Preparation And Properties Of Loe Smoke Flame Retardant Polyurethane Foam

Polyurethane Foam(PUF)is a polymer material with a porous structure,which has the characteristics of light weight,low thermal conductivity,high specific strength,excellent stability and high bonding strength.Coupled with its diversity and controllability,PUF has a wide range of applications in building thermal insulation materials,aerospace,various waterproof pipes and transportation.However,due to the problem of its own structure,PUF is flammable in case of fire,and its burning speed is fast,which limits its wide application.Most of the flame retardants with better flame retardant effect are additive flame retardants containing nitrogen and phosphorus,but such flame retardants often lead to poor mechanical properties of materials and are used in large amounts.In this paper,a silicon-containing reactive flame retardant was synthesized,and then compounded with additive flame retardant dimethyl methyl phosphonate(DMMP)and expandable graphite(EG)to improve the flame retardant properties of PUF.Polyether modified silicone oil(PESO)was synthesized by hydrosilation reaction between polysiloxane and allyl polyether.The structure of PESO was characterized by combining infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy.The endpoint of the reaction was determined by observing the properties of the product,and the optimal reaction conditions obtained were as follows: the molar ratio of Si-H and C=C was 1/1.2,the reaction temperature was 110℃,the platinum catalyst was 5ppm,and the reaction time was 3h.Then,PESO is uniformly mixed with polyether polyol,dibutyltin dilaurate,triethanolamine and foaming agent as a white material,and is uniformly mixed with polyphenyl polymethylene polyisocyanate(PAPI)to prepare PUF.The effects of each component content on the PUF cell structure,water absorption,compressive strength,apparent density,limiting oxygen index,carbon residue morphology and carbon residue rate were studied.The optimal formula is obtained as follows: 20 parts of PESO,80 parts of polyether polyol,0.67 parts of dibutyltin dilaurate,1.34 parts of triethanolamine,15 parts of HCFC-141 b,2 parts of water,and 150 parts of PAPI.The cell structure is relatively stable and the comprehensive performance is the best.Add the additive flame retardants DMMP and EG to the above system.The effects of DMMP-EG(1/2)addition amount on the compressive strength,apparent density,pore structure,carbon layer morphology,LOI and smoke density of PUF were studied,and the thermal degradation process of the PUF flame retardant system was analyzed by thermogravimetric analysis.The results show that when the mass ratio of PESO and polyether polyol is 2/8 and the addition amount of DMMP-EG(1/2)is 30%,the LOI of PUF/DMMP-EG can reach 31.8%,and the smoke density grade is 18.3%.