Study On Plastification And Controlled Depolymerization/Polycondensation Of Polycarbonate

The purpose of this paper is to improve the melt fluidity of polycarbonate (PC), and dropits processing temperature down to below200℃while retaining good mechanical properties,which will be applied to specific areas. The main research results of this paper are as follows:(1) The melt fluidity of PC is improved significantly with the addition of Acetyl TributylCitrate (ATBC), and the equilibrium torque of PC and PC/ATBC (50/5) are16.1~16.8and6.1~6.3respectively at the set temperature200℃. The glass transition temperature (Tg) ofPC/ATBC decreased by about27℃,49℃,71℃and above85℃respectively when ATBCwt%=5,10,15and20respectively. With ATBC content increased, weight loss of water isappeared gradually in the thermo gravimetric (TG) curves of PC/ATBC, and the initial weightloss temperature of ATBC decreased. The melt flow rate (MFR) of pure PC is MFR (260℃/1.2kg)=5.1, and MFR of PC/ATBC(85/15) are MFR (210℃/1.2kg)=8.4and MFR (190℃/1.2kg)=2.6, so the processing temperature of PC/ATBC can be reduced to nearly200℃when ATBC wt%≥15%. The apparent viscosity of PC/ATBC increases at first and then tendsto be stabilized with shear rate increases. Mechanical properties of PC/ATBC decline sharplywhen ATBC wt%≥20%. Summarily, the processing temperature of PC/ATBC can be droppeddown to below200℃and retention rate of mechanical properties can be above70%withoptimum amount of ATBC wt%=20%.(2) Controlled depolymerization of PC through glycolysis was studied. The resultsshowed that the degree of depolymerization can be improved with the addition of0.2wt%ofcatalyst, and the catalytic efficiency of NaOH is higher than Zn(Ac)2. The result of orthogonalexperiment indicated that the order of each factor, which can impact the degree ofdepolymerization, from the primary to the secondary is (A) reaction temperature>(B)reaction time>(C) the amount of EG>(D) the amount of catalyst. What is more, factor A andfactor B have a significant effect on the test results, while the factor C and factor D did not.There is absorption peck of–OH in IR spectra of glycolysis products, and the greater thedegree of depolymerization, the larger A-OH/A3045in IR spectra. The glycolysis products havepoorer thermal stability and smaller Tgthan PC.(3) Controlled depolymerization of PC through hydrolysis in high temperature andwithout any solvent was studied, and the results showed that: Tgof products decreased lessthan1℃without addition of H2O and NaOH; Tgof products decreased by about2.3℃with addition of H2O only; Tgof products decreased more than7℃with addition of NaOH only;Tgof products decreased more than27℃with addition of H2O and NaOH.(4) The polycondensation conditions through solution polymerization was studied, andthe results showed that: the optimum amount of triethylamine and adipoyl chloride aretriethylamine/BPA=2.0~2.2and adipoyl chloride/BPA=1.00~1.02respectively; the initialdecomposition temperature of the polycondensate is above300℃and its Tgis about39℃~43℃; higher reaction temperature will help improve the molecular weight of polyester; themolecular weight of the polycondensate increases at first and then decreases with the reactiontime increases, and the optimum reaction time is about3h.