This article describes the use of commercial silica (SiO 2 ) and calcium carbonate (CaCO 3 ) nanofillers as compatibilizers in immiscible polylactide/low-density polyethylene (PLA/LDPE) blends. The general aim of the study was to investigate the possibilities of replacing standard commodity plastics such as LDPE based on non-renewable mineral oil resources with the biodegradable renewable polymer PLA in compatibilized PLA/LDPE blends for use in the packaging industry. The calculations of the minimal interfacial energy and optimal wetting abilities indicated that SiO 2 filler was a better potential compatibilizer than CaCO 3 for a given PLA/ LDPE blend. This was due to its preferential localization at the interface. The significantly improved morphology of the ternary PLA/ LDPE/SiO 2 blend was found to present an increased strength, toughness, and crystallinity.

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Nanocomposites are expected to exhibit new and improved properties when compared to their microcomposite counterparts. By lowering the particle size to nanodimensions (<100 nm), the special effects in polymer composites appear. In this study we compared the properties of composites lled with micro-and nano-sized calcium carbonate (CaCO 3 ) ller particles in poly (vinyl acetate) (PVAc) matrix. The morphology of the composite was found to be responsible for the composite properties. The ller nanoparticles are dispersed in the matrix in the form of a 'net-like' structure, contrary to microparticles, which are dispersed as 'islands' in the matrix. The other systems investigated in this study were based on polyacrylate (PA) copolymer matrices lled with layered kaolin ller, which is well suited for creating nanocomposites. Mathematical models were used to quantify the interfacial interactions in the composites under investigation. Improved mechanical properties are obtained where there is a strong interfacial bond between the matrix and the ller. It seems that a key characteristic of the nanocomposites is the formation of a three-dimensional interphase with a signi cant amount of matrix with restricted chain mobility. The restricted molecular mobility in PVAc / CaCO 3 nanocomposites resulted in changes of relaxation behavior, i.e. in the appearance of a second transition above the T g but only at large enough loading.

Polyurethane (PU) and poly(vinyl acetate) (PVAc) are partially miscible polymers. The aim of this study was to investigate the influence of untreated and surface pretreated calcium carbonate (CaCO3) on the interphase properties of PU/PVAc polymer blends with possible compatibilization effects when the conditions of effective adhesion are achieved. With the aim to modify interface between filler and matrices, CaCO3 was pretreated by grafting PVAc on the filler surface using 60Co γ‐ray irradiation polymerization of vinyl acetate. A series of the PU/PVAc blends without and with the addition of CaCO3 were prepared using a Brabender plasticorder at 140°C. Surface characterization of the PU and PVAc polymers as well as the untreated and surface pretreated CaCO3 fillers was carried out by determination of the surface free energy. The adhesion between CaCO3 and phases in the polymer blends was predicted on the basis of the calculated adhesion parameters (interfacial free energy, spreading coefficient and work of adhesion) obtained from the surface free energy of components. Thermal and mechanical properties were investigated by tensile strength measurements and differential scanning calorimetry (DSC). The adhesion parameters were correlated with the mechanical and thermal properties as well as phase morphology observations. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

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