Engineering of novel cellulose-based biocomposites and biofoams

G5 Doctoral dissertation (article)


Internal Authors/Editors


Publication Details

List of Authors: Jasmina Obradovic
Publisher: Åbo Akademi University
Place: Turku
Publication year: 2017
ISBN: 978-952-12-3635-8
eISBN: 978-952-12-3636-5


Abstract

Biomass is a renewable feedstock for producing fine chemicals, polymers, energy, and a variety of commodities. Transformation of biomass into diverse valuable products is the key concept of a bioeconomy. Chemical and mechanical conversion of biomass, which reduces the use of toxic chemicals is one of the important approaches to improve the profitability of bioeconomy. Utilization of green materials under environmentally-friendly conditions, was the main goal of this research.

Wood fibres were converted into cellulose-based 3D objects through swelling of cellulose fibres in an N,N-dimethylacetamide and lithium chloride solvent system followed by a moulding step. Swollen cellulose pulp in the form of gel was solidified with two different anti-solvents. The choice of solidification solvent had a great influence on the structure and mechanical properties of the final cellulose material which was studied with x-ray diffraction and nanoindentation technique. The mechanical properties and optical properties of solid swollen cellulose fibres can be significantly increased with forging technique.

Bio-based composite materials composed of a mixture of shellac resin and cellulose fibres were developed. The influence of the reinforcement content and the concentration of additives on the mechanical performance and processing were investigated. A high amount of cellulose and low concentrations of ethanol and polyethylene glycol produced bio-based composites with high stress resistance, while a low amount of cellulose and high concentration of additives provided specimens with an increased elasticity.

Acrylated epoxidized soybean oil and variable amounts of wood fibres were used in a production of bio-based foam. The developed macroporous polymers were characterized by several techniques, including porosity measurements, nanoindentation testing, scanning electron microscopy and thermogravimetric analysis. It was found that the introduction of pulp fibres during the foaming process was necessary to create the polymer foams. Cellulose fibres behaved as foam stabilizer while simultaneously acting as reinforcing agent in the polymer foam.


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