Study On Thermal Analysis Of The Barks, Leaves And Several Active Ingredients Of Eucommia Ulmoides Oliv.

Through differential scanning calorimetry(DSC) and thermogravimetry(TG) analysis, thermalanalysis curves of barks, leaves and its waste residue of Eucommia ulmoides Oliv. from differentregions at different heating rates were established, and then thermal analysis kinetics was used toresearch the thermal decomposition characteristics and calculate kinetic parameters, which couldprovide references to thermal processing and transforming of Eucommia ulmoides Oliv.Gutta-percha, a natural polymeric material, was tested by multiple heating rates while thermalstability, decomposition and kinetics were studied by thermal analysis kinetics methods, and thenthermal aging storage period of gutta-percha was calculated by kinetic triplets. In order to reveal thethermal decomposition processing and mechanism, genipin, geniposide, ursolic acid and caffeicacid, which are iridoids compounds with similar structure and organic acids in Eucommia ulmoidesOliv. respectively, were analyzed by DSC and TG while molecular simulation andThermogravimetry-Fourier transform infrared spectroscopy combined technology were carried outto verify the cracking of chemical bonds. The shelflives of these four active ingredients werecalculated by thermal analysis kinetics triplets. Main conclusions of this study are as follow:(1) There were the same heating effect and tendency of the barks and leaves of Eucommiaulmoides Oliv. from different regions at the same heating rate, only with minor deviation. With theheating rate increasing, thermal decomposition temperature turned to high temperature little by little.During the pyrolysis processing, after a little water lost, three-stage decomposition processes wereoccurred. Although these three stages had different thermal decomposition mechanisms and kineticparameters, the changing trends of apparent activation energy(Ea) and pre-exponential factor(A)were consistent.An intensive thermal decomposition of waste residue of leaves began at153℃and ended upat569℃with only a single and smooth peak. After278℃, the weight loss rate of waste residuewas higher than the leaves. Until the end of decomposition, the mass percentage of waste residuewas lower. Activation energy Eaof waste residue was lower than Eucommia ulmoides Oliv. leaves,which theoretically revealed that waste residue was more suitable to thermolysis andthermochemical conversion.(2) The thermal decomposition of gutta-percha began at268℃and ended up at459℃whiledecomposition rate reached the maximum at375℃. With the heating rate increasing, hysteresisphenomena to high temperatures during thermal decomposition occured little by little. Thermaldecomposition mechanism was chemical reaction, corresponding with reaction order equation.Compared with the barks and leaves of Eucommia ulmoides Oliv., the value of Eawas higher, whichshowed its greater stability. After calculated by using integral for kinetic equation, it was estimated that the thermal aging storage period of gutta-percha at200℃was0.47a.(3) Through linear regressions by Van’t Hoff equation, the purity and melting points of genipin,geniposide, ursolic acid and caffeic acid were detected, which were99.53%,99.29%,99.61%,99.84%and120.85℃,161.53℃,284.95℃,198.86℃, respectively. The thermal decomposition ofgenipin started at151℃with two stages while decomposition of geniposide began at213℃andended up at361℃after a little water lost. Also after a little water lost the crystal powders of ursolicacid decomposed completely during236.8~431.2℃with a stage while the decomposition of caffeicacid began at153.0℃with two stages. The deduction by quantum chemistry method and infraredspectral analysis of the evolved gases could verify the experiment weightlessness datas.(4) The two-stage thermal decomposition mechanism of genipin were Chemical Reaction andThree Dimensional Diffusion, respectively, corresponding with Reaction Order Equation andZ.-L.-T. Equation, respectively while the mechanism of geniposide was Chemical Reaction,corresponding with Reaction Order Equation. The Eavalues of two-stage thermal decomposition ofgenipin approached to each other, but they were much lower than the one of geniposide, whichshowed the glucosidic bond brought into the molecular structure made it more stable. Thedecomposition rate of genipin at first stage was faster than the second stage. Although thedecomposition of geniposide was more difficult than genipin at low temperature, the decompositionrate was faster than the two stages of genipin once the decomposition temperature reached.(5) The thermal decomposition mechanism of ursolic acid was Two Dimensional Diffusion ofcylindrical symmetric type, corresponding with Valensi Equation while the two-stagedecomposition of caffeic acid were Two Dimensional Diffusion and Three Dimensional Diffusion,respectively, corresponding with Jander Equation and Z.-L.-T. Equation, respectively. The Eaof thesecond stage decomposition of caffeic acid was much higher than the first stage, which showeddecomposition of second stage was more difficult. Although The high value of Eashowed thedecomposition of ursolic acid was difficult, decomposition rate got higher when the decompositiontemperature reached.