Binary mixtures of polyethylene and oxidized wax: Dependency of thermal and mechanical properties upon mixing procedure
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The influence of the preparation procedure on the thermal and mechanical properties of linear low-density polyethylene (LLDPE)- and LDPE-oxidized wax blends was investigated. It was found that mechanically mixed blends show reduced thermal stability as well as ultimate mechanical properties (stress and strain at break) compared to that of extrusion mixed blends. However, the structure of the blend and consequently its thermal and mechanical behavior also depend on the initial morphology of polyethylene. DSC measurements show miscibility up to high wax contents in both blend types, but increasing the amount of wax in LDPE blends induces increasing crystallinity. As a result, the LDPE/wax blends show improved thermal stability of between 20 and 50degreesC at low wax concentrations. Although the elasticity modulus of the blends increases, increasing the amount of wax generally degrades the mechanical properties. The main reason for this is the reduced number of tie chains. Changes in the ...average concentration of tie chains with increasing wax content were calculated and a correlation was made with the ultimate properties of the blends. (C) 2003 Wiley Periodicals, Inc.