Study On The Preparation And Properties Of Tung Oil-Based Flame Retardant Polyurethane Foam

The unique structural and mechanical properties of polyurethane?PU?polymers have led to their wide-spread application in material products such as building insulation,domestic mattresses,furniture,adhesives,leathers and various biomedical products.Polyurethane foam is one of the best heat insulation materials.Using renewable natural biomass resources to replace fossil resources to prepare polyurethane foam is one of hotspots at home and abroad.Tung oil is a special resource of our country,it has been widely grown in China's Yunnan Province,Henan Province,Hunan and Hubei provinces.Further processing of tung oil,and the deep processing and reuse of coproduct of tung oil have great potential value.This paper used tung oil?TO?as raw material,obtain tung oil-based flame retardant polyols?TOBP?through transesterification,epoxidation and ring opening reaction.And made it combined with isocyanate?PAPI?to prepared tung oil-based flame retardant polyurethane foam?TO-RPUF?.A variety of analysis method were used to characterize the structure feature and properties of catalyst and products.1.Preparation and characterization of catalyst: phosphotungstic acid quaternary ammonium salt phase transfer catalyst was prepared by using dodecyl pyridine chloride,30% H₂O₂ and phosphotungstic acid as raw materials through ion-exchange,and then study the elements of the composition and it's structure feature by analysis methods such as FT-IR,XRD,EDS and SEM,demonstrating that the quaternary ammonium salt of phosphotungstic acid catalyst has the festures of Dawson structure.2.Preparation of epoxy tung oil methyl ester?ETOME?and the study of it's properties:TOME was first prepared through transesterification by using TO and methanol as raw materials,and then?C17H30ClN?3O40PW12·xH2O was used to catalysis epoxidation reaction of TOME,the factors of epoxidation reaction were studied.Results showed that the optimum conditions were 50 ? reaction temperature,3 h reaction time,1.6:1 molar ratio of hydrogen peroxide to double bond and catalyst dosage is 3.0%,the ETOME gives an epoxy value of 4.9%,a viscosity of 1667 mPa·s under these optimum conditions.Thermogravimetric analysis showed that the thermal stability of ETOME is much better than that of TOME,recovery rate for the first time of catalyst was 90%.3.Tung oil-based flame retardant polyols?TOBP?and the preparation and properties of flame retardant polyurethane foam:Tung oil-based flame retardant polyols was prepared through ring opening reaction,using ETOME and diethyl phosphate as reagents and toluene as solvent.TOBP gives an hydroxyl value of 223.6 mgKOH/g,a viscosity of 3270 mPa·s.Reaction conditions as follows: m?ETOME?: m?solvent?= 1:1,m?ETOME?: m?catalyst?=1:0.001.m?ETOME?: m?diethyl phosphate?=2.6:1,5 h in 80 ? reflux reaction.And TOBP was combined with PAPI to prepare polyurethane foams.Observed SEM photographs of polyurethane foams and found that the bubble holes were larger and more uniform than that of general polyurethane.The thickness of the combustion residue of carbonaceous layer was getting thicker with the increase of adding amount of TOBP.TO-RPUF has excellent flame retardant effect,it's limiting oxygen index can reach 26.1% without any other flame retardants.Thermogravimetric analysis showed that initial thermal degradation temperature of general PUF was 325.9 ?,it's maximum thermal weight loss rate was 18.74% at 369.7 ?,the carbon residue rate was 16.60% after temperature of 500 ?.Initial thermal degradation temperature of PUF prepared from tung oil-based flame retardant polyols decreased to 274.8 ?.Due to the lower degradation temperature of small molecules,for instance,phosphorus which were released in the process of thermal degradation of the flame retardant polyurethane foams system.With the increase of the amount of tung oil-based flame retardant polyols in the combustion process,the amount of flame retardant group that contains phosphorus in condensed phase was increasing,which played a good role in the process of inflaming retarding,leading to higher carbon residue rate of PUF,final carbon residue rate of PUF rising from 16.60% to 22.37%.