A halogen‐free intumescent flame retardant expandable graphite composite (EG), with an initial expansion temperature of 202°C and expansion volume of 517 mL g−1, was successfully prepared via a facile two‐step intercalation method, i.e. using KMnO4 as oxidant and H2SO4, Na2SiO3·9H2O as intercalators. The prepared EG flame retardant was characterized by field emission scanning electron microscope, X‐ray diffraction spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. Furthermore, flame retardancy and thermal property of various ethylene vinyl acetate copolymer (EVA) composites, including EVA/EG and EVA/EG/APP (ammonium polyphosphate) specimens, were studied through limiting oxygen index instrument (LOI), vertical combustion UL‐94 rating, thermal gravimetric and differential thermal analysis. The results indicate that the EVA/EG and EVA/EG/APP composites exhibit a better flame retardancy. Addition of EG at a mass fraction of 30% leads LOI of 70EVA/30EG composite improved to 28.7%. Even more, the synergistic effect between EG and APP improves the LOI of 70EVA/10APP /20EG composite to 30.7%. This synergistic efficiency is attributed to the formation of compact and stable layer‐structure, and the prepared EG can make EVA composite reach the UL‐94 level of V‐0. POLYM. COMPOS., 36:1407–1416, 2015. © 2014 Society of Plastics Engineers

A titanium dioxide modified expendable graphite (EGT) was prepared and characterized. The synergistic effect between EGT and ammonium polyphosphate (APP) on the combustion characteristics and thermal stability of rigid polyurethane foam (RPUF) were investigated through limiting oxygen index (LOI), vertical‐combustion, microscale combustion calorimeter tests, and thermogravimetric/differential thermal gravimetric (TG/DTG) analysis. Results showed that EGT modified RPUF presented better thermal stability and flame retardancy than the normal expandable graphite (EG) modified RPUF. Addition of EGT improved the LOI value of 80RPUF/20EGT from 19.0% to 26.9%. Furthermore, the combination of EGT and APP caused the 80RPUF/10APP/10EGT to exhibit a LOI value of 27.8%, a vertical burning level of V‐0 and a total heat release of 16.5 kJ g−1. The research gave a body of evidence for synergistic performance between EGT and APP, and the effect of condensed phase mechanism was believed to be the main reason for such synergistic effect. POLYM. ENG. SCI., 58:2008–2018, 2018. © 2018 Society of Plastics Engineers

A borate-modified expandable graphite (written as MEG) was prepared through one step intercalating reaction of natural graphite, using KMnO 4 as oxidant, H 2 SO 4 and sodium tetraborate as intercalator and assistant intercalator, respectively. The dilatability, structure, element contents, thermal stability, and flame retardancy on acrylonitrile-butadiene-styrene (ABS) were investigated. Compared with the normal expandable graphite (written as EG, which was prepared with only H 2 SO 4 as intercalator), the results show that MEG exhibits higher expandable property, thermal stability and flame retardancy on ABS. The EDS, FT-IR, and XRD results reveal that borate has been inserted into graphite layers. With the addition of MEG or EG at a 30 wt%, LOI of 70ABS/30MEG composite improved to 27.9%, 2.2% higher than that of 70ABS/30EG. Moreover, the synergistic effect between MEG and traditional intumescent flame retardant (IFR, consists of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) with a mass ratio of 7.5:4.5:3.0) improves the LOI of 70ABS/15MEG/15IFR composite to 32.6%, and the UL-94 level reaches V-0. This synergistic efficiency is attributed to the formation of continuous and compact residual char. Addition of MEG together with IFR changes the ABS pyrolysis behavior, and there is not only physical synergy, but also chemical reaction. POLYM. COMPOS., 37:2673-2683, 2016.

To promote the performance of fast-growing poplar wood for furniture applications, this study proposes and investigates the feasibility of modifying fast-growing poplar wood with a urea-formaldehyde resin impregnating agent by adding nano-SiO2 as a way to improve its physical and mechanical properties. By observing the solubility of nano-SiO2 addition in urea-formaldehyde resin, determine the optimal ratio of nano-SiO2 addition to the solid content of the urea-formaldehyde resin solution. After the fast-growing poplar specimens were treated with nano-SiO2/UF resin, the water absorption, wet swelling, dry shrinkage, nail grip, flexural strength, and modulus of flexural elasticity of the fast-growing poplar specimens were compared and analyzed to determine the effect of impregnation modification and the optimal impregnation ratio. The results showed that the physical and mechanical properties of fast-growing poplar wood were significantly improved by impregnating the fast-growing poplar wood with urea-formaldehyde resin with SiO2, and the impregnation modification was beneficial to reducing the wet swelling and dry shrinkage of poplar wood, increasing its dimensional stability, improve the grip nail strength, and increase the flexural strength and flexural modulus of elasticity with the increase in nano-SiO2 concentration.

In this research, the individual influence and synergistic behavior between titanium dioxide modified expendable graphite and ammonium polyphosphate on combustion behavior and physicomechanical properties of rigid polyurethane foam (RPUF) were investigated. Combustion behavior was evaluated by limiting oxygen index, and vertical-combustion tests. Thermal stability was studied via thermogravimetric/differential thermal gravimetric (TG/DTG) analysis. Results showed that the modified expendable graphite presented better thermal stability and flame retardancy for RPUF than the normal expandable graphite. Furthermore, the combination of the modified expendable graphite and ammonium polyphosphate with the mass ratio of 1 : 1 caused the RPUF to exhibit better flame retardancy, compression strength and high temperature thermal stability. Especially, the compression strength of this polymer composite sharply increased by 52.4 % over RPUF.