A solventless method was adopted to synthesize two benzoxazine monomers from naturally occurring sources, i.e., eugenol (an extraction from clove), furfurylamine, stearylamine, and paraformaldehyde. The structure of the extracted eugenol and synthesized monomers were supported by FT-IR, 1 H NMR, 13 C NMR, and mass spectral analysis. The monomers were polymerized/copolymerized via ring-opening polymerization by heating as shown by FT-IR (disappearance of the peak due to oxazine ring at 920 cm −1 ) and differential scanning colorimetry (DSC). The exothermic peak associated with curing was observed between 198−254 °C. DSC analysis shows that the onset of curing temperature for the copolymers decreased linearly from 207−202 °C on increasing the content of F-Bz. The results from TGA analysis indicate that PF-Bz shows the maximum thermal stability when compared with PS-Bz and their copolymers. In the case of the copolymers, as the F-Bz content is increased, the thermal stability also increases. All the polymers also exhibit good flame retardant properties as shown by their LOI values (more than 26).

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Fully bio-based composites composed of polybenzoxazine resins obtained from renewable natural resources (such as cardanol, furfurylamine, and stearylamine) and bio-fiber such as jute fiber were prepared. The purity of the isolated cardanol was determined by Gas Chromatography. The structure of cardanol and its benzoxazine monomers were characterized by FT-IR, 1 H-NMR, 13 C-NMR, and Mass spectroscopic analysis and its polymerization process was monitored by Differential scanning calorimetry analysis. The composites' tensile and flexural strengths were measured by UTM and its impact strength was measured by IZOD impact tester respectively. The bio composite (PCF-Bzo/Jute fiber) shows superior thermal and mechanical (from thermogravimetric analysis and dynamic mechanical analysis) properties when compared with stearylamine-based composite (PCS-Bzo/Jute fiber). The surface morphologies of the fractured composites were analyzed by Scanning Electron Microscopy. POLYM. COMPOS., 37:573-582, 2016.

Bio-based polybenzoxazines from BGF were prepared by a solventless method as an alternative to poly(BA-a) showing enhanced thermal, mechanical and dielectric properties.

Polybenzoxazine-tethered polyhedral oligomeric silsesquioxane nanocomposites with well-defined architecture were prepared by the reaction of bio-phenols: eugenol, guaiacol, vanillin; poss-octaamine with paraformaldehyde. FT-IR measurements evidenced the 10 occurrence of Mannich reaction between phenolic group of bio-phenols and amino group of POSS molecule, with the consequent formation of a heterocyclic benzoxazine ring binding POSS in its backbone. Their chemical structures were proved by 1 H and 13 C-NMR analysis. Thermo-mechanical properties and thermal stability of the POSS-polybenzoxazine hybrid networks were determined by DSC, DMA and TGA. SEM, EDX, AFM and TEM micrographs show that POSS-Pbz nanocomposites exhibit featureless morphologies with no discernible phase separation, suggesting that the POSS nanoparticles are dispersed homogeneously throughout the matrix. The 15 homogeneity of these networks with octafunctional POSS is also indicated by their moduli in the range of 2.63 to 2.91 GPa. Moreover, their dielectric values [both dielectric constant (1.85) and dielectric loss (0.28)] and moisture absorption values are very low (<0.01%) which makes them suitable materials for use in microelectronics packaging.

Nanocomposites of eugenol‐based polybenzoxazines/amine containing polyhedral oligomeric silsesquioxane (POSS) have been prepared through copolymerization of allyl‐containing benzoxazine compounds and amine containing POSS. Their structures, curing behaviour, and thermomechanical properties were characterized by Fourier transform infrared, 1H‐NMR, 13C‐NMR, X‐ray diffraction, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The nanoscale dispersion of POSS cores in the nanocomposites was verified by scanning electron microscopy, atomic force microscopy, and transmission electron microscopy studies. The results from DMA and TGA show that the thermal stability, crosslink density and flame retardance of the nanocomposites increased when small amounts of POSS cores (5 wt%) were incorporated into the system. Further the POSS incorporation reduces the dielectric constant of the benzoxazines to about 1.32. Hence, the prepared nanocomposites could be used as ultra‐low‐k materials for advanced microelectronics. POLYM. COMPOS., 36:1973–1982, 2015. © 2014 Society of Plastics Engineer

Renewable natural resources such as eugenol, furfurylamine, stearylamine, and jute fiber were used to prepare polybenzoxazine composites. The purity of eugenol which is extracted from clove was confirmed by gas chromatography. FTIR, 1H, and 13C NMR spectroscopic analysis were used to determine the structure of eugenol and the benzoxazine monomers namely 6‐allyl‐3‐furfuryl‐8‐methoxy‐3,4‐dihydro‐2H‐1,3‐benzoxazine (EF‐Bz) and 6‐allyl‐3‐octadecyl‐8‐methoxy‐3,4 dihydro‐2H‐1,3‐benzoxazine (ES‐Bz) synthesized from it. The curing analysis from differential scanning calorimetric analysis shows that the onset of curing is shifted to lower temperature (161°C) for EF‐Bz, when compared with ES‐Bz (174°C). The thermal stability analyzed from thermogravimetric analysis shows that the polybenzoxazine EF‐Pbz has higher thermal stability (T5% = 361°C) with that of ES‐Pbz (T5% = 313°C). The storage modulus, tensile, and flexural strength of the EF‐Bz/Jute fiber composite show high value when compared with ES‐Bz/Jute fiber composites. POLYM. COMPOS., 37:1821–1829, 2016. © 2014 Society of Plastics Engineers

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