Silane pre-treatment of calcium carbonate nanofillers for polyurethane composites (original) (raw)
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Influence of stearic acid treated nano-CaCO3 on the properties of silicone nanocomposites
Journal of Polymer Research, 2011
The aim of the work reported here was to study the influence of treated nano-CaCO 3 on the silicone:dicumyl peroxide system. Thermal degradation was studied using TGA of treated and untreated nano-and commercial CaCO 3 :silicone rubber composites. Thermal stability as well as % char yield increased with increasing content of treated nano-CaCO 3 as compared to untreated and commercial CaCO 3. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were performed to study the degree of dispersion of treated and untreated nano-CaCO 3 and commercial CaCO 3 in silicone rubber composites. Moreover, the nanocomposites were subjected to various tests, such as those for tensile strength, % elongation at break, flammability and abrasion resistance. The tensile strength (8.5 kg/cm 2) and elongation at break (780%) showed their greatest improvements at 10 wt% loading with treated nano-CaCO 3 in comparison to the untreated nano-and commercial CaCO 3 : silicone rubber composites. The improvements in the properties of treated CaCO 3 :silicone composites compared to the untreated nano-and commercial CaCO 3 silicone rubber composites were due to the uniform dispersion of nanoparticles in the treated composites and their good compatibility with the rubber chains, as shown by AFM and SEM studies.
Hybrid silica generated In situ in polyurethane-based composites
Journal of Applied Polymer Science, 2014
A series of composites of commercial polyurethane (PU) and hybrid silica have been prepared by the sol-gel process through the in situ synthesis of hybrid silica in a solution of dichloromethane. Mechanical properties, small angle x-ray scattering (SAXS) and differential scanning calorimetry measurements were performed to evaluate the effects that hybrid silica has on the properties of the resulting PU composites. A series of 13 different organosilane differing in polarity and alkyl chain length has been employed. Compared with pristine PU, composites bearing hybrid silicas were more likely to exhibit reductions in the yield stress and increase in the elongation at break. Samples also showed a negligible variation in the glass transition temperature and a reduction in the DC p. The enthalpy of the crystallization process showed a trend towards reduction. Based on the SAXS measurements, the composites showed a small reduction in the interdomain spacing, an increase in the degree of phase separation and a tendency towards reduction in the size of the interphase thickness between domains. These results can be better explained as being caused by the volume of the organic group from the organosilane rather than by the chemical interaction of the organic group with the PU organic moieties.
Composites Science and Technology, 2012
Polycarbonate/silica nanocomposites with different silica quantities were prepared by a melt compounding method. The effect of silica amount, in the range 1-5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of polycarbonate (PC) was investigated. Clusters of silica nanoparticles were well dispersed in the polycarbonate whose structure remained amorphous. NMR results showed intermolecular interactions involving the carbonyl groups of different polymeric chains which did not affect the intramolecular rotational motions. The presence of the lowest silica content showed a decrease in the storage and loss moduli below the glass transition temperature, probably due to a plasticization effect. However, an increase in the amount of silica increased the moduli. The presence of silica in PC slightly increased the thermal stability, except for the highest silica content which showed a decrease. The activation energies of thermal degradation for the nanocomposites depended on the amount of silica and on the degree of conversion.
Journal of Applied Polymer Science, 2011
The present study was aimed to see the effect of surface treatment on nanocomposites with different fatty acids (stearic acid and oleic acid) having two different coupling agents (titanate and silane). Nanocomposites were prepared via melt mixing in Haake 90 twin screw extruder. The characterization of nanocomposites had been carried out using various advance analytical techniques such as dynamic mechanical analysis, thermogravimetric analysis, heat distortion temperature, melt flow index, and scanning electron microscopy. The strength and stiffness were also improved with the incorporation of maleic-anhydride grafted ethylene propylene rubber in PP/ Nano-CaCO 3 nanocomposites. The tensile, flexural, and impact strength properties of PP/MA-g-EPR/treated-CaCO 3 and untreated nanocomposites were determined. These studies revealed that stearic acid treated nanofiller filled composites had better properties than those of untreated and oleic acid treated nanofiller filled composites. The SEM studies demonstrated that the dispersion and distribution of Nano-CaCO 3 (nCaCO 3) particles within the polypropylene matrix were dependent on the nature of surface treating agents. V
Polymer, 2013
Nanocomposites consisting of thermoplastic polyurethane-urea (TPU) and silica nanoparticles of various size and filler loadings were prepared by solution blending and extensively characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal analysis, tensile tests, and nanoindentation. TPU copolymer was based on a cycloaliphatic diisocyanate and poly(tetramethylene oxide) (PTMO-2000) soft segments and had urea hard segment content of 20% by weight. TPU/silica nanocomposites using silica particles of different size (29, 74 and 215 nm) and at different loadings (1, 5, 10, 20 and 40 weight%) were prepared and characterized. Solution blending using isopropyl alcohol resulted in even distribution of silica nanoparticles in the polyurethane-urea matrix. FTIR spectroscopy indicated strong interactions between silica particles and polyether segments. Incorporation of silica nanoparticles of smaller size led to higher modulus and tensile strength of the nanocomposites, and elastomeric properties were retained. Increased filler content of up to about 20 weight% resulted in materials with higher elastic moduli and tensile strength while the glass transition temperature remained the same. The fracture toughness increased relative to neat TPU regardless of the silica particle size. Improvements in tensile properties of the nanocomposites, particularly at intermediate silica loading levels and smaller particle size, are attributed to the interactions between the surface of silica nanoparticles and ether linkages of the polyether segments of the copolymers.
Materials Research, 2019
This study aimed at evaluating the effects of the incorporation of micro and nanoparticles of CaCO 3 on the properties of poly(vinyl chloride) (PVC), intended to industrial application. The PVC compounds added with particles of different sizes were achieved in an intensive mixer. Rheological, microstructural, mechanical and thermal properties of the compounds obtained were evaluated. The rheology test showed that the compound with the addition of two-particle size plasticized faster compared than other formulations. Microstructural analysis showed a poor particle size distribution for the micro-CaCO 3 charges, and the nano-CaCO 3 samples have agglomerated particles. The thermal analysis showed the compound added with two particle size with higher gelation, and in the loss modulus E' and E", the values also were close. The analyses showed that the combination of the two-particle sizes presented superior results when compared with the micro or nano used singly.
Journal of Applied …
The present study was aimed to see the effect of surface treatment on nanocomposites with different fatty acids (stearic acid and oleic acid) having two different coupling agents (titanate and silane). Nanocomposites were prepared via melt mixing in Haake 90 twin screw extruder. The characterization of nanocomposites had been carried out using various advance analytical techniques such as dynamic mechanical analysis, thermogravimetric analysis, heat distortion temperature, melt flow index, and scanning electron microscopy. The strength and stiffness were also improved with the incorporation of maleic-anhydride grafted ethylene propylene rubber in PP/ Nano-CaCO 3 nanocomposites. The tensile, flexural, and impact strength properties of PP/MA-g-EPR/treated-CaCO 3 and untreated nanocomposites were determined. These studies revealed that stearic acid treated nanofiller filled composites had better properties than those of untreated and oleic acid treated nanofiller filled composites. The SEM studies demonstrated that the dispersion and distribution of Nano-CaCO 3 (nCaCO 3 ) particles within the polypropylene matrix were dependent on the nature of surface treating agents.