2920 antioxidants without heat stabilization action can be used in this composition they are typically a phenol derivatives hindered phenols other known antioxidants are aromatic amine derivatives their main function is a free radical scavenging and to prevent dehydrochlorination the antioxidants can be but is not limited to 4 6 bis octylthiomethyl o cresol irgastab kv 10 dioctadecyl 3 3 u2032 thiodipropionate irganox ps802 poly 6 1 1 3 3 terramethylbutyl amino 1 3 5 triazine 2 4 diyl 2 2 6 6 tetramethyl 4 piperidinyl imino 1 6 hexanediyl 2 2 6 6 tetramethyl 4 piperidinyl imino chimassorb u00ae 944 benzenepropanoic acid 3 5 bis 1 1 dimethyl ethyl 4 hydroxy c7 c9 branched alkyl esters irganox u00ae 1135 isotridecyl 3 3 5 di tert butyl 4 hydroxyphenyl propionate songnox u00ae 1077 lq if used the preferred heat stabilizer is 4 6 bis octylthiomethyl o cresol irgastab kv 10 dioctadecyl 3 3 u2032 thiodipropionate irganox ps802 and or poly 6 1 1 3 3 terramethylbutyl amino 1 3 5 triazine 2 4 diyl 2 2 6 6 tetramethyl 4 piperidinyl imino 1 6 hexanediyl 2 2 6 6 tetramethyl 4 piperidinyl imino chimassorb u00ae 944 heat stabilizers are needed to prevent the degradation of pvc compositions during processing they prevent the unzipping of pvc chains by reacting with the generated hcl gas.