), which is available for the production of high-strength and high-modulus materials. The effect of PIF on the thermal stability and mechanical properties UHMWPE gel state has been investigated using four kinds of gel formed from 4, 6, 8 and 10% of UHMWPE. The microstructures of UHMWPE gel were studied by using scanning electron microscope (SEM). The thermal and mechanical properties of the UHMWPE gel were investigated by thermogravimetric analysis (TGA), diffraction scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and the universal test machine (UTM). The images obtained by SEM present a gel-like layers structure of UHMWPE gel sheet as a result of the deformation and re-arrangement of the gel sheets during PIF process. From the DSC, DMA and TGA results, we found that the thermal stability of the UHMWPE gel increased as the UHMWPE content increased. The thermal stability and the increase of strength are discussed with respect to the effect of PIF deformation.
Highlights
Gel process of ultra-high molecular weight polyethylene (UHMWPE) is familiar technique to obtain ultra-high strength polyethylene materials
UHMWPE is used in medicine for the manufacture of artificial joints in most orthopaedic replacements, especially for hips and knees. (Hoogsteen et al, 1988; 1990) stated that the UHMWPE fiber can be prepared by gel spinning using general solution under a low spin draft and a low quenching temperature by appropriate extraction and drying conditions. (Pennings et al, 1990; 1986; 1983) showed the possibility of gel-spinning of UHMWPE at high speed under high extrusion rate and temperature
The difference in the degree of crystallinity estimated from diffraction scanning calorimetry (DSC) reflects the differential result of pressure-induced flow (PIF) processing on the crystalline phase, interface, and amorphous phase
Summary
Gel process of ultra-high molecular weight polyethylene (UHMWPE) is familiar technique to obtain ultra-high strength polyethylene materials. Materials with an ultra high tensile strength, a young's modulus can be prepared by using this method, Ruan et al (2006) claimed that mixing of nanostructure with UHMWPE gel lead to ultimate fiber reinforcement nanocomposites with improved mechanical properties. Morye et al (1999) optimized the ballistic and mechanical properties of the hot compacted materials by merely changing the compaction temperature of gel spun polyethylene. The other advantages it offers include ease of processing into complex parts and ease of recycling. Since the extended chain structure has fewer molecular terminals and a higher orientation and crystallinity, the fibers possess better mechanical properties than those formed by a regular spinning technology. The structure and orientation produced by plastic deformation in such large specimens could be investigated
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