The Development of Novel Biocomposites from Waste Derived Biochar

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dc.contributor.advisor Bhattacharyya, D en
dc.contributor.advisor Shamseldin, A en Das, Oisik en 2017-11-07T20:27:31Z en 2017 en
dc.identifier.uri en
dc.description.abstract Sustainability and safety along with acceptable mechanical properties are the cornerstones for the development of contemporary industrial products. Due to this, polymer composites are manufactured with bio-based materials instead of synthetics. However, these 'biocomposites' often lack the required mechanical properties and are also very susceptible to fire. This necessitates the application of new bio-based materials which are inherently robust, resistant to fire and promote utilisation of wastes. Besides, the amount of organic wastes in New Zealand would be about 7 million metric tonnes by 2020 and if not managed effectively, these wastes would contaminate the air, land, and water. Therefore, it is critical to reduce, reuse, and recycle these wastes to curb pollution, save energy, and conserve resources. These organic wastes could be converted into a carbon-based porous solid material called 'biochar' through the process of pyrolysis (i.e. heating at high temperatures without oxygen). Conventionally the distinct properties of biochar are mostly used for filtration, contaminant removal, and soil amendment. Hence, to simultaneously impart versatility in biochar's application and create a new product, this research attempted to manufacture biochar based biocomposites. It was envisaged that the addition of biochar in composites would enhance certain properties while reducing the synthetic polymer content, concurrently. Initially, suitable manufacturing conditions (both process and material) were attempted to be identified. Polypropylene (PP) based composites were manufactured through the processes of compounding and compression moulding with numerous loading amounts of biochar. A loading amount of 24 wt% was found to be the most desirable for enhanced mechanical properties. After that, the material properties of six diverse waste-derived biochars were analysed using the technique of nanoindentation among others. The hardness and modulus of the high temperature biochar (made at 900°C) were determined to be 4.3 and 25 GPa, respectively, which also produced composites with desirable mechanical properties. In addition, it was observed that nanoindentation of individual constituents could be used to predict the bulk mechanical properties of the composites. Following this, an attempt was made to find suitable bio-based reinforcements (for biochar based composites) and measure the fire performance (also mechanical) of the resulting composites. The wood based composite was found to possess the best balance between mechanical and fire properties among the other biomasses. Two different fire retardants (ammonium polyphosphate and magnesium hydroxide) were applied to composites made from the most suitable type and loading amount of biochar (made at 900°C and 24 wt%, respectively) and biomass (wood). The amounts of biochar and the wood were varied to accommodate each of the fire retardants. As expected it was seen that having more biochar than wood was beneficial for fire properties (e.g. peak heat release rates, limiting oxygen indices). However, the higher proportion of biochar (than wood) compromised the mechanical properties of the composites albeit not significantly. The production costs were reduced by a significant 18 % when biochar was added to the composites. This is because the amount of costly coupling agent (here maleic anhydride grafted polypropylene) in the composite could be reduced from usual 3 wt% to 1wt %, in conjunction with biochar, without compromising the performance properties (both mechanical and fire). Finally, the pure effect of just biochar on PP was investigated wherein it was observed that that increasing amount of biochar enhanced the tensile/flexural moduli and flexural strengths of the resulting composites. Furthermore, the peak heat release rates were decreased and the amount of thermal residues increased as a result of biochar application in the composites. This PhD research has demonstrated that wastes can be converted into a value-added product of biochar whose application in polymeric composites makes them stronger, more fire resistant, cheaper, and can simultaneously promote sustainability. Therefore, biochar being inexpensive, renewable, and having attractive physical properties aptly fits into the paradigm for new industrial, economic, and social development where it can be used to both mitigate wastes and create novel and improved composite products. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99265049314102091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri en
dc.title The Development of Novel Biocomposites from Waste Derived Biochar en
dc.type Thesis en Civil Engineering en The University of Auckland en Doctoral en PhD en
dc.rights.holder Copyright: The author en
dc.rights.accessrights en
pubs.elements-id 708793 en
pubs.record-created-at-source-date 2017-11-08 en

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