Effect of Polyvinyl Alcohol with a Thiol End Group on the Properties of Polyacrylic Dispersions and Spray-dried Powder

摘要

The emulsion polymerization of highly shear-stable copolymer dispersions of methyl methac-rylate and butyl acrylate were carried out using poly(vinyl alcohol)with a thiol end group(PVA-SH)as protec-tive colloid.The dispersions can be transformed into corresponding redispersible powder via a spray drying-cooling process.On-line FT-IR monitoring shows that grafting polymer of PVA-g-PMMA was formed mainly at the stage-1 of the emulsion polymerization.TEM images show,the PVA-SH shell was fragmentary when adding SDS at initial stage and integrated when adding at particle growing or final stage.The particle size turns to be smaller when delayed adding SDS surfactant.Triethanolamine,a co-regulator of PVA-SH,controlled the M n to 50 000-70 000 and reduced the PDI to 1.5-1.7.The acrylic dispersions with 0.8wt%-1.5wt%PVA-SH 1 can be spray-dried into super dispersible polymer powder(SDPP),which can easily disperse in water and form recon-stituted dispersions with an average particle size smaller than 1 micron.