Joint effects of molecular structure and crystal morphology of organophosphate monovalent salts on nucleated isotactic poly(propylene)

The nucleation ability of organophosphate monovalent salts in isotactic poly(propylene) (iPP) was elucidated from the crystalline morphology and molecular structure with different size of cationic radius (r) of substitute parts. Differential scanning calorimetry result showed that the degree of crystallinity of nucleated iPP increased linearly with the increasing of r following the order of lithium (NA-10), sodium (NA-11), potassium (NA-12), ammonium (NA-13) salts of 2,2′-methylene- bis-(4,6-di-t-butylphenylene) phosphate. Moreover, small-angle X-ray scattering result displayed a large increase in the periodical length of nucleated iPP, which arises from an increment of both lamella thickness and amorphous thickness. Further, at 0.15 wt% concentration, the haze values of nucleated iPP presented a decrease tendency in the order of iPP/NA-10 (16.7 %), iPP/NA-11 (15.1 %), iPP/NA-12 (14.6 %), iPP/NA-13 (14.8 %), and their flexural strength was increased by 26.2 %, 30.8 %, 31.4 % and 31.7 %, respectively, as comparison to virgin iPP. These results demonstrated that the nucleating ability of these nucleating agents increased with the increase of r of substitute parts.