中国塑料 ›› 2023, Vol. 37 ›› Issue (10): 117-124.DOI: 10.19491/j.issn.1001-9278.2023.10.016

• 高分子功能改性与极端服役应用 • 上一篇    下一篇

增压对聚丙烯/多壁碳纳米管复合材料结晶行为的影响

李贞印1,2(), 张效琳1,2, 魏聪1,2, 施智勇1,2, 邵春光1,2()   

  1. 1.郑州大学材料成型及模具技术教育部重点实验室,郑州 450002
    2.橡塑模具国家工程研究中心,郑州 450002
  • 收稿日期:2023-06-08 出版日期:2023-10-26 发布日期:2023-10-23
  • 通讯作者: 邵春光(1982-),男,教授,从事高分子加工过程中的物理问题研究,shaochg@zzu.edu.cn
    E-mail:liming20210420@163.com;shaochg@zzu.edu.cn
  • 作者简介:李贞印(1997-),男,硕士研究生,主要从事聚合物高压结晶研究,liming20210420@163.com
  • 基金资助:
    国家自然科学基金面上项目(52273027)

Effect of pressurization on crystallization behavior of iPP/MWCNTs melts

LI Zhenyin1,2(), ZHANG Xiaolin1,2, WEI Cong1,2, SHI Zhiyong1,2, SHAO Chunguang1,2()   

  1. 1.Key Laboratory of Materials Processing and Mold (Zhengzhou University),Ministry of Education,Zhengzhou 450002,China
    2.National Engineering Research Center for Advanced,Zhengzhou 450002,China
  • Received:2023-06-08 Online:2023-10-26 Published:2023-10-23
  • Contact: SHAO Chunguang E-mail:liming20210420@163.com;shaochg@zzu.edu.cn

摘要:

利用广角X射线衍射仪和差示扫描热仪研究了不同增压速率、不同增压温度下等规聚丙烯/多壁碳纳米管(iPP/MWCNTs )复合材料的结晶行为。结果表明,慢速增压条件下(1 MPa/s),增压温度较低时有利于α⁃iPP的生成,增压温度越高越有利于γ⁃iPP的生成,且慢速增压条件下MWCNTs对iPP的结晶具有诱导作用,制备的γ⁃iPP较稳定,在升温过程中不会发生熔融重结晶现象;快速增压条件下(200 MPa/s),较低的增压温度就能够制备出纯的γ⁃iPP,但MWCNTs的存在使iPP的熔体黏度增大,阻碍分子链运动,不利于晶体生长,形成的γ晶结构完善性较差,在升温过程中会发生熔融重结晶,增压温度较高时,快速增压能够制备出亚稳态中间相iPP。对比发现,增压速率和熔体记忆效应的协同作用共同决定了复合材料中iPP的结晶结构,慢速增压条件下熔体记忆效应对iPP的结晶结构影响较大,增压速率升高后,熔体记忆效应对其结晶行为的影响减弱。

关键词: 等规聚丙烯, 多壁碳纳米管, 增压速率, 熔体记忆效应, 结晶结构

Abstract:

The crystallization behavior of isotactic polypropylene (iPP)/multi⁃walled carbon nanotubes (MWCNTs) composites at different pressurization rates and temperatures was studied by using wide angle X⁃ray diffractometer (WAXD) and differential scanning calorimetry (DSC). The results indicated that a lower temperature was advantageous to the formation of α⁃iPP under the condition of low pressurization rate (1 MPa/s), but a higher temperature was more conducive to γ⁃iPP. MWCNTs could induce the crystallization of iPP. The formed γ⁃iPP has a stable structure and cannot recrystallize during the heating process. Pure γ⁃iPP could be prepared at a lower pressurization temperature under the condition of a high pressurization rate (200 MPa/s). However, the presence of MWCNTs resulted in an increase in the viscosity of iPP melt and hindered the movement of its molecular chains, which was disadvantageous to crystal growth. The γ⁃iPP crystal was formed in a poor structural perfection, and it was unstable and tended to recrystallize during the heating process. Therefore, the metastable mesophase iPP can be prepared at a higher pressurization temperature. The crystalline structure of iPP was determined by the synergistic effect of pressurization rate and melt memory effectiveness. At a low pressurization rate, melt memory effect generated a greater impact on the crystallization structure of the composite, and this effect weakened with an increase in the pressurization rate.

Key words: isotactic polypropylene, multi?walled carbon nanotube, pressurization rate, melt memory effect, crystalline structure

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