Phosphorylated cardanol-formaldehyde oligomers as flame-retardant and toughening agents for epoxy thermosets

IF 12.5 1区工程技术 Q1 ENGINEERING, CHEMICAL

Chemical Engineering Journal Pub Date : 2021-11-01 Epub Date: 2021-05-04 DOI:10.1016/j.cej.2021.130192

Wenwen Guo , Xin Wang , Jiali Huang , Xiaowei Mu , Wei Cai , Lei Song , Yuan Hu

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引用次数: 40

Abstract

Presently, flammability and brittleness are two major problems for EP which has restricted its development and application in industrial. Under the global advocacy of green and sustainable development, developing bio-based flame-retardant and toughening agents which can endow epoxy resins with high fire resistance and satisfactory mechanical properties is of significant demand for its industrial applications. Herein, three kinds of phosphorylated cardanol-formaldehyde oligomers (CF-PO(OPh)₂, CF-POPh₂, and CF-PPh₂) were synthesized and introduced into epoxy thermosets. The incorporation of CF-PO(OPh)₂, CF-POPh₂, and CF-PPh₂ can remarkably improve the mechanical performance of EP composites, especially the tensile strength and elongation at break. With 10 wt% of CF-PO(OPh)₂, CF-POPh₂, and CF-PPh₂, the tensile strength of epoxy thermosets reached 67.1, 74.5, and 70.3 MPa, respectively; the elongation at break of epoxy thermosets was raised by 133.3%, 162.5%, and 150.0%, respectively, as compared to neat EP. EP composites containing CF-PO(OPh)₂, CF-POPh₂, and CF-PPh₂ also exhibited remarkably enhanced flame retardancy simultaneously. Besides, CF-PO(OPh)₂ exhibited the best flame-retardant efficiency by comparison with CF-POPh₂ and CF-PPh₂, and the results manifested that epoxy composite with only 2.5 wt% CF-PO(OPh)₂ could pass the UL-94 V-0 rating as well as a high LOI value of 28%, and the LOI value of EP/CF-PO(OPh)₂–10 reached up to 32%. Moreover, CF-PO(OPh)₂ also displayed an excellent catalytic charring effect and great suppression effect on heat and smoke release. The cone calorimeter test results showed that EP composite containing 10 wt% CF-PO(OPh)₂ exhibited the most significant PHRR reduction which was 53.8% lower than pure EP, and the char yield of EP/CF-PO(OPh)₂–10 after the cone calorimeter test was 14.0% which was much higher than that of pure EP (5.7%). This work opens a new vision for the synthesis of bio-based flame-retardant and toughening agents with a special oligomeric structure combining rigidity with flexibility, and contributes to the production of high-performance epoxy thermosets.

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环氧热固性阻燃剂和增韧剂的磷酸化腰果酚-甲醛低聚物

目前，易燃性和脆性是制约环氧丙烷工业发展和应用的两个主要问题。在全球倡导绿色可持续发展的背景下，开发生物基阻燃增韧剂，使环氧树脂具有较高的耐火性能和满意的力学性能，是环氧树脂工业应用的重要需求。本文合成了三种磷酸化腰果酚甲醛低聚物(CF-PO(OPh)2、CF-POPh2和CF-PPh2)并将其引入到环氧热固性树脂中。CF-PO(OPh)2、CF-POPh2和CF-PPh2的掺入可以显著提高EP复合材料的力学性能，尤其是抗拉强度和断裂伸长率。当CF-PO(OPh)2、CF-POPh2和CF-PPh2添加量为10 wt%时，环氧热固性树脂的拉伸强度分别达到67.1、74.5和70.3 MPa;与纯EP相比，环氧热固性树脂的断裂伸长率分别提高了133.3%、162.5%和150.0%。含有CF-PO(OPh)2、CF-POPh2和CF-PPh2的EP复合材料也同时表现出显著的阻燃性。与CF-POPh2和CF-PPh2相比，CF-PO(OPh)2表现出最好的阻燃效果，结果表明，仅添加2.5 wt%的CF-PO(OPh)2的环氧复合材料就能通过UL-94的V-0等级，LOI值高达28%，EP/CF-PO(OPh)2 - 10的LOI值高达32%。此外，CF-PO(OPh)2还表现出优异的催化炭化效果，并对热释放和烟释放有良好的抑制作用。锥量热试验结果表明，含10 wt% CF-PO(OPh)2的EP复合材料的PHRR降幅最大，比纯EP降低53.8%，经锥量热试验后，EP/CF-PO(OPh)2 - 10的炭产率为14.0%，远高于纯EP的5.7%。这项工作为合成具有特殊寡聚结构的生物基阻燃剂和增韧剂开辟了新的视野，并有助于高性能环氧热固性材料的生产。

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来源期刊

Chemical Engineering Journal 工程技术-工程：化工

CiteScore

21.70

自引率

9.30%

发文量

6781

审稿时长

2.4 months

期刊介绍： The Chemical Engineering Journal is an international research journal that invites contributions of original and novel fundamental research. It aims to provide an international platform for presenting original fundamental research, interpretative reviews, and discussions on new developments in chemical engineering. The journal welcomes papers that describe novel theory and its practical application, as well as those that demonstrate the transfer of techniques from other disciplines. It also welcomes reports on carefully conducted experimental work that is soundly interpreted. The main focus of the journal is on original and rigorous research results that have broad significance. The Catalysis section within the Chemical Engineering Journal focuses specifically on Experimental and Theoretical studies in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. These studies have industrial impact on various sectors such as chemicals, energy, materials, foods, healthcare, and environmental protection.