Research For Synthesis And Properties Of Polyphosphazenes For Liner Of Solid Rocket Motor

As the adhesion materials between propellant and insulation layer in solid rocket motor,the main function of liner is to provide enough bonding strength between propellant and insulation,so as to ensure the structural integrity of solid rocket motor.Phosphorus and nitrogen atoms of polyphosphazenes' backbone alternates with alternating single and double bond.A wide variety of polyphosphazenes,which have different even contrary performance or possess a special kind of function,can be synthesized mainly by replacement of the reactive chlorine atoms in poly(dichlorophosphazene) with different nucleophiles.Poly(fluoro -alkoxyphosphazene) have an important application value in solid rocket motor liner because of its unique structure and properties.Some work about poly(fluoroalkoxyphosphazene) for solid rocket motor liner are showed as follows:1.Research progress of solid rocket motor liner at home and abroad and factors affecting lining interface bonding properties was overviewed.The development history,structure and performance, synthesis method of Polyphosphazenes and its applications in elastomers, fire-retardant materials and biomedical materials,etc.,were also introduced.On this basis,the significance and main research content of this paper was proposed.2.Poly[bis(trifluoroethoxy)phosphazene],poly[bis(octafluoropent oxy)phosphazene],trifluoroethoxy and octafluoropentoxy cosubstituting polyphosphazene were synthesized and characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy.Side group exchange reactions of poly(fluoroalkoxyphosphazene) was studied,and it was fund that octafluoropentoxy of polyphosphazene was more easily replaced by trifluoroethoxy.Thermal transition temperatures,thermal stability and hydrophobic property of the three kinds of poly(fluoroalkoxyphosphazene) was characterized respectively by differential scanning calorimetry,thermogravimetric analysis and the measure of water contact angle.And the results indicates that the three kinds of fluorinated alkoxy polyphosphazenes with a low glass transition temperature,good thermal stability and hydrophobic performance have similar performance in these areas.3.A kind of poly(fluoroalkoxyphosphazene) containning 4-formylphenoxy was synthesized by two steps of substituting reactions, and then was reduced to poly(fluoroalkoxyphosphazene) containning hydroxy.Their molecular structures were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy.Dynamic mechanical properties,thermal stability,static mechanical properties and hydrophobic property of fluorinated alkoxy polyphosphazenes with different hydroxyl content were researched respectively by means of dynamic mechanical thermal analysis,thermogravimetric analysis,tensile test and water contact angle test.Reaults indicates that the content of hydroxyl of the polyphosphazene significantly affects the glass transition temperature and mechanical properties of the polymers,but has little effect on the thermal stability and hydrophobic property of the polymers.