Preparation And Application Of Biomass-based Flame Retardant Polyether Olyols

Polyurethane(PU)is a class of high-performance polymer synthesized from polyols and isocyanates.The polymer has been used in various fields depending on type and property.Traditional PU materials are derived from petroleum and are difficult to degrade or recycle after use,causing serious environmental problems.With the development of human society,the demand for polyurethane materials is increasing and petroleum resources are depleting.Therefore,renewable biomass resources have gradually come into people’s mind.Preparing renewable polyurethane materials from bio-based polyol has become a research focus.In this paper,corn starch is used as raw material and boron phosphate with flame retardant function is used as a catalyst to prepare flame retardant polyether polyol,from which flame-retardant rigid polyurethane foam is prepared.The specific experimental results are as follows:(1)Preparation of flame retardant polyether polyols by catalytic liquefaction of starch.The effects of reaction temperature,catalyst dosage,reaction time,liquid to solid ratio,and solvent ratio on the liquefaction yield and hydroxyl value were investigated by a single factor experimental design.The optimal liquefaction conditions are as follows:reaction temperature 140℃,catalyst dosage 3%of the total mass,reaction time 3 h,liquid to solid ratio 4:1,solvent ratio(polyethylene glycol 400:glycerol)=7:3,the maximum liquefaction yield of corn starch was 97.8%,a hydroxyl value of the product was 487.4 mg KOH/g,viscosity was 680±20 m Pa·s,water content was 0.08%,the acid value was 5.33 mg KOH/g,and molecular weight was 303.(2)Influence of process parameters on foam properties of flame-retardant polyurethane foam prepared by partial or total replacement of petroleum-based polyols with starch-based polyols was investigated.The ratio of liquefied polyol to polyether 303 on the properties of the foam was determined.When 60%liquefied products substitution was used,the foam had the maximal comprehensive performance with a limiting oxygen index of 24.7%,compressive strength of 296.8 k Pa,the apparent density of 58.2 kg/m~3,the thermal conductivity of 0.022 W/(m·K),and better flame retardancy was demonstrated.(3)The mechanical properties and limiting oxygen index of the foam were soundly improved by adding inorganic filler solid sodium silicate and graphene to the foaming system with 15%sodium silicate addition.The foam has the best comprehensive performance with a limiting oxygen index of 28.2%,compressive strength of 387.2 k Pa,and apparent density of 59.7 kg/m~3;When 3%graphene is added,the foam has the best comprehensive performance with a limiting oxygen index of 27.1%,compressive strength of 356.5 k Pa,the apparent density of 59.5 kg/m~3.The foam achieved self-extinguishing flame retardant performance.