Study On The Influencing Factors Of The Adhesive Strength Of The White Glue

The influence factors of the adhesive strength of white glue (polyvinyl acetate emulsion, PVAc-Em) and of PVAc-Em's simulated commercial products, polyvinyl alcohol and polyvinyl acetals solution were studied in this paper.The following was studied in this paper: (1) The adhesive strength of polyvinyl alcohol (PVA) with different degree of polymerization (DP) and different degree of alcoholysis (2) The adhesive strength of polyvinyl acetals with different acetalization degree (3) Effects of polyvinyl acetate (PVAc) on adhesive strength of white glue (PVAc emulsion) when PVA or polyvinyl acetals was used as its protective colloid. Preparation of the modified white glue with high viscosity and high adhesive strength was also discussed.As to the PVA samples not commercially available that needed to be prepared, the preparation of PVA with different degree of alcoholysis was discussed.The adhesive strength of the PVAc with the same DP varied from near 0 to 3.1MPa when the concentration changed from 5% to 13%. Averagely the PVAc solution increased by 1%, the adhesive strength increased 0.38MPa. When PVAc solution was alcoholysised to 99% and the concentration of PVA water solution obtained varied from 5% to 13%, the adhesive strength of the PVA would varied from 0.4MPa to 4.6MPa. Averagely the PVA solution increased by 1%, the adhesive strength increased 0.53MPa. It was showed that the adhesive strength of the PVAsolution was larger than that of the PVAc solution when their DP was kept the same. The adhesive strength of PVA increased by enhances the degree of alcoholysis.As to the concentration of PVA water solution was 5% and 13%, its adhesive strength increased by 0.2MPa and 1.2MPa respectively when DP of the PVA with the same degree of alcoholysis(99%) changed from 1700 to 2400.The effect of polyvinyl acetals on its adhesive strength was investigated. Averagely the acetalization degree of polyvinyl acetals solution increased by 10%, the adhesive strength of polyvinyl formal increased 0.45MPa, polyvinyl acetal increased 0.55MPa. The increasing of crosslinking extent in polyvinyl butenal had more contribution to adhesive strength of its aqueous solution than enhance of the acetalization degree.In the white glue composed by PVA or polyvinyl acetals (protective colloid) and PVAc emulsion, as far as one of the compositions was concerned, the adhesive strength of the polyvinyl acetals solution was larger than that of the PVA solution and the adhesive strength of the PVAc was the smallest. As to the protective colloid using PVA or polyvinyl formal with the same concentration (7%), when the solid content of white glue enhanced 1%, the adhesive strength of PVAc would increase 0.27MPa and 0.33MPa respectively. It was showed that the adhesive strength of the PVAc in solution was larger than that in emulsion.