HYDROLYSIS AND STABILIZATION PERFORMANCE OF BIS(2,4-DI-T-BUTYLPHENYL)PENTAERYTHRITYL DIPHOSPHITE IN POLYPROPYLENE

The mechanism of hydrolysis under the conditions of long-term storage and the effect on stabilization efficiency of bis(2,4-di-t-butylphenyl )pentaerythrityl diphosphite (PA) was studied. Hydrolysis of P-1 under air in normal humidity begins by the cleavage of P-O-phenol bond, and both 2,4-di-t-butylphenols (DTBP) from one P-1 molecule are preferabl y released. A series of samples hydrolyzed to different degrees was te sted both alone and in blends with tetrakis (methylene 3-(3,5-di-t-but yl-4-hydroxyphenyl)propionate) methane (AO-1) as processing and long-t erm antioxidants in polypropylene. P-1 was found to perform as an effi cient processing antioxidant even in the absence of phenolics. Hydroly zed P-1, characterized by the presence of 7% of free DTBP released, ex hibited an improved performance. P-1 subjected to hydrolysis up to 48% was shown to retain good stabilization efficiency.