Abstract
These tests have clearly shown the desirability of compounding this polymer with zinc oxide, magnesia, and rosin, and have demonstrated that these three ingredients when used together have a desirable effect that cannot be obtained with, or even predicted from, the results obtained with any one of them alone or the combination of any two of them. It has been shown further that, although it is possible to obtain good vulcanized products from this polymer without the addition of sulfur, a great increase in the rate of cure and substantial improvement in physical properties of vulcanized products result from the use of as little as 0.5 per cent of sulfur on the weight of the polymer. it is further shown that pine tar and rosin oil may be substituted for rosin but that they are somewhat less efficacious. The authors postulate that the value of rosin, pine tar, and rosin oil is probably due to the organic acids that they contain. Coumarone resin and brown factice are shown to be desirable compounding ingredients for chloroprene polymers.
