Research on the effect of the common flame retardant in reducing the flammability of the bitumen

The bituminous defect that the binder is flammable will bring road safety risk.Once it catches fires,large quantities of heat,smoke and poisonous gas are produced,released and spread quickly,which seriously hinder escape and rescue and harms heavily traffic safety.The common flame retardant system is used to modify the asphalt.Cone Calorimeter is adopted to evaluate the burning property of asphalt.The performance of the flame retardant is evaluated by limiting oxygen index and orthogonal design method.The paper analyzes the synergism of the asphalt and flame-retardant,and analyzes the effect of the flame on preventing the smoke to spread and demonstrates that the use of common flame retardants which is added into binder is good at reducing the flammability of the binder.This way can increase the safety of asphalt pavement when fire occurs in the tunnel.The study suggests that flame retardancy of asphalt can be evaluated by Limit Oxygen Index (LOI) and the flame retardancy property of asphalt has marked change according to the content of flame retardant.SB has perfect flame retardancy property,and ATH is better than MH in the effect of flame retardant.

Research on Alkaline Filler Flame-Retarded Asphalt Pavement

Used as flame returdant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame- retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained ; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel patement.

SYNTHESIS AND CHARACTERIZATION OF POLYBENZOXAZINE CONTAINING PHOSPHORUS

The novel benzoxazine monomer containing phosphorus has been synthesized based on multifianctional amine route from bis（4-aminophenyl）phenylphosphate, p-cresol and formaldehyde. Subsequently, the benzoxazine monomer was thermo-cured into polybenzoxazine containing phosphorus. The chemical structures were identified by nuclear magnetic resonance （NMR）, Fourier transform infrared spectroscopy （FT-IR）. The curing reaction was monitored by differential scanning calorimetry （DSC） and FT-IR. The thermal and flame-retardant properties of obtained polybenzoxazine were evaluated by dynamic mechanical thermal analysis （DMA）, thermal gravimetric analysis （TGA） and oxygen index meter, respectively. The results show that the novel polybenzoxazine has high limiting oxygen index （38.1） and glass transition temperature （232℃）.

OPTICALLY ACTIVE AND FLAME-RETARDANT POLY(AMIDE-IMIDE)S BASED ON PHOSPHINE OXIDE MOIETY AND N,N′-(PYROMELLITOYL)BIS-L-AMINO ACID IN THE MAIN CHAIN:SYNTHESIS AND CHARACTERIZATION

Six new optically active and flame-retardant poly（amide-imide）s PAls 5a-5f containing phosphine oxide moiety as a flame-retardant unit in the main chain were synthesized from direct polycondensation reaction of six chiral N,N＇-（pyromellitoyl）-bis-L-amino acid 3a-3f with bis（3-aminophenyl）phenyl phosphine oxide 4 in a medium consisting of N-methyl-2-pyrrolidone （NMP）, triphenyl phosphite （TPP）, calcium chloride （CaCl2） and pyridine. The polymerization reactions produced a series of optically active poly（amide-imide）s with good yield and good inherent viscosity of 0.34-0.70 dLg^-1. The resulted polymers were fully characterized by means of FTIR and ^1H-NMR spectroscopy, gel permeation chromatography （GPC）, elemental analyses, inherent viscosity and solubility tests. Thermal properties and flameretardant behavior of the PAIs 5a-5f were investigated using thermal gravimetric analysis （TGA and DTG） and limiting oxygen index （LOI）. Data obtained by thermal analysis （TGA and DTG） revealed that these polymers showed good thermal stability. Furthermore, high char yield in TGA and good LOI values indicated that the resulting polymers were capable of exhibiting good flame retardant properties. N,N＇-（pyromellitoyl）-bis-L-amino acids 3a-3f were prepared in quantitative yields by the condensation reaction of pyromellitic dianhydride （1,2,4,5-benzenetetracarboxylicacid-1,2,4,5-dianhydride） 1 with L-alanine 2a, L-valine 2b, L-leucine 2c, L-isoleucine 2d, L-phenyl alanine 2e and L-2-aminobutyric acid 2f in acetic acid solution.