Investigation On Precise Synthesis And Structure-activity Relationship Of NPBA

NPBA(Neutral Polymeric Bonding Agent), an essential bonding agent in NEPE(Nitrate Ester Plasticized Polyether) propellant curing system,directs large impact on the curing system structure, and relates to the propellant energy and the mechanical properties. It is trusted that researches on NPBA structure design, synthesis and its reactions with curing agent have been hot in this years. But how to control the synthesis process to obtain NPBA with designed structural parameters and the relationship between NPBA molecuar stucture and NEPE propellant have not been reported by now.Research in this paper is on the free-radical solution copolymerization with acrylonitrile(AN) and hydroxyethyl methacrylate(HEA) as the monomer, Azobisisbutyronitrile(AIBN) as the initiator, β-mercaptoethanol (β-ME) as the chain transferer and acetone as the solvent. Based on theorys of polymer chemistry, considering the relationship of monomer composition and molecular structure in free-radical copolymerization, considering the effects of reaction temperature and reaction time on the decomposition of initiator, considering the influence of concentration of chain transfer agent on the molecular weight and hydroxyl value, we optimizate synthesis method of NPBA, and make sure that NPBA with designed molecular weight, hydroxyl value and uniform structure can be produced.According to the optimizated method of synthesis, we synthesize series of different NPBA samples and calculate their solubility parameter use molar gravitational constant method. The sythesized series of different NPBA samples have been used in film experiment and in NEPE propellant, and their mechanical properties have been mesured. Accord to this, we have disscussed the effection of NPBA structure on matrix network and of mechanical properties NEPE propellant. In the end, the structure-activity relationship of NPBA have been found, and it can be guide of NPBA designing and using process optimization, meanwhile the NPBA mechanism is comprehensive elaborated. Finally, we achieve the best way to use NPBA.The result shows that NPBA with uniform and designed structural parameters can be produced by precise synthesis method. Best reaction conditions for synthesize NPBA with number-average molecular weight (Mn) of3000, hydroxyl value [OH] of2.00mmol/g are:total mass ratio of HEA and AN is1:3.95, Control of feeding quality ratio of HEA and AN is1:10.42, the use of AIBN is8.05%of the monomer total wight, the use of β-ME is4.0%of the monomer total wight, reaction temperature is65℃, and reaction time is6h.The effects of NPBA on NEPE propellant mechanical properties include two side:the effects on matrix network structure and the effects on the filler interfacial effect. With the increase of molecular weight of NPBA, propellant’s tensile strength decrease, and the enlongation first increasing and then decreasing; with the increase of hydroxyl value, propellant’s tensile strength increase, and the enlongation first decreasing and then increasing; with the decrease of NPBA, propellant’s tensile strength increase, and the enlongation first decreasing and then increasing. When using NPBA with number-average molecular weight of4000, hydroxyl value of2.20mmol/g, solubility parameter of12.43(cal/cm3)1/2,the propellant has the best mechanical properties.