Examples of suitable chlorinated polyethylene elastomers are known to the literature and to the art and specific commercial examples of such compounds include Tyrin CM 0836 which contains approximately 36% by weight of chlorine and has a Mooney viscosity (ML 1+4/100??? C.) of about 100, Tyrin CM 0136 which contains approximately 36% by weight of chlorine and has a Mooney viscosity of about 80, and