title: Harakeke fibre as reinforcement in epoxy matrix composites and its hybridisation with hemp fibre

authors: Le, Tan Minh

subjects: Harakeke

abstract: Over the last few decades, due to increasing global awareness of environmental issues, there has been great interest and motivation in research to develop natural fibre composites to replace glass fibre composites in certain applications. Harakeke fibre known as New Zealand flax or Phormium tenax used to be an important export material in New Zealand in the early twentieth century, but its production reduced due to the availability of synthetic fibres midcentury and competition from other natural fibres such as sisal and flax. Now, harakeke plants are planted mainly for landscaping with some fibre extracted from harakeke leaves used for craft goods and traditional products of Maori people who were the earliest settlers in New Zealand. Only two family workshops in the country are currently extracting harakeke fibre for this purpose. The aim of this thesis was to assess if harakeke fibre has potential for reinforcement in polymer composites and to assess the hybridisation of harakeke/hemp hybrid composites. 
Both short and long fibres were used as reinforcement, while a low viscosity epoxy resin was used as the matrix. Short fibres were alkali treated before being used to reinforce epoxy, while long fibres were used as supplied. Short and long fibres were aligned using dynamic sheet forming and manual carding, respectively. Composites were produced using hand lay-up and compression moulding. The physical and mechanical properties of fibres and composites were tested following ASTM and ISO standards. The surfaces of fibres and fracture surfaces of composites were assessed microscopically using optical microscopes and scanning electron microscope (SEM). 
Short harakeke and hemp fibres were alkali treated at elevated temperatures in a fibre pulping digester with a solution of 2wt% NaOH or 5wt% NaOH/2wt% Na2SO3. Single fibre tensile testing was carried out on untreated and treated fibres. It was found that harakeke fibre treated with NaOH and hemp fibre treated with NaOH/Na2SO3 retained their tensile strength and Young’s modulus compared to the untreated, while harakeke fibre treated with NaOH/Na2SO3 was degraded. Fibre surfaces and fibre separation were evaluated revealing that fibres treated with NaOH/Na2SO3 had better separation and rougher surfaces compared to those treated with NaOH. Densities of harakeke and hemp were found to increase after alkali treatment. Fibre lumens were found to make up significant volume of fibres with 41% of single fibre volume and 21% of fibre bundle volume for harakeke fibre and 18% and 11% for hemp fibre, respectively. Lumens were found to be a major factor contributing to porosity of long aligned harakeke composites. 
Mechanical properties including tensile, flexural and fracture toughness of composites containing aligned short 2%NaOH treated harakeke fibre with different fibre contents were evaluated and compared with randomly oriented harakeke/epoxy composites. It was found that all properties increased with fibre content. Tensile strength and Young’s modulus of the aligned short fibre composites at the optimum fibre content of 46wt% were 136 MPa and 10.5 GPa, respectively. These values are higher than any reported in the literature to date for natural fibre composites excluding those where hand-layup or a continuous fibre form has been produced and furthermore, these values overlap with those achieved using these procedures. 
Mechanical properties of aligned long harakeke composites were also evaluated. The tensile strength and Young’s modulus were comparable to those for sisal and hemp composites in the literature and their specific values were comparable to those for glass fibre composites. Impact strength and fracture toughness of harakeke fibre composites that have not been seen previously in the literature were found to be 132 KJ/m2 and 7.69 MPa.m-1/2, respectively, at a fibre content of 63wt% for aligned long harakeke/epoxy composites. These values are higher than any reported in the literature to date for natural fibre polymer composites. A Rule of Mixtures based model was developed for predicting aligned long harakeke fibre composite strength with the assumption that composites fail when fibres with the lowest failure strains failed and considering the effect of porosity. It was found that porosity affected tensile strength as well as Young’s modulus of the composites.
Aligned long or short harakeke/hemp hybrid biocomposites were prepared with different fibre lay-up and weight ratios between harakeke and hemp and their mechanical properties were assessed. While tensile properties, impact strength and fracture toughness (KIC) of the harakeke/hemp hybrid biocomposites were found to be independent on fibre lay-up, flexural properties were found to be dependent as would be expected due to the influence of second moment of area. The fibre failure strain based hybrid effect (FS hybrid effect) defined as the enhancement of low elongation fibre due to presence of high elongation fibre in composite and the Rule of Mixtures based hybrid effect (ROM hybrid effect) termed as the deviation of a certain property from the Rule of Mixtures were assessed for harakeke/hemp hybrid biocomposites. While the FS hybrid effect was found not to be observed, ROM positive hybrid effects were found to be observed for fracture toughness of aligned short harakeke/hemp hybrid biocomposites with different fibre lay-ups and different relative fibre contents. ROM positive hybrid effects were also found to be observed for flexural modulus for comingled harakeke/hemp fibre composites at different relative fibre contents. Tensile properties and impact strength were found to obey the Rule of Mixtures.

text: Harakeke fibre as reinforcement in epoxy matrix composites and its hybridisation with hemp fibre Over the last few decades, due to increasing global awareness of environmental issues, there has been great interest and motivation in research to develop natural fibre composites to replace glass fibre composites in certain applications. Harakeke fibre known as New Zealand flax or Phormium tenax used to be an important export material in New Zealand in the early twentieth century, but its production reduced due to the availability of synthetic fibres midcentury and competition from other natural fibres such as sisal and flax. Now, harakeke plants are planted mainly for landscaping with some fibre extracted from harakeke leaves used for craft goods and traditional products of Maori people who were the earliest settlers in New Zealand. Only two family workshops in the country are currently extracting harakeke fibre for this purpose. The aim of this thesis was to assess if harakeke fibre has potential for reinforcement in polymer composites and to assess the hybridisation of harakeke/hemp hybrid composites. 
Both short and long fibres were used as reinforcement, while a low viscosity epoxy resin was used as the matrix. Short fibres were alkali treated before being used to reinforce epoxy, while long fibres were used as supplied. Short and long fibres were aligned using dynamic sheet forming and manual carding, respectively. Composites were produced using hand lay-up and compression moulding. The physical and mechanical properties of fibres and composites were tested following ASTM and ISO standards. The surfaces of fibres and fracture surfaces of composites were assessed microscopically using optical microscopes and scanning electron microscope (SEM). 
Short harakeke and hemp fibres were alkali treated at elevated temperatures in a fibre pulping digester with a solution of 2wt% NaOH or 5wt% NaOH/2wt% Na2SO3. Single fibre tensile testing was carried out on untreated and treated fibres. It was found that harakeke fibre treated with NaOH and hemp fibre treated with NaOH/Na2SO3 retained their tensile strength and Young’s modulus compared to the untreated, while harakeke fibre treated with NaOH/Na2SO3 was degraded. Fibre surfaces and fibre separation were evaluated revealing that fibres treated with NaOH/Na2SO3 had better separation and rougher surfaces compared to those treated with NaOH. Densities of harakeke and hemp were found to increase after alkali treatment. Fibre lumens were found to make up significant volume of fibres with 41% of single fibre volume and 21% of fibre bundle volume for harakeke fibre and 18% and 11% for hemp fibre, respectively. Lumens were found to be a major factor contributing to porosity of long aligned harakeke composites. 
Mechanical properties including tensile, flexural and fracture toughness of composites containing aligned short 2%NaOH treated harakeke fibre with different fibre contents were evaluated and compared with randomly oriented harakeke/epoxy composites. It was found that all properties increased with fibre content. Tensile strength and Young’s modulus of the aligned short fibre composites at the optimum fibre content of 46wt% were 136 MPa and 10.5 GPa, respectively. These values are higher than any reported in the literature to date for natural fibre composites excluding those where hand-layup or a continuous fibre form has been produced and furthermore, these values overlap with those achieved using these procedures. 
Mechanical properties of aligned long harakeke composites were also evaluated. The tensile strength and Young’s modulus were comparable to those for sisal and hemp composites in the literature and their specific values were comparable to those for glass fibre composites. Impact strength and fracture toughness of harakeke fibre composites that have not been seen previously in the literature were found to be 132 KJ/m2 and 7.69 MPa.m-1/2, respectively, at a fibre content of 63wt% for aligned long harakeke/epoxy composites. These values are higher than any reported in the literature to date for natural fibre polymer composites. A Rule of Mixtures based model was developed for predicting aligned long harakeke fibre composite strength with the assumption that composites fail when fibres with the lowest failure strains failed and considering the effect of porosity. It was found that porosity affected tensile strength as well as Young’s modulus of the composites.
Aligned long or short harakeke/hemp hybrid biocomposites were prepared with different fibre lay-up and weight ratios between harakeke and hemp and their mechanical properties were assessed. While tensile properties, impact strength and fracture toughness (KIC) of the harakeke/hemp hybrid biocomposites were found to be independent on fibre lay-up, flexural properties were found to be dependent as would be expected due to the influence of second moment of area. The fibre failure strain based hybrid effect (FS hybrid effect) defined as the enhancement of low elongation fibre due to presence of high elongation fibre in composite and the Rule of Mixtures based hybrid effect (ROM hybrid effect) termed as the deviation of a certain property from the Rule of Mixtures were assessed for harakeke/hemp hybrid biocomposites. While the FS hybrid effect was found not to be observed, ROM positive hybrid effects were found to be observed for fracture toughness of aligned short harakeke/hemp hybrid biocomposites with different fibre lay-ups and different relative fibre contents. ROM positive hybrid effects were also found to be observed for flexural modulus for comingled harakeke/hemp fibre composites at different relative fibre contents. Tensile properties and impact strength were found to obey the Rule of Mixtures.

year: 2016

title: 'Don't you perceive gender as different because of the chromosomes': Examining the Impact of Gender Discourses on Early Childhood Pre-Service Teachers?

authors: Lyall, Margaret Vida

subjects: gender

abstract: This thesis is a qualitative study located within the context of contemporary New Zealand early childhood education. It investigates the impact and implications on pedagogy resulting from the gender discourses held by pre-service early childhood teachers, each of whom had just begun the final semester of the 3rd year of their Bachelor of teaching early childhood education. Specifically, using data generated through focus groups, it investigates the participant’s location and framing of gender, gender development and the participant’s understandings of gender diversity. The research, which extensively used post-structural feminism and Foucault’s notion of discourse as a theoretical framework, identified the participant’s discourses around gender which were conflicting, uncontested and confused.

A series of influential discourses regarding gender were identified as potentially shaping pre-service teachers developing teacher subjectivity. I claim that the shaping of teacher subject, who are indifferent to gender, results, from a reduction of focus on gender in the early childhood sector in both professional practice and state policy. The increased dominance of the biological determinist discourse in lay society is keenly felt in these domains. The increased biologically determinist view inferring that gender difference is natural and therefore unchallengeable and the reduced focus on gender in professional and government fields decreases the importance placed on gender. As such, this thesis suggests that the importance placed on gender by the developing teacher subject may be inconsistent with the important role gender plays in the early years and may therefore inhibit pedagogy and practice.

This research has implications for policy and teacher education. The results identify early childhood teacher education as being in a unique position to attempt to mitigate such issues. Specifically this can be done by supporting the development of the reflexive skills needed for pre-service teachers to consider and challenge the gender discourses that influence them.

text: 'Don't you perceive gender as different because of the chromosomes': Examining the Impact of Gender Discourses on Early Childhood Pre-Service Teachers? This thesis is a qualitative study located within the context of contemporary New Zealand early childhood education. It investigates the impact and implications on pedagogy resulting from the gender discourses held by pre-service early childhood teachers, each of whom had just begun the final semester of the 3rd year of their Bachelor of teaching early childhood education. Specifically, using data generated through focus groups, it investigates the participant’s location and framing of gender, gender development and the participant’s understandings of gender diversity. The research, which extensively used post-structural feminism and Foucault’s notion of discourse as a theoretical framework, identified the participant’s discourses around gender which were conflicting, uncontested and confused.

A series of influential discourses regarding gender were identified as potentially shaping pre-service teachers developing teacher subjectivity. I claim that the shaping of teacher subject, who are indifferent to gender, results, from a reduction of focus on gender in the early childhood sector in both professional practice and state policy. The increased dominance of the biological determinist discourse in lay society is keenly felt in these domains. The increased biologically determinist view inferring that gender difference is natural and therefore unchallengeable and the reduced focus on gender in professional and government fields decreases the importance placed on gender. As such, this thesis suggests that the importance placed on gender by the developing teacher subject may be inconsistent with the important role gender plays in the early years and may therefore inhibit pedagogy and practice.

This research has implications for policy and teacher education. The results identify early childhood teacher education as being in a unique position to attempt to mitigate such issues. Specifically this can be done by supporting the development of the reflexive skills needed for pre-service teachers to consider and challenge the gender discourses that influence them.

year: 2013

title: Co-constructions of gender and ethnicity in New Zealand television advertising

authors: Michelle, Carolyn

subjects: television advertising

abstract: This paper reports key findings from a content analysis of gender and ethnic depictions in a sample of 2,120 New Zealand prime-time television advertisements screened in 2006. The study explored the following questions: With what product categories are male and female White, Māori/Pasifika and Asian characters most commonly associated? What are the most common occupational roles of male and female White, Māori/Pasifika and Asian characters? The results reveal highly stereotypical depictions of women and men within each ethnic category. White men dominated advertisements for foodstuffs, telecommunications and financial/corporate/legal services and were over-represented as professionals/white collar workers, while White women were over-represented in advertisements for household products, personal products, and medical products and featured predominantly as homemakers. Māori/Pasifika men were over-represented as athletes and service and sales workers. Non-White women featured prominently within multi-ethnic groups in advertisements for personal grooming products and most frequently featured as glamour models, while non-White men were over-represented as blue collar workers. Largely absent were Māori/Pasifika women and Asians of both genders, potentially exacerbating the multiple axes of subordination encountered by these groups in the New Zealand context.

text: Co-constructions of gender and ethnicity in New Zealand television advertising This paper reports key findings from a content analysis of gender and ethnic depictions in a sample of 2,120 New Zealand prime-time television advertisements screened in 2006. The study explored the following questions: With what product categories are male and female White, Māori/Pasifika and Asian characters most commonly associated? What are the most common occupational roles of male and female White, Māori/Pasifika and Asian characters? The results reveal highly stereotypical depictions of women and men within each ethnic category. White men dominated advertisements for foodstuffs, telecommunications and financial/corporate/legal services and were over-represented as professionals/white collar workers, while White women were over-represented in advertisements for household products, personal products, and medical products and featured predominantly as homemakers. Māori/Pasifika men were over-represented as athletes and service and sales workers. Non-White women featured prominently within multi-ethnic groups in advertisements for personal grooming products and most frequently featured as glamour models, while non-White men were over-represented as blue collar workers. Largely absent were Māori/Pasifika women and Asians of both genders, potentially exacerbating the multiple axes of subordination encountered by these groups in the New Zealand context.

year: 2011