Three dimensional (3D) printing of bio-polymers from agricultural wastes

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2022-8-8
Bahçegül, Eylül Gökçe
Lignocellulosic biomass, which is a composite structure made up of cellulose, hemicellulose and lignin biopolymers, is the most abundant biopolymer resource on earth. Among the biopolymers found in lignocellulosic agricultural wastes, hemicellulose and lignin receive significantly less attention compared to cellulose for material applications despite the fact that these two biopolymers constitute almost a half of a given biomass. In this context, three novel strategies were developed that render hemicellulose and lignin 3D printable. Corn cobs (CCs) were used as the lignocellulosic resource in which hemicellulosic pastes and CC extracts in the form of thermoreversible cold-setting gels with different formulations were obtained following different extraction approaches and parameters. Water and NaOH contents as well as the extraction parameters such as KOH concentration coupled to the correct 3D printing parameters including printing temperature and speed, extrusion multiplier and layer height was the key to render the pastes and extracts 3D printable. Hemicelluloses containing lignin were rendered 3D printable for the first time without any chemical modifications and without using auxiliary polymers or additives by determining the very narrow process window that enables 3D printability. A blending strategy that relies on thermoplasticity, which involves mixing hemicellulose and lignin with polyvinyl alcohol via solvent casting, was also developed in order to obtain filaments for 3D printing, which allow for the 3D printing of more complex shapes. Thermal, mechanical, chemical, complex and apparent viscosities, morphological and printability properties of the polymers and the 3D printed materials were characterized by different methods.

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Citation Formats
E. G. Bahçegül, “Three dimensional (3D) printing of bio-polymers from agricultural wastes,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.