EFFECTS OF HYDROCARBON TACKIFIERS ON THE ADHESIVE PROPERTIES OF CONTACT ADHESIVES BASED ON POLYCHLOROPRENE .2. NATURE OF THE HYDROCARBON TACKIFIER

50 phr each of three hydrocarbon resins of different aliphatic-aromati c nature was added to a solvent based polychloroprene adhesive. The hy drocarbon resins were characterized using infra-red (IR) spectroscopy and differential scanning calorimetry (DSC) measurements. The properti es and compatibility of the polychloroprene/resin blends were studied using thermal mechanical analysis (TMA), DSC, scanning electron micros copy (SEM) and rheology. Tack measurements were carried out, and the j oint strength was obtained from T-peel tests of roughened styrene-buta diene rubber-polychloroprene adhesive joints. The addition of aromatic hydrocarbon resins produced a compatible resin-polychloroprene blend, whereas an incompatibility was obtained between an aliphatic hydrocar bon resin and the polychloroprene. The compatibility of aromatic hydro carbon resin-polychloroprene blends was responsible for the enhanced t ack and improved adhesion to roughened rubber materials. On the other hand, the incompatibility of aliphatic hydrocarbon resin-polychloropre ne blend produced a reduced tack, phase separation, and a reduced prac tical adhesion. Viscoelastic properties of adhesives were affected dif ferently depending on the temperature and the frequency of the experim ents and also on the aliphatic-aromatic nature of the resin.