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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (10): 1003-1009. 上一篇    下一篇

研究论文

硅氧烷液晶共聚物作为β晶成核剂对等规聚丙烯结晶结构与形态的影响

孙静，胡建设*，钞春英，郭志兴，祁阳   

  1. (东北大学理学院 沈阳 110004)
  • 投稿日期:2009-10-20 修回日期:2009-12-18 发布日期:2010-01-19
  • 通讯作者: 胡建设 E-mail:hujs@mail.neu.edu.cn

Influence of Liquid Crystalline Copolysiloxane as a β-Form Nucleator on Crystallization Structure and Morphology of Isotactic Polypropylene

SUN Jing, HU Jian-She, CHAO Chun-Yang, GUO Zhi-Xin, QI Yang   

  1. (School of Science, Northeastern University, Shenyang 110004)
  • Received:2009-10-20 Revised:2009-12-18 Published:2010-01-19

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采用广角X射线衍射(WAXD)与偏光显微镜(POM)等手段研究了硅氧烷液晶共聚物(LCP-O2)作为新型成核剂对聚丙烯(PP)共混样品结晶结构与形态的影响. 结果表明, 低浓度的LCP-O2在PP共混体系中起到异相成核的作用, 使PP的晶核数目增多, 球晶细化, 并提高了结晶速度, 同时也诱导出了β晶的形成. LCP-O2的成核效果主要依赖于其在PP中的相对含量、液晶的分子结构与结晶的热处理过程, 且随着结晶温度或成核剂含量的增加, 对应PP试样的β晶含量(Kβ)呈现先增加, 后降低的趋势. 当LCP-O2质量分数为1.0%, 在130 ℃等温结晶1 h, 对应PP试样的Kβ最大, 为58%. 此外, 属于单斜晶的α球晶呈现黑白颜色, 晶束呈放射状生长, 边界清晰; 而属于三方晶的β球晶亮度要高于α球晶, 其颜色艳丽多彩, 束状晶片聚集体呈支化生长, 内部排列比α晶疏散, 边界相对模糊, 且β晶与α晶的形态分别在157和171 ℃完全消失.

关键词: 液晶共聚物, β晶成核剂, 等规聚丙烯, 结晶结构与形态, 共混

The influence of liquid crystalline copolysiloxane (LCP-O2) as a new nucleator on crystallization structure and morphology of isotactic polypropylene (PP) has been investigated by means of wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). The experimental results showed that LCP-O2 with low concentration in PP played a role in the heterogeneous nucleation effect, enhanced the crystallization velocity, and the spherulites became smaller and more homogeneous. Moreover, β-phase was induced in PP. The nucleating activity of LCP-O2 mainly depended on its concentration, molecular structure of liquid crystalline, and thermal history of processing. The relative content of β-form (Kβ) increased with increasing crystallization temperature or LCP-O2 concentration, reached a maximum value, and then decreased as the temperature or LCP-O2 concentration further increased. Kβ was 58% when the mass fraction of LCP-O2 was 1.0%, and the crystalline temperature and time were 130 ℃ and 1 h, respectively. The trigonal β spherulite with the sheaflike grain growth is bright and colorful compared with the black and white monoclinic α one with the cross-hatched radial grain growth. In addition, the rotundity of α-spherulites was clear, while that of β-spherulites was relative obscure. With increasing temperature, the morphology of β and α spherulite disappeared at 157 and 171 ℃, respectively.

Key words: liquid crystalline copolymer, β-form nucleator, isotactic polypropylene, crystallization structure and morphology, blend