| Rigid polyurethane foam (RPUF) is the best thermal insulation material with its optimalinsulating performance. However, with the increasing depletion of fossil resources and theimprovement in awareness of the environmental protection, researches on natural renewableresources replacing petrochemicals has attracted more and more attention. Cardanol and castoroil are important feedstock for the renewable production of flame-retardant polyurethane foamin biomass resources. Less expensive cardanol and castor oil can replace phenol fossilresources to formulate polyurethane foam thermal insulation material, which has significantpromotion to make biomass resource advantage, improve ecological environment and developpolyurethane material industry.In the present work, a series of novel polyether, polyester polyols were explored from thebiomass resources cardanol and castor oil by Mannich reaction, alkyl oxidation reaction,alcoholysis, esterification reaction and so on. Further, flame-retardant RPUFs with goodphysical and thermal performance were obtained. The main purpose of the thesis was to revealeffect of structure of biomass-based polyols on properties of rigid RPUF. The main researchcontents and conclusions were summarized as follows.1. Cardanol-based Mannich bases with different structures and properties weresynthesized from cardanol, paraformaldehyde, diethanolamine and melamine by Mannichreaction. The intermediate and products were characterized and tested using FT IR,1H NMR,GPC, GC-MS and TG. The mechanism of first step aldehyde and amine adduct was confirmedin Mannich reaction. The main factors affecting the structure and properties of productcomposition, viscosity, hydroxyl value and molecular weight of cardanol-based Mannichpolyether polyols were discussed, such as reaction temperature, amount of cardanol, cardanolalternative of phenol, melamine and so on.2. Cardanol-based Mannich polyether polyols were synthesized by initiator cardanol-based Mannich bases and propylene oxide through alkoxylation reaction, which havesome advantages such as low viscosity, adjustable functionality and containing flame retardantgroups.The structure and properties of Mannich polyether polyol were determined by studyingthe initiator structure, catalyst type, quality of propylene oxide and other factors. The optimumprocess conditions for cardanol-based Mannich polyether polyols were obtained throughtesting hydroxyl value, viscosity and characterizing FT IR, TG, GPC and1H NMR The smallerthe amount of cardanol, the lower the amount of phenol substitution, the more the amount ofmelamine added, the viscosity and hydroxyl value of the polyol larger and the thermal stabilityhigher. The cardanol-based Mannich polyether polyols suitable for preparing flame-retardantRPUF were chosen.3Castor oil-based polyether polyols were synthesized using small molecule polyols(ethylene glycol, glycerol and pentaerythritol), castor oil and phthalic anhydride as rawmaterial by alcoholysis and esterification reaction, which have good compatibility with otherpolyester and polyether polyols and in favor of combination polyols system of long-termstorage. The effects of small molecule polyol species and reaction time on hydroxyl value,viscosity and molecular weight of castor oil-based alcoholysis products were investigated. Themonoglyceride and diglyceride content and conversion rate significantly reduced, the hydroxylvalue increased with increasing functionality of small molecule polyols. Compared to thealcoholysis of castor oil, the monoester and diester content of castor oil-based polyester polyolssubstantially reduced, and the primary hydroxyl groups relatively content of was higher. Thethermal stability of castor oil-based polyester polyols were higher than the commercialpolyester polyol PS-3152because of the high thermal stability of castor oil fatty acid chain.4A series of composite flame-retardant RPUFs were prepared with cardanol-basedMannich polyether polyols, blowing agent, surfactant, flame retardants and isocyanate. Theresults showed that the higher foaming behavior of cardanol-based Mannich polyether polyolwith different amount of cardanol were almost same. The higher cardanol amount of phenolsubstitution, the better miscible with blowing agent cyclopentane, the smaller compressive strength and thermal conductivity, the lower thermal stability, residue char yield and limitiedoxygen index, the higher heat release and smoke emission of the RPUFs, and the moreopenings and cracking carbon layer after combustion. The properties of flame retardant RPUFsamples from different amounts of melamine-based Mannich polyether polyols addinghalogen-free flame retardants expanded graphite (EG), ammonium polyphosphate (APP) andDiethyl ethylphosphonate (DEEP) were analyzed. It was found that the higher the amount ofmelamine replacement foam, the greater the relative compressive strength, thermalconductivity, and the limitied oxygen index, the higher thermal stability and residue char yield.For EG filled RPUFs, the heat release peak, the total heat release and amount of smoke releaseparameters were significantly decreased, the mechanical properties, thermal stability, limitiedoxygen index, the yield and dense continuity of the char layer after combustion significantlyenhanced. EG was better in improving limited oxygen index, smoke production and releaseareas than DEEP and APP. Compared to non-flame retardant PUF, the curing times and thermalconductivities of RPUFs adding flame retardants DEEP, APP and EG were slightly increased.The flame retardant properties of the RPUF samples increased with the amount of the sameflame retardant. The solid flame retardants APP and EG were better in increasing themechanical properties, thermal stability and lowering ratio of CO/CO2than the liquid flameretardant DEEP. And, the phosphorus flame retardants APP and DEEP were better in reducingheat release rate than EG, the different flame retardants compound in the density and continuityof the carbon layer better than single flame.5A series of castor oil-based flame retardant RPUFs were prepared from castor oil-basedpolyols, isocyanate, blowing agent, surfactant and flame retardant APP, and commercialpolyester polyol PS-3152were compared. The results showed that the foaming activities ofcastor oil-based polyester polyols were higher than alcoholysis products, the correspondingfoam compressive strength and thermal stability better. Compared to PS-3152based PUF, thefoaming activity of the oxygen index and the combustion performance of PUFs prepared fromcastor oil-based polyester polyol were quite, and higher thermal stability and lower thermal conductivity. This is mainly due to the introduction of benzene ring, improving the hardsegment content and residue char yield. The flame retardant properties of APP-filled PUFssignificantly improved with the limited oxygen index25.9-26.8. |
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