Synthesis Of THF/GAP Copolyether And Study On Properties Of THF/GAP Elastomer

Azide groups are contained in the molecular chain segments of polymer binders ofglycidyl azide polymer (GAP),with low mechanical sensitivity, density, carrying more energyof perunit volume, because of its side chain of azide groups, GAP has bad mechanicalproperties, meawhile, it is difficult to have high molecular weigh, according to its drawbacks,by using tetrahydrofuran (THF) modified, a binder for solid propellant with excellentmechanical properties, high energy density are composed.First, by using tetrahydrofuran (THF) and epichlorohydrin (ECH) as sample borontrifuoride (BF3·OEt2) as catalyst,1,4-butanediol as initiator, The THF/GAP copolyether wassynthesized by cationic ring-opening polymerization reation, and synthesized conditions andthe formula were optimized, by characterized through infrared spectroscopy (IR), nuclearmagnetic resonance (1H-NMR), gel permeation spectrum (GPC), better reaction conditions is:the initiator dosage was5%of the total amount of monomer, the catalyst was3%of the totalquality of monomer, the reaction time was4h, the reaction temperature was0℃, thenumber-average molecular weight distribrtion of copolymerization was narrow, the number-averagemolecular weight of copolymerization was controllable.Then THF/ECH copolyether was azided using sodium azide,THF/GAP copolyether wassynthesized by solvent method and phase transfer catalyst method, characterized throughinfrared spectroscopy (IR), nuclear magnetic resonance (1H-NMR), gel permeation spectrum(GPC), differential scanning calorimetry (DSC) test, the results showed that syntheticTHF/GAP copolyether was the target product，and the process chditions were optimized. Theoptimal technological conditions for synthesis of THF/GAP copolyether through the solventmethod were as follows: the amount of sodium azide was1.2mole percent of the THF/GAPcopolyether, azide time was18h, azide temperature was100℃; The optimal technological conditions for synthesis of THF/GAP copolyether through the phase transfer catalyst methodwere as follows: the amount of sodium azide was1.2mole percent of the THF/GAPcopolyether, tetrabutylammonium bromide for catalyst was4%mole percent of the THF/GAPcopolyether, azide time was24h, azide temperature was100℃. Compared with the solventmethod and the phase transfer catalyt method synthesizing the THF/GAP copolyether, thephase transfer catalyst method had the higher azide rate and the yield, the longer reaction time,the phase transfer method was more safety, environmental protection and economic.At last the polyurethane elastomers was synthesyed by one-step method using THF/GAPcopolyether as one of raw materials, glycerine as chain extender, toluene diisocyanate (TDI)as curing agent, dibutyltin dilaurate (DBTDL) as cayalyst, examined the curing parameters,curing temperature, catalyst dosage, glycerol and the comparison of the hydroxyl of glycerineand THF/GAP copolyether on the properties of polyurethane elastomer, and by differentialscanning calorimetry (DSC) and thermogravimetric analysis (TG) test, the performance ofpolyurethane was studied, results showed that the optimal technological conditions with bettermechanical properties was as follows: curing parameter R=1.2, curing temperature is65℃,the comparison of the hydroxyl of glycerine and THF/GAP copolyether, the catalyst dosagewas0.5%of total amount of THF/GAP copolyether, results showed that the breakingelongation was452%, the tensile strength of the binder film was4.07MPa, meanwhilehomopolymerization GAP polyurethane elastomer had296%elongation at break, tensilestrength of the binder film was0.87MPa, compared with the homopolymerization GAPpolyurethane elastomer, THF/GAP polyurethane elastomer had better mechanicalperformance.