The effect of plasticizer on adhesive properties was determined by comparing T-peel adhesion to polyester film. T g was measured to indicate how the low-temperature properties of the system are modified by plasticizer addition. The addition of a plasticizer that increases viscosity may be desirable in cases where the emulsion must be thickened before coating. Another measure of a plasticizer's effect on a given polymer is a shift in glass transition temperature. A plasticizer that is soluble in a polymer will reduce the T g of the system when the T g of the plasticizer is significantly lower than that of the base polymer.
Peel adhesion is a critical test for an adhesive.
In this study, all plasticizer additions were observed to result in significantly greater T-peel strength than the unplasticized base polymer, especially in the PVA system. Another purpose for adding a plasticizer to a polymer is to extend its open or working time properties. Additional strips of paper were laid down on the wet coating with slight manual pressure at 5-second intervals and allowed to air dry. The open time was judged to be the time at which the adhesive became too dry to form a paper-tearing bond. The open time of all plasticized systems was observed to be equal to or greater than the open time for unplasticized base polymer.