The Effects of type and amount of organically modified montmorillonites on thermal degradation behavior and mechanical properties of poly(lactic acid)

Özdemir, Esra
Biodegradable polymers have gained considerable interest as a consequence of significant environmental friendly properties like biocompatibility and ability to synthesis from renewable resources. Even though many biodegradable polymers present comparable properties with petrochemical polymers, there are still many technical barriers like poor thermal resistance, and/or mechanical properties. To overcome these drawbacks, generally, nano-sized materials are incorporated into the continuous matrix. Therefore, in this work, the effects of montmorillonites on thermal and mechanical properties of polylactide were examined. Poly(lactic acid) (PLA) and organically modified montmorillonite (commercially named as Cloisite 15A, Cloisite 20A and Cloisite 30B) nanocomposites were prepared by solution and melt mixing. Morphological characterization studies were conducted by X-ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses. When XRD and TEM results were evaluated together, it was concluded that exfoliated and intercalated polymer nanocomposites were produced by melt blending. Although SEM images of solution mixed samples showed well dispersion of nanoclays through PLA matrix, big tactoids were also detected. Thermal properties were examined with various techniques involving Thermogravimeter (TGA), Differential Scanning Calorimeter (DSC) and Direct Pyrolysis Mass Spectrometer (DP-MS). After the incorporation of the clays, thermal degradation of PLA shifted noticeably to lower temperatures for solution mixed samples and shifted to higher temperatures for melt-extruded nanocomposites. The crystallinity behavior and melting point of PLA were also changed due to the nucleation effects of clays. Also, thermal degradation mechanisms of melt mixed nanocomposites were investigated by DP-MS and it was observed that the relative yields of products due to trans-esterification and cis-elimination reactions were increased. For nanocomposite with Cloisite 30B, the relative yields of the products generated by cis-elimination reactions were more pronounced which were associated with the reaction between organic modifier of Cloisite 30B and PLA. Also, it was deduced that in general presence of nanoclays only slightly affected the mechanical properties of melt mixed nanocomposites.


Preparation of antimicrobial films from agricultural biomass
Seber, Ayşe Gizem; Bakır, Ufuk; Department of Biotechnology (2010)
Mainly used food packaging materials are petro-chemical based polymers which present environmental problems since they are not biodegradable and ecologically sustainable. In this study, biodegradable biofilms are produced from xylan, extracted from cotton stalk which is an agricultural biowaste without nutritional value. Antimicrobial property was given to the biofilms with either titanium dioxide sol-gel coatings or titanium dioxide powder addition into the biofilm forming solutions. The antimicrobial acti...
The use of nuclear techniques in source apportionment studies, exemplified by recent studies in Turkey
GÜLLÜ, GÜLEN; Tuncel, Süleyman Gürdal (2004-01-01)
Nuclear analytical methods are very important atmospheric tools as they provide multielement data, which is essential for receptor modeling. In this study, the application of receptor modeling is discussed on rural data to determine source regions affecting chemical composition of aerosols in the Eastern Mediterranean. The factor analysis revealed 4 sources, two of which represent anthropogenic component in aerosol mass. The source regions that determine the composition of particles is investigated using tr...
The effects of emulsifier type, phase ratio, and homogenization methods on stability of the double emulsion
YILDIRIM, Merve; Şümnü, Servet Gülüm; Şahin, Serpil (Informa UK Limited, 2017-01-01)
The double emulsion technology has a potential effect on the development of diversity and quality of functional foods by means of decreasing oil or salt concentration, encapsulating and controlling release of valuable components. In this study, it was aimed to formulate stable double emulsions to be used in food systems. W1/O ratios of primary emulsions, stabilized by polyglycerol polyricinoleate (PGPR), were designed as 2:8 and 4:6, and (W1/O)/W2 ratios of the double emulsions were used as 2:8 and 4:6. W/O...
The influence of nutrient loading, climate and water depth on nitrogen and phosphorus loss in shallow lakes: a pan-European mesocosm experiment
Coppens, Jan; Hejzlar, Josef; Sorf, Michal; Jeppesen, Erik; Erdogan, Aeyda; Scharfenberger, Ulrike; Mahdy, Aldoushy; Noges, Peeter; Tuvikene, Arvo; Baho, Didier L.; Trigal, Cristina; Papastergiadou, Eva; Stefanidis, Kostas; Olsen, Saara; Beklioğlu, Meryem (2016-09-01)
Losses of phosphorus (P) and nitrogen (N) have important influences on in-lake concentrations and nutrient loading to downstream ecosystems. We performed a series of mesocosm experiments along a latitudinal gradient from Sweden to Greece to investigate the factors influencing N and P loss under different climatic conditions. In six countries, a standardised mesocosm experiment with two water depths and two nutrient levels was conducted concurrently between May and November 2011. Our results showed external ...
Film fabrication using corncob as lignocellulosic biomass
Ergün, Eylül Gökçe; Çulfaz Emecen, Pınar Zeynep; Bölükbaşı, Ufuk; Department of Chemical Engineering (2014)
Renewable biopolymer resource, lignocellulosic biomass, has emerged as an alternative raw material to petroleum-based resources for the sustainable production of materials, fuels and chemicals. In this study, the main focus was to constitute a novel and eco-friendly process to fabricate films from low value lignocellulosic agricultural residues in the absence of any additional film-forming compounds. In this scope, raw lignocellulosic biomass, namely corn cobs, was turned into films using the ionic liquid 1...
Citation Formats
E. Özdemir, “The Effects of type and amount of organically modified montmorillonites on thermal degradation behavior and mechanical properties of poly(lactic acid),” M.S. - Master of Science, Middle East Technical University, 2014.