Peroxidic compositions

Compositions for the polymer curing comprising:

• a) one or more organic peroxides selected from the following general formulae:
• (R1—C(CH3)2—OO—C(CH3)2)n —R2 (I)
• wherein R1 is an alkyl, aryl and aryl-alkyl-substituted group having from 1 to 9 carbon atoms, R2 is selected from phenylene, ethylene, —C═C—, alkyl, aryl and aryl-alkyl-substituted group;
• said groups having from 1 to 9 carbon atoms;
• n is an integer equal to 1 or 2;
• wherein the two R3 substituents are independently alkyl, aryl, aryl-alkyl-substituted groups having from 1 to 9 carbon atoms, R4 and R5 are independently linear or branched, when possible, alkyl groups, having from 1 to 6 carbon atoms or —(CH2)m—C(O)OR6 wherein R6 is an alkyl group from 1 to 4 carbon atoms;
• m is an integer from 1 to 3, or they jointly form a not substituted or substituted cyclohexane or cyclododecane ring with 1 up to 3 alkyl groups having from 1 to 4 carbon atoms;
• and
• b) trans-stillbene having the formula