Study on the dual-curing mechanism of epoxy/allyl compound/sulfur system

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• 作者：Qingsong Lian ; Yan Li ; Tao Yang ; Kai Li ; Yifen Xu…
• 刊名：Journal of Materials Science
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：51
• 期：17
• 页码：7887-7898
• 全文大小：1,679 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Materials Science
  Characterization and Evaluation Materials
  Polymer Sciences
  Continuum Mechanics and Mechanics of Materials
  Crystallography
  Mechanics
  
• 出版者：Springer Netherlands
• ISSN：1573-4803
• 卷排序：51

文摘

Allyl-based epoxy resin/Sulfur (S) system is a facile and novel dual-curing system which conducts a unique curing mechanism. In this paper, Bisphenol-A diglycidyl ether (BADGE) and 2-Allylphenol (OAP) cured by S were comparatively investigated to clarify the dual-curing mechanism of Epoxy (EP)/Allyl Compound (AC)/S system. When the temperature was above 170 °C, DSC and FTIR data showed that S could cleave to form thiyl radicals, and FTIR, NIR, and 1H NMR measurements proved the disappearance of allyl groups and the generation of thiol groups by the thiyl radicals abstracting α-H atoms of allyl groups in the OAP/S reaction system. Real-time infrared spectroscopy (RT-FTIR) results showed that the reaction of the generation of thiol groups is the dominant reaction in the two possible pathways of the OAP/S system; allyl groups and epoxy groups disappeared sequentially in the OAP/S/BADGE system. DSC curve also revealed the one-stage reaction for OAP/S system and two-stage reaction for OAP/S/BADGE system. These data were used to develop a detailed, experimentally validated pathway for the dual-curing of EP/AC/S system, in which thiol groups are important intermediate, and the dual-curing process included the crosslinking of double bonds that initiated by thiyl radicals and the ring-opening reaction of epoxy groups with thiol groups. Besides, the dual-curing mechanism of EP/AC/S system shares a close resemblance to the classical rubber vulcanization mechanism and the recent thiol-ene radical addition mechanism.