Synthesis And Properties Of Pu And Its Composite Grafted Vinyl Chloride Emulsion Resins

Anionic waterborne polyurethane emulsion was prepared from toluene diisocyanate (TDI), polypropylene glycol (PPG) and dimethylol propionic acid (DMPA) , following a self-emulsification process. Polyurethane/polyacrylate (PUA) hybrid emulsion was prepared with PU as seeds. In the presence of PU and PUA hybrid emulsion, PU/PVC and PUA/PVC composite emulsion resins were obtained by in-situ emulsion copolymerization in autoclave. There have been few reports about this aspect of study.The particle sizes and distributions of PU/PVC and PUA/PVC composite latices were characterized via a laser particle size analyzer. The morphology of the composite latices particles was observed via transmission electron microscopy (TEM) . The result shows that PU/PVC composite latices have the typical core/shell structure, but the PUA/PVC hybrid particles have a multi-core/shell structure like an island. The increasing of particle sizes of PU/PVC and PUA/PVC latices obviously indicate that a large number of VC monomers polymerized around PU and PUA rubbery phase. Using 1,2-dichloroethane as the solvent, we separated the hybrid resins. The study results show that the grafting efficiency of composite resins increases with increasing of rubbery phase content, but the grafting ratio decreases.The influence of PU molecular weight and the content of PU or PUA rubbery phase on the mechanical properties of modified PVC resins were investigated in detail. The adding of suited content of PU or PUA rubbery phase caused notched impact strength of the composite materials improved. When PU or PUA content was 12wt%, the notched impact strength was almost four to eight times as large as that of pure PVC. PU molecular weight had the influence on the mechanical properties of composite resins, too. When PU molecular weight was 7000 to 10000,the notched impact strength was almost ten times as large as that of pure PVC, but tensile strength of PU/PVC and PUA/PVC composite resins decreased a little. Through investigating, we find that the effect of composite resins is best when chain-extended agent of PU isl,4-butanediol. Furthermore, proper cross-linked PU was attributed to the improving of composite resins' properties.The various properties of composite resin and materials made out of it, such as dynamic mechanical property > thermal property > Vicat softening temperature > morphological structure and the broken profile of the materials, were determined and characterized with the aid of DMA > TA-2000 type thermal analyzes XWB-300F type detector of Vicat softening temperature> TEML SEM, respectively. DMA results reveal that the maximum value of the loss peak in low temperature region gradually shifts to higher temperature with increasing PU or PUA content. The compatibility between rubbery phases with PVC has been well improved to some extent. TEM shows that rubbery phase is much uniformly dispersed in PVC matrix. The interface between two phases was indistinct. SEM shows that the fractured surface of the notched sample has a very good toughness. The stability of heat-resistance of composite resins decreased a little with the adding of PU or PUA rubbery phase.