Structure of hexagonal boron nitride (h-BN) is similar to that of graphite before functionalization and exfoliation.

A biobased flame retardant toughening agent, phosphaphenanthrene groups-containing triscardanyl phosphate (PTCP), was successfully synthesized via debydrochlorination, epoxidation and ring opening reaction from renewable resource cardanol. The chemical structure of PTCP was confirmed by the proton and phosphorus nuclear magnetic resonance. Epoxy resins (EPs) with different contents of PTCP were prepared through a simple mixing method. Thermogravimetric analysis results indicated that the earlier degradation of PTCP catalyzed the char formation of epoxy resins that was beneficial to protecting underlying polymers from further decomposition. The flame retardant properties were enhanced with the increase of the PTCP content. The EP composite containing 30 wt % PTCP showed a limiting oxygen index of 30.5%. Meanwhile, its peak heat release rate, total heat release and average effective heat of combustion values were decreased by 50%, 27% and 32%, respectively, in comparison to those of neat EP. The enhanced flame retardant behavior was attributed to the improved quality of char residue, which effectively inhibited the flammable volatiles, oxygen and heat transfer between degradation zone and flame zone. The impact strength was increased to 19.14 kJ/m2 for EP/PTCP-30% composite from 14.85 kJ/m2 for neat EP, indicating the toughening effect of PTCP on EP. The findings in this study demonstrated that PTCP could be used as a promising flame retardant toughening agent for epoxy resins to overcome their drawbacks of intrinsic brittle and high flammability.

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Various metal-modified HMOR catalysts for the carbonylation of dimethyl ether (DME) were prepared by ion exchange with Cu, Ni, Co, Zn, or Ag. The catalysts were characterized by the Brunauer−Emmett−Teller method, X-ray diffraction measurements, transmission electron microscopy, X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy, temperature-programmed desorption of ammonia, and temperature-programmed oxidation. We found that the pore structure of mordenite (HMOR) was well maintained and that the metal species were highly dispersed on the zeolite. On HMOR subjected to ion exchange with Cu, Ni, Co, or Zn, the metal ions were mainly at the zeolite exchange sites with some corresponding metal oxides. Some Brønsted acid sites were converted to Lewis acid sites, and some strong acid sites were formed together. HMOR modified with Cu, Ni, or Co showed good catalytic performance, with Cu/HMOR exhibiting the highest performance. DME conversion and methyl acetate selectivity were close to 100% under the optimum reaction conditions, which is attributed to the joint participation of Brønsted acid sites contributing to DME conversion and metal Lewis acid sites contributing to CO binding, along with the appropriate coordination structure. Modification with Cu not only improved the catalytic activity, but also suppressed carbon deposition and extended the catalyst lifetime.

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