Synthesis and characterization of polyvinyl acetate/montmorillonite nanocomposite by in situ emulsion polymerization technique
Department of Chemical Engineering, Amirkabir University of Technology, Tehran, Iran Polymer Bulletin
(Impact Factor: 1.44).
05/2010; 66(9):1255-1265. DOI: 10.1007/s00289-010-0399-2
Exfoliated polyvinyl acetate/montmorillonite nanocomposite (PVAc/MMT) was prepared via in situ emulsion polymerization. The
resulting PVAc with various organophilic MMT contents was investigated. In the nanocomposite latex preparation, sodium lauryl
sulfate (SLS), ammonium persulfate (APS), and poly (vinyl alcohol) (PVA) are used as anionic emulsifier, conventional anionic
initiator, and stabilizer, respectively. The samples were characterized using elemental analysis, X-ray diffraction (XRD),
scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM). The XRD and AFM
results demonstrate that the MMT well dispersed at molecular level in the PVAc matrix. Thermal properties of the nanocomposite
were studied by using differential scanning calorimetric analysis (DSC). The exfoliated PVAc/MMT nanocomposite showed a higher
glass transition temperature and a better thermal stability compared to the pure PVAc.
KeywordsNanocomposite–Emulsion polymerization–Polyvinyl acetate–Montmorillonite–Exfoliation–Thermal properties
Available from: Jaiswar Gautam
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ABSTRACT: The effects of calcium carbonate (CaCO3) and calcium sulfate (CaSO4) nanoparticles on the thermal and UV-absorbing properties of polyvinyl acetate (PVAc) were analyzed in this study. Nanoparticles of CaCO3 and CaSO4 were synthesized by in situ deposition technique. The size and shape of nanoparticles were recognized by X-ray diffraction and scanning electron microscope (SEM) analyses which confirmed that the particle was having a diameter of 25–33 nm. In this technique, the surface modification of nanoparticles was done by non-ionic polymeric surfactant. PVAc/CaCO3 and PVAc/CaSO4 nanocomposites film samples with an average thickness of 30 µm and in the mass ratio of nanoparticles (0–4% (w/w)) were prepared by solution mixing technique. Chemical, structural, and elemental characterizations of nanocomposites were done by, fourier transform infrared, SEM, and energy dispersive X-ray spectroscopy analyses, respectively. Thermal properties of pure polymer and nanocomposites were characterized through differential scanning calorimetric, thermogravimetric, and differential thermogravimetry techniques. The glass transition temperature of nanocomposites increases with increase in content of nanoparticles. It may be due to the interaction between inorganic and organic components. The thermogravimetric analysis results indicate that the thermal degradation temperatures of nanocomposites were enhanced upon the addition of nanosized inorganic fillers. The thermal results show that PVAc/CaSO4 nanocomposites were more thermally stable than PVAc/CaCO3 nanocomposites. The addition of nanoparticles affects degradation mechanism and consequently improves thermal stability of PVAc. The reduction of polymer chain mobility and the tendency of nanoparticles to eliminate free radicals were the principal effects responsible for these enhancements. The ultraviolet–visible (UV–Vis) absorbance spectra of PVAc and its nanocomposites films show that the intensity of absorbance increases with increasing filling content, suggesting that nanocomposites films have greater UV-shielding property.
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conversion of P(VAc-co-MMA)/C30B were studied. Thermal properties of the nanocomposite were studied by dynamic mechanical thermal analysis. The XRD and TEM results demonstrated that the synthesized polymer chains were aggregated into the C30B interlayer regions and consequently complete exfoliation was produced.
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