Synthesis And Properties Of Furfuralcohol Resin Based Polyurethane:Flame Retardancy And Thermal Insulation

Polyurethane(PU)is applied in foam plastics and insulation coatings widely.Recently,the research of PU focus on the flame retardancy,thermal insulation and environmental friendly.Furfuryl alcohol(FA)resin has high carbonization rate and macromolecular aromatic heterocycles.FA resin can be used as a synergistic carbonizing agent in the compound system of PU by introducing functional groups or flame-retardant elements.As a layered compound,hydrotalcite-like(HTLCs)have good adsorption,flame retardancy and smoke suppression properties,but poor compatibility with flame retardants.To enhance compatibility,HTLCs can be modified by means of in-situ intercalation synthesis.This paper has carried out the following work around the above issues:(1)Flame retardancy of modified furfuryl alcohol resin.Intercalated hydrotalcite was prepared by in-situ intercalation with phosphoric acid modified furfuryl alcohol resin.The products were characterized by thermogravimetric analysis(TG),X-ray diffraction(XRD),FTIR(FT-IRT),specific surface area(BET)analysis and elemental analysis(EDS).The specific surface area of intercalated hydrotalcite is as high as 52.64 m~2/g after calcination,indicating that intercalated HTLCs has good flame retardancy and smoke suppression.(2)Flame-retarding synergistic effect between PU,furfuryl alcohol resin and ammonium polyphosphate(APP).The samples were tested by limiting oxygen index(LOI),vertical combustion(UL-94),mechanical properties,conecalorimetry(CONE),TG,FTIR and scanning electron microscope(SEM-EDS).Results show that,as the weight ratio of polyfurfuryl alcohol:ammonium polyphosphate:polyurethane is 20:25:55,the LOI of polymer composite is 31.8%and the vertical combustion level is V-0.The maximum heat release rate(PHRR)of PU/FA/APP decreased from 119.5 kw/m~2(PU)to 51.4 kw/m~2.The decrease is as high as 56.9%.The maximum smoke release rate(PSRR)fell from 0.55m~2/s to 0.24 m~2/s by 56.3%decrease.Results of mechanical test show that,the compression strength of PU/FA/APP is 1.26 Mpa.The thermal conductivity coefficient of polymer composites is 0.0195 w/m·k.The flame-retarding mechanism of PU/FA/APP was discussed by means of FT-IR and SEM.It was concluded that the modified furfuryl alcohol resin had good charring property and synergistic effect with APP.(3)Synergistic effect of modified furfuryl alcohol intercalated HLTCs with APP.PU material is prepared by one-step water foaming method.As the mass ratio of HTLCs/APP/PU is 9/22.5/68.5,the LOI of polymer composite reaches a maximum of31.3%and vertical combustion test reached V-0 level.Also,the compressive strength of sample was 0.85 MPa,thermal conductivity was 0.0194 w/m.k,and the rate of residual heat loss was 45%.These show that,PU has a good combination of flame retardant,thermal insulation and smoke suppression because of its small holes of residue and dense carbon layer after burn.