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Hongbing Chen - One of the best experts on this subject based on the ideXlab platform.

  • preparation and flammability of Poly Vinyl Alcohol composite aerogels
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Hongbing Chen, Yuzhong Wang, David A Schiraldi
    Abstract:

    Poly(Vinyl Alcohol) (PVOH)-based aerogel composites with nanoscale silica, halloysite, montmorillonite (MMT), and laponite were prepared via a freeze-drying method. The PVOH/MMT and PVOH/laponite composites exhibit higher compressive moduli than the PVOH/SiO2 or PVOH/halloysite samples. Layered microstructures were observed for the samples except with PVOH/laponite, which showed irregular network morphologies. Thermogravimetric analysis of the aerogel samples showed increased thermal stability with the addition of nanofillers. The heat release measured by cone calorimetry, smoke release, and carbon monoxide production of the aerogel composites are all significantly decreased with the addition of nanofillers; these values are much lower than those for commercial expanded Polystyrene foam. The fillers did not lead to obvious increases in the limiting oxygen index values, and the corresponding time to ignition values decrease. The ability to adjust the nanofiller levels in these foamlike aerogel composites a...

  • facile fabrication of Poly Vinyl Alcohol gels and derivative aerogels
    Polymer, 2014
    Co-Authors: Hongbing Chen, Yuzhong Wang, Erin Hollinger, David A Schiraldi
    Abstract:

    Abstract A facile preparation of Poly(Vinyl Alcohol) (PVOH) hydrogels and their derivative PVOH/montmorillonite clay aerogels is reported, using water as solvent and diVinylsulfone as crosslinking agent, making use of an environmentally friendly freeze drying process. The materials exhibit significantly increased mechanical properties after crosslinking. The compressive modulus of an aerogel prepared from an aqueous suspension containing 2 wt% PVOH/8 wt% clay increased 29-fold upon crosslinking, for example. Crosslinking of the Polymer/clay aerogels decreased the onset decomposition temperature as measured by thermogravimetric analysis, and generated a more continuous structure at higher clay contents. Such Polymer/clay aerogels are promising materials for low flammability applications.

David A Schiraldi - One of the best experts on this subject based on the ideXlab platform.

  • preparation and flammability of Poly Vinyl Alcohol composite aerogels
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Hongbing Chen, Yuzhong Wang, David A Schiraldi
    Abstract:

    Poly(Vinyl Alcohol) (PVOH)-based aerogel composites with nanoscale silica, halloysite, montmorillonite (MMT), and laponite were prepared via a freeze-drying method. The PVOH/MMT and PVOH/laponite composites exhibit higher compressive moduli than the PVOH/SiO2 or PVOH/halloysite samples. Layered microstructures were observed for the samples except with PVOH/laponite, which showed irregular network morphologies. Thermogravimetric analysis of the aerogel samples showed increased thermal stability with the addition of nanofillers. The heat release measured by cone calorimetry, smoke release, and carbon monoxide production of the aerogel composites are all significantly decreased with the addition of nanofillers; these values are much lower than those for commercial expanded Polystyrene foam. The fillers did not lead to obvious increases in the limiting oxygen index values, and the corresponding time to ignition values decrease. The ability to adjust the nanofiller levels in these foamlike aerogel composites a...

  • facile fabrication of Poly Vinyl Alcohol gels and derivative aerogels
    Polymer, 2014
    Co-Authors: Hongbing Chen, Yuzhong Wang, Erin Hollinger, David A Schiraldi
    Abstract:

    Abstract A facile preparation of Poly(Vinyl Alcohol) (PVOH) hydrogels and their derivative PVOH/montmorillonite clay aerogels is reported, using water as solvent and diVinylsulfone as crosslinking agent, making use of an environmentally friendly freeze drying process. The materials exhibit significantly increased mechanical properties after crosslinking. The compressive modulus of an aerogel prepared from an aqueous suspension containing 2 wt% PVOH/8 wt% clay increased 29-fold upon crosslinking, for example. Crosslinking of the Polymer/clay aerogels decreased the onset decomposition temperature as measured by thermogravimetric analysis, and generated a more continuous structure at higher clay contents. Such Polymer/clay aerogels are promising materials for low flammability applications.

M H V Mulder - One of the best experts on this subject based on the ideXlab platform.

  • sorption of Alcohol toluene mixtures in Poly acrylic acid Poly Vinyl Alcohol blend membranes and its role on pervaporation
    Industrial & Engineering Chemistry Research, 1998
    Co-Authors: Hyunchae Park, R M Meertens, M H V Mulder
    Abstract:

    The overall and preferential sorption of Alcohol-toluene mixtures in homogeneous blends of Poly(acrylic acid) and Poly(Vinyl Alcohol) were determined. Both the overall solubility and the equilibrium sorption selectivity were strongly dependent on the composition of the blend and of the liquid feed mixture. The swelling of the blends increased with increasing Poly(acrylic acid) content and with increasing Alcohol content in the liquid mixtures. Alcohols were sorbed preferentially over toluene in all cases tested. The equilibrium sorption selectivity increased with increasing Poly(Vinyl Alcohol) content in the blends and with decreasing Alcohol content in the liquid mixtures. The equilibrium sorption selectivity was predicted by a model which was derived from Flory-Huggins thermodynamics. The agreement between the predicted and the experimental results was very good. In addition, the equilibrium sorption results were compared with the pervaporation results, and this clearly shows that preferential sorption dominates the pervaporation selectivity in the systems studied.

  • pervaporation of Alcohol toluene mixtures through Polymer blend membranes of Poly acrylic acid and Poly Vinyl Alcohol
    Journal of Membrane Science, 1994
    Co-Authors: H C Park, R M Meertens, M H V Mulder, C A Smolders
    Abstract:

    Homogeneous membranes were prepared by blending Poly(acrylic acid) with Poly(Vinyl Alcohol). These blend membranes were evaluated for the selective separation of Alcohols from toluene by pervaporation. The flux and selectivity of the membranes were determined both as a function of the blend composition and of the feed mixture composition. The results showed that a Polymer blending method could be very useful to develop new membranes with improved permselectivity. The pervaporation properties could be optimized by adjusting the blend composition. All the blend membranes tested showed a decrease in flux with increasing Poly(Vinyl Alcohol) content for both methanol?toluene and ethanol?toluene liquid mixtures. The Alcohols permeated preferentially through all tested blend membranes, and the selectivity values increased with increasing Poly(Vinyl Alcohol) content. The pervaporation characteristics of the blend membranes were also strongly influenced by the feed mixture composition. The fluxes increased exponentially with increasing Alcohol concentration in the feed mixtures, whereas the selectivities decreased for both liquid mixtures.

Jianhong Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Poly Vinyl Alcohol nanocomposites filled with Poly Vinyl Alcohol grafted graphene oxide
    ACS Applied Materials & Interfaces, 2012
    Co-Authors: Henry Kuo Feng Cheng, Nanda Gopal Sahoo, Yan Pei Tan, Yongzheng Pan, Hongqian Bao, Siew Hwa Chan, Jianhong Zhao
    Abstract:

    We present a novel approach to the fabrication of advanced Polymeric nanocomposites from Poly(Vinyl Alcohol) (PVA) by incorporation of PVA-grafted graphene oxide. In this work, we have synthesized PVA-grafted graphene oxide (PVA-g-GO) for the strong interfacial adhesion of graphene oxide (GO) to the PVA matrix. It was found that the mechanical properties of PVA were greatly improved by incorporating PVA-g-GO. For example, the tensile strength and Young’s modulus of the PVA nanocomposite films containing 1 wt % net GO in the PVA-g-GO significantly increased by 88 and 150%, respectively, as compared to unfilled PVA. The elongation at break was also increased by 22%, whereas the GO/PVA nanocomposite containing 1 wt % pristine GO was decreased by 15%. Therefore, the presence of the PVA-g-GO in the PVA matrix could make the PVA not only stronger but also tougher. The strong interfacial adhesion between PVA-g-GO and the PVA matrix was attributed to the good compatibility between PVA-g-GO and the matrix PVA as w...

Weihsiang Lin - One of the best experts on this subject based on the ideXlab platform.

  • preparation and properties of Poly Vinyl Alcohol clay nanocomposite materials
    Polymer, 2003
    Co-Authors: Chingyi Lin, Juiming Yeh, Weihsiang Lin
    Abstract:

    Abstract A series of Polymer–clay nanocomposite (PCN) materials that consist of Poly(Vinyl Alcohol) (PVA) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PVA matrix via an in situ free radical Polymerization with AIBN as initiator. Organic Vinyl acetate monomers are first intercalated into the interlayer regions of organophilic clay hosts and followed by a one-step free radical Polymerization. The prepared Poly(Vinyl acetate)–clay (PVAc–clay) solution are then saponified via direct-hydrolysis with NaOH solution to form PVA–clay nanocomposite materials. The as-synthesized PCN materials are typically characterized by Fourier-Transformation infrared (FTIR) spectroscopy, wide-angle X-ray diffraction and transmission electron microscopy. The molecular weights of Poly(Vinyl Alcohol) (PVA) extracted from Polymer-clay nanocomposite (PCN) materials and bulk PVA are determined by gel permeation chromatography (GPC) analysis with THF as eluant. The viscosity property of PCN materials with different feeding amount of MMT clay is studied by an ubbelohode capillary viscometer. The morphological image of as-synthesized materials is studied by scanning electron microscopy (SEM) and optical polarizing microscope (OPM). Effects of the material composition on the thermal stability, mechanical strength, optical clarity of PVA along with a series of PCN materials, in the form of fine powder and free-standing film, are also studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMA) and UV–visible transmission spectra, respectively.