EFFECTS OF HYDROCARBON TACKIFIERS ON THE ADHESIVE PROPERTIES OF CONTACT ADHESIVES BASED ON POLYCHLOROPRENE .1. INFLUENCE OF THE AMOUNT OF HYDROCARBON TACKIFIER

Amounts between 20 and 120 phr of an aromatic hydrocarbon resin were a dded to a solvent-based polychloroprene adhesive. The hydrocarbon resi n was characterized using infra-red (IR) spectroscopy and differential scanning calorimetry (DSC) measurements. The properties and compatibi lity of the polychloroprene/resin mixture were studied using contact a ngle measurements, mechanical tests, DSC, thermal mechanical analysis (TMA), and theology. Tack measurements were also carried out, and the adhesion strength was obtained from T-peel tests on roughened styrene- butadiene rubber/polychloroprene adhesive joints. The addition of resi n produced an increase in the contact angle, and a decrease in the mec hanical and viscoelastic properties of the adhesives. For amounts of r esin lower than 50 phr, there was adequate compatibility with polychlo roprene, which could be the reason for the improved tack and practical adhesion of the polychloroprene adhesives. Amounts of resin higher th an 50 phr produced a lesser degree of compatibility with polychloropre ne, which was responsible for the reduced tack and lower cohesive prop erties of the adhesives. On the other hand, there was a decrease in jo int strength which can be related to the change in the locus of failur e of the joints, from an adhesional (for a resin content lower than 50 phr) to a cohesive failure of the polychloroprene (for a resin conten t higher than 50 phr).