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Preparation and characterization of nanocomposites with a thermoplastic matrix and spherical reinforcement

Ersu, Dilek
The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co); ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader® resins; as silica Cab-o-sil® M5 fumed silica were used. All samples were prepared by means of a lab scale co-rotating twin screw extruder and injection molded into standard samples. In the first step, individual effects of filler and compatibilizers were studied in binary systems with LDPE. Then, keeping the amount of compatibilizer constant at 5%, ternary nanocomposites were prepared by adding 2 or 5% of fumed silica using different component mixing orders. Among investigated mixing orders, mechanical test results showed that the best sequences of component addition are FO1 [(LDPE+Co)+M5] and FO2 [(LDPE+M5)+Co] mixing orders. Considering the compatibilizers, E-nBA-MAH terpolymer showed the highest performance in improving the mechanical properties, E-GMA copolymer also gave satisfactory results. According to the DSC analysis, since addition of fumed silica and compatibilizer does not influence the crystallization behavior of the compositions, it is concluded that, neither fumed silica nor any of the compatibilizers have nucleation activity on LDPE. MFI test results showed that, addition of fumed silica increases the melt viscosity, decreasing MFI values of samples. This change seems to be directly proportional to fumed silica amount.