High Heat-Resistant and Degradable Polybenzoxazines with a Diacetal Structure

Abstract

Thermosetting resins with high heat resistance are difficult to degrade because of their cross-linking structures. In this work, a kind of diphenol (ACE) with a diacetal strucure is used to synthesize two novel benzoxazine monomers, ACE/aniline-type benzoxazine (ACE-a) and ACE/p-methylaniline-type benzoxazine. Their chemical structures are characterized by Fourier transform infrared (FTIR) spectra and NMR spectra, and the results show that the diacetal structure is successfully introduced. Their curing behaviors and polymerization reactions are studied by differential scanning calorimetry and FTIR spectra. Different cross-linking structures containing the diacetal are proposed for two polybenzoxazines. Their thermal properties are analyzed by dynamic mechanical analysis and thermogravimetric analysis, and the results show that they have excellent heat resistance and thermal stability. For cured ACE-a [P­(ACE-a)], its T g reaches as high as 301 °C and the char yield at 800 °C under N2 is 55%. Additionally, these polybenzoxazines can be completely degraded under mild acidic conditions, and the effects on the degradation are investigated systematically. Furthermore, ACE-a is used as a matrix to prepare fiber-reinforced composites with carbon fiber or glass fiber, and then, these fibers can be easily recovered from the composites by degrading the resin.

High-Tg and Degradable Isosorbide-Based Polybenzoxazine Vitrimer

“…In this context, the recent development of polybenzoxazine vitrimers paves the way toward such materials. , Indeed, polybenzoxazine are thermosets with high mechanical and thermal properties . Like traditional thermosets, they suffer from similar drawbacks, but the versatility of their chemical design offers opportunities to develop their self-healing, ,,− recyclability, ,,, and degradability, , among many other characteristics. − They are also known to be easily produced from natural resources. − …”

High-Performance and Degradable Polybenzoxazine/VU Vitrimer and Its Application for Carbon Fiber Recycling

“…The introduction of acetal polymers, imine bonds, diacetal structures, etc., into the thermosetting resin can degrade the thermosetting resin and recycle the CFs. However, modified thermosetting resins that introduce these structures do not simultaneously possess good mechanical and thermal properties.…”

“…The autocatalytic vitrimer system depends on its own free, abundant reactive groups as the catalytic reaction part to realize dynamic exchange, which is more environmentally friendly. However, at the same time, its T g value is still low, and its mechanical stability at high temperatures is poor. ,,− Therefore, researching new methods to prepare environmentally friendly and high-performance thermosetting resin systems with excellent performance (mechanical and thermal properties) and degradation under mild conditions is of great significance for the application of CF composites and the recycling of CFs.…”

Facile preparation and properties of polybenzoxazine/graphene porous nanocomposites for electromagnetic wave absorption

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