Physical properties of hydrocolloid wet glues

The potential properties of 26 gums to serve as a basis for wet-gum glues were studied. Preliminary tests revealed that only 13 of these, namely gum talha, gum ghatti, gum karaya, gum tragacanth, arabinogalactan, dextran, pectin, tapioca-dextrin, carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), hydroxypropylmethyl cellulose (HPMC) and carbopol, can serve as bioadhesives in hydrophilic systems. Wet glues were produced from these hydrocolloids. They were tested over a wide range of loadings, Le. 10-75% (w/w). The color and pH of each glue were determined. Their ability to adhere to two separate films-cellulose acetate and a skin-surface model-was studied. After checking the performance of the glues by peel testing, seven gums were chosen for further study. Adhesion was evaluated by tensile-bond and lap-shear tests. The deformation rate, the adhesive layer thickness, the degree of hydration of the films and glue, the length of drying time, and the type of hydrocolloid used were found to influence the wet glue band strength.