Material behaviour Influence of various starch types on PCL/starch blends anaerobic biodegradation Jitka Hubackova a , Marie Dvorackova a , Petr Svoboda b, d, * , Pavel Mokrejs b, d , Jan Kupec a , Iva Pozarova a , Pavol Alexy e , Peter Bugaj e , Michal Machovsky c , Marek Koutny a, d a Department of Environmental Engineering, Faculty of Technology, Tomas Bata University in Zlín, Nam. TGM 275, 762 72 Zlin, Czech Republic b Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. TGM 275, 762 72 Zlin, Czech Republic c Polymer Centre, Faculty of Technology, Tomas Bata University in Zlín, Nam. TGM 275, 762 72 Zlin, Czech Republic d Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 01 Zlin, Czech Republic e Department of Plastics and Rubber, Institute of Polymer Materials, Slovak University of Technology, Radlinského 9, 812 37 Bratislava 1, Slovak Republic article info Article history: Received 10 April 2013 Accepted 21 May 2013 Keywords: Poly( 3 -caprolactone) Starch Anaerobic biodegradation SEM Mechanical properties abstract Research concentrated on the biodegradable capability of PCL blends with various types of starch in an anaerobic aqueous environment of mesophilic sludge from a municipal wastewater treatment plant. For blend preparation, use was made of a native starch Meritena from maize, another from Waxy – a genetically modified type of maize, as well as Gel Instant, a gelatinized starch, and an amaranth starch. Additional PCL/starch blends were prepared from the same starch types, but these were initially plasticized with glycerol. The biodegradability tests were supplemented with thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC); morphology was identified using scanning elec- tron microscopy (SEM), plus mechanical properties were also tested. While mixtures of PCL with starches plasticized with glycerol exhibited improved mechanical properties and a higher degree of biodegradation in the anaerobic environment, mixtures of PCL with pure forms of starch were ascertained as rather resistant to the anaerobic aqueous envi- ronment. TGA and DSC analysis confirmed the removal of starch and glycerol from the PCL matrix. SEM then proved these results through the absence of starch grains in the samples following anaerobic biodegradation. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction In recent years, production of biodegradable polymers has become ever more popular, these finding application mainly in medicine, packaging technology and agriculture. After reaching the end of their life, the materials are much more susceptible to external influences than conventional plastics. Biodegradable materials, along with other organic substances, such as organic residues, can then form suitable matter for activities like composting or the anaerobic treatment of waste (fermentation). While the biodegrad- ability of such materials in an aerobic environment has been extensively explored, their anaerobic biodegradability has not been given sufficient attention. Polycaprolactone (PCL) is biodegradable synthetic polymer that is currently used in controlled drug release systems as well as in other medical applications [1]. For improving further the processing and mechanical proper- ties, PCL is usually modified by blending with resins or * Corresponding author. Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. TGM 275, 762 72 Zlin, Czech Republic. Tel.: þ420 576 031 335; fax: þ420 577 210 172. E-mail address: svoboda@ft.utb.cz (P. Svoboda). Contents lists available at SciVerse ScienceDirect Polymer Testing journal homepage: www.elsevier.com/locate/polytest 0142-9418/$ – see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.polymertesting.2013.05.008 Polymer Testing 32 (2013) 1011–1019