Light weight LDPE composites with surface modified hollow glass microspheres

Hollow glass microspheres (HGMs) are mainly used as an inert low density filler in polymeric matrices. HGMs made of chemically stable soda-lime-borosilicate glass with high crush-strength allow to attain light weight composites with a reduced resin content. The present work is aimed at obtaining low density polyethylene (LDPE) composites filled with HGMs as suitable light weight material for the manufacturing of plastic items by rotational molding. HGMs were used as such or surface modified by treatment with dodecyl(triethoxy)silane (DDTES), a commercial coupling agent bearing an alkyl chain, in order to enhance compatibility between the inorganic particles and the hydrocarbon polymer matrix. The effectiveness of the silanization process was established using FTIR spectroscopy. LDPE composites at various HGMs content were prepared by melt blending. Morphology of untreated and silane-modified HGMs, their dispersion in the ensuing composites as well as filler/matrix adhesion were investigated by means of SEM microscopy. Uniaxial tensile tests carried out on the composites revealed an increase in the elastic modulus with respect to the neat LDPE and confirmed the good filler/matrix adhesion observed by SEM for the silane-modified HGMs.