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Yang X, Li Y, Lei W, Bai Z, Zhan Y, Li Y, Li K, Wang P, Feng W, Liu Q. Understanding the Thermal Degradation Mechanism of High-Temperature-Resistant Phthalonitrile Foam at Macroscopic and Molecular Levels. Polymers (Basel) 2023; 15:3947. [PMID: 37835995 PMCID: PMC10575044 DOI: 10.3390/polym15193947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 09/24/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
Polymer foam, a special form of polymer, usually demonstrates some unexpected properties that rarely prevail in the bulky polymer. Studying the thermal degradation behavior of a specific polymer foam is important for its rational design, quick identification, objective evaluation, and industrial application. The present study aimed to discover the thermal degradation mechanism of high-temperature-resistant phthalonitrile (PN) foam under an inert gas atmosphere. The macroscopic thermal decomposition of PN foam was carried out at the cost of size/weight loss, resulting in an increasing number of open cells with pyrolyzation debris. Using the TGA/DTG/FTIR/MS technique, it was found that PN foam involves a three-stage thermal degradation mechanism: (I) releasing gases such as H2O, CO2, and NH3 generated from azo-containing intermediate decomposition and these trapped in the closed cells during the foaming process; (II) backbone decomposition from C-N, C-O, and C-C cleavage in the PN aliphatic chain with the generation of H2O, CO2, NH3, CO, CH4, RNH2, HCN, and aromatic gases; and (III) carbonization into a final N-hybrid graphite. The thermal degradation of PN foam was different from that of bulky PN resin. During the entire pyrolysis of PN foam, there was a gas superposition phenomenon since the release of the decomposition volatile was retarded by the closed cells in the PN foam. This research will contribute to the general understanding of the thermal degradation behavior of PN foam at the macroscopic and molecular levels and provide a reference for the identification, determination, and design of PN material.
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Affiliation(s)
- Xulin Yang
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
- Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637009, China
- Institute for Advanced Study, Chengdu University, Chengdu 610106, China;
| | - Yi Li
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
| | - Wenwu Lei
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
- Chengdu Hongbo Industrial Co., Ltd., Chengdu 610199, China
| | - Zhongxiang Bai
- Institute for Advanced Study, Chengdu University, Chengdu 610106, China;
| | - Yingqing Zhan
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, China
| | - Ying Li
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
| | - Kui Li
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
| | - Pan Wang
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
| | - Wei Feng
- School of Mechanical Engineering, Chengdu University, Chengdu 610106, China (Y.L.)
| | - Qi Liu
- Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637009, China
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Poliakova DI, Morozov OS, Nechausov SS, Afanaseva EA, Bulgakov BA, Babkin AV, Kepman AV, Avdeev VV. Fast curing phthalonitrile modified novolac resin: Synthesis, curing study and preparation of carbon and glass fibric composites. REACT FUNCT POLYM 2022. [DOI: 10.1016/j.reactfunctpolym.2022.105450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fast-Processable Non-Flammable Phthalonitrile-Modified Novolac/Carbon and Glass Fiber Composites. Polymers (Basel) 2022; 14:polym14224975. [PMID: 36433102 PMCID: PMC9699085 DOI: 10.3390/polym14224975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/19/2022] Open
Abstract
Phthalonitrile resins (PN) are known for their incredible heat resistance and at the same time poor processability. Common curing cycle of the PN includes dozens hours of heating at temperatures up to 375 °C. This work was aimed at reducing processing time of phthalonitrile resin, and with this purpose, a novolac oligomer with hydroxyl groups fully substituted by phthalonitrile moieties was synthesized with a quantitative yield. Formation of the reaction byproducts was investigated depending on the synthesis conditions. The product was characterized by 1H NMR and FT-IR. Curing of the resins with the addition of different amounts of novolac phenolic as curing agent (25, 50 and 75 wt.%) was studied by rheological and DSC experiments. Based on these data, a curing program was developed for the further thermosets' investigation: hot-pressing at 220 °C and 1.7 MPa for 20 min. TGA showed the highest thermal stability of the resin with 25 wt.% of novolac (T5% = 430 °C). The post-curing program was developed by the use of DMA with different heating rates and holding for various times at 280 or 300 °C (heating rate 0.5 °C/min). Carbon and glass fiber plastic laminates were fabricated via hot-pressing of prepregs with Tg's above 300 °C. Microcracks were formed in the CFRP, but void-free GFRP were fabricated and demonstrated superior mechanical properties (ILSS up to 86 MPa; compressive strength up to 620 MPa; flexural strength up to 946 MPa). Finally, flammability tests showed that the composite was extinguished in less than 5 s after the flame source was removed, so the material can be classified as V-0 according to the UL94 ratings. For the first time, fast-curing phthalonitrile prepregs were presented. The hot-pressing cycle of 20 min with 150 min free-standing post-curing yielded composites with the unique properties. The combination of mechanical properties, scale-up suitable fast-processing and inflammability makes the presented materials prospective for applications in the electric vehicle industries, fast train construction and the aerospace industry.
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High performance carbon–carbon composites obtained by a two-step process from phthalonitrile matrix composites. MENDELEEV COMMUNICATIONS 2022. [DOI: 10.1016/j.mencom.2022.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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