Thermosetting resin has excellent mechanical properties, thermal properties, dimensional stability, processing performance and chemical stability. It is widely used in electronic packaging materials, composite materials, adhesives and coatings. However, due to its highly chemical crosslinked three-dimensional network, thermosetting resin is difficult to be recovered. The introduction of dynamic covalent bond into the crosslinking network of thermosetting resin can realize the recycling and reuse of thermosetting resin like thermoplastic, and has the properties of controllable degradation recovery, welding, self repair, stimulation response, etc. However, the existence of dynamic covalent bond will lead to creep and poor dimensional stability of resin, which is difficult to be used in structural materials. Therefore, based on acetal chemistry, researchers such as Ma Songqi, the team of bio based polymer materials of Ningbo Institute of materials technology and engineering, Chinese Academy of Sciences, developed a new type of remodeled thermosetting resin, which can achieve high temperature (about 100 ℃) without creep. Acetaldehyde is a kind of group with rapid and controllable pH degradation, which is often used as a protective group in organic synthesis. In 2019, Ma Songqi and others found that acetals can exchange dynamically in the presence of high temperature and no catalyst, and successfully obtained acetal type catalyst free remolding thermosetting resin. The resin has obvious stress relaxation at high temperature, showing excellent ductility and reprocessing. At the same time, the starting material can be completely recovered in hot water at 100 ℃ for 1H (J. mater. Chem. A 2019, 7, 18039-18049). Recently, researchers further designed the structure of asymmetric acetals to achieve excellent water resistance, high temperature creep resistance, thermal and mechanical properties. Through the reaction of linear phenolic resin with cyclohexanedimethyldivinyl ether, a remodeled thermosetting resin containing asymmetric acetals was obtained. The remodeled thermosetting resin has excellent thermal and mechanical properties, and its performance is flexible. It is found that the asymmetric acetal type can remodel thermosetting resin, which shows excellent creep resistance at high temperature and does not creep at 100 ℃. But at the same time, it has excellent remolding properties. Through the study of small molecular model compounds, acetal exchange follows the dissociation mechanism at high temperature. In addition, the resin will not degrade in hot water. Through the study of small molecular model compounds, it is found that the asymmetric acetal structure itself has good stability in hot water or water / organic solvent mixture. However, its excellent water resistance does not affect its degradation and recovery performance. The resin can be degraded and recovered in the mixed solution of 0.1M HCl water and acetone at 50 ℃ to obtain the starting material of phenolic resin, which is difficult to degrade under the conditions of acetic acid or room temperature, so the controllable degradation and recovery of thermosetting resin can be realized under the mild conditions. The results have been applied for patent (cn2020100523086) and published in macrolecules.
Fig. 1 Preparation of remodeled thermosetting resin containing asymmetric acetals by reaction of novolac resin with divinyl ether and its dual recovery process and high temperature creep resistance
Fig. 2 stability of remodeled thermosetting resin containing asymmetric acetals in aqueous environment
"China International composite Exhibition" is the largest and most influential composite industry exhibition in China and even in Asia. It ranks the top three in the world and shows its professional style and mature charm as a "leader". Relying on 25 years of experience accumulation and influential advantages at home and abroad, the organizer has widely publicized, carefully organized and provided warm services, invited professional audiences from government, industry and society to visit, and made every exhibition a festival for entrepreneurs and a grand event for the industry. Its professional image, brand and status have not only been strongly supported by relevant government departments, but also been greatly supported by relevant government departments Industry consensus. "China International composite Exhibition" is aptly called "wind vane of composite industry" in the industry. Only through this platform can the development track of China's composite industry be reflected to the greatest extent and the latest trend of composite development be expressed most accurately. 1、 Exhibition time: September 2-4, 2020 2. Exhibition address: Shanghai World Expo exhibition hall 3. Exhibition scale: exhibition area: 53000m2, over 700 exhibitors (over 130 overseas exhibitors), and over 30000 participants. 4、 Exhibition fee:
5、 Exhibition area 1. Raw materials and production equipment: epoxy, phenolic, fiber and reinforcement materials, adhesives, additives, fillers, pigments and premixes, prepregs, etc. 2. Composite production technology and equipment: spray, winding, molding, injection, pultrusion, RTM, LFT, vacuum induction and other new molding technology and equipment; 3. Final products and applications: composite materials in anti-corrosion Corrosion engineering, construction engineering, automobile and other rail transit, boat, aerospace, aviation, machinery, chemical industry, new energy, power electronics, sports equipment, daily life and other fields of products and application, manufacturing equipment, etc.; 4. Composite material quality control and testing: quality monitoring technology and material testing equipment, automation control technology and robot and other equipment, nondestructive testing technology And equipment; 5. Energy saving, environmental protection recovery, recycling, repair and other technologies and equipment of composite materials and their products; 6. Advanced reinforcement materials such as carbon fiber, aramid fiber, high polymer polyethylene fiber, renewable biological fiber and their products and related technologies and equipment.
6、 Highlight activities: nearly 40 special lectures on the latest products and technologies of enterprises; practical special technical training to solve practical problems encountered in production and operation for enterprises; high-level enterprise forum with forward-looking analysis and prediction of industry development trend.
7、 Contact: Xie Yong, 18163333266, Jia Nan, 13691581276, to accept all kinds of business cooperation such as technical report, manual, lanyard, chest card, handbag, customer docking, etc. for details, please refer to the meeting affairs group.
End
Scan the QR code below and add administrator wechat
Remark name phone + company name and product, free access
Real name exchange group of epoxy resin for infrastructure
Disclaimer: This article is only for readers' exchange and study. Some data, charts or other contents are from the Internet or other public materials. The copyright belongs to the author and the original source. If there is any infringement, please contact the editor to deal with it in time