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By following the rules of green chemistry, a novel composite is developed from a renewable and ecofriendly resource, namely, vanillin. The latter was used as a phenolic precursor for the microwave synthesis of a bio-based benzoxazine resin (Va-BZ). Afterward, high-performance green composites were developed by reinforcing Va-BZ with various amounts of chopped silane surface modified carbon fibers (CFs). The chemical structure of the Va-BZ monomers was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The grafting of the silane moiety on the CF surface was assessed by FTIR and TGA analyses. The autocatalytic ring opening polymerization of the Va-BZ monomers was confirmed by DSC analysis. The mechanical performances of the developed green composites were studied by flexural and tensile investigations. The findings suggested that the maximum amount of 20 wt. CFs afforded the best results, with flexural and tensile strengths of 450 and 462 MPa, respectively. The SEM was used to study the fractured tensile surfaces and elucidated the toughening mechanism. Meanwhile, the TGA showed that the introduction of the CFs markedly improved the thermal stability of the benzoxazine matrix. Overall, this study confirmed that greener approaches can also result in high-performance composites satisfying the needs of exigent applications.

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Benzoxazine containing phthalonitrile, as one of the most advanced high performance thermosetting resin, has gained a lot of attention in the last decades. Indeed, the combination of the thermally activated ring-opening polymerization of the benzoxazine and the cyano addition reaction of the phthalonitrile allows the development of robust polymeric networks. Following this path, a renewable natural resource, vanillin, was used to develop a new benzoxazine containing phthalonitrile thermosetting system. The newly developed monomers present the advantage of a simple synthesis process along with an autocatalytic polymerization mechanism. The molecular structures of the synthesized monomers were characterized by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (1H NMR). The curing behavior was assessed by differential scanning calorimetry (DSC). The newly developed monomers were then reinforced with a silane surface modified basalt fibers (BFs) allowing the preparation of a high performance green composite. The silane surface modification of the BFs was confirmed by FTIR and thermogravimetric analysis (TGA). The tensile and bending tests highlighted the remarkable mechanical properties of the developed green composite. Finally, the scanning electron microscopy (SEM) was used to study the mechanism of stress transfer between the matrix and the fillers. Overall, the developed green composite can be seen as a promising substitute to composites made from glass fibers.

Benzoxazine containing phthalonitrile, as one of the most advanced high performance thermosetting resin, has gained a lot of attention in the last decades. Indeed, the combination of the thermally activated ring-opening polymerization of the benzoxazine and the cyano addition reaction of the phthalonitrile allows the development of robust polymeric networks. Following this path, a renewable natural resource, vanillin, was used to develop a new benzoxazine containing phthalonitrile thermosetting system. The newly developed monomers present the advantage of a simple synthesis process along with an autocatalytic polymerization mechanism. The molecular structures of the synthesized monomers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy . Thermal properties were also characterized by differential scanning calorimetry and thermogravimetric analysis . Typically, the newly developed monomers showed excellent thermal stability with starting decomposition temperatures over 496.4°C with a char yield at 800°C of about 80.7%. The thermomechanical properties were investigated by dynamic mechanical analyzer and the fractured surfaces were studied by scanning electron microscopy Globally, the newly developed partially bio polymer showed outstanding thermal resistance along with excellent thermomechanical properties.