title: Bio-inspired plastic derived from aquaculture by-product

authors: Howarth, Zachary

subjects: Bioplastics

abstract: The deliberate cultivation of seafood through aquaculture is expanding with a focus on environmental sustainability, specifically decreasing global emissions and waste. In New Zealand this industry is growing at a rapid pace with intentions to scale up the farming of species such as salmon, pacific oysters and Greenshell™ Mussels.  During processing by-products such as mussel shell are produced and often sent to land fill. Greenshell™ mussel shells consisted of approximately 90% calcium carbonate  (Hamester, Balzer, & Becker, 2012) making it a valuable resource.  This study focuses on the creation of polymer composites and foams which have been inspired by the marine environment and the materials in it such as calcium carbonate from mussel shells. It specifically aimed to incorporate mussel shell powder (0-30wt% for composites and 0-10wt % for foams) into polylactic acid (PLA) and low-density polyethylene (LDPE). These polymers were chosen for their bioderived nature and degree of recyclability respectively. This work creates, characterises, and tests these materials to determine potential applications.   Composite materials were successfully extruded and then processed into 3D printing filaments to extend the applications of these materials. These samples were tensile tested, and granulated composites were used for thermal analysis. PLA composites showed far superior tensile strength and stiffness over LDPE samples, reaching 60.69 MPa yield stress and 3748 MPa Youngs’ modulus at 8wt% of mussel shell powder, with LDPE composites reaching 8.9 MPa yield stress and 197 MPa Youngs’ modulus. At 30wt% of mussel shell both PLA and LDPE samples showed less plastic deformation with PLA + 30wt% sample reaching failure almost instantly.  Thermal stability of PLA and LDPE composites showed varying properties. The most notable difference between the two polymers was the change in thermal degradation temperature as the weight percentage of mussel shell powder was increased. PLA samples showed a reduction in thermal degradation temperature due to the introduction of moisture and hydrolysis as the weight percentage of mussel shell powder increased, decreasing from 340℃ (0wt%) to 287℃ (30wt%). LDPE samples showed an increase in thermal degradation temperature due to the high volumes of ceramic mussel shell powder and no hydrolysis. ii  Thermal degradation of LDPE composites was seen to increase by 22℃ between the control sample to 30wt% samples. Extruded foams were moulded into small blocks for compression and microscopy. PLA foams showed higher expansion ratios than LDPE foams and much lower density. PLA 0.5wt% reached three times the expansion of un-foamed PLA and showed the highest expansion ratio of all samples tested. The expansion of PLA foams decreased between 0.5wt% and 10wt% as expected while the compressive strength showed a good improvement from 5 MPa to 20 MPa. Overall, LDPE foams had both lower compressive stress (13 MPa) and expansion (1.5) than the PLA samples. LDPE samples showed far greater recovery at 70%, which was 40% higher than PLA foams.  In summary, PLA displayed best reinforcement at 8wt%, best thermal properties between 0-2wt% and best foam nucleation results at 0.5wt%. Finally, LDPE samples showed comparable results with best reinforcement at 8wt%, best thermal properties between 20-30wt% and best foam nucleation results at 0.5-1wt%. This thesis has thoroughly investigated composites and foams that could be introduced into a circular economy, resulting in a beneficial impact on the environment. Options for biodegradable (PLA) and recyclable (LDPE) polymers were shown while valuable by-product material (mussel shell) was introduced to composites and foams as a method of reducing stress on landfills and improving the properties of these materials. These materials could be made into complex containers, sandwich composites, and equipment in the medical, automotive, and aerospace industries.

text: Bio-inspired plastic derived from aquaculture by-product The deliberate cultivation of seafood through aquaculture is expanding with a focus on environmental sustainability, specifically decreasing global emissions and waste. In New Zealand this industry is growing at a rapid pace with intentions to scale up the farming of species such as salmon, pacific oysters and Greenshell™ Mussels.  During processing by-products such as mussel shell are produced and often sent to land fill. Greenshell™ mussel shells consisted of approximately 90% calcium carbonate  (Hamester, Balzer, & Becker, 2012) making it a valuable resource.  This study focuses on the creation of polymer composites and foams which have been inspired by the marine environment and the materials in it such as calcium carbonate from mussel shells. It specifically aimed to incorporate mussel shell powder (0-30wt% for composites and 0-10wt % for foams) into polylactic acid (PLA) and low-density polyethylene (LDPE). These polymers were chosen for their bioderived nature and degree of recyclability respectively. This work creates, characterises, and tests these materials to determine potential applications.   Composite materials were successfully extruded and then processed into 3D printing filaments to extend the applications of these materials. These samples were tensile tested, and granulated composites were used for thermal analysis. PLA composites showed far superior tensile strength and stiffness over LDPE samples, reaching 60.69 MPa yield stress and 3748 MPa Youngs’ modulus at 8wt% of mussel shell powder, with LDPE composites reaching 8.9 MPa yield stress and 197 MPa Youngs’ modulus. At 30wt% of mussel shell both PLA and LDPE samples showed less plastic deformation with PLA + 30wt% sample reaching failure almost instantly.  Thermal stability of PLA and LDPE composites showed varying properties. The most notable difference between the two polymers was the change in thermal degradation temperature as the weight percentage of mussel shell powder was increased. PLA samples showed a reduction in thermal degradation temperature due to the introduction of moisture and hydrolysis as the weight percentage of mussel shell powder increased, decreasing from 340℃ (0wt%) to 287℃ (30wt%). LDPE samples showed an increase in thermal degradation temperature due to the high volumes of ceramic mussel shell powder and no hydrolysis. ii  Thermal degradation of LDPE composites was seen to increase by 22℃ between the control sample to 30wt% samples. Extruded foams were moulded into small blocks for compression and microscopy. PLA foams showed higher expansion ratios than LDPE foams and much lower density. PLA 0.5wt% reached three times the expansion of un-foamed PLA and showed the highest expansion ratio of all samples tested. The expansion of PLA foams decreased between 0.5wt% and 10wt% as expected while the compressive strength showed a good improvement from 5 MPa to 20 MPa. Overall, LDPE foams had both lower compressive stress (13 MPa) and expansion (1.5) than the PLA samples. LDPE samples showed far greater recovery at 70%, which was 40% higher than PLA foams.  In summary, PLA displayed best reinforcement at 8wt%, best thermal properties between 0-2wt% and best foam nucleation results at 0.5wt%. Finally, LDPE samples showed comparable results with best reinforcement at 8wt%, best thermal properties between 20-30wt% and best foam nucleation results at 0.5-1wt%. This thesis has thoroughly investigated composites and foams that could be introduced into a circular economy, resulting in a beneficial impact on the environment. Options for biodegradable (PLA) and recyclable (LDPE) polymers were shown while valuable by-product material (mussel shell) was introduced to composites and foams as a method of reducing stress on landfills and improving the properties of these materials. These materials could be made into complex containers, sandwich composites, and equipment in the medical, automotive, and aerospace industries.

year: 2023

title: From Al-Qaida to ISIL: The decisions and practices of the UN Security Council related to the right to self-defense against non-state actors from 2002–2014: A deafening silence after Resolutions 1368 and 1373 (2001)

authors: Alvarez-Jimenez, Alberto

abstract: Security Council Resolution 1373, adopted in the aftermath of the 9/11 attacks and “recognizing the inherent right of individual … self-defense,” was regarded as having expanded the scope of Article 51 to cover armed attacks by autonomous non-state actors. However, the ICJ refused to recognize such expansion in its Wall Opinion. The ICJ’s conclusion cannot be regarded as the last word. As Bruno Simma has highlighted: “The rules of treaty interpretation … of international law do not exclude the possibility that Art. 51 is reinterpreted … on the basis of subsequent practice.” The question is whether or not the SC practice from 2002 to 2014 has expanded the scope of Article 51. This project has reviewed 34 resolutions, 44 presidential statements by the SC, and 115 press statements by its members dealing with threats to peace and security caused by terrorism. The conclusions of this research are that the SC has devised and strengthened only multilateral instruments to face the challenge posed by terrorism from 2002 to 2014; that there has been no explicit subsequent practice related to the right to self-defense against terrorist groups by the Council in its 78 decisions during this period; that there have been some subsequent decisions going in the opposite direction to Resolution 1373 from 2007 to 2014; that the SC has halted this emerging trend as a result of ISIL; and that there seems to be some implicit subsequent practices, fully identified in the paper, that, nonetheless, have been insufficient to expand the scope of Art. 51.

text: From Al-Qaida to ISIL: The decisions and practices of the UN Security Council related to the right to self-defense against non-state actors from 2002–2014: A deafening silence after Resolutions 1368 and 1373 (2001) Security Council Resolution 1373, adopted in the aftermath of the 9/11 attacks and “recognizing the inherent right of individual … self-defense,” was regarded as having expanded the scope of Article 51 to cover armed attacks by autonomous non-state actors. However, the ICJ refused to recognize such expansion in its Wall Opinion. The ICJ’s conclusion cannot be regarded as the last word. As Bruno Simma has highlighted: “The rules of treaty interpretation … of international law do not exclude the possibility that Art. 51 is reinterpreted … on the basis of subsequent practice.” The question is whether or not the SC practice from 2002 to 2014 has expanded the scope of Article 51. This project has reviewed 34 resolutions, 44 presidential statements by the SC, and 115 press statements by its members dealing with threats to peace and security caused by terrorism. The conclusions of this research are that the SC has devised and strengthened only multilateral instruments to face the challenge posed by terrorism from 2002 to 2014; that there has been no explicit subsequent practice related to the right to self-defense against terrorist groups by the Council in its 78 decisions during this period; that there have been some subsequent decisions going in the opposite direction to Resolution 1373 from 2007 to 2014; that the SC has halted this emerging trend as a result of ISIL; and that there seems to be some implicit subsequent practices, fully identified in the paper, that, nonetheless, have been insufficient to expand the scope of Art. 51.

year: 2014

title: Maori & Psychology Research Unit annual report 2004

authors: Rua, Mohi

subjects: Māori & Psychology Research Unit annual report

abstract: Annual report of the Maori and Psychology Research Unit (MPRU) 2004. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

text: Maori & Psychology Research Unit annual report 2004 Annual report of the Maori and Psychology Research Unit (MPRU) 2004. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

year: 2004