Study On Preparation Of Polyaminocyclotriphosphazene Modified With Phenoxy And Phenyl And Its Flame Retardance

Polyaminocyclotriphosphazene(PHACTPA) is a kind of novel phosphazene flame retardant which had a good flame retardancy in polyolefins and epoxy resin. But the hygroscopeicity of PHACTPA is stronger and the water solubility is higher. The thermal stability is not ideal. Therefore, in this paper, the modification of PHACTPA with phenoxy and phenyl and their flame retardancy in cured epoxy resin were studied.Using hexachlorocyclotriphosphazene(TCP), phenol, potassium hydroxide and ammonia as raw materials, PPHACTPA-1 and PPHACTPA-2 were prapared by the condensation, ammoniation and polycondensation. The optimum conditions of the preparation of PPHACTPA-1 and PPHACTPA-2 were respectively as follows: PPHACTPA-1: n(TCP): n(phenol): n(KOH) =1:1.1:1.34, the condensation temperature being 85℃, the condensation time being 5h, the ammoniation temperature being 0℃, the ammoniation time being 24 h, the polycondensation temperature being 180℃, the polycondensation time being 20 min; PPHACTPA-2: n(TCP): n(phenol): n(KOH) = 1:2.2:2.68, the condensation temperature being 95℃, the condensation time being 7h, the ammoniation temperature being 0℃, the ammoniation time being 24 h, the polycondensation temperature being 180 ℃, the polycondensation time being 20 min.Using TCP, aniline and ammonia as raw materials, BPHACTPA was prapared by the condensation, ammoniation and polycondensation. The optimum conditions of the preparation of BPHACTPA were as follows: n(TCP): n(aniline):n(triethylamine) =1:1.2:1.1,w(TCP):w(chlorophenyl) =1:3.5, the condensation temperature being 90℃, the condensation time being 8h. the ammoniation temperature being 0℃, the ammoniation time being 24 h, the polycondensation temperature being 180 ℃, the polycondensation time being 20 min.The thermal stability of the product were improved, and the hygroscopeicity and the water-solubility were reduced significantly by the modification with phenoxy and phenyl. And the hygroscopeicity and the water-solubility of product became lower, thermal stability of the product became better with increasing phenoxy groups.PPHACTPA-1, PPHACTPA-2 and BPHACTPA had poor flame retardancy for E-44/DG593, but PPHACTPA-1 and PHACTPA had a good flame retardancy in E-44/NX-2003 and PPHACTPA-1 effect was better, which indicated that the flame retardancy were related to the structures of retardants and polymers. The LOI of E-44/ NX-2003 with 25 wt.% dosage of PPHACTPA-1 and PHACTPA were both 26.5%, and the vertical burning level were respectively FV-0 and FV-1. Compared with E-44/ NX-2003, the PHRR of 30%PPHACTPA-1/E-44/NX-2003 and 30%PHACTPA/ E-44/ NX-2003 decreased by 90% and 75% respectively, and the THR decreased by 17% and 30% respectively, the MMLR decreased by 38.3% and 33.3% respectively. Though the results of LOI and the vertical burning test indicated PPHACTPA-2 and BPHACTPA had poor flame retardancy in E-44/NX-2003, the cone calorimetry test showed that they had a better retardancy in E-44/NX-2003.Thermogravimetric analysis showed both PHACTPA and PPHACTPA-1 reduced the thermal stability of the E-44/NX-2003, but the influence of PPHACTPA-1 was less.PHACTPA and PPHACTPA-1 played the role of flame retardance mainly by condensed phase mechanism. They were decomposed into phosphoric acid compounds in the combustion process, which promoted charing of E-44/NX-2003. Meanwile, inert gases released from the decomposetion of E-44/NX-2003 foamed the carbon layer. The formed intumescent layer resulted in the barrier effect on heat, air and further decomposition of epoxy system.While the residual rate was maximum for BPHACTPA/E-44/NX-2003, but its effect of flame retardancy was not best, which indicated that the flame retardancy was associated with the structure of carbon layer.