Research On The Micro-structure And Crystalline Properties Of BAMO-THF Copolymer

It is one of the effective methods to improve the properties of propellant adhesive through changing the sequence structure of polymer by copolymerization of two or more kinds of monomers.In-depth understanding of the sequence structure characteristics of BAMO-THF copolymers has theoretical significance for the modification and molecular design of solid propellants for wide temperature and high energy tactical missiles.In this paper,BAMO-THF copolymer was studied through theoretical calculation,computer simulation and experimental analysis,The BAMO-THF copolymers were characterized by¹³C-NMR,¹H-NMR and 2D-NMR,The crystallization characteristics of BAMO-THF copolymer were studied by DMA,POM,DSC and XRD.The main results are as follows:?1?Research on the Micro-structure of BAMO-THF CopolymerThe reactivity ratio of BAMO/THF monomer copolymerization was studied theoretically.The average sequence length and segment distribution of BAMO-THF copolymer with different feed ratio were predicted,and BAMO was easier to form block.Elemental analysis showed that the molar content of BAMO copolymerization monomer is higher than THF.The molar ratio,alternation degree,unit structure,the proportion of the triad units,the degree of randomness,and the average sequence length of the BAMO-THF copolymer system were studied by means of NMR.We have established a set of calculation method to study the micro-sequence structure of BAMO-THF copolymer.?2?Research on the BAMO-THF copolymer terminated structure characteristicsThe mechanical properties of the elastomer network were affects by the terminated structure of BAMO-THF copolymer.The species and content of terminal hydroxyl groups and the reactivity of terminal hydroxyl groups were studied by means of NMR and computer simulation.BAMO-THF copolymerization system has BB-OH,BT-OH,TB-OH,BBT-OH and other 12 kinds of hydroxyl groups with different end-capping structure,The Hirshfeld charge and the Mulliken charge of hydrogen and oxygen atoms in different structures were studied by using the Gaussian 09 calculation program.The sequence of activity of terminal hydroxyl was obtained:HO-TT>HO-BTB>HO-TTT>HO-BB.?3?Studies on crystallization characteristics of BAMO-THF copolymerThe relationship between the crystallization properties of BAMO-THF copolymer and the temperature was studied.The copolymer has the Maltese cross-extinction phenomenon under orthogonally polarized light and conforms to the general morphology of the polymer crystal-spherulite.The crystal melting temperature ranges from 38?to 45?,and the BAMO segment is the main crystal unit.The presence of the crystal in the copolymer increases the viscosity of the system and affects the temperature sensitivity of the viscosity,because the crystallization can form a cross-linking point and increases the viscosity the viscosity curve shows a significant inflection point before 40?.the viscosity-temperature curve is consistent with the crystallization behavior.