A novel schiff base (BD) containing nitrogen and silicone
was prepared,
and a phosphorus–nitrogen silicone flame retardant (BDD) was
synthesized based on BD and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide
(DOPO). It was found that the structure of BD changed continuously
during the heating process and formed a self-cross-linking network
structure at about 400 °C, while the porous fluffy shape was
formed by BDD as an intumescent flame retardant. The char yields of
BD and BDD at 700 °C were 62% and 38% in nitrogen, respectively.
The obtained BD and BDD were blended to enhance the flame retardancy
of cellulose membranes via a cooperative effect, and the properties
were significantly achieved, which can be proved by the limit oxygen
index (LOI), cone calorimeter test, and thermogravimetric results.
The results showed that the incorporation of 25 wt % BD brought a
29% LOI, and the peak heat release rate (PHRR) was reduced to 732.2
kW/m2, in contrast with an LOI of 18% and PHRR of 1050.1
kW/m2 for pure cellulose. The addition of 25% BDD increased
the LOI to 27% and decreased the PHRR to 644.9 kW/m2. The
improved flame-retardant performance for cellulose membranes was primarily
assigned to the synergistic effect from the physical barriers of self-cross-linking
properties in the condensed phase and capturing or dilution of combustible
gases by free radicals. This suggested that wielding BD as a self-crossing
monomer and applying BDD as an intumescent flame retardant to achieve
effective results on fire suppression had great potential for fire-safe
cellulose.
Termites are among the few arthropods that emit methane to the atmosphere, which is a significant source of global greenhouse gas due to their huge biomass on earth. In this study, phylogenetic diversity of Archaea of five termite species from different lineages were analyzed based on 16S rRNA genes. Archaea associated with wood-feeding lower termite, R. chinensis were exclusively Methanobrevibacter in the order Methanobacteriales. This type of methanogens was also found in Nasutitermes sp. and Microcerotermes sp. but not in the fungus-cultivating termites, Odontotermes formosanus and Macrotermes barneyi, which harbor Archaea of the order Methanoplasmatales and Methanosarcinales in their guts. Archaeal diversity of wood-feeding higher termites was higher than wood-feeding lower termites. The highest archaeal diversity was found in Nasutitermes sp. In addition to methanogens affiliated with the orders Methanobacteriales, Methanomicrobiales, and Methanoplasmatales, 37% of archaeal clones were affiliated with non-methanogenic Thaumarchaeota. The results of this study will be significant for further understanding of symbiotic relationship between intestinal microbiota and termites.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.