Cardanol-lmidazole Based Benzoxazine Blends and Bio-silica Reinforced Composites with Enhanced Surface, Thermal and Dielectric Properties

摘要

In the present work, imidazole core mono-amine (ima) was synthesized and used with cardanol (C) and bisphenol-F (BF) to obtain corresponding benzoxazines (C-ima and BF-ima) respectively. Similarly aniline (a) was used as amine precursor for synthesis of benzoxazines (C-a and BF-a) of cardanol (C) and bisphenol-F (BF) respectively for the purpose of blending and comparative studies with ima based benzoxazines. Benzoxazines (C-ima, C-a, BF-ima and BF-a) matrices and blends were prepared using both monofunctional and bifunctional benzoxazines in different weight percent (25/75 wt%, 50/50 wt% and 75/25 wt%) ratios and were characterized using different analytical techniques. From DSC analysis, it was observed that the curing temperature obtained for imidazole based benzoxazines (C-ima and BF-ima) was significantly lower than that of benzoxazines (C-a and BF-a) made using conventional aniline. Similarly, the blends prepared using ima based benzoxazine possess the lower curing temperature, with enhanced thermal stability and char yield than those of conventional cardanol-aniline benzoxazines to an appreciable extent. Hybrid blend composites were developed by reinforcing varying weight percentages (1, 3, 5, 7 and 10 wt%) of GPTMS functionalized bio-silica with selected blends (50:50) of imidazole based benzoxazines (C-ima and BF-ima) and their properties were studied. Data obtained from different studies, suggest that these hybrid composites possess an enhanced thermal stability, higher values of T-g, improved hydrophobic behavior, higher value of char yield and lower dielectric constant than those of neat matrices and blended matrices. It is concluded that the imidazole amine based benzoxazines (C-ima and BF-ima) blends and hybrid composites developed in the present work possess better properties than those of conventional benzoxazine based materials, hence it is suggested that these blends and composites can be used for high performance thermal and dielectric applications.