Chlorinated maleinized guayule rubber as an adhesion promoter for polypropylene

Chlorinated maleinized guayule rubbers (CMGR) were synthesized and applied as coatings onto polypropylene panels. CMGR orientation was critical to adhesion and was verified by contact angle measurements. Reducing the quantity of tetrahydrofuran (THF) decreased adhesion from 57 N/cm exp 2 with pure THF to 23 N/cm exp 2 with four percent THF in water. Percent maleinization above a critical concentration of 15 by weight decreased adhesion. However, 10% maleinization was required for dispersion stability in water while 5-10% concentration provided maximum adhesion. A five percent maleic CMGR dispersion at 240 g/L THF concentration was stable for less than 24 hr while a 10% maleic anhydride concentration has shown long-term stability.