The British Petroleum Company, P.l.c.

Brian Weeks

Anthony John Park

Alan C Aldred

Blends of chlorosulphonated polyethylene and defined bituminous material are modified by the addition of not more than 15% by weight, based on total weight of chlorine-containing synthetic elastomer, of a thermoplastic olefin polymer having a softening point in the range 110.degree.-160.degree. C. The incorporation of this polymer reduces shrinkage when sheets formed from the blend are exposed to heat while in use.

Polymer/bituminous material blends, process for making articles from

Surfaces of a blend of (1) unvulcanized chlorosulphonated polyethylene and/or chlorinated polyethylene, (2) a bituminous petroleum derivative of softening point in excess of 100.degree. C. and an asphaltene content in excess of 25% by weight and (3) a noninterfering anti-blocking agent are joined by radio frequency dielectric welding.

Method for making articles by radio frequency welding

The residual vinyl halide content of vinyl halide polymer is reduced by radiofrequency dielectric heating of a water-containing layer of particulate polymer over which is disposed a layer of material through which vinyl chloride can pass but which restricts the passage of water e.g. perforated plastic sheet.

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Epsom, United Kingdom

Brian Weeks