反气相色谱法研究聚丙烯结晶动力学及对熔点和结晶度的测定

<正> 研究聚合物的结晶动力学,过去大多采用膨胀计法和解偏振光法。曾有文献报道采用反气相色谱法测得聚乙烯等温结晶线。通过实验可知,测定聚丙烯结晶度时,试样热历史和测定前陈化温度的选择均影响测定结果。此外在测定聚丙烯试样的熔点时,保留图中出现了两个转折,经反复实验证实:此两转折对应于聚丙烯中不同晶形(α-、β-形)的熔点。

STUDIES OF POLYPROPYLENE CRYSTALLIZATION KINE-TICS AND DETERMINATIONS OF ITS MELTING POINT AND CRYSTALLINITY BY INVERSE GAS CHROMA- TOGRAPHY

The isothermal crystallization curves of polypropylene over a wide range of temperatures were obtained by the inverse gas chromatography. The calculated velocity constants are in accord with those derived by other methods. The experimental data have been treated with Avrami's equation the crystalline index n equals to 2.1. The crystallinity and the melting point of this polymer were studied. The crystallinity are influenced by experimental conditions and the thermal history of the sample. The melting points of both α-and β-form have been found by this method. In case there are two crystalline forms coexisted in one sample, a higher value of crystallinity is obtained as compared with that by other methods.