Effects of hydrocarbon tackifiers on the adhesive properties of contact adhesives based on polychloroprene. II. Nature of the hydrocarbon tackifier

50 phr each of three hydrocarbon resins of different aliphatic-aromatic nature was added to a solvent based polychloroprene adhesive. The hydrocarbon resins were characterized using infra-red (IR) spectroscopy and differential scanning calorimetry (DSC) measurements. The properties and compatibility of the polychloroprene/ resin blends were studied using thermal mechanical analysis (TMA), DSC, scanning electron microscopy (SEM) and rheology. Tack measurements were carried out, and the joint strength was obtained from T-peel tests of roughened styrene-butadiene rubber-polychloroprene adhesive joints. The addition of aromatic hydrocarbon resins produced a compatible resin-polychloroprene blend, whereas an incompatibility was obtained between an aliphatic hydrocarbon resin and the polychloroprene. The compatibility of aromatic hydrocarbon resin-polychloroprene blends was responsible for the enhanced tack and improved adhesion to roughened rubber materials. On the other hand, the incompatibility of aliphatic hydrocarbon resin-polychloroprene blend produced a reduced tack, phase separation, and a reduced practical adhesion. Viscoelastic properties of adhesives were affected differently depending on the temperature and the frequency of the experiments and also on the aliphatic-aromatic nature of the resin.