中国塑料 ›› 2025, Vol. 39 ›› Issue (10): 54-59.DOI: 10.19491/j.issn.1001-9278.2025.10.010

• 材料与性能 • 上一篇    下一篇

软质PVC引发的PC塑料件开裂分析

刘中平(), 肖银河, 葛会军   

  1. 株洲中车时代电气股份有限公司,湖南 株洲 412001
  • 收稿日期:2024-11-15 出版日期:2025-10-26 发布日期:2025-10-21
  • 作者简介:刘中平(1982-),男,工程师,研究方向为机车车辆部件防火和材料失效分析,liuzp3@csrzic.com

Cracking analysis of PC component initiated by plasticized PVC

LIU Zhongping(), XIAO Yinhe, GE Huijun   

  1. Zhuzhou CRRC Times Electric Co,Ltd,Zhuzhou 412001,China
  • Received:2024-11-15 Online:2025-10-26 Published:2025-10-21

摘要:

安装于某设备上的连接器组件,在运行过程中连接器母座螺纹管处出现脆性断裂。为了分析断裂的原因和机理,通过差示扫描量热分析、热失重分析、气相色谱⁃质谱分析和傅里叶变换红外光谱分析等方法对比分析断裂样品和运行正常的未断裂样品。结果表明,断裂样品存在可挥发的邻苯二甲酸二丁酯(DBP)成分,而未断裂样品则无此成分;进一步分析,该DBP成分来源于断裂样品通孔内安装的软质聚氯乙烯(PVC)套管。从Hansen溶度参数的角度分析,DBP与聚碳酸酯(PC)的相对能量差异(RED)值为0.72,说明DBP能够较好的溶解PC,即DBP能够侵蚀连接器母座。因此,连接器的断裂机理是环境应力开裂(ESC),连接器受到了PVC套管中的DBP污染,DBP渗透到螺纹处PC塑料内,消弱了PC分子间作用力,在锁紧螺母的拉伸应力作用下,导致由内向外的脆性开裂。

关键词: 聚氯乙烯, 聚碳酸酯, 邻苯二甲酸二丁酯, 环境应力开裂, 溶度参数

Abstract:

This study investigates the root cause of cracking in the screw areas of a polycarbonate (PC) connector assembled within a device. A combination of analytical techniques, including differential scanning calorimetry, thermogravimetric analysis, gas chromatography⁃mass spectrometry (GC⁃MS), and Fourier⁃transform infrared spectroscopy, was employed to compare cracked and normal samples. GC⁃MS analysis identified dibutyl phthalate (DBP), a plasticizer, exclusively in the cracked components. The source of the DBP was traced to a polyvinyl chloride (PVC) soft tube installed through the connector. Hansen solubility parameter analysis confirmed a high affinity between DBP and PC (with a relative energy difference, RED, of 0.72), indicating DBP's capability to solubilize and plasticize the PC matrix. The failure mechanism was identified as environmental stress cracking (ESC): DBP migrated from the PVC tube into the PC housing, reducing its cohesive strength and enabling brittle fracture initiation under the stress concentrated at the screw threads. This case provides a classic example of ESC and highlights the critical need for compatibility screening between adjacent polymer components and their additives.

Key words: polyvinyl chloride, polycarbonate, dibutyl phthalate, environmental stress cracking, solubility parameter

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