Fubin Luo

Thermal degradation and flame retardancy of microencapsulated ammonium polyphosphate in rigid polyurethane foam

Abstract Microencapsulated ammonium polyphosphate MFAPP or VMFAPP with shell of melamine–formaldehyde or poly (vinyl alcohol)–melamine–formaldehyde resin was prepared by in situ polymerization, respectively. The flame-retardant performance of rigid polyurethane foam (PU) containing MFAPP or VMFAPP was analyzed by limiting oxygen index and UL-94 test. Thermal degradation behaviors of PUAPP, PUMFAPP and PUVMFAPP were studied using TG and TG–FTIR. Above results indicated that VMFAPP and MFAPP have better water resistance and flame retardancy compared with ammonium polyphosphate (APP) in PU composites. Flame-retardant properties of PUMFAPP and PUVMFAPP composites were rarely changed after hot water treatment. Due to better compatibility and the presence of active groups on the surface of APP, microencapsulation demonstrated a positive effect on the mechanical property of PU composites.

Effect of cellulose whisker and ammonium polyphosphate on thermal properties and flammability performance of rigid polyurethane foam

AbstractCellulose whisker (CW) is employed as a novel carbonization agent to build green and efficient intumescent flame retardant (CWAPP) with ammonium polyphosphate (APP). Due to the presence of CW, CWAPP exhibits more excellent flame retardancy compared with APP in rigid polyurethane foam (PU). PU-added CWAPP (PU/CWAPP) obtains higher LOI value than that with the same loading of APP. Results also indicate that CWAPP have better water resistance compared with APP in PU. Flame-retardant property of PU/APP is decreased remarkably after soaked in hot water. By comparison, that of PU/CWAPP is rarely changed after the same treatment. CWAPP also shows a positive effect on the mechanical property in PU, and compression strength of PU/CWAPP is higher than that of PU/APP with the same content of flame retardant.

Green reduction of graphene oxide by polydopamine to a construct flexible film: superior flame retardancy and high thermal conductivity

Inspired by mussels, dopamine (DOPA) was used as a green reducing agent for graphene oxide (GO) to prepare a superior flame retardant and high thermal conductive flexible film. The self-polymerization of dopamine occurred on the surface of GO nanosheets, accompanied by the reduction of GO. As the solvent was gradually removed, the reduced graphene sheets covered by polydopamine formed a layer-by-layer stacked film, where polydopamine acted as a linkage filled in the interlayer space. Herein, the experimental results indicated that the tensile strength of the constructed graphene/polydopamine composites film (GPF) was as high as 25 MPa. The in-plane thermal conductivity of this prepared film was 13.42 W m−1 K−1, whereas that in the cross-plane direction was 0.69 W m−1 K−1. The high anisotropy of the thermal conductivity was verified to be due to the high alignment of reduced graphene. Fire experiments showed that the GPF could effectively prevent flame spreading and propagation without ignition, and the heat release rate (HRR) curve showed that the GPF had no heat release below 500 °C. The peak HRR is only 40 W g−1 at 528 °C, whereas that of GO is 360 W g−1 at 165 °C. This phenomenon demonstrates that the GPF has excellent flame retardancy.

Synthesis and Characterization of a Lateral Phthalonitrile Functionalized Main-Chain Polybenzoxazine Precursor

A lateral phthalonitrile functionalized main-chain polybenzoxazine precursor has been successfully synthesized. The structure was characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FTIR). The formation of benzoxazine rings were confirmed by the characteristic resonances observed at about 4.55 (C-CH2-N) and 5.30 ppm (N-CH2-O) and the absorbance at 950 cm-1 of benzene attached with an oxazine ring. The curing behavior was monitored by differential scanning calorimetry (DSC) and in situ FTIR. The completion of polymerization was proved by the disappearance of the band located at 950 cm-1 in FTIR. Thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the results indicated that the thermal stability of the cured polymer gained significant improvement than that without phthalonitrile functionalization.