| Anionic waterborne polyurethane emulsion was prepared with isophorone diisocyanate (IPDI), polypropylene glycol (PPG)and dimethylol propionic acid (DMPA), following a self-emulsification process. Polyurethane/polyacrylate (PUA-â… ) hybrid emulsion was prepared using PU dispersion as seeds. Mixmonomer was prepared with IPDI, polyethylene glycol monomethylether (MPEG) and hydroxyl ethyl methacrylate (HEMA). Then it was copolymerized with butyl acrylate to prepare polyurethane-acrylate (PUA-â…¡) composite latex. In the presence of PU, PUA-â… and PUA-â…¡hybrid emulsions, PU/PVC, PUA-â… /PVC and PUA-â…¡/PVC composite emulsion resins were obtained by in-situ emulsion copolymerization in autoclave.The particle sizes and distributions of the PU/PVC and PUA-â…¡/PVC composite latices were characterized via a laser particle size analyzer. The increasing particle sizes of the PU/PVC and PUA-â…¡/PVC latices obviously indicated that a large number of VC monomer was polymerized around PU and PUA-â…¡rubbery phase. The morphology of the PUA-â…¡/PVC composite latex particles was observed via transmission electron microscopy (TEM). The result showed that PUA-â…¡/PVC composite latex has the typical core/shell structure.The mechanical properties of the modified PVC resins were investigated in details. When DMPA content was 6wt% and the PU content was 9wt%, among the range of researches, the notched impact strength of the PU/PVC composite resins was biggest. It was shown that the mechanical properties of composite resins was better when 1, 4-butanediol was used as chain-extended agent of PU. The notched impact strength of the PUA-â… /PVC composite resins increased with increasing PA content. The notched impact strength of the PUA-â…¡/PVC composite resins decreased with increasing PUA-â…¡content.Various properties of the composite resin and resulted materials, such as dynamic mechanical properties, thermal properties, broken profiles of the materials and rheological behaviors, were determined and characterized with the aid of DMA, TA-2000 type thermal analyzer, SEM and capillary rheometer, respectively. DMA results revealed that the compatibility between PU and PVC was better by chain-extending before dispersion. And Tg of the PUA composite latices decreased because of incorporating BA composition. SEM showed that the fractured surface of the notched sample has toughness. The stability of heat-resistance of the composite resins decreased a little with the adding of PU or PUA rubbery phase. Because of adding PU or PUA rubbery phase, the mobility of the composite resin became better than that of pure emulsion PVC. |
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