The influence of oxidized paraffin wax on the physical properties of LLDPE/wax and LDPE/wax blends
Mtshali, Thato Nicholas
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In this work, the characterization, thermal and mechanical properties of mechanically and extrusion mixed LLDPE/wax and LDPE/wax blends were investigated. Mechanically and extrusion mixed samples were melt pressed into sheets on which analyses were done. The samples were first characterized by using FTJR spectroscopy and GPC. From the FTJR results it was found that linking and degradation occurred. The GPC results showed that the molecular weight of the blends increased. Thermal analyses were done using DSC and TGA From the DSC analyses, it was found that at low wax content both wax and polyethylene (in the blend) are apparently miscible in both crystalline and molten states. At higher wax content phase separation was observed. It was also found that an increase in wax content has an effect on (a) lamellar thickness of the blends, (b) the degree of crystallinity of the blends and (c) thermal stability of the blends. The mechanical properties were determined with a tensile tester. An increase in wax content affects the yield points and the ultimate properties of the blends. It was found that elongation at yield and elongation at break decrease with an increase in wax content. Yield stress decreases for LLDPE/wax blends and increases for LDPE/wax blends. Stress at break decreases, except for the mechanically mixed LDPE/wax blends, which show an increase. Young's modulus of the blends increased with an increase in wax content.