title: Evaluation of composite laminates interleaved with nanofibre and microfibre veils.

authors: Collins-Gargan, Rosalie

abstract: The research covered in this thesis aimed to investigate the use of nanofibre and microfibre veils in carbon fibre reinforced composites and assessed the potential of the veils to improve damage resistance during impact and fatigue loading. It was hypothesised that the interleavings would increase the amount of energy required for crack propagation because of toughening due to fibre reinforcement mechanisms such as crack deflection, fibre pull out and fibre breakage. The work was undertaken as a combined project between the University of Waikato (Hamilton, New Zealand) and Revolution Fibres Ltd (Auckland, New Zealand). 
During this investigation, six thermoplastic polymers were chosen (acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polystyrene (PS), chlorinated polyvinyl chloride (CPVC), polymethyl methacrylate (PMMA) and polycarbonate (PC)) that could potentially be used for the electrospinning of polymer nanofibre veils. Nanofibre veils were successfully produced from PMMA, and a polymer blend of polyamide 6,6 (PA6,6) and PMMA, (referred to as 'nanoNyplex'). These veils, along with three other nanofibre veils (nanoPA6,6, poly vinyl butyral (nanoPVB), and poly ether sulfone (nanoPES)), three microfibre veils (polyphenylene sulfide (microPPS), polyetherimide (microPEI), and woven polyamide 6 (microtricot)) procured from other manufacturers, and three veils combining one of the nanofibre veils with each of the microfibre veils (microPPSnanoPA6,6, microPEInanoPA6,6, and microtricotnanoPA6,6) were then used as interleaves in the manufacture of carbon fibre reinforced epoxy composite panels. Interleaves were placed between every ply of prepreg. After curing the panels, test specimens were created to assess fatigue, vibration damping and compression after impact performance.
From the vibration damping study, it was found that the nanoNyplex interleaving improved damping the most. It was thought that energy dissipation was due friction brought about by the movement of the interleaving fibres in the matrix, resulting in friction due to weak adhesion between the nanoNyplex fibres and the epoxy matrix.
From the compression after impact (CAI) section of this study, it was found that specimens interleaved with nanoPA6,6, microPPS and microPPSnanoPA6,6 had the highest CAI strengths. From optical inspection, it appeared (in general) that as the CAI strength of the specimen increased, the length of the damage region also increased. However, those identified with the highest CAI strengths had shorter damage regions.
From the fatigue section of this study, it was found that the use of most interleavings, (apart from microtricot) increased the number of cycles to failure. Post fatigue test scanning electron microscopy confirmed that crack deflection was present for most interleaved specimens. Some evidence of pull out and breakage of the interleaving fibres was seen on the fracture surfaces of the nanoPA6,6, microPPS, microPEI, microPEInanoPA6,6 and microPPSnanoPA6,6 interleaved specimens.
For both CAI and fatigue, it was found that improvement was generally greater with veils that had a large number of fibres per unit area and high adhesion strength with the matrix. However, for CAI it seems that high fracture toughness was also desirable.

text: Evaluation of composite laminates interleaved with nanofibre and microfibre veils. The research covered in this thesis aimed to investigate the use of nanofibre and microfibre veils in carbon fibre reinforced composites and assessed the potential of the veils to improve damage resistance during impact and fatigue loading. It was hypothesised that the interleavings would increase the amount of energy required for crack propagation because of toughening due to fibre reinforcement mechanisms such as crack deflection, fibre pull out and fibre breakage. The work was undertaken as a combined project between the University of Waikato (Hamilton, New Zealand) and Revolution Fibres Ltd (Auckland, New Zealand). 
During this investigation, six thermoplastic polymers were chosen (acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polystyrene (PS), chlorinated polyvinyl chloride (CPVC), polymethyl methacrylate (PMMA) and polycarbonate (PC)) that could potentially be used for the electrospinning of polymer nanofibre veils. Nanofibre veils were successfully produced from PMMA, and a polymer blend of polyamide 6,6 (PA6,6) and PMMA, (referred to as 'nanoNyplex'). These veils, along with three other nanofibre veils (nanoPA6,6, poly vinyl butyral (nanoPVB), and poly ether sulfone (nanoPES)), three microfibre veils (polyphenylene sulfide (microPPS), polyetherimide (microPEI), and woven polyamide 6 (microtricot)) procured from other manufacturers, and three veils combining one of the nanofibre veils with each of the microfibre veils (microPPSnanoPA6,6, microPEInanoPA6,6, and microtricotnanoPA6,6) were then used as interleaves in the manufacture of carbon fibre reinforced epoxy composite panels. Interleaves were placed between every ply of prepreg. After curing the panels, test specimens were created to assess fatigue, vibration damping and compression after impact performance.
From the vibration damping study, it was found that the nanoNyplex interleaving improved damping the most. It was thought that energy dissipation was due friction brought about by the movement of the interleaving fibres in the matrix, resulting in friction due to weak adhesion between the nanoNyplex fibres and the epoxy matrix.
From the compression after impact (CAI) section of this study, it was found that specimens interleaved with nanoPA6,6, microPPS and microPPSnanoPA6,6 had the highest CAI strengths. From optical inspection, it appeared (in general) that as the CAI strength of the specimen increased, the length of the damage region also increased. However, those identified with the highest CAI strengths had shorter damage regions.
From the fatigue section of this study, it was found that the use of most interleavings, (apart from microtricot) increased the number of cycles to failure. Post fatigue test scanning electron microscopy confirmed that crack deflection was present for most interleaved specimens. Some evidence of pull out and breakage of the interleaving fibres was seen on the fracture surfaces of the nanoPA6,6, microPPS, microPEI, microPEInanoPA6,6 and microPPSnanoPA6,6 interleaved specimens.
For both CAI and fatigue, it was found that improvement was generally greater with veils that had a large number of fibres per unit area and high adhesion strength with the matrix. However, for CAI it seems that high fracture toughness was also desirable.

year: 2015

title: The characterisation of a thermostable endo-β-1,4-mannanase cloned from “Caldocellum saccharolyticum”

authors: Bicho, Paul A.

subjects: biology

abstract: An endo-gb-1,4-mannanase cloned from  caldocellum saccharolyticum  and expressed in Escherichia coli was partially purified. The purification involved heat treatment, anion exchange and gel filtration. The mannanase was only active against mannan, glucomannans and galactoglucomannans and obeyed Michaelis-Menten kinetics on these substrates. The rate and extent of hydrolysis was dependent on the type of substrate. Galactomannans were not as readily depolymerized as the mannan and glucomannans investigated. The glucose content of the glucomannans did not affect the rate of hydrolysis and only slightly affected the extent. The molecular mass of the mannanase was estimated at 39 kDa. The pH and temperature optima were 6.5 and 80° C respectively. The mannanase was very thermostable with a half life of 48 min at 85° C and no loss in activity after 24 h at 70° C.

text: The characterisation of a thermostable endo-β-1,4-mannanase cloned from “Caldocellum saccharolyticum” An endo-gb-1,4-mannanase cloned from  caldocellum saccharolyticum  and expressed in Escherichia coli was partially purified. The purification involved heat treatment, anion exchange and gel filtration. The mannanase was only active against mannan, glucomannans and galactoglucomannans and obeyed Michaelis-Menten kinetics on these substrates. The rate and extent of hydrolysis was dependent on the type of substrate. Galactomannans were not as readily depolymerized as the mannan and glucomannans investigated. The glucose content of the glucomannans did not affect the rate of hydrolysis and only slightly affected the extent. The molecular mass of the mannanase was estimated at 39 kDa. The pH and temperature optima were 6.5 and 80° C respectively. The mannanase was very thermostable with a half life of 48 min at 85° C and no loss in activity after 24 h at 70° C.

year: 1991

title: Housing, mental health, and homelessness: Exploring lived experiences of homelessness to identify barriers to sustainable housing for vulnerable populations

authors: Cresswell, Caitlin Grace

subjects: Homelessness

abstract: Homelessness has become a much talked about topic in Aotearoa New Zealand in 2018 and the preceding years. This thesis explores the experiences of five people who have mental illness and have lived experience of homelessness in Aotearoa New Zealand, and two staff members who work closely with people who experience both mental illness and homelessness. The theoretical frameworks that inform this thesis are narrative research, social constructionism and humanistic psychology. Particular attention was paid to using theoretical frameworks and interview methods that suited Māori (the indigenous population of Aotearoa New Zealand) due to the inequities experienced by Māori in mental health and homelessness, and the majority of participants identifying as New Zealand Māori. Participants’ narratives were gathered using semi- structured interviews. This study argues the importance of a humanistic perspective being used for research on homelessness. In contrast to traditional psychology, humanistic psychology emphasises respecting individual participants’ voice and narratives about their personal experiences of homelessness while considering the environment that influence these narratives. The participants’ narratives reflected their desire to be viewed as more than their life circumstances and illness through the sharing of their life stories. While there has been growing public awareness about mental illness, stigma still exists about mental illness which influences social narratives and how people who have mental illness understand their experiences. I argue that people who are vulnerable to homelessness, like those who experience mental illness, should have better protection from homelessness. To achieve this, I argue that structural barriers to finding, gaining and sustaining housing need to be addressed,
iii
including the design of welfare and housing services. Additionally, there needs to be recognition that the solutions to homelessness are complex and require a whole of system approach to effectively address and prevent homelessness. Recognising the complex nature of homelessness and it’s solutions will help bring a focus to establishing predominantly preventative solutions while also providing emergency housing for people in need.

text: Housing, mental health, and homelessness: Exploring lived experiences of homelessness to identify barriers to sustainable housing for vulnerable populations Homelessness has become a much talked about topic in Aotearoa New Zealand in 2018 and the preceding years. This thesis explores the experiences of five people who have mental illness and have lived experience of homelessness in Aotearoa New Zealand, and two staff members who work closely with people who experience both mental illness and homelessness. The theoretical frameworks that inform this thesis are narrative research, social constructionism and humanistic psychology. Particular attention was paid to using theoretical frameworks and interview methods that suited Māori (the indigenous population of Aotearoa New Zealand) due to the inequities experienced by Māori in mental health and homelessness, and the majority of participants identifying as New Zealand Māori. Participants’ narratives were gathered using semi- structured interviews. This study argues the importance of a humanistic perspective being used for research on homelessness. In contrast to traditional psychology, humanistic psychology emphasises respecting individual participants’ voice and narratives about their personal experiences of homelessness while considering the environment that influence these narratives. The participants’ narratives reflected their desire to be viewed as more than their life circumstances and illness through the sharing of their life stories. While there has been growing public awareness about mental illness, stigma still exists about mental illness which influences social narratives and how people who have mental illness understand their experiences. I argue that people who are vulnerable to homelessness, like those who experience mental illness, should have better protection from homelessness. To achieve this, I argue that structural barriers to finding, gaining and sustaining housing need to be addressed,
iii
including the design of welfare and housing services. Additionally, there needs to be recognition that the solutions to homelessness are complex and require a whole of system approach to effectively address and prevent homelessness. Recognising the complex nature of homelessness and it’s solutions will help bring a focus to establishing predominantly preventative solutions while also providing emergency housing for people in need.

year: 2018