Cardanol-based bisbenzoxazines: Effect of structure on thermal behaviour

ISSN： 1388-6150

Source： Journal of Thermal Analysis and Calorimetry, Vol.107, Iss.2, 2012-02, pp. : 661-668

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Abstract

A new class of thermoset polymers was synthesized based on agrochemical renewable cardanol-a by-product of cashew nut industry. A solventless synthesis of bisbenzoxazine monomers based on bisphenol-A (b) and aniline (abbreviated as Bzb-A) and cardanol (c) with diamines namely bis-(4-(4-aminophenoxy)phenyl)ether (HP), bis-(3-(4-aminophenoxy)phenyl)ether (HM), 4,4′-diaminodiphenylsulphone (DDS) and 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BA) was carried out. The benzoxazine monomers (Bzc-HP, Bzc-HM, Bzc-DDS and Bzc-BA) were characterized by ¹H-NMR and FTIR spectroscopy. The curing exotherm depended on the structure of the monomers. The onset curing temperature (T _o) was lowest for Bzb-A (460 K) and highest in Bzc-HM (518 K). The decomposition temperature for 5% mass loss (T _5%) of resins followed the order PBzb-A < PBzc-DDS < PBzc-BA < PBzc-HM ≍ PBzc-HP. The materials showed their potential as adhesives. Lap shear strength on steel plates followed the trend PBzc-DDS < PBzc-HM < PBzc-BA < PBzc-HP.