title: Processing of Hemp Fibre Using Enzyme/Fungal Treatment for Composites

authors: Li, Yan

subjects: Fibre

abstract: Hemp fibres compete very well with glass fibres in terms of their specific strength and stiffness and so can replace glass fibres as reinforcement in composites. Combining them with thermoplastics results in potentially cheap recyclable composite materials. The adhesion between the hemp fibre and thermoplastics such as polypropylene is a major factor in the mechanical properties of the composite. Interfacial bonding can be improved by modifications to the fibres, the matrix or both the fibres and the matrix. The aim of this thesis was to investigate low cost and efficient fibre treatment methods with low environmental impact such as bag retting and white rot fungi, and chelator/enzyme treatments which could be applied to hemp fibre in order to create better bonding fibre for potentially recyclable composite materials. 
	
Bag retting was carried out by keeping fresh green hemp fibres in a sealed plastic bag for 1 to 2 weeks to allow natural retting to occur under sealed conditions. For white rot fungi treatments, the dried non-retted hemp fibres were gamma irradiated, and then inoculated with white rot fungi for 2 weeks. Chelator/enzyme treatment was achieved by immersing the fresh green non-retted hemp fibres in solutions consisting of either EDTMP.Na5 (ethylene diamine tetra (methylene phosphonic acid pentasodium salt) or pectinase (P2401) and laccase (53739) for 6 hours.

Several characterization techniques, namely wet chemical analysis, Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), fibre density testing, X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TGA), zeta potential and single fibre tensile testing were used to assess the effect of treatment on hemp fibres. Wet chemical analysis and FT-IR, were used to measure the chemical compounds present in untreated and treated hemp fibres and showed all treatments removed non-cellulosic compounds from hemp fibre. The separation of untreated and treated fibres was investigated by visual inspection. An examination of surface morphology of hemp fibres carried out using SEM revealed that all treated fibres had cleaner hemp surfaces than untreated ones. The fibre density testing showed that the treated fibre had higher density than untreated fibre. XRD was carried out to assess modification of the crystallinity of fibres and the results showed hemp fibre crystallinity index increased in all treated fibres. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were used to obtain the activation energies and relative thermal stability of fibres, and indicated that all treatments improved fibre thermal stability. Zeta potential indicated that all treated fibres were more hydrophilic than untreated fibre. Single fibre tensile testing was used to obtain the tensile strength of untreated and treated fibres and it was found that the tensile strength of all treated fibres was reduced.

Short fibre composites were produced by extrusion and injection moulding. Fibres, polypropylene (PP) and a maleated polypropylene (MAPP) coupling agent were compounded using a twin-screw extruder, and then injection moulded into composite tensile test specimens. It was found that all fibre treatments increased the tensile strength of composites. White rot fungi Schizophyllum commune (S.com) treated fibre gave the highest tensile strength of 45 MPa, an increase of 28% compared to composites using untreated fibre. Both the single fibre pull-out test and the Bowyer and Bader model were used to determine the interfacial shear strength (IFSS) of untreated fibre and S.com treated fibre composites. The results obtained from both methods showed that IFSS of the treated fibre composites was higher than that for untreated fibre composites. This supports that the hemp fibre interfacial bonding with PP was improved by white rot fungi treatment. The Bowyer and Bader model was also used to calculate the tensile strength of untreated and S.com treated short fibre composites and results closely match the experimentally values.

text: Processing of Hemp Fibre Using Enzyme/Fungal Treatment for Composites Hemp fibres compete very well with glass fibres in terms of their specific strength and stiffness and so can replace glass fibres as reinforcement in composites. Combining them with thermoplastics results in potentially cheap recyclable composite materials. The adhesion between the hemp fibre and thermoplastics such as polypropylene is a major factor in the mechanical properties of the composite. Interfacial bonding can be improved by modifications to the fibres, the matrix or both the fibres and the matrix. The aim of this thesis was to investigate low cost and efficient fibre treatment methods with low environmental impact such as bag retting and white rot fungi, and chelator/enzyme treatments which could be applied to hemp fibre in order to create better bonding fibre for potentially recyclable composite materials. 
	
Bag retting was carried out by keeping fresh green hemp fibres in a sealed plastic bag for 1 to 2 weeks to allow natural retting to occur under sealed conditions. For white rot fungi treatments, the dried non-retted hemp fibres were gamma irradiated, and then inoculated with white rot fungi for 2 weeks. Chelator/enzyme treatment was achieved by immersing the fresh green non-retted hemp fibres in solutions consisting of either EDTMP.Na5 (ethylene diamine tetra (methylene phosphonic acid pentasodium salt) or pectinase (P2401) and laccase (53739) for 6 hours.

Several characterization techniques, namely wet chemical analysis, Fourier-transform infrared (FT-IR), scanning electron microscopy (SEM), fibre density testing, X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TGA), zeta potential and single fibre tensile testing were used to assess the effect of treatment on hemp fibres. Wet chemical analysis and FT-IR, were used to measure the chemical compounds present in untreated and treated hemp fibres and showed all treatments removed non-cellulosic compounds from hemp fibre. The separation of untreated and treated fibres was investigated by visual inspection. An examination of surface morphology of hemp fibres carried out using SEM revealed that all treated fibres had cleaner hemp surfaces than untreated ones. The fibre density testing showed that the treated fibre had higher density than untreated fibre. XRD was carried out to assess modification of the crystallinity of fibres and the results showed hemp fibre crystallinity index increased in all treated fibres. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were used to obtain the activation energies and relative thermal stability of fibres, and indicated that all treatments improved fibre thermal stability. Zeta potential indicated that all treated fibres were more hydrophilic than untreated fibre. Single fibre tensile testing was used to obtain the tensile strength of untreated and treated fibres and it was found that the tensile strength of all treated fibres was reduced.

Short fibre composites were produced by extrusion and injection moulding. Fibres, polypropylene (PP) and a maleated polypropylene (MAPP) coupling agent were compounded using a twin-screw extruder, and then injection moulded into composite tensile test specimens. It was found that all fibre treatments increased the tensile strength of composites. White rot fungi Schizophyllum commune (S.com) treated fibre gave the highest tensile strength of 45 MPa, an increase of 28% compared to composites using untreated fibre. Both the single fibre pull-out test and the Bowyer and Bader model were used to determine the interfacial shear strength (IFSS) of untreated fibre and S.com treated fibre composites. The results obtained from both methods showed that IFSS of the treated fibre composites was higher than that for untreated fibre composites. This supports that the hemp fibre interfacial bonding with PP was improved by white rot fungi treatment. The Bowyer and Bader model was also used to calculate the tensile strength of untreated and S.com treated short fibre composites and results closely match the experimentally values.

year: 2009

title: Environmental and biogeographical drivers of the Leptospermum scoparium (mānuka) phyllosphere microbiome

authors: Noble, Anya Sophia

subjects: phyllosphere

abstract: A substantial body of research exists on the physiology and genetics of Leptospermum scoparium (mānuka); however, the mānuka phyllosphere has not yet been investigated. This research, therefore, provides the first exploration of the bacterial communities comprising the mānuka phyllosphere. In total, 89 samples were collected from five native mānuka forests during the November 2016 – January 2017 mānuka flowering season, and examined alongside spatial, environmental, and host-tree related metadata. Cultivation-independent methods, including DNA extraction and 16S rRNA gene PCR amplicon sequencing analysis, were used to characterise phyllosphere communities. Using a combination of statistical tests, the BLAST algorithm, and a PICRUSt analysis, a habitat-specific core microbiome comprising members of Acidobacteria, Alphaproteobacteria, Bacteroidetes, and Verrucomicrobia, was present in all samples. Distinct microbial biogeographical patterning was also identified in the mānuka phyllosphere whereby spatially structured gradients in environmental variables, such as temperature and precipitation, correlated with bacterial community structure.  The results from this study provide new insight pertaining to the structure, composition, and driving factors of the bacterial communities of the mānuka phyllosphere and shed light on theories of microbial ecology, such as microbial biogeography and core microbiomes. This research has the potential to open new avenues in both mānuka and microbial ecology fields of investigation within New Zealand.

text: Environmental and biogeographical drivers of the Leptospermum scoparium (mānuka) phyllosphere microbiome A substantial body of research exists on the physiology and genetics of Leptospermum scoparium (mānuka); however, the mānuka phyllosphere has not yet been investigated. This research, therefore, provides the first exploration of the bacterial communities comprising the mānuka phyllosphere. In total, 89 samples were collected from five native mānuka forests during the November 2016 – January 2017 mānuka flowering season, and examined alongside spatial, environmental, and host-tree related metadata. Cultivation-independent methods, including DNA extraction and 16S rRNA gene PCR amplicon sequencing analysis, were used to characterise phyllosphere communities. Using a combination of statistical tests, the BLAST algorithm, and a PICRUSt analysis, a habitat-specific core microbiome comprising members of Acidobacteria, Alphaproteobacteria, Bacteroidetes, and Verrucomicrobia, was present in all samples. Distinct microbial biogeographical patterning was also identified in the mānuka phyllosphere whereby spatially structured gradients in environmental variables, such as temperature and precipitation, correlated with bacterial community structure.  The results from this study provide new insight pertaining to the structure, composition, and driving factors of the bacterial communities of the mānuka phyllosphere and shed light on theories of microbial ecology, such as microbial biogeography and core microbiomes. This research has the potential to open new avenues in both mānuka and microbial ecology fields of investigation within New Zealand.

year: 2018

title: Māori cultural definitions of sexual violence.

authors: Pihama, Leonie

abstract: Exploring definitions of sexual violence in Aotearoa highlights that on the whole such definitions are located within dominant Pākehā frameworks that do not provide adequately for understanding the context of sexual violence for Māori. As such Māori working in the area of healing the trauma of sexual violence have been developing frameworks which are enabling of culturally defined understandings and traditional knowledge as a basis by which to understand sexual violence in Aotearoa. Informed by te reo and tikanga Māori (Māori language and culture) Māori healers, social workers and health providers have moved beyond western definitions and have highlighted the link between acts of sexual violence and the violence of colonial invasion. This article explores Māori perspectives of the origins and impacts of sexual violence for Māori and advocates for Kaupapa Māori and decolonising approaches to be more fully supported and engaged in dealing with these issues within our communities.

text: Māori cultural definitions of sexual violence. Exploring definitions of sexual violence in Aotearoa highlights that on the whole such definitions are located within dominant Pākehā frameworks that do not provide adequately for understanding the context of sexual violence for Māori. As such Māori working in the area of healing the trauma of sexual violence have been developing frameworks which are enabling of culturally defined understandings and traditional knowledge as a basis by which to understand sexual violence in Aotearoa. Informed by te reo and tikanga Māori (Māori language and culture) Māori healers, social workers and health providers have moved beyond western definitions and have highlighted the link between acts of sexual violence and the violence of colonial invasion. This article explores Māori perspectives of the origins and impacts of sexual violence for Māori and advocates for Kaupapa Māori and decolonising approaches to be more fully supported and engaged in dealing with these issues within our communities.

year: 2016