Fabrication and properties of hybrid Mo-CPF/P1B from cardanol

Abstract

A Mo-CPF/P₁B hybrid has been prepared from molybdenum modified cardanol phenolic resin (Mo-CPF) and cardanol benzoxazine with phosphorus (P₁B). Cardanol benzoxazine with phosphorus (P₁B) has been synthesized from cardanol-allylamine-based benzoxazine (BZc-a) and DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide). Cardanol phenolic resin modified with molybdenum (Mo-CPF) has been synthesized by reacting cardanol-based phenolic resin (CPF) with ammonium molybdate tetrahydrate at 150 °C, where the CPF was synthesized from cardanol and paraformaldehyde in the presence of sodium hydroxide at 65 °C. The synthesized CPF and Mo-CPF were characterized by ¹H-NMR and size exclusion chromatography (SEC). Mo-CPF was mixed with P₁B, and the mixtures were cured at 110 °C for 4 h and got the Mo-CPF/P₁B hybrid. The properties of the Mo-CPF/P₁B hybrid were investigated; the results demonstrated that the mechanical and thermal properties, together with flame retardance, were greatly improved. Dynamic Mechanical Analysis (DMA) measurement results indicated that CPF, Mo-CPF and Mo-CPF/P₁B could all sustain a large amount of stress and the elongations at break were different. DMA measurements suggested that the T_g of CPF, Mo-CPF and Mo-CPF/P₁B was 98 °C, 170 °C and 131 °C respectively. Mo-CPF/P₁B exhibited better flame retardance after conjugating with molybdenum and phosphorus. TGA results suggested that Mo-CPF/P₁B exhibited better thermal properties. Field emission electron microscopy (FE-SEM) suggested that molybdenum was randomly distributed in Mo-CPF and Mo-CPF/P₁B, and EDX indicated that molybdenum and phosphorus were randomly distributed in Mo-CPF/P₁B.