Abstract: Alkyloxyalkanoic acids, salts or esters having the formulaR.sup.1 --O--(CR.sup.3 R.sup.4).sub.x CO.sub.2 R.sup.2where R.sup.1 represents an alkyl or alkenyl group, or a hydroxy- or alkoxy- substituted alkyl or alkenyl group, said group containing (apart from the alkoxy carbon atoms in an alkoxy-substituted alkyl or alkenyl group) from 1 to 22 carbon atoms, R.sup.2 represents hydrogen, a metallic or other cationic group, each of R.sup.3 and R.sup.4 represents independently hydrogen or an alkyl group, and x has a value of from 1 to 10, act as agents useful for modifying rubber properties. Compared with conventional processing aids, they improve the processing characteristics of unvulcanised rubber compositions and can have beneficial effect on the physical properties of vulcanisates obtained by the vulcanisation of such compositions.

Abstract: Alkylthioalkanoic acids, salts or esters having the formulaR.sup.1 S(CR.sup.3 R.sup.4).sub.x CO.sub.2 R.sup.2where R.sup.1 represents an alkyl or alkenyl group, or a hydroxy- or alkoxy-substituted alkyl or alkenyl group, said group containing (apart from the alkoxy carbon atoms in an alkoxy-substituted alkyl or alkenyl group) from 4 to 22 carbon atoms, R.sup.2 represents hydrogen, a metallic or other cationic group, or an esterifying group, each of R.sup.3 and R.sup.4 represents independently hydrogen or an alkyl group, and x has a value of from 1 to 10, act as viscosity-modifying agents in unvulcanized rubber compositions. Compared with conventional processing aids, they improve the processing characteristics of unvulcanized rubber compositions and can have beneficial effect on the physical properties of vulcanisates obtained by the vulcanization of such compositions.

Abstract: The bond strength between a sulphur-vulcanizable rubber and a metal, especially brass, is increased by using as bonding promoter a compound having the formula[.sup.- O.sub.2 C CH.sub.2 S--B--S CH.sub.2 CO.sub.2.sup.- ]M.sup.++or a hydrate thereof, where B represents a divalent organic radical and M represents cobalt or nickel.