Synthesis of DOPO-g-GPTS modified wood fiber and its effects on the properties of composite phenolic foams

A novel 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) grafted γ-glycidoxy propyl trimethoxy silane (GPTS) was synthesized and introduced on the surface of wood fiber (WF). DOPO-g-GPTS modified wood fiber (DGMWF) was then used to prepare DGMWF composite phenolic foam (DGMWFCPF). The structures of DOPO-g-GPTS were verified by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H-NMR). The structure of DGMWF was confirmed by FT-IR. The crystallinity of DGMWF was slightly increased, however, the diffraction peak positions were basically unchanged. In addition, the thermal stability was dramatically improved, and T _i and T_max increased by 26.6 and 33.2 °C respectively. The carbon residue (800 °C) was reduced by 3.65%. By comparison with pure phenolic foam, the mechanical properties, flame retardancy of DGMWFCPF were increased. No significant changes were observed for the microstructure. By comprehensive analysis, the interfacial compatibility was significantly improved between DGMWF and phenolic resin. The suitable dosage of DGMWF was 4–6%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46917.