Isotactic polypropylene (iPP) resin was doped with 1% of pimelic acid/calcium stearate (composition ratio ¼ 1/1.5). It was crystallized in a two-step isothermal process, first at 130°C and then at 95°C, and finally cooled at a rate of 0.5°C min ¹1 to room temperature. The specimens were basically free of a-crystals and could be considered as pure b-PP. The crystallinity of the specimens was determined on the basis of their density. The heat of fusion of the b-crystal was found to be 168.5 J g ¹1. In comparison, the heat of fusion of the a-crystal in the undoped resin was slightly higher at 177.0 J g ¹1.
Посилання на статтю:
A study on the heat of fusion of b-polypropylene / J.X. Lia, W.L. Cheung, Demin Jia // Polymer. – 1999. – N 40. – P. 1219–1222.