Flame retardancy of chlorinated elastomers

Elastomers, that contain halogens in their structure have been found to be resistant to flame. Industry uses many elastomers containing halogens, particularly chlorine, in the structure in varying proportions. Traditionally, chlorinated polymers such as polychloroprene (CR), containing different number of chlorine atoms in the structure, are used as flame resistant polymers in industry. However, as the polymer usage in day to day activities for domestic, office and particularly in the transport industry is on the increase, eliminating the fire hazard of polymers is currently of great concern. Hence, there is an absolute need to develop polymers with better flame resistance.

Three elastomers namely polychloroprene(CR) chlorinatedpolyethylene (CM) and epichlorohydrene(ECO) with the same content of chlorine were used in this study. Two popular flammability tests were used and they are the UL 94 testing method developed by the Underwriters Laboratory and the LOI test. The minimum quantity of oxygen required for combustion were measured according to the relevant BS and ASTM standards. Tensile strength and hardness tests were performed in accordance with the relevant BS standards.

According to the results observed in the UL 94 testing method, all three elastomers were rated for vertical burn as V0. Values obtained from the LOI test clearly shows that CM has a higher value. When comparing mechanical properties, even though CR has the highest tensile strength, CM has the highest hardness. According to our results CM has low flammability and better mechanical properties than the other two elastomers.

Keywords: Chlorinated polymers, elastomers, flame retardancy, flammability, LOI test  

doi: 10.4038/jnsfsr.v37i1.455

J.Natn.Sci.Foundation Sri Lanka 2009 37(1): 33-39