Renewable furan-derived diamine as primary amine source to prepare fully bio-based bis-benzoxazine monomer under solvent-free condition

Recent advances in the development of green furan ring-containing polymeric materials based on renewable plant biomass

“…Polybenzoxazines derived from a mixture of two or three BOx can often exhibit better thermal stability and flame retardancy, along with improved mechanical and barrier properties, compared with their mono-sourced analogues. 301–309 Few other studies have been devoted to the co-curing of furan-based BOx with the commercial epoxy EPON Resin 828, 310 polypyrrole 311 and epoxidized castor oil, 312,313 as well as mechanochemical preparation of pBOx-based polyamide resin, 314 resulting in a variety of materials with tunable properties depending on the nature and the ratio of the reagents.…”

Improved curing reactivity, thermal resistance and mechanical properties of furylamine‐based benzoxazine using melamine as an amine source

“…As Table 1 shows, T i decreased from 158.0 to 145.0°C, T p1 decreased from 207.3 to 176.6°C, and T p2 decreased from 272.3 to 219.7°C from BAfa to BAfa‐70ma. The third one appearing in the range of 276.5–296.6°C may correspond to the polymerization of furan ring 32,34 . It is interesting to note that with the increase of melamine content, the curing enthalpy gradually decreased from 361.5 J/g for BAfa to 171.0 J/g for BAfa‐30ma, and further decreased to 102.8 J/g for BAfa‐70ma.…”

“…On the contrary, the peak intensity of furan ring and benzoxazine ring gradually weakened, which indicated that melamine was involved in the reaction and hindered ring‐closure of benzoxazine, and as a consequence, more active functional groups such as phenolic hydroxyls and amino groups were remained in the precursors. The resonance peaks at 3.83 and 4.77 ppm can be assigned to proton in OCH 2 N and ArCH 2 N in closed benzoxazine ring, and two weak resonance peaks at 3.79 and 4.74 ppm may be attributed to the proton in OCH 2 N and ArCH 2 N structure in N,O‐acetal type oligomeric polybenzoxazine 3132 (Scheme 1). It should be noted that the N,O‐acetal structures were formed by ring‐opening polymerization of benzoxazine when the carboncations attacked the oxygen atoms of other benzoxazine rings, hence the chemical bonds were the same but the steric configuration varied, leading to slight change of chemical shift.…”

“…The third one appearing in the range of 276.5-296.6 C may correspond to the polymerization of furan ring. 32,34 It is interesting to note that with the increase of melamine content, the curing enthalpy gradually decreased from 361.5 J/g for BAfa to 171.0 J/g for BAfa-30ma, and further decreased to 102.8 J/g for BAfa-70ma. The main reason for such phenomenon may be the decrease of benzoxazine rings, that is, the ringopening of benzoxazine is an exothermic process, and the reduction of benzoxazine moities in the precursor may result in the reduction of exothermic enthalpy.…”

High Temperature Composites From Renewable Resources: A Perspective on Current Technological Challenges for the Manufacturing of Non-Oil Based High Char Yield Matrices and Carbon Fibers

“…Even if the current common approach to have highly crosslinked polybenzoxazines is related to the selection of bifunctional monomers, monobenzoxazines are simpler to formulate and are more flexible, having the possibility to introduce substituents into their structures giving special properties to final materials: in their research, Martos et al (2020) described the effect of monobenzoxazines substitution in meta positions on T g and crosslinking density (Figure 6B): the results confirm that higher char yields and increased T g can be obtained, proposing also the successful incorporation of this type of benzoxazine into other benzoxazine mixtures (as doping material) to increase the final crosslinking network (Wen et al, 2021). Zhang et al (2021) also found that diamine derived from furfurylamine (PDFA), when able to react with cardanol/eugenol, had a char yield of ~65% at 850 °C. The thermal stability of highly crosslinked polybenzoxazines can be also enhanced when the biobased matrix is combined with other polymers or specific fillers. As an example (Gao et al, 2019), Gao et al studied the behavior of a new silicon rubber based composite containing benzoxazine resins and ZrO 2 : the limited ablation rate (~0.11 mm/s) of the control sample was reduced to ~0.06 mm/s with a 20% resin formulation.…”