title: Bio-composites materials from engineered natural fibres for structural applications

authors: Mohd Ghazali, Aruan Efendy

subjects: Aligned discontinuous natural fibre composites

abstract: The large environmental footprint caused by conventional synthetic fibre reinforced petrochemical-derived polymer composites along with potential improvement in mechanical properties for natural fibre reinforced bio-derived polymer composites, have long been a motivation for further research and innovation in natural fibre composites. Harakeke and hemp fibres, amongst other natural fibres, possess respectable mechanical properties along with other advantages such as low cost, low production energy requirements and abundant availability. Polylactic acid (PLA), a sustainable alternative to petrochemical-derived polymers, is produced on a mass scale from 100% renewable resources and can be degraded at end of life by simple hydrolysis under the appropriate conditions. It has high stiffness, strength, thermal and UV stability, but is low in toughness. Limited applications of natural fibre reinforced PLA composites so far is mainly due to low mechanical properties of discontinuous fibre composites made using injection moulding or compression moulding using randomly oriented fibre mats attributed to poor fibre orientation and fibre-matrix incompatibility. Presented in this study are experimental investigations of the properties of PLA reinforced aligned discontinuous harakeke and hemp fibre mats produced using a dynamic sheet former (DSF) to provide improved performance of discontinuous fibre composites.

Harakeke and hemp fibres were treated using either a solution of 5 wt% or 10 wt% NaOH or combination of 5 wt% NaOH with 2 wt% Na2SO3 at elevated temperatures in a small pressure vessel. Treated fibres were assessed using single fibre tensile testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was found that 5 wt% NaOH/2 wt% Na2SO3 and 5 wt% NaOH effectively removed non-cellulosic materials from harakeke and hemp fibre surfaces, respectively, giving good fibre separation without greatly reducing the tensile strength of the fibres. It was also found that these treatments lead to a higher crystallinity index and improved thermal stability of fibres.

Fibre alignment in fibre mats produced using a DSF was observed using light microscopy. Visual observation supported that the fibre alignment had occurred. Fibre orientation factors (Kɵ) determined for harakeke and hemp composites using the Bowyer-Bader model were found higher compared to Kɵ values obtained for other natural composites prepared using injection and compression moulding. Improved fibre orientation resulted in improved reinforcement giving large increases for tensile strengths up to approximately 90 and 60% for harakeke and hemp composites reinforced with inclusion of 30 and 25 wt% fibre respectively. 

The effect of silane and peroxide as additional fibre treatments and MA-g-PLA as a coupling agent was evaluated by scanning electron microscopy (SEM), composite swelling analysis, tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Scanning electron micrographs of fractured composite surfaces revealed that the gaps between fibres and matrix for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA were smaller compared to the surfaces for composites with fibres treated using just alkali. Improved interfacial strength was also supported by lower swelling indices, lower peaks on tan δ and higher residual composites weights, compared to those values obtained for composites with fibres treated using just alkali, which was found to lead to higher composite tensile strengths.

Harakeke and hemp fibre composites were plasticised using hyper-branched polymer (HBP) and assessed using SEM, tensile and impact testing. SEM micrographs for plasticised composites revealed longer pultruding fibres than un-plasticised composites, with gaps between the fibre and matrix appearing to be slightly larger, indicating a weaker interface between fibres and matrix compared to those composites without plasticiser. Improved composite ductility and impact strength were demonstrated for plasticised composites without dramatic reduction of composite tensile strength.

text: Bio-composites materials from engineered natural fibres for structural applications The large environmental footprint caused by conventional synthetic fibre reinforced petrochemical-derived polymer composites along with potential improvement in mechanical properties for natural fibre reinforced bio-derived polymer composites, have long been a motivation for further research and innovation in natural fibre composites. Harakeke and hemp fibres, amongst other natural fibres, possess respectable mechanical properties along with other advantages such as low cost, low production energy requirements and abundant availability. Polylactic acid (PLA), a sustainable alternative to petrochemical-derived polymers, is produced on a mass scale from 100% renewable resources and can be degraded at end of life by simple hydrolysis under the appropriate conditions. It has high stiffness, strength, thermal and UV stability, but is low in toughness. Limited applications of natural fibre reinforced PLA composites so far is mainly due to low mechanical properties of discontinuous fibre composites made using injection moulding or compression moulding using randomly oriented fibre mats attributed to poor fibre orientation and fibre-matrix incompatibility. Presented in this study are experimental investigations of the properties of PLA reinforced aligned discontinuous harakeke and hemp fibre mats produced using a dynamic sheet former (DSF) to provide improved performance of discontinuous fibre composites.

Harakeke and hemp fibres were treated using either a solution of 5 wt% or 10 wt% NaOH or combination of 5 wt% NaOH with 2 wt% Na2SO3 at elevated temperatures in a small pressure vessel. Treated fibres were assessed using single fibre tensile testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It was found that 5 wt% NaOH/2 wt% Na2SO3 and 5 wt% NaOH effectively removed non-cellulosic materials from harakeke and hemp fibre surfaces, respectively, giving good fibre separation without greatly reducing the tensile strength of the fibres. It was also found that these treatments lead to a higher crystallinity index and improved thermal stability of fibres.

Fibre alignment in fibre mats produced using a DSF was observed using light microscopy. Visual observation supported that the fibre alignment had occurred. Fibre orientation factors (Kɵ) determined for harakeke and hemp composites using the Bowyer-Bader model were found higher compared to Kɵ values obtained for other natural composites prepared using injection and compression moulding. Improved fibre orientation resulted in improved reinforcement giving large increases for tensile strengths up to approximately 90 and 60% for harakeke and hemp composites reinforced with inclusion of 30 and 25 wt% fibre respectively. 

The effect of silane and peroxide as additional fibre treatments and MA-g-PLA as a coupling agent was evaluated by scanning electron microscopy (SEM), composite swelling analysis, tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Scanning electron micrographs of fractured composite surfaces revealed that the gaps between fibres and matrix for composites with fibres treated using silane and peroxide and composites coupled with MA-g-PLA were smaller compared to the surfaces for composites with fibres treated using just alkali. Improved interfacial strength was also supported by lower swelling indices, lower peaks on tan δ and higher residual composites weights, compared to those values obtained for composites with fibres treated using just alkali, which was found to lead to higher composite tensile strengths.

Harakeke and hemp fibre composites were plasticised using hyper-branched polymer (HBP) and assessed using SEM, tensile and impact testing. SEM micrographs for plasticised composites revealed longer pultruding fibres than un-plasticised composites, with gaps between the fibre and matrix appearing to be slightly larger, indicating a weaker interface between fibres and matrix compared to those composites without plasticiser. Improved composite ductility and impact strength were demonstrated for plasticised composites without dramatic reduction of composite tensile strength.

year: 2016

title: The DiY ['Do it yourself'] Ethos: A participatory culture of material engagement

authors: Snake-Beings, Emit

subjects: Material agency

abstract: Do it Yourself (DiY) is a participatory culture which exemplifies a particular ethos in its approach to technology and materials. Rather than engage with ‘complete’ technologies, such as a technology supplied as ready-to-go item, the DiY practitioners examined in this thesis engage with the raw materials of garbage and recycling, ‘incomplete’, broken and discarded technologies. In this type of DiY practice the emphasis is towards creating individualised and custom-built forms of technology: often made from components and materials which have been re-functioned from their original intention to produce new and unexpected functionalities; practices which disrupt the dominant discourses of technology. This thesis involves a situated application of theory to DiY practices in the field: focusing on three case studies featuring New Zealand-based DiY sound practitioners and their embracing of functional ‘errors’ as a means of increasing the participatory potential of materials.
My initial argument is, that the social perspectives and ‘human-biased’ view examined in current literature on DiY culture, depicts an attitude towards power and knowledge which obscures the recognition of material agency. In this thesis, ‘power’ is defined within a social constructivist, or as a ‘human-biased’ view, whereas ‘agency’, as the ability to make something happen, is more expansive and incorporates the capacities of materials to become active participants in the production of cultural artefacts. Through engaging with the work of contemporary theorists relevant to material agency (including Karen Barad, Jane Bennett, Levi R. Bryant, Susan Kelly, Lambros Malafouris and Bruno Latour), the limitations of the ‘human-biased’ view of DiY culture are highlighted and the emphasis is shifted from DiY participatory culture as a social phenomenon towards the idea of ‘extended agency’: agency which includes both human and material actants within the entangled assemblages of DiY practices and the material environment.
When extended agency is applied in the three case studies, the initial question asked is: ‘How does the intra-action of human and material environment influence the processes of DiY practices and what specific strategies are used to increase the participatory potential of materials?’. 
In this sense, DiY culture challenges the way we see ‘power’ and ‘structure’ as being exclusively human traits, influencing our way of relating to the material environment and creating consequences and considerations which extend from the localised DiY practices examined in this thesis. The suggestion is that the extended agency of DiY culture represents a timely re-evaluation of the relationship between the human and the material environment, challenging prevalent discourses which place the human at the centre of power and knowledge.

text: The DiY ['Do it yourself'] Ethos: A participatory culture of material engagement Do it Yourself (DiY) is a participatory culture which exemplifies a particular ethos in its approach to technology and materials. Rather than engage with ‘complete’ technologies, such as a technology supplied as ready-to-go item, the DiY practitioners examined in this thesis engage with the raw materials of garbage and recycling, ‘incomplete’, broken and discarded technologies. In this type of DiY practice the emphasis is towards creating individualised and custom-built forms of technology: often made from components and materials which have been re-functioned from their original intention to produce new and unexpected functionalities; practices which disrupt the dominant discourses of technology. This thesis involves a situated application of theory to DiY practices in the field: focusing on three case studies featuring New Zealand-based DiY sound practitioners and their embracing of functional ‘errors’ as a means of increasing the participatory potential of materials.
My initial argument is, that the social perspectives and ‘human-biased’ view examined in current literature on DiY culture, depicts an attitude towards power and knowledge which obscures the recognition of material agency. In this thesis, ‘power’ is defined within a social constructivist, or as a ‘human-biased’ view, whereas ‘agency’, as the ability to make something happen, is more expansive and incorporates the capacities of materials to become active participants in the production of cultural artefacts. Through engaging with the work of contemporary theorists relevant to material agency (including Karen Barad, Jane Bennett, Levi R. Bryant, Susan Kelly, Lambros Malafouris and Bruno Latour), the limitations of the ‘human-biased’ view of DiY culture are highlighted and the emphasis is shifted from DiY participatory culture as a social phenomenon towards the idea of ‘extended agency’: agency which includes both human and material actants within the entangled assemblages of DiY practices and the material environment.
When extended agency is applied in the three case studies, the initial question asked is: ‘How does the intra-action of human and material environment influence the processes of DiY practices and what specific strategies are used to increase the participatory potential of materials?’. 
In this sense, DiY culture challenges the way we see ‘power’ and ‘structure’ as being exclusively human traits, influencing our way of relating to the material environment and creating consequences and considerations which extend from the localised DiY practices examined in this thesis. The suggestion is that the extended agency of DiY culture represents a timely re-evaluation of the relationship between the human and the material environment, challenging prevalent discourses which place the human at the centre of power and knowledge.

year: 2016

title: Efficacy of an incentive intervention on secondary prophylaxis for young people with rheumatic fever: a multiple baseline study

authors: Oetzel, John G.

subjects: Science & Technology

abstract: Background
Acute rheumatic fever in New Zealand persists and is a barometer of equity as its burden almost exclusively falls on Māori and Pacific Island populations. The primary objective of this study is to determine whether an incentive programme will result in increased secondary prophylaxis injections over a one-year period compared to a baseline period prior to the intervention.

Methods
The evaluation used a multiple baseline study to determine whether an incentive consisting of a mobile phone and monthly “top-up” (for data/calls) resulted in increased injections, increased texts/calls with nurses, reduced number of visits to get a successful injection, less medicine wasted, and increased nurse satisfaction. Participants were 77 young people (aged 14–21) on an acute rheumatic fever registry in Waikato region, New Zealand classified as either fully adherent (all injections received and no more than one late) or partially adherent based on injections at baseline.

Results
There was a sharp increase in injections for intermittent patients post-intervention and then a slight decrease overtime, while fully adherent patients maintained their high rate of injections (p = .003). A similar pattern for nurse satisfaction emerged (p = .001). The number of calls/texts increased for all patients (p = .003). The number of visits went down for partially adherent patients and up for fully adherent patients (p = .012). The overall incremental cost-effectiveness was $989 per extra successful injection although costs increased sharply toward the end of the intervention.

Conclusions
Incentivising secondary prophylaxis appears to have a strong impact for partially adherent patients, particularly during the early periods following the initiation of the intervention. Enhancing communication with patients who returned to care may result in more sustainable adherence.

Trial registration
Retrospectively registered: Australia New Zealand Clinical Trials Registry ACTRN12618001150235, 12 July 2018.

text: Efficacy of an incentive intervention on secondary prophylaxis for young people with rheumatic fever: a multiple baseline study Background
Acute rheumatic fever in New Zealand persists and is a barometer of equity as its burden almost exclusively falls on Māori and Pacific Island populations. The primary objective of this study is to determine whether an incentive programme will result in increased secondary prophylaxis injections over a one-year period compared to a baseline period prior to the intervention.

Methods
The evaluation used a multiple baseline study to determine whether an incentive consisting of a mobile phone and monthly “top-up” (for data/calls) resulted in increased injections, increased texts/calls with nurses, reduced number of visits to get a successful injection, less medicine wasted, and increased nurse satisfaction. Participants were 77 young people (aged 14–21) on an acute rheumatic fever registry in Waikato region, New Zealand classified as either fully adherent (all injections received and no more than one late) or partially adherent based on injections at baseline.

Results
There was a sharp increase in injections for intermittent patients post-intervention and then a slight decrease overtime, while fully adherent patients maintained their high rate of injections (p = .003). A similar pattern for nurse satisfaction emerged (p = .001). The number of calls/texts increased for all patients (p = .003). The number of visits went down for partially adherent patients and up for fully adherent patients (p = .012). The overall incremental cost-effectiveness was $989 per extra successful injection although costs increased sharply toward the end of the intervention.

Conclusions
Incentivising secondary prophylaxis appears to have a strong impact for partially adherent patients, particularly during the early periods following the initiation of the intervention. Enhancing communication with patients who returned to care may result in more sustainable adherence.

Trial registration
Retrospectively registered: Australia New Zealand Clinical Trials Registry ACTRN12618001150235, 12 July 2018.

year: 2019