Characterization of renewable PET from the bottle industry applying DSC and other physical methods K. Toncheva 1, A.A. Apostolov 2, S. Djoumaliisky 1, E. Simeonova-Ivanova 1, V.L. Zvetkov 1 1 Institute of Mechanics – BAS, Acad. G. Bonchev St., Bl. 1, 1113 Sofia, Bulgaria 2 Sofia University, Faculty of Chemistry and Pharmacy, 1 J. Baurchier Blvd, 1164 Sofia, Bulgaria text EXPERIMENTAL INTRODUCTION MATERIALS Six PET waste bottle materials from the producers of mineral water, beer, and soda drinks were tested together with PET pre-forming samples. METHODS The following methods have been applied to characterize the renewable PET materials: Fourier transformed Infra-red Spectroscopy, FTIR, IRaffinity-1 (with Miracle Total Attenuated Reflectance Attachment), Shimadzu. Differential Scanning Calorimetry, DSC, Perkin-Elmer Pyrex and TA instruments Q200 DSC’s; Wide Angle X-ray Scattering, WAXS, Siemens D500; References [1] Zhu Z.M., Kelley M.J., Polymer, 2005 (46) [2] Chen Z.Y., Hay J.N., Jenkins M.J., Eur. Polym. J., 2012 (48) [3] Chen Z.Y., Hay J.N., Jenkins M.J., Thermochim.Acta, 2013 (552) 123. [4] Nunes R.A.X, Costa V.C., de Araujo Calado V.M., Branco J.R.T., Mater. Res (12) 121. Figure 4. DSC curves of the PET samples studied by X-ray diffraction. First melting at dT/dt = 10 K.min -1 a)b) Acknowledgement The authors thank text RESULTS AND DISCUSSION The problem concerning renewable poly (ethylene glycol tereftalate), PET, becomes more and more significant, since its relative part among the other polymer wastes increases in the last few years, at least in Bulgaria. Gaining a research project, we have developed some applications of renewable PET, namely: (i) incompatible polymer blend of PET with waste polyolefines – bulk, foamed, and micro-fiber materials and (ii) epoxy – PET composites. In our knowledge, it is important to characterize well PET prior to its use and the PET characterization is the aim of the report. The DSC method is very appropriate to characterize PET attended for recycling. It can give important information about the renewable PET processing. Some additional information can be obtained applying other physical methods, such as X-ray diffraction and FTIR spectroscopy. In this respect, the measurement of M w is also necessary. Figure 3. X-ray diffraction pattern for typical renewable PET samples Comparative DSC analysis Figure 2. FTIR spectra of six renewable PET samples ACKOWLEDGEMENT CONCLUSIONS The authors gratefully acknowledge the financial support of the Bulgarian Ministry of the Education and Science - National Scientific Fund (Projects DTK 02/7-2010) Analysis of renewable PET by the DSC method The data in Fig. 4 are in agreement with those calculated from the data presented in Fig. 3. These samples are obviously amorphous – semi-crystal. The ratio between the amorphous and semi-crystal phase differs. 13 th Lähnwitzseminar on Calorimetry, Interplay between Nucleation, Crystallization, and the Glass Transition, Rostock, Germany, June 15 – June 20, 2014 The data in this figure show the following: Above T g, all samples exhibit cold crystallization; The cold crystallization enthalpy varies within 18 – 25 against the enthalpy of the subsequent melting; Two overlapping melting peaks appear to exist that indicate at least two crystal phases – see also Fig. 1a. The data in Fig. 4 show nearly identical spectra of all PET specimens that imply homo- polymer chains. The important bands of FTIR spectra within 1000 – 1750 cm -1 [1-3] were analyzed. The bands which relate to the physical structure indicate both amorphous and semi- crystal structures. Analysis of the FTIR spectra Analysis of x-ray diffraction graphs Diffraction patterns of a single wide peak characteristics of the reflection correspond to the plain with a Miller index (100) for 2  of about 26 o. The data in Fig. 3 for the same samples presented below in Fig. 4 imply an amorphous – semi-crystal structure [4]. The peak height and the full width at the half of the peak maximum indicate different ratios between the semi-crystal and amorphous phase. Except the pre-forming sample 5, all tested samples in Fig. 1 were obtained from PET bottle products. The pre-forming sample 5 was established almost amorphous showing cold crystallization. The T g transition is well observed within 65 – 70 o C, especially for the amorphous pre- forming sample. a) First melting curves b) Crystallization curves The crystallization process is rather specific. In our opinion, the crystallization probably relates to the molecular weight, M w, of PET, i.e. as lower M w of PET sample, it crystallizes with higher rate at higher temperature range. The enthalpy of crystallization of sample 1 is lowest compared to that of the other samples. Sample 1 crystallizes at the lowest temperature range. c) Second melting curves Figure 1. DSC curves of the PET samples studied at dT/dt = 10 K.min -1 : a) First melting; b) Crystallization; c) Second melting Sample 1 exhibit cold crystallization after cooling at dT/dt = 10 K.min -1. In our opinion, it is the highest M w PET sample.