Study On The Synthesis And Properties Of Poly(Butylenes Succinate)

A high molecular weight Poly(butylenes succinate) (PBS) was synthesized via two steps: esterification and polycondensation. The number average molecular weight of PBS was 20,000～100,000g/mol. The molecular weight distribution index was near 1.50 which was between 1.35 and 1.75.The condition of esterification has effection on the extent of reaction and reaction time. In the range of this research, the results shows that at 170℃,the molar ratio of SA and BD was 1:1.5, the catalyst content was 0.1%(mol), the extent of reaction was highest; at 170℃,the molar ratio of SA and BD was 1:1.1～1:1.2, the catalyst content was 0.05%(mol), the reaction time was shortest at the extent of reaction was 70%.The kinetics of esterification and polycondensation was also researched. The result shows that the total order of esterification was 3, it was second-order for the SA and first-order for the BD in esterification step, respectively. The rate equation can be written as: r=dx/dt=k.CCOOH 2 .COH, The experimental data was in accord with theoretical data. The activation energy of esterification was 597.51 kJ/mol with none catalyst, the addition of catalyst can greatly reduce the activation energy. It was second order for the reactant (the concentration of hydroxyl group) in polycondensation. The experimental data was also in accord with theoretical data. The activation energy of polycondensation was 60.95 kJ/mol with Ti(OBu)4 as catalyst.Via experimental research and data fitting, educed for the first time that the value ofαwas 0.788 and the value of K was 1.71×10-4 in the Mark-Houwink equation when the number-average molecular weight of PBS was less than 100,000g/mol at 25℃. When the molar ratio of SA and BD was 1:1.2; catalyst content was 0.05%(mol) at 120～140℃, the number average molecular weight of PBS was highest. By the research of relationship between Melting Index and viscosity average molecular weight, the empirical formula is: Log(MI)=11.317-2.118log(M).