Molecular Design Of Phosphazene Polyurethane And Its Flame Retardant Properties For Tpu

The phosphazene compound is rich in phosphorus and nitrogen and has a unique six-membered ring structure with excellent flame retardancy and thermal stability.However,there are few phosphazene flame retardants on the market,and most of them are small molecule flame retardants.In this paper,hexachlorocyclotriphosphazene was used as the main raw material to synthesize two kinds of polymer flame retardants containing phosphazene ring for TPU flame retardant,respectively,phosphazene polyurethane P-EIPU and phosphazene polyurethane P-PMPU,and their structure and performance were characterized and studied.At the same time as green high-efficiency flame retardant,the flame retardant is well compatible with the material and does not affect the mechanical properties of the material.This article mainly includes the following work:1.Three hydroxyl-containing cyclophosphazene derivatives were prepared,which were 2,4-dihydroxyethoxy-2,4,6,6-tetraethoxycyclophosphazene(DHETECP),2,4,6-trihydroxyethoxy-2,4,6-triethoxycyclophosphazene(THETECP)and 2,4,6-trihydroxyethoxy-2,4,6-triphenyloxycyclophosphazene(THETPCP).The cyclophosphazene derivative was characterized by IR,31P-NMR,1H-NMR.To synthesize a polymer flame retardant containing a phosphazene ring,a hydroxyl functional group is introduced on the phosphazene ring.2.The polymer flame retardant P-EIPU was synthesized by self-made polyhydroxycyclophosphazene derivative DHETECP and THETECP and isophorone diisocyanate.The structure was characterized by IR,31P-NMR and GPC.The TG test indicated that P-EIPU has good thermal properties.The flame retardant modification of the TPU was carried out.When the flame retardant was added in an amount of 15%,the flame retardant grade of the TPU was V-0,and the LOI value was 27.3%.But at this time,the mechanical properties of flame retardant TPU decreased by nearly 50%.3.The self-made phenoxy-containing THETPCP cyclophosphazene derivative was reacted with diphenylmethyl diisocyanate(MDI)to synthesize a polymer flame retardant P-PMPU having a structure similar to that of TPU.The structure was characterized by IR,31P-NMR and GPC.The flame retardant modification of TPU is carried out.When the amount of P-PMPU is 5%,the LOI value is 27.7%.The TPU droplets are not solved,but they are self-extinguishing materials,and have little effect on the mechanical properties of TPU,within 10%.