Biodegradation of Polylactide and Gelatinized Starch Blend Films Under Controlled Soil Burial Conditions
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ORIGINAL PAPER
Biodegradation of Polylactide and Gelatinized Starch Blend Films Under Controlled Soil Burial Conditions Worasak Phetwarotai • Pranut Potiyaraj Duangdao Aht-Ong
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Published online: 18 August 2012 Ó Springer Science+Business Media, LLC 2012
Abstract The biodegradability of polylactide (PLA) and gelatinized starches (GS) blend films in the presence of compatibilizer was investigated under controlled soil burial conditions. Various contents (0–40 wt%) of corn and tapioca starches were added as fillers; whereas, different amounts of methylenediphenyl diisocyanate (MDI) (0–2.5 wt%) and 10 wt% based on PLA content of polyethylene glycol 400 (PEG400) were used as a compatibilizer and a plasticizer, respectively. The biodegradation process was followed by measuring changes in the physical appearance, weight loss, morphological studies, and tensile properties of the blend films. The results showed that the presence of small amount of MDI significantly increased the tensile properties of the blends compared with the uncompatibilized blends. This is attributed to an improvement of the interfacial interaction between PLA and GS phases, as evidenced by the morphological results. For soil burial testing, PLA/GS films with lower levels (1.25 wt%) of MDI had less degradation; in contrast, at high level of MDI, their changes of physical appearance and weight loss tended to increase. These effects are in agreement with their water absorption results. Furthermore, biodegradation rates of the films were enhanced with increasing starch contents, while mechanical performances were decreased. Keywords Polylactide Starch Blend Film Biodegradation W. Phetwarotai P. Potiyaraj D. Aht-Ong (&) Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand e-mail: [email protected] W. Phetwarotai P. Potiyaraj D. Aht-Ong Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330, Thailand
Introduction In last decades, biodegradable plastics have attracted much interest in several applications e.g. medical implants, drugdelivery systems, and agricultural industries, etc. due to their biodegradability, biocompatibility, and no toxicity [1–4]. The most important biodegradable polymer is aliphatic polyesters e.g. poly(e-caprolactone) (PCL), poly(3-hydroxybutyrate) (PHB), polyethylene oxide (PEO), polyglycolic acid, especially poly(lactic acid) (PLA) [5–7]. PLA is a linear aliphatic polyester, produced by ring-opening polymerization of lactides and direct condensation of lactic acid monomers which are obtained from the fermentation of sugar feed stocks [8, 9]. PLA is comparable to poly(ethylene terephthalate) (PET) in many properties such as highly transparent and rigid material. In addition, PLA exhibits high mechanical properties and good barrier properties to aromas, including the permeability to carbon dioxide, oxygen, and water vapor [10]. However, PLA is still expensive for disposable materials like plastic bag or film pac
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