engleski

Surface engineering of fillers in polymer composites and blends

We have studied the various surface modifications of the selected nanofillers with stearate, silane, as well as by grafting polymer at surface thus changing its surface chemistry and energy, in order to optimize the interactions at the interphase and improve the properties of the related composites and blends. The silane pretreatment of calcium carbonate (CaCO3), with -aminopropyltriethoxysilane (AMPTS), as well as the stearate pretreatment in polyurethane (PU) and poly (vinyl acetate) (PVAc) change composite morphology, failure and mechanical properties. The results are in correlation with the higher work of adhesion and lower interfacial energy in composites filled with the optimally pretreated filler in comparison to the effects of the untreated filler. Examples of the surface engineering effects of silica nanofillers (SiO2) by various silane pretreatment with -methacryloxypropyl trimethoxysilane (MPS), aminopropylsilanetriol (APTO) in PVAc composites and commercialy pretreated silica in PU composites are also presented. Results indicate that filler surface modification influence on the composite morphology and matrix crystallinity. Surface modification of CaCO3 filler by grafting PVAc and even more by combined PVAc and silane modification significantly improve miscibility of polymer constituents in PU /PVAc blends and consequently improve mechanical properties. The calculations of interactions at the blend interphases by using models and the related micrographs proved that the optimally pretreated CaCO3 filler with stearate are embedded at the interphase between two phases in PU/PVAc blend. It was concluded that it is important to preserve the phase structure in blend with the filler acting as a compatibilizer at the interphase. Thus addition of modified filler significantly improves the strength as well as the elasticity of blend. The results confirmed the basic hypothesis that the interfacial properties in composites and blends could be quantitatively predicted using adhesion parameters such are thermodynamic work of adhesion, interfacial free energy and spreading coefficient at the interface.1

surface engineering of nanofillers; filled composites and blends

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