Polyphosphonate Flame Retardant For Polyurethane Material With Corn Stalk Powder Composite

Rigid polyurethane foam(RPUF)is a good wall insulation materials,with good insulation properties,light weight,waterproof,corrosion resistance and other excellent performance.However,polyurethane foam is flammable,and the combustion process emits a large amount of toxic gases.The research on the flame retardancy of polyurethane foam greatly affects its application and promotion.In recent years,the burning of agricultural wastes,such as corn stalks,has caused great environmental pollution.Therefore,the efficient utilization of straw has significant social significance.In this paper,corn straw powder(SP)was added to RPUF,and samples were studied from the following three aspects.First,the effect of particle size of corn straw on the performance of RPUF was studied.The corn stalks were crushed and added to the RPUF foaming system(black materials and white materials)to prepare S-RPUF.The compressive strength,apparent density and limit oxygen index of S-RPUF were tested.The results showed that the apparent density of RPUF increased slightly with the addition of corn stover powder,the change of particle size had no obvious effect on the apparent density,and the compressive strength of RPUF decreased significantly and the limiting oxygen index increased obviously.With the increase of straw particle size,the compressive strength in the growth direction increased and the horizontal direction decreased gradually.The LOI of RPUF showed an overall increasing trend.Comprehensive comparison of different particle size of straw powder on the performance of polyurethane foam was made to determine the 160 mesh for the best particle size.Follow-up study with 160 mesh com stover powder as an additive.Then the 160-mesh corn stalk meal was used instead of the polyhydric alcohol component,the apparent density and compressive strength were used as reference quantities to study the optimized formulation of RPUF.1,4-butanediol,corn stalk powder as polyol component,polymethylene polyphenyl polyisocyanate as black material,stilled water as chemical foaming agent,stannous octoate as catalyst,N,N-Dimethyl formamide as solvent and silicone oil as foam stabilizer were used and the addition amount of 1,4-butanediol,water and silicone oil were changed,respectively.The foaming stage and foaming time of different formulations were recorded,The compressive strength and the apparent density of the polyurethane foams were discussed.The influence of every agent amount on the foaming process and the physical properties of polyurethane foams was discussed.The components and the proportion of polyurethane foam foaming system were preliminarily determined.The content of 1,4-butanediol is 14 g/copy,water content is 1.6 g/copy,and silicone oil content is 0.4 g/copy.Through the orthogonal test,the effects of temperature,isocyanate index,N,N-dimethyl formamide,1,4-butanediol on the apparent density and compressive strength of polyurethane foam were analyzed.Through the analysis of factors and interaction,the formulation of polyurethane foams witih the best mechanical properties was determined.The temperature was 40?,the isocyanate Index of 1.0,N,N-dimethylformamide 4g/copy,1,4-butanediol content of 12g/copy,so as to obtain corn stalks compounded rigid polyurethane foam(SP-RPUF)optimization formula.Polymethyl phosphonic acid ethylene glycol ester was used as flame retardant to flame-retard the SP-RPUF with corn stalk powder to obtain(FR-SP-RPUF).The effects of flame retardant on apparent density,compressive strength,cell structure,thermal stability and flame retardancy were studied.The results showed that the apparent density of FR-SP-RPUF increased with the increase of flame retardant content.The compressive strength of PU foams in both the growth and horizontal directions increased with the increase of flame retardant content.The addition of flame retardant made the cell structure more uniform,while when the content of the flame retardant increases gradually,more macropores appear in the foam,which destroyed the uniformity of cell structure.The flame retardant properties of materials increased.The experimental results of TG-FTIR showed that the decomposition temperature of flame retardant samples(FR-SP-RPUF-15)with 15%flame retardant added do not generate any further volatile compounds due to the presence of dense carbon layers.Finally,the comparative analysis of RPUF/S-RPUF/SP-RPUF and FR-SP-RPUF was carried out.The results showed that SP-RPUF had better mechanical properties,flame retardancy and thermal stability than S-RPUF.After addition of flame retardant,The mechanical properties and flame retardancy of FR-SP-RPUF continued to increase with the addition of flame retardants,while the thermal stability was reduced,similar to RPUF/S-RPUF.