Improvement of water sensitivity, mechanical properties and utilization of hemicellulose based polymeric materials

Akkuş, Merve
Hemicelluloses are sustainable resources of biopolymers with a huge potential to be converted into materials substituting petroleum-based products, but their hydrophilic characteristics pose a challenge to their industrial adoption. The main aim of this study is to decrease the water sensitivity of alkaline extracted xylan-based corn cob hemicelluloses (xylans) by heat-treatment and acetylation also by addressing their extrusion processing with sorbitol, glycerol and blends. Heat-treatment resulted in extruded strips with less moisture uptake, less normalized water vapor transfer rate (NWVTR) and enhanced mechanical properties, but without any significant change in their water solubilities. Acetylation was studied by exploiting the potassium acetate (KAc) salt that is formed during the alkaline extraction, which is usually removed. Moisture uptake, water solubility, and NWVTR of KAc containing acetylated xylans decreased significantly, with an increase in mechanical properties and thermal stability, showing that acetylation with KAc is an efficient method without salt purification steps and toxic catalysts like pyridine. Extrusion of xylans with sorbitol and glycerol was studied alternative to the plasticization by moisture conditioning where both plasticizers rendered xylans extrudable. Similar to the effect of KAc, vi acetylation carried out in the presence of sorbitol and glycerol resulted in reduced water solubilities; however the mechanical properties were only enhanced for glycerol containing strips. Xylan-and-polyvinyl alcohol (PVA) blends and their heat treatment and acetylation were also studied to reduce their water sensitivity. Extrusion of xylan/PVA blends was successful which might increase the industrial utilization of xylans, but their heat treatment and acetylation resulted in brittle strips


Investigation of processing parameters on production of hemicellulose based films from different agricultural residues via extrusion
Akınalan, Büşra; Bölükbaşı, Ufuk; Özkan, Necati; Department of Chemical Engineering (2014)
Today, due to the environmental concerns about petroleum based polymers, the use of renewable polymers including polysaccharides in food packaging applications is increasing rapidly. In the present study, hemicellulose was extracted from corn cobs, wheat straw and sunflower stalks, and two different techniques, solvent casting and extrusion, were utilized for biodegradable film production. Films produced from different types of biomasses were compared in terms of their mechanical, thermal and morphological ...
Environmental transformation and nano-toxicity of engineered nano-particles (ENPs) in aquatic and terrestrial organisms
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The rapid development in nanotechnology and incorporation of engineered nano-particles (ENPs) in a wide range of consumer products releasing the massive quantities of ENPs in different environmental compartments. The released ENPs from nano-enabled products during their life cycle raising environmental health and safety issues. This review addresses the recent state of knowledge regarding the ENPs ecotoxicity to various organisms lying at different trophic levels. Studies show that reactive oxygen species (...
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...
Effects of hemicellulose extraction and extrusion parameters on the properties of hemicellulose based polymeric materials obtained from different lignocellulosic biomass
Erdemir, Duygu; Bölükbaşı, Ufuk; Özkan, Necati; Department of Chemical Engineering (2015)
There is growing interest worldwide in utilization of renewable sources for fuels, materials and chemicals due to depletion of fossil sources and the environmental damages of synthetic products. Lignocellulosic biomass is the most promising material to become a substitute for fossil sources because of its abundancy in nature, low price and utilization area which does not compete with the food. Biodegradable films can be produced from hemicellulosic part of biomass and their main use can be especially food p...
Investigation Of Influencing Factors For Biological Hydrogen Production By R. Capsulatus In Tubular Photo-Bioreactors
Boran, E.; Ozgur, E.; Gebicki, J.; van der Burg, J.; YÜCEL, MUSTAFA; Gündüz, Ufuk; Modigel, M.; Eroglu, I. (2009-05-13)
Biological hydrogen production processes are considered as an environmentally friendly way to produce hydrogen. They offer the chance to produce hydrogen from renewable energy sources, like sunlight and biomass. This study aims the process development for a photo-fermentative hydrogen production by photosynthetic purple-non-sulfur bacteria, Rhodobacter capsulatus, in a large scale (80L) tubular photo-bioreactor, in outdoor conditions, using acetate as carbon source. It was shown that Rhodobacter capsulatus ...
Citation Formats
M. Akkuş, “Improvement of water sensitivity, mechanical properties and utilization of hemicellulose based polymeric materials,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.