Nucleation effects of sodium and ammonium salts of 2,2′-methylene-bis-(4,6-di-t-butylphenylene)phosphate in isotactic polypropylene



The nucleation ability of isotactic poly(propylene) (iPP) to ammonium 2,2′-methylene-bis-(4,6-di-t-butylphenylene) phosphate (An) was investigated in the present work comparing with sodium 2,2′-methylene-bis-(4,6-di-t-butylphenylene) phosphate (NA-11). Scanning electron microscope (SEM) revealed the crystalline morphology of both An and NA-11 with planar surface characteristics. The observation of the fracture surface of nucleation iPP samples by SEM showed An particles were dispersed uniformly in polymer and had a better compatibility with iPP matrix than NA-11 particles. Differential scanning calorimeter (DSC) showed that the melting temperature of An was 262°C significantly lower than that measured from NA-11 group (above 400°C). Crystallization behaviors of iPP/NA-11 and iPP/An were also investigated by DSC analysis, respectively. The results showed the crystallization peak temperature and the crystallinity of iPP/An were almost near to that of iPP/NA-11. Furthermore, mechanical and optical properties of iPP were strongly improved in the presences of An and NA-11. The flexural strength of iPP was elevated 34 and 35% and the haze value was reduced from 40.4 to 15.1 and 14.9% by the addition of 0.15 wt% NA-11 and An, respectively. These results demonstrate that the nucleating agent of An described here is a good nucleating agent for the crystallization of iPP as well as NA-11. POLYM. ENG. SCI., 55: 22–28, 2015. © 2014 Society of Plastics Engineers