Redispersible polymer powder functionalized with NMA and its adhesive properties in dry-mixed coatings

Abstract

One type of redispersible polymer powder functionalized with N-hydroxymethyl acrylamide (NMA) was developed in this work. The addition of NMA proved to have great influence on the properties of the original emulsion as well as the corresponding powders. The particle size and viscosity of original emulsions both increased with the increasing of NMA amount while the colloidal stability decreased due to the generation of oligomers. However, the fluidity and adhesive performance of the resultant powders were improved obviously by adding more amounts of NMA in polymerization. Taking the above factors into consideration, we found that 3.0 wt.% of total monomers was an acceptable percentage for the NMA to be used. Poly (vinyl alcohol) (PVA) was used as protective colloids in spray drying to prevent the coalescence of emulsion particles so that the reversible dispersion of powders could be realized. The morphology of powder particles was proved to turn into ‘donut’ shape with the increasing of PVA amount, and their reconstitution ability became better. Compared with original emulsion, the reconstituted emulsion had poorer stability and dispersity due to the coalescence of polymer particles in spray drying.