Yu Cao,Zhanxin Liu,Jin Jiang,Ping Song,Shuyang Shao,Hui Zhao,Zhi Wang
Benzoxazine has aroused a lot of research interest because of its high mechanical performance and excellent thermal stability in polybenzoxazines. However, it suffers from its high curing temperature and long curing time, which necessitate resolution. This study addresses this issue by employing a surface-modified fly ash-assisted microwave curing method to achieve ultra-fast benzoxazine curing within 15 min. The impact strength of the resulting cured product displayed an increasing-then-decreasing trend with the addition of fly ash, reaching a maximum impact strength of 18.71 ± 1.20 kJ/m 2 at a 3% fly ash content. This value is 113.3% higher than the impact strength of pure PBA-a. Additionally, when using the same amount of fly ash, the microwave-cured product exhibited a flexural strength of up to 135.9 MPa and a flexural modulus of up to 6.71 GPa, surpassing those of pure PBA-a by 28.7% and 33.1%, respectively. Moreover, the glass transition temperature ( T g ) increased by 19.56°C. Furthermore, there was a slight improvement in flexural strength compared to the heat-cured product, and no significant loss in thermal properties was observed. The method demonstrated in this study presents a novel approach for the rapid molding and preparation of benzoxazine in composites.
Graphical Experimental Overview: A molybdenum phenolic fiber has been developed.The synthetic solution was mixed with PVB, wet spinning, and then molybdenum phenolic fiber with better performance were obtained by four different curing methods. With the addition of molybdenum acid, the Mo-o bond enters the molecular chain of high-neighborhood phenolic fibers, which improves the cross-linking degree and thermal stability. The study aims to produce thermosetting resin from synthesized molybdenum-modified high-ortho thermoplastic phenolic resin through an addition reaction. Then, molybdenum-modified high-ortho thermosetting phenolic resin is blended with polyvinyl butyral and undergoes wet spinning to prepare as-spun fibers and obtain high-ortho molybdenum phenolic fibers via solution curing, microwave curing, or heat curing. Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis, scanning electron microscopy, and fiber strength testing were used to investigate the structure and properties of molybdenum-modified high-ortho phenolic fibers. Results showed that adding molybdic acid introduced Mo−O bonds into the molecular chain of high-ortho phenolic resin, thereby improving the degree of cross-linking and thermal stability. The residual carbon content of the fibers after heat treatment exceeded 60%, and the elongation at break and the breaking strength of the microwave-cured fibers reached 4.2% and 155 MPa, respectively, and the mechanical properties were relatively good. The study of high-ortho phenolic fibers aims to improve their properties and expand their applications through resin modifications. It provides a possible fiber preparation strategy for improving heat-resistant phenolic fibers, thereby guiding the research of modified high-ortho phenolic fibers.
危险品化学品经营许可证（带存储）