Glotova, Valentina Nikolaevna

Izhenbina, T. N.

Krutas, D. S.

Zamanova, Margarita Karimovna

Electronic archive of Tomsk Polytechnic University

 Секция 7 Химия и химическая технология (на английском языке) 199molar hydrogen / feedstock ratio. The dynamics of flow changes in the reactor is carried out from 4.0 l/h to 12.0–14.0 l/h for the entire cycle with the tem-perature increase in the reactor.References 1. Bannov P.G. Processes of oil refining.– M.: TSNIITE-neftekhim, 2011.– 429 p.Comparison of HPLC, GPC and MS-TOF techniques for determination of the average molecular mass of PLA oligomerV.N. Glotova, M.K. Zamanova, D.S. Krutas, T.N. IzhenbinaScientific supervisor – PhD, Associate Professor, V.T. NovikovNational Research Tomsk Polytechnic University Russia, 634050, Tomsk, 30 Lenin Avenue, glotovavn@gmail.comPoly-lactic acid (PLA) is a biodegradable aliphatic polyester produced industrially both on large and small scale. It is used for a wide variety of applications, ranging from biomedical applications to raw material for food packaging, bottles and consumables in general. The most popular industrial production process is actually a multistep process. Firstly, lactic acid (LA) is polymerized to low molecular weight pol-ymer (LMW PLA, < 10 kDa) by bulk Melt Polycondensation and then depo-lymerized and converted to the lactide, cyclic dimer of LA, in a catalytic step usually carried out at high temperature and low pressure. Finally, purified and dried lactide undergoes the Ring-Opening Polymerization for obtaining high molecular weight polymer (HMW PLA, > 100 kDa). The first step has to be carefully performed in order to optimize the extent of polymerization and minimize the multiple side reactions like discoloration, cyclization, transes-terification and racemization which affect the purity of the final cyclic dimer produced from the PLA oligomers itself [1, 2].The purpose of this study is to compare the various characterization techniques for monitoring the molecular weight of PLA oligomers.PLA oligomer was obtained from lactic acid (PUREAC, Spain) in pres-ence of ZnO as a catalyst and at constant temperature 160 °C. Average molecular mass of obtained oligomer was determined by Gel Permeation Chromatography (GPC), High Performance Liquid Chroma-tography (HPLC) and High Resolution Mass-Spectrometry with Time-of-Flight detection (MS-TOF). GPC analysis was carried out on a PLgel 5 μm MIXED-C column (300 mm × 7.5 mm) using a series apparatus Agilent 1200 200 XVI Международная научно-практическая конференция имени профессора Л.П. Кулёваequipped with RI detector. MS-TOF analysis was performed on Time-of-Flight detector Agilent 6320, sample ionization was performed with sodium acetate solution. Reversed phase HPLC analysis was done using an YL9100 HPLC system with UV/Vis detector, the analytical column was a Tracer Excel 120 ODSA (250 mm × 4.6 mm, 5 μm), chromatographic separation and calcu-lation were carried out in accordance with article [3]. MS-TOF mass-spectra of LMW PLA is shown in Figure 1.Among the various analytical techniques for molecular weight of poly-mers GPC is the most popular since the complete molecular weight distribu-tion is provided. However, for LMW PLA the calibration with expensive PLA standards is required. The universal calibration based on polystyrene stand-ards can be applied, but the selection of reliable values of the Mark-Houwink constants is an issue, due to the largely different values that leading to the significant error in calculations. HPLC represents an alternative analytical technique for investigating the entire chain length distribution of LMW PLA. This provided the basis for the development of a new separation method which was more accurate, easy and efficient. The developed HPLC technique is validated by comparison to MS-TOF method. Results are shown in Table 1.Fig. 1. Mass-spectra of PLA oligomer ionized with Na+, positive modeTable 1.	 Comparison	of	values	of	average	molecular	mass	of	LMW	PLAParameter GPC HPLC MS-TOFMn 1190 443 512Mw 2110 498 557D 1.8 1.1 1.1 Секция 7 Химия и химическая технология (на английском языке) 201References 1. Garlotta D.J. Polymers and the Environment, 2001.– Vol.9.– №2.– P.63–84.  2. Auras R., L.L.T., Selke S., Tsuji H. Poly (Lactic Acid): synthesis, structures, properties, processing, and application. New Jersey: John Wiley & Sons., 2010.– 510 p. 3. Codari F., Moscatelli D., Storti G., Morbidelli M., Macromol J. Materials and Engineering, 2010.– Vol.295.– P.58–66.Spectroscopic Methods Applied to the Characterization of Phenol Oxidation IntermediatesE.V. Sukhoroslova, A.B. Iadykina Scientific supervisor – PhD, Associate Professor, O.S. Kukurina National Research Tomsk Polytechnic University Russia, 634050, Tomsk, 30 Lenin Avenue, annaanna.borisovna@mail.ru, kukurina@tpu.ruPhenols and substituted phenols are important raw materials for wide variety of organic compounds, dyes, pharmaceuticals, plasticizers, antioxi-dants, etc. Phenols are present effluent from the chemical process industries which are either manufacturing or using them.Combined oxidation of phenolic wastes offers an alternative treatment method to destroy phenolics totally. It consist, in essence, of the electrochem-ical generation of high-reactivity intermediates, and on either a cathode or an anode (or, possibly, on both the cathode and the anode simultaneously) and their subsequent chemical decay of phenol in an electrolytic solution. In this work oxidizing agent is generated in aqueous sulfuric acidic solutions under direct current. It has been identifed that the maximum rate of phenol cleavage achieved with the sulfuric acid concentration of 30 %. The assumed scheme of phenol cleavage by electrogenerated oxidizing system is a typical oxida-tion process of phenol in the liquid phase [1].Phenol → o,p-hydroquinone → o,p-benzoquinone → dicarboxilic acids → CO2 and H2O.We carried out the identification of intermediates and final products by means of UV spectrophotometry, gas chromatography with mass selective detector and high performance liquid chromatography. For UV spectrophotometry a samples were prepared by following pro-cedure: 0.1 ml of a solution from electrolyzer diluted to 1 ml with distilled water and then record the spectrum using quartz cell. A sample preparation for gas chromatography with mass selective detec-

Comparison of HPLC, GPC and MS-TOF techniques for determination of the average molecular mass of PLA oligomer

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