X-射线衍射法研究稀土顺-1,4-聚丁二烯低温结晶动力学

本文用广角X-射线衍射法(WAXD)研究了稀土催化聚合顺-1,4-聚丁二烯(Ln-PB)低温下分子量和温度对结晶过程的影响.随着分子量的改变,结晶速度在M_η=8×10~5左右有一极小值;在M_η=29×10~5左右有一极大值.最大结晶速度发生在T_(c,max)=-60～-70℃之间.最大平衡结晶度值,在M_η大于10~6以上与分子量无关,而最大平衡结晶度值所对应的温度与M_η呈线性关系.随着温度上升,晶胞参数略有增大.Ln-PB主级结晶属于非均相成核,以原纤状和盘状混合生长.

WAXD STUDIES ON LOW TEMPERATURE CRYSTALLIZATION BEHAVIOR OF THE CIS-1,4 POLYBUTADINE PREPARED WITH RARE-EARTH CATALYST SYSTEM

The effects of molecular weight and temperature on crystallization processes at low temperature for cis-l,4-polybutadine prepared with rare-earth catalyst (Ln-PB) have been studied by WAXD method. In the range of molecular weight from Mη≈2.13× 105 to 46.8×105 there are a maximum of crystallization rate at Mη≈29 × 105 and a minimum at Mη≈8×105. The temperature related to maximum crystallization rate, Tc, max is observed to be between -60℃ and -70℃. The degree of equilibrium crystallinity of Ln-PB is independent of molecular weight at Mη greater than 106, also the linearity is shown between the correspondent temperature, degree of equilibrium crystallinity and molecular weight. Values of unit cell parameters of Ln-PB increase with temperature. The main crystallzation of Ln-PB belongs to heterogeneous nucleation. The crystallization processes are mixed growth one and two dimensions.