the effects of solvent, temperature, time, weight percent of catalyst on the rate and mechanism of cyclization of natural rubber (nr) was studied in toluene and xylene solutions having tin tetra chloride catalyst (sncl4). iodometric titration show, with 8% sncl4 (based on polymer weight) cyclization occurs, leaving 27.4% of the total unsaturation. infrared spectra of cyclized nr show decreased ...