Study On Synthesis And Adhesion Performance Of Poly(vinyl Acetate)-based Core/shell Emulsion

Owing to its superior performance and cheap price,polyvinyl acetate(PVAc)emulsion has been widely used.However,the application of PVAc emulsion has been restricted due to its poor water resistance and cold resistance.Thus,For the purpose of improving the performance of PVAc emulsion,combining particle designing method and inverted core/shell structured emulsion polymerization approach to construct core/shell structured latex particle.To clarify the control mechanism of the size of latex with core-shell structure and the formation mechanism of morphology,the influence of the reaction condition on the size of latex and the morphology was systematically investigated through FTIR,DLS,DSC,SEM,TEM.Moreover,the mechanical property,water resistance,cold resistance of the prepared core/shell structured emulsion was investigated by the test of mechanical properties?water absorption?Heatresistant stability and Freeze-thaw stability.The detailed content of research are as following:Using direct core/shell structured emulsion polymerization method,direct core/shell emulsions with PS cores and PVAc shells were prepared,the average particle size of core/shell latex particles was about 100~200nm.With the adjustment of the ratios of core-to-shell,the particle size and morphology of core/shell latex significantly changed.On the basis of the size control of PVAc-based core/shell latex,the synthesis of PVAc-based core/shell with high solid content was studied.PVAc-based core/shell emulsion with the solid content of 55.5% and the morphology of ?strawberry? of core/shell structured latex was obtained.The particle size of core latex could be controlled under the combining effect of emulsifier and competition monomer butyl acrylate(BA),the average particle size of the latex decreased from about 190 nm to 115 nm.Combining particle designing method and inverted core/shell structured emulsion polymerization approach,with the kinetically controlling mechanism of the graft transition layer,a PVAc/PS inverted core/shell structured emulsion which average particle size was 205 nm was prepared.The morphology and particle size of Core-shell emulsion latex was affected by the BA content,the adhesion and cold resistance performance of emulsion was improved.Adjusting to the content of maleic anhydride(MA),and the water absorption of latex membrane decreased with the increase of MA content;the morphology of core/shell structure latex changed from strawberry to fully covered.The dry shear strength remained unchanged and the wet shear strength was improved.Grafting the monomer with specific functional groups to the surface of inverted PVAc / PS core/shell latex structure,the application performance of the emulsion could be significantly improved.The particle size and morphology of the latex were affected by the functional monomer type and content.The adhesion performance of the emulsion was significantly improved,the maximum values of adhesive dry strength and wet strength were up to 16.2MPa and 5.7MPa,but latex film was not completely destroyed after 30 min in boiling water,there has no influences on the water resistance of the latex film and the cold resistance of the emulsion.However,Grafting N-methylol acrylamide(NMA)monomer on the surface of latex shell,the wet strength of the emulsion increased but the dry strength decreased significantly,but latex film still had a certain adhesion after 180 min in boiling water.