Preparation Of Flame-retardant Polyurethane And Its Effect On The Compression Elastic Of Space Fabrics

Spacer fabric/flexible polyurethane composite material is a new composite material made of warp knitted spacer fabric and polyurethane material,which is made by physical and chemical way.It has excellent specific strength,specific modulus,shock absorption,heat insulation and light weight,ect.However,the soft PU forms with large surface-area and open cell structure is particularly easy to ignite and has poor flame-retardant properties.Meanwhile,it shows evolution of smoke and toxic gases as its burns,serious threat to lives and property of people.Thus,it is challenge to develop high flame retardancy and low-smoke for polyurethane foams simultaneously.In order to enhance the flame-retardant property of PU forms,it has important practical significance to develop a new small price and environmentally friendly flame retardant.Studies have found that phosphorus-containing flame retardants and inorganichydroxide（such as aluminum hydroxide and magnesium hydroxide）have been widely used in inorganic flame retardants because of their non-toxic and environment-friendly characteristics.However,the high addition（30-60wt%）of the flame retardant requirements resulted in the increase of cost,the increase of production difficulty,and the decrease of the physical properties of the polymer.The development of halogen-free flame retardants,such as phosphate,ammonium salt and molybdate,as well as silica based（such as silica）,has attracted people’s attention.In order to solve the problem of flame retardant additives and high production costs,this paper studies design two systems.First,the ammonium molybdate coated aluminum phosphate（ALP）form ALP microcapsule flame retardant,composing a synergistic flame retardant system of nitrogen–phosphorus-molybdenum-aluminum.Secondly,the SiO₂microcapsule flame retardants was formed by coating silica（SiO₂）with ammonium molybdate,composed of silicon-molybdenum-phosphorus-nitrogen flame retardant system.Meanwhile,the ALP microcapsule flame retardant and SiO₂ microcapsule flame retardants was carried out a series of characterization.And the effects of two kinds of flame retardants on the flame retardancy and smoke suppression properties of PU foam materials were studied,then the influence of two kinds of flame retardant PU foams on the compression properties of spacer fabric/polyurethane composites were studied.Using powder X-ray diffraction（XRD）,filed emission scanning electron microscopy（SEM）,Energy dispersive X-ray（EDX）,thermal gravimetric analysis（TGA）,Fourier transform infrared spectroscopy（FTIR）and pyrolysis gas chromatography-mass spectrometry（Py-GC/MS）to characterize the flame retardant polyurethane composites and their carbon residue.The results are as follows:The PU/ALP microcapsule composite material showed great flame retardancy,anti-melt drop and synergistic flame retardant effect.In the vertical horizontal burning test,the remaining residual length of polyurethane composite material was significantly increased.When the content of ALP microcapsule flame retardant was 15%,the LOI value of PU/ALP microcapsule composite material was 28.5%and UL 94 v-0.When the amount of flame retardant was 20%,the smoke density decreased to 16%.The PU/SiO₂ microcapsule composite showed excellent flame retardancy effect.And the LOI value of PU/25%SiO₂ microcapsule composite material reached 34.8%and UL-94 V-0rating,and the smoke density decreased significantly,from 29%to 1.8%;pyrolysis gas chromatography mass spectrometry and analysis,SiO₂ microcapsules can promote the formation of continuous compact carbon residue in polyurethane foam,showing excellent flame retardancy effect in condensed phase.Finally,using Instron 3369 to carry out the quasi static compression experiment on the spacer fabric/polyurethane composite materials,studies show that the compression performance of ALP microcapsules polyurethane foam and SiO₂ microcapsules polyurethane foam has large improvement;when the filling rate increased,the load capacity of the spacer fabric/polyurethane composite material was obviously improved,the deformation quantity was reduced,and the elastic performance was improved;when the mass fraction of polyurethane was 30%,spacer fabric/flexible polyurethane composite materials can maintain compression deformation trend of spacer fabrics,with excellent cushioning properties.