Measurement of surface crystallinity of PAA and PAANa coatings and its effect on hydrophilicity of c

The solutions of poly(acrylic acid)(PAA), poly(acrylic acid sodium)(PAANa) were coated on aluminium fins by roll coating method. The coatings with different crystallinity were obtained by varying baking time and temperature. Their surface crystallinity and surface tension were measured, and their spreading speed constant and equilibrium contact angle were tested also. The correlation of surface crystallinity, surface tension, spreading speed constant and surface hydrophilicity was discussed. It is demonstrated that surface tension and spreading speed constant increase, while equilibrium contact angle declines with increasing surface crystallinity of coatings, that is to say, the hydrophilicity of coatings is improved with surface crystallinity of coatings increasing.