The Studies On Synthesis Process And Kinetics Of Poly Ethylene Glycol Adipate Glycol

In this paper,poly(ethylene adipate)(PEA)samples were prepared by the esterification and polymerization between adipic acid(AA)and ethylene glycol(EG).By investigating the effects of reaction temperature,concentration of catalyst,heating model and the initial reactant ratio of EG to AA on the molecular weight of PEA,the optimal process condition for the reaction was obtained as follows:n(EG):n(AA)is 1.3:1,polymerization temperature is 493K-503K,vacuum degree is 5 kPa,the catalyst is tetrabutyl titanate[Ti(OBu)4],stirring speed is 500 RPM/min,and the molecular weight is about 7000-8000.An eight-step mechanism of esterification reaction between adipic acid(AA)and ethylene glycol(EG)catalyzed by tetrabutyl titanate[Ti(OBu)4]was studied.Based on the mechanism,the kinetic model was proposed.The kinetic data for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate[Ti(OBu)4]were measured in the temperature range of 403K-433K,and the model parameters were obtained through an optimization procedure The results demonstrate that the model is suitable for the experimental data.The esterification reaction rate increases with the increase of reaction temperature,concentration of catalyst and the initial reactant ratio of EG to AA.Two series of poly(ethylene adipate)(PEA)samples with broad and narrow molecular weight distribution(MWD)were prepared by the polymerization between adipic acid and ethylene glycol.An accurate and swift method,one-point method,was used to determine the intrinsic viscosity of PEA samples.On the basis of Mark-Houwink-Sakurada(MHS)equation,the relationship between the intrinsic viscosity and molecular weight was built for PEA in tetrahydrofuran at 298K.The average molecular weights(Mn,Mv,Mw and Mz)were determind by using Gel-Permeation chromatography(GPC).The constants,a and K of MHS equation for the PEA samples dissolved in tetrahydrofuran at 298 K were determined by a numerical method,and the influence of polydispersity correction factor(qMHS)on the relationships were studied for PEA.