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Intumescent flame retardant poly(butylene succinate) (IFRPBS) composites with enhanced fire resistance were prepared using graphene as synergist. The morphology of fracture surfaces of the composites was investigated by scanning electron microscopy (SEM). The limiting oxygen index (LOI) values increased from 23.0 for the pure PBS to 31.0 for IFRPBS with 20 wt % IFR loading. The addition of graphene further improved the LOI values of the composites and exhibited excellent antidripping properties. The UL-94 V0 materials were obtained with a formulation of 18 wt % IFR and 2 wt % graphene. MFI measurement indicated that the presence of graphene significantly enhanced the melt viscosity and restrained the melt dripping. The thermal degradation and gas products of IFRPBS/graphene systems were monitored by thermogravimetric analysis (TGA), real time Fourier transform infrared spectrometry (RTFTIR), and thermogravimetric analysis-Fourier transform infrared spectrometry (TG-FTIR). X-ray photoelectron spectroscopy (XPS) was utilized to explore the chemical components of the outer and inner char residues.

Simultaneous reduction and surface functionalization of graphene oxide (GO) was realized by simple refluxing of GO with octa-aminophenyl polyhedral oligomeric silsesquioxanes (OapPOSS) without the use of any reducing agents. The presence of OapPOSS made the hydrophilic GO hydrophobic, evidenced by the good dispersion of the OapPOSS-reduced GO (OapPOSS-rGO) in tetrahydrofuran solvent. The structure of OapPOSS-rGO was confirmed by XPS, FTIR and TEM. Morphologic study showed that, due to the good interfacial interaction between the functionalized graphene and epoxy, OapPOSS-rGO was dispersed well in the matrix. With the incorporation of 2.0 wt% of OapPOSS-rGO, the onset thermal degradation temperature of epoxy composite was significantly increased by 43 o C. Moreover, the peak heat release rate, total heat release and CO production rate values of OapPOSS-rGO/EP were significantly reduced by 49%, 37% and 58%, respectively, 2 compared to that of neat epoxy. This dramatically reduced the fire hazards were mainly attributed to the synergestic effect of OapPOSS-rGO: the adsorption and barrier effect of reduced graphene oxide inhibited the heat and gas release and promoted the formation of graphitized carbons, while OapPOSS improved the thermal oxidative resistance of the char layer.

J o u r n a l P r e -p r o o f  RH=95% induces less droplets suspended in air and more deposition fraction(85%-100%). Wet air, sitting at nonadjacent seats, supply to bus backward reduce infection risk. AbstractDroplet dispersion carrying viruses/bacteria in enclosed/crowded buses may induce transmissions of respiratory infectious diseases, but the influencing mechanisms have been rarely investigated. By conducting high-resolution CFD simulations, this paper investigates the evaporation and transport of solid-liquid mixed droplets (initial diameter 10μm and 50μm, solid to liquid ratio is 1:9) exhaled in a coach bus with 14 thermal manikins. Five air-conditioning supply directions and ambient relative humidity (RH=35% and 95%) are considered. Results show that ventilation effectiveness, RH and initial droplet size significantly influence droplet transmissions in coach bus. 50μm droplets tend to evaporate completely within 1.8s and 7s as RH=35% and 95% respectively, while 0.2s or less for 10μm droplets. Thus 10μm droplets diffuse farther with wider range than 50μm droplets which tend to deposit more on surfaces. Droplet dispersion pattern differs due to various interactions of gravity, ventilation flows and the upward thermal body plume. The fractions of droplets suspended in air, deposited on wall surfaces are quantified. This study implies high RH, backward supply direction and passengers sitting at nonadjacent seats can effectively reduce infection risk of droplet transmission in buses. Besides taking masks, regular cleaning is also recommended since 85%-100% of droplets deposit on object surfaces.J o u r n a l P r e -p r o o f