Research On Design And Combustion Characteristics Of Flame Retardancy Polyurea Composite

Due to its low production cost,low density,non-toxic,corrosion-resistant,easy processing,superior mechanical properties,polymer materials have been widely used in residential,chemical,electronic,power industry,transportation equipment and other people’s lives and production of general materials.However,the flammability of polymer materials increases the risk of fire.For example,a large number of carbon monoxide and toxic gases will be produced in the combustion process,which seriously threatens the safety of human property and life.In addition,polymer materials are prone to drop during combustion,which leads to flame diffusion.Polyurea elastomer coatings are considered to be polymer materials for strategic applications,especially shock absorption and bullet proof protection.In view of its excellent shock absorption performance and ballistic protection performance,the polyurea synthesized by the rapid and gradual polymerization of polyether amine and isocyanate has been widely used in national defense and military projects(such as tank chassis,bullet proof helmet,protective armor),concrete coating,pipeline anticorrosion,tank lining and building waterproofing.In this dissertation,based on the review of the research on flame retardant polyurea polymer composite materials,study on the synthesis of hyperbranched flame retardants,flame retardant properties of polyurea composite materials,and fire-retardant coatings prepared by hybridization of isocyanate and inorganic materials.Through the technical characterization of various physical properties and chemical structure of the material,the chemical structure,surface morphology,thermal stability and flame retardancy of the material are obtained.Then,through small-scale and large-scale combustion experiments,the flame retardant mechanism was investigated.The specific work is as follows:1.Using THPO and TDI as raw materials,a polycondensation reaction was carried out at room temperature to synthesize a HPPU flame retardant.The chemical structure of HPPU was characterized by NMR and FT-IR.The thermal stability of HPPU and APP was studied by TGA,and the flame retardant effect of PUA composites was analyzed from the initial degradation temperature and the carbonaceous residue.In addition,real time Fourier transform infrared spectra(RT-FTIR)was also used to investigate the changes of the pyrolysis substances in the condensed phase of PUA composites at different temperatures.2.Inorganic nano-materials reinforced PUA.In-situ polymerization technology was used to covalently linking polycarbodiphenylmethane diisocyanate(MDI-100L)and polytetramethoxydiaminobenzoate(PTMO,P1000)to prepare hydroxyapatite HAP/PUA nanocomposite material.By observing the dispersion and interface effects of nanocomposites,the enhancements of composites properties were studied.In terms of mechanical properties,the tensile test results showed that the tensile stress of PUA/HAP nanocomposites with 0.2 wt%HAP nanorods increased by 52.4%.SEM,EDSM,ATR-FTIR and XRD test results show that the dispersion of HAPs and the hydrogen bonding interaction between HAP nanorods and PUA are important factors for the increase in tensile strength and the decrease in rigidity of PUA composites.In addition,the addition of HAP nanorods can effectively suppress the self-hardening phenomenon of PUA with the increase of HAP content.3.Doors of high-rise buildings,furniture in kitchen and other places easily accessible to fire all require woods with a high flame resistance and a low thermal conductivity.Traditional inorganic coatings are restricted by complex process and high cost.Similarly,organic insulation coatings are limited by their poor structural integrity and fire resistance.Herein,we developed an inorganic/organic composite coating with a lower thermal conductivity and brilliant fire resistance.Isocyanate and sodium silicate are polymerized to form the final Si-O-Si network structure.The results of the LOI test showed that the coating has very excellent fire resistance,and its value can reach 48.0 vol%.According to the fire resistance standard of the CC test,the coating can make wooden materials reaching the fire resistance standard.After exposed to butane flame 30 min,coated wood still maintained its structural integrity with only 180℃ on the non-exposed side.As a fast spray-formed coating,it exhibits a great potential in the field of fire-safe materials,both from practicality and thermal insulation.