Enhanced Thermal Property and Flame Retardancy via Intramolecular 5-Membered Ring Hydrogen Bond-Forming Amide Functional Benzoxazine Resins

Abstract

Polybenzoxazines containing an ortho-amide group in the backbone with a significant degree of aromaticity have been synthesized and characterized in this study. This class of materials makes use of smart chemistry to be able to readily process the monomer and later transform from polybenzoxazine into polybenzoxazole. All the benzoxazine monomers studied contain amide groups that form 5-membered intramolecular hydrogen bonds with the oxazine rings. Systematic manipulation of the diamine structure has allowed the structure–property relationship of polybenzoxazines to be examined. Polymerization behavior of monomers is studied by differential scanning calorimetry (DSC) and in situ Fourier transform infrared spectroscopy (FT-IR). Thermal stability and flammability are characterized by thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC), respectively. The experimental results are fitted to the major thermal decomposition processes contributing to the specific heat release rate histories Q′(T). This family of materials show one of the lowest heat release capacity values of all polymers indicating the excellent flame retardancy.

A naringenin-based benzoxazine with an intramolecular hydrogen bond as both a thermal latent polymerization additive and property modifier for epoxy resins

“…Among these thermosets obtained in this study, poly(NAR-a/DGEBA) showed the lowest ammability, supported by its very low HRC and THR values, indicating that the higher degree of cross-linking can enhance the ame retardancy of epoxy-related thermosetting systems. Though the HRC value of poly(NAR-a/DGEBA) is higher than many polybenzoxazines with excellent ame retardancy, 41,42 it is substantially lower than the traditional and some recently reported high-performance epoxy thermosetting systems. 5 Therefore, the NAR-a/DGEBA thermosetting system may have great potential in applications that benet both high thermal stability and low ammability.…”

Effect of particle size on flame retardancy and mechanical properties of hydroxyethyl diphosphate modified aluminum hydroxide intrinsic polyethylene terephthalate

“…6,7 The most promising approach toward resolving the flammability issue is imparting the flame retardancy feature to PET materials. [8][9][10] The effective and durable implementation of flame retardancy in PET materials can be achieved by the chemical grafting of functional monomers to the PET chains. 3,11 Nowadays, flame retardants need to fulfill higher requirements, 11 for example, to be halogen-free, nontoxic, and environmentally friendly, 12 which oriented current research in that direction.…”

Developing Further Versatility in Benzoxazine Synthesis via Hydrolytic Ring-Opening

“…As a new class of thermosets, polybenzoxazines have drawn great attention from academic as well as industrial communities for their outstanding characteristics compared with other thermosets, such as epoxies, phenolics, bismaleimides and even polyimides. Notable advantages include their remarkable molecular design flexibility [1][2][3][4][5][6][7], excellent thermal and mechanical properties [8], high char yield [9], excellent flame retardancy [10][11][12][13][14], autocatalysis for ring-opening polymerization [15], near-zero shrinkage upon polymerization [16,17], excellent electrical properties [18][19][20][21][22][23][24][25] and surface energy lower than polytetrafluoroethylene [26][27][28][29][30].…”