Cardanol based benzoxazine blends and bio-silica reinforced composites: Thermal and dielectric properties

In the present work, a novel cardanol based benzoxazine was synthesised by reacting three different amines (Aniline (CrAb), N, N-dimethylaminopropylamine (CrDb) and caprolactam modified N, N-dimethylaminopropylamine (CrCb)) with cardanol in the
presence of formaldehyde at appropriate experimental conditions. The resulting benzoxazines were characterised for their molecular structure and thermal behaviour by
using different analytical methods. Among the different systems studied, the tertiary amine derivatives was found to reduce the curing temperature efficiently (CrAb-275 °C > CrDb265 °C > CrCb-251 °C) and are confirmed by DSC analysis. These cardanol based CrAb benzoxazine was blended with conventional benzoxazines (Bzs), bismaleimides (BMIs) as binary and ternary systems and studied their thermal properties. Three different catalysts (4-hydroxy acetophenone, 4-aminophenol, and 4-hydroxyphenyl maleimide) have been used to study the effect of lowering of curing temperature. Further, prepared benzoxazines
were reinforced with varying weight percentages (1, 3, 5 and 10 wt %) of bio-silica derived from rice husk to obtain hybrid composites. The dielectric studies of bio-silica reinforced
cardanol benzoxazines infer that the values of dielectric constant are decreased with increasing wt % of bio-silica. It was further observed that, 10 wt % of bio-silica reinforced
cardanol benzoxazines contributes to the lowest value of dielectric constant of 1.9 at 1MHz. From the data resulted from different studies, it is concluded that the blends of cardanol
based benzoxazines can be used in the form of sealants, encapsulants, adhesives and matrices in the fields of microelectronics and automobile applications for better
performance