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In this article, the influence of fumed silica nanofiller on the structure and properties of segmented polyurethane elastomer (PUR) was investigated. In order to investigate the interactions at the filler-matrix interface, nonmodified and commercially modified fillers (with methacrylsilane and octylsilane) were used. The PUR composites with 1.0, 2.0, 4.0, 6.0, and 9.0 vol % of all fillers were prepared by solution casting method. Surface free energy of the fillers and polymer matrix was determined using contact angle measurements with different testing liquids. Change in morphology was analyzed using optical polarization microscopy and distribution of the filler in polymer matrix using scanning electron microscopy. The influences of silica fillers on mechanical and thermal properties of PUR were investigated. Results showed that sur-face treatment of silica filler with methacrylsilane and octylsilane reduces the agglomeration of particles that improves dispersion at microlevel. Addition of all fillers disrupts spherulite morphology and decreases crystallinity of the PUR matrix. Nonmodified silica nanofiller has the least pronounced influence on spherulite morphology and the lowest influence on polyurethane crystallinity and thus the best mechanical properties. Surface modification of silica with octylsilane has less influence on polyurethane crystallinity and on decreasing of mechanical properties than modification with methacrylsilane. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125: E181-E190, 2012

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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Bacterial contamination of the membranes used during guided bone regeneration directly influences the outcome of this procedure. In this study, we analyzed the early stages of bacterial adhesion on two commercial dense polytetrafluoroethylene (d-PTFE) membranes in order to identify microstructural features that led to different adhesion strengths. The microstructure was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR). The surface properties were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM), and surface free energy (SFE) measurements. Bacterial properties were determined using the microbial adhesion to solvents (MATS) assay, and bacterial surface free energy (SFE) was measured spectrophotometrically. The adhesion of four species of oral bacteria (Streptococcus mutans, Streptococcus oralis, Aggregatibacter actinomycetemcomitas, and Veilonella parvula) was studied on surfaces with or without the artificial saliva coating. The results indicated that the degree of crystallinity (78.6% vs. 34.2%, with average crystallite size 50.54 nm vs. 32.86 nm) is the principal feature promoting the adhesion strength, through lower nanoscale roughness and possibly higher surface stiffness. The spherical crystallites (“warts”), observed on the surface of the highly crystalline sample, were also identified as a contributor. All bacterial species adhered better to a highly crystalline membrane (around 1 log10CFU/mL difference), both with and without artificial saliva coating. Our results show that the changes in polymer microstructure result in different antimicrobial properties even for chemically identical PTFE membranes.

In this study influence of monomer ratio, butyl acrylate (BA), and methyl methacrylate (MMA) as well as silica nanofiller morphology (pyrogenic and colloidal) and concentration on the emulsion particle size distribution and properties of polyacrylate film (PA) synthesized by in situ emulsion polymerization were investigated. The ratios of the monomers BA/MMA were 100/0, 70/30, 50/50, 30/70, 0/100 and the filler concentration 0–10.0 mass%. PA nanocomposite films were characterized by using thermogravimetric analysis, differential scanning calorimetry, and tensile test. Research has shown that monomer ratio has significant influence on glass transition temperature (Tg). The addition of both types of silica filler, pyrogenic and colloidal, has no effect on Tg. Thermogravimetric analysis showed that systems with higher BA fraction have better thermal stability than systems with higher MMA fraction. Addition of the both type of silica nanofiller enhanced thermal stability of PAs, however, systems with colloidal silica are more stable. Pyrogenic silica and higher amounts of colloidal silica nanofiller increased PA emulsion particle size up to several micrometers. Addition of higher amounts of colloidal silica improved mechanical properties compared to the neat PA matrix. POLYM. ENG. SCI., 53:2292–2298, 2013. © 2013 Society of Plastics Engineers

In this work we have investigated the effects of CaCO 3 nanofiller pretreatment on the properties of polyurethane (PU) composites prepared by a mixing procedure. The aim was to enhance interactions at the matrix/filler interface and to improve the distribution of the filler in the polyurethane matrix. CaCO 3 nanofiller was treated with two different functional trialkoxysilanes, viz. γ-aminopropyltriethoxysilane (AMPTES) and γ-glycidoxypropyltrimethoxysilane (GPTMS). Fourier transform IR spectroscopy of the pre-treated CaCO 3 surface indicates that AMPTES formed a high-molecular-weight ladder-type structure on the CaCO 3 surface, while GPTMS was adsorbed in the form of a lower-molecular-weight oligomeric structure. Increased ultimate tensile strength and elongation were obtained for PU + CaCO 3 nanocomposites with silane pre-treated filler. This can be explained as the consequence of better stress transfer through the composite, observed on scanning electron micrographs, due to an improved adhesion between PU matrix and silane-treated fillers. The reinforcement effect is more pronounced for PU composites with aminosilane-treated CaCO 3 filler in comparison to filler treated with glycidoxysilane.

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