Abstract: There is disclosed an improved process for the manufacture of a foundry core or mould, comprising forming into the foundry core or mould a composition comprising a granular filler, a synthetic resin which cures under the action of an acid and a desensitized ketone peroxide composition and treating said formed composition with sulphur dioxide, wherein the improvement comprises using as the desensitizing agent a dialkyl ester of an aliphatic dicarboxylic acid of the general formula ##STR1## wherein n=1-7 and R.sub.1 and R.sub.2 =a branched or non-branched alkyl group having 3 to 5 carbon atoms.

Abstract: A polymerizable or copolymerizable unsaturated polyester composition contains a peroxide initiator and a compound of the formula: ##STR1## wherein Y is hydroxy, alkoxy having 1-12 carbon atoms, or alkyl having 1-12 carbon atoms, and Z is hydrogen, hydroxycarbonyl, alkyl, cycloalkyl, aralkyloxycarbonyl having 1-20 carbon atoms, benzoyl, or alkanoyl having 1-4 carbon atoms.

Abstract: 1,1-dihydroperoxycyclohexane is desensitized by dissolving it in water, an alcohol, an ester or ketoether. The solution can be handled safely. 1,1-dihydroperoxycyclohexane may be used as an initiator in polymerizing ethylenically unsaturated compounds.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A copolymerizable composition containing an unsaturated polyester resin and a metal accelerator, suitable for copolymerization with an ethylenically unsaturated monomer, has incorporated therein as a peroxide initiator composition an alkylaldehyde peroxide which may be unsubstituted, or alkyl- or aryl-substituted, the alkylaldehyde peroxide containing not more than 20 carbon atoms and at least 1.5 active oxygen atoms per carbonyl group of said alkylaldehyde.

Abstract: A process for the polymerization of vinyl or vinylidene-group-containing esters in the presence of a free radical generating compound as an initiator and a metal compound as an accelerator comprising, as an initiator, an organic peroxidic composition consisting essentially of a compound having the general formula ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 may be the same or different and each represents hydrogen, branched or unbranched alkyl, if desired substituted by hydroxy, alkoxy, alkoxycarbonyl or halogen, aryl, if desired substituted by alkyl, hydroxy, alkoxy or halogen, or aralkyl wherein the aryl group may be substituted by alkyl, hydroxy, alkoxy or halogen, and wherein R.sub.1 together with R.sub.2, R.sub.3 together with R.sub.4, and R.sub.1 together with R.sub.4 form a branched or unbranched alkylene group, and R.sub.1 together with R.sub.2 and R.sub.3 form a branched or unbranched alkylylidene group.