Show simple item record  

dc.contributor.advisorPickering, Kim L.
dc.contributor.advisorLin, Richard J.T.
dc.contributor.authorOliveira, Maria A.S.
dc.date.accessioned2022-07-20T01:34:15Z
dc.date.available2022-07-20T01:34:15Z
dc.date.issued2022
dc.identifier.urihttps://hdl.handle.net/10289/14984
dc.description.abstractThe increasing demand for rotationally moulded products highlights the necessity to develop cost-effective and sustainable materials to expand the application of such products. Natural fibres are a potential reinforcement for rotationally moulded products due to their high specific strength and stiffness. However, few attempts have been reported using natural fibres in rotational moulding. The most-reported challenges in incorporating natural fibres in this process are poor adhesion between fibre and matrix, fibre agglomeration and porosity, which require improvement. Accordingly, this research proposes methods to address these issues to increase rotationally moulded composites' tensile properties. Initially, hemp fibres were alkali-treated to improve the fibre-matrix interface along with the coupling agent, maleic anhydride polyethylene (MAPE). The effect of alkali treatment on hemp fibre was assessed by single fibre tensile testing, X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Subsequently, materials were melt-compounded and chopped into pellets of different sizes to produce rotationally moulded composites with increased fibre length and uniform fibre distribution. The porosity within the final composites was assessed using optical microscopy, Archimedes density tests and micro-CT. To mitigate porosity within these composites, additives including mineral oil, stearic acid and recycled carbon fibre were tested. Fibre orientation in optical microscopy cross-sectional images of composites produced with pellets of aspect ratio larger than 1 were assessed using ImageJ. The results showed that the alkali treatment removed the non-cellulosic components from hemp fibre, improving fibre separation, fibre resistance to thermal degradation, and fibre-matrix adhesion along with MAPE. In addition, composite pellets of up to 1.5 mm size were found suitable to produce rotationally moulded composites with increased fibre length and moderate porosity, with the addition of 3 wt.% of stearic acid. It was also observed that using pellets with an aspect ratio higher than 1 improved fibre orientation parallel to the composite mould wall, resulting in higher tensile properties than pure polyethylene. Finally, the addition of recycled carbon fibre improved the melting of composite pellets of hemp-PE which reduced the void size in the final hybrid composites. This reduction in composite porosity, combined with the high stiffness of RCF, resulted in higher tensile properties with increasing RCF content. In conclusion, this research showed innovative methods and materials to produce reinforced rotationally moulded polyethylene composites with superior strength and stiffness, and moderate porosity.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikato
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectRotational moulding
dc.subjectHemp fibre
dc.subjectComposites
dc.subject.lcshFiber-reinforced plastics -- Mechanical properties
dc.subject.lcshPolymeric composites -- Mechanical properties
dc.subject.lcshHemp -- Processing
dc.subject.lcshFibrous composites -- Mechanical properties
dc.subject.lcshRotational molding of plastics
dc.subject.lcshFiber-reinforced plastics -- Microscopy
dc.subject.lcshPorosity
dc.subject.lcshInjection molding of plastics
dc.subject.lcshPolyethylene -- Mechanical properties
dc.titleRotationally moulded polyethylene reinforced with alkali treated hemp fibre
dc.typeThesis
thesis.degree.grantorThe University of Waikato
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (PhD)
dc.date.updated2022-07-04T06:25:43Z
pubs.place-of-publicationHamilton, New Zealanden_NZ


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record