title: Development of 2nd Generation Proteinous Bioplastics

authors: van den Berg, Lisa E.

subjects: Bioplastic

abstract: Current environmental and economic concerns surrounding the use of petroleum-based plastics, has led to increased study of renewable natural polymers, such as proteins.  Bloodmeal (BM) is a by-product of the meat industry and large volumes is sold as a low-cost fertilizer or animal feed.  It contains 90 wt% proteins giving it the potential as a renewable precursor for bioplastic production.  The objective of this study was to investigate the use of BM for the production of bioplastics, focusing on the use of chemical additives to facilitate thermoplastic extrusion.
Literature revealed that bioplastics formation from proteins requires denaturation and unfolding using thermal and chemical means, allowing new interactions to form between chains.  Thermoplastic extrusion also requires sufficient chain mobilization, enabling flow through the barrel.  The proteins physiochemical characteristics, plasticizer content and chemical additives will govern its processing behavior, structural and material properties.
Bloodmeal powder was extruded and injection moulded using water, sodium sulfite, sodium dodecyl sulfate (SDS) and urea as additives.  The efficiency of these chemical additives was characterized by: 
 	Processability.  Temperatures between 100 and 125  C produced a successful material, above this excessive covalent cross-linking occurred which reduced chain mobilization.  Sodium sulfite was essential, breaking covalent bonding which allowed chain extension.  The plasticizer content also strongly influenced the processability, while water and urea were essential for improved processing.
 	Consolidation, water absorption and solubility.  It was found that SDS's influence on hydrophobic interactions in combination with sodium sulfites cleavage of covalent cross-links resulted in good consolidation, water absorption and solubility.  Increasing sodium sulfite increased water absorption, indicative of cross-link reduction.  However, high sodium sulfite at low water concentration resulted in a degraded material.  The degraded polymer showed an increase in ordered structures, due to the formation of helical conformations of the short peptide chains.
 	Protein conformation.  It was found that BM was already highly denatured, with considerable amounts of β-structures.  Successful processing with required increased chain mobilization through the reduction of inter- and intra-molecular interactions which led to less ordered structures.
 	Mechanical Properties.  Water was shown to be critical for processing, enhancing the action of sodium sulfite, SDS and urea.  During conditioning, water would evaporate, allowing new intermolecular forces between chains, often resulting in a brittle material.  SDS was essential for consolidation, but excessive amounts could restrict formation of new intermolecular forces during conditioning.  The highly plasticized proteins resulted in ductile materials after conditioning.  Lowering the water, sodium sulfite or urea concentration would result in a brittle material after conditioning.  
Successful processability, consolidation, water absorption, solubility, and mechanical properties were achieved using 3 pphbm sodium sulfite, 60 pphbm water, 3 pphbm SDS and 20 pphbm urea.  This optimal material resulted in increased unordered structures shown by Fourier transform infra-red spectroscopy.  The resulting bioplastic was ductile after conditioning and had a tensile strength of 9.6 MPa and a Young's modulus of 536 MPa, comparable to low-density polyethylene.

text: Development of 2nd Generation Proteinous Bioplastics Current environmental and economic concerns surrounding the use of petroleum-based plastics, has led to increased study of renewable natural polymers, such as proteins.  Bloodmeal (BM) is a by-product of the meat industry and large volumes is sold as a low-cost fertilizer or animal feed.  It contains 90 wt% proteins giving it the potential as a renewable precursor for bioplastic production.  The objective of this study was to investigate the use of BM for the production of bioplastics, focusing on the use of chemical additives to facilitate thermoplastic extrusion.
Literature revealed that bioplastics formation from proteins requires denaturation and unfolding using thermal and chemical means, allowing new interactions to form between chains.  Thermoplastic extrusion also requires sufficient chain mobilization, enabling flow through the barrel.  The proteins physiochemical characteristics, plasticizer content and chemical additives will govern its processing behavior, structural and material properties.
Bloodmeal powder was extruded and injection moulded using water, sodium sulfite, sodium dodecyl sulfate (SDS) and urea as additives.  The efficiency of these chemical additives was characterized by: 
 	Processability.  Temperatures between 100 and 125  C produced a successful material, above this excessive covalent cross-linking occurred which reduced chain mobilization.  Sodium sulfite was essential, breaking covalent bonding which allowed chain extension.  The plasticizer content also strongly influenced the processability, while water and urea were essential for improved processing.
 	Consolidation, water absorption and solubility.  It was found that SDS's influence on hydrophobic interactions in combination with sodium sulfites cleavage of covalent cross-links resulted in good consolidation, water absorption and solubility.  Increasing sodium sulfite increased water absorption, indicative of cross-link reduction.  However, high sodium sulfite at low water concentration resulted in a degraded material.  The degraded polymer showed an increase in ordered structures, due to the formation of helical conformations of the short peptide chains.
 	Protein conformation.  It was found that BM was already highly denatured, with considerable amounts of β-structures.  Successful processing with required increased chain mobilization through the reduction of inter- and intra-molecular interactions which led to less ordered structures.
 	Mechanical Properties.  Water was shown to be critical for processing, enhancing the action of sodium sulfite, SDS and urea.  During conditioning, water would evaporate, allowing new intermolecular forces between chains, often resulting in a brittle material.  SDS was essential for consolidation, but excessive amounts could restrict formation of new intermolecular forces during conditioning.  The highly plasticized proteins resulted in ductile materials after conditioning.  Lowering the water, sodium sulfite or urea concentration would result in a brittle material after conditioning.  
Successful processability, consolidation, water absorption, solubility, and mechanical properties were achieved using 3 pphbm sodium sulfite, 60 pphbm water, 3 pphbm SDS and 20 pphbm urea.  This optimal material resulted in increased unordered structures shown by Fourier transform infra-red spectroscopy.  The resulting bioplastic was ductile after conditioning and had a tensile strength of 9.6 MPa and a Young's modulus of 536 MPa, comparable to low-density polyethylene.

year: 2009

title: Effects of introduced fish on zooplankton – fact sheet

authors: Duggan, Ian C.

abstract: Zooplankton are small animals that feed on algae and bacteria in lakes, and are in turn food for small fish. Three major zooplankton groups exist in lakes; the cladocerans and copepods, which are both small crustaceans, and the rotifers (Figure 1). Like other animals, many zooplankton species have naturally distinct geographies, meaning New Zealand has species that are not known from other parts of the world. Many zooplankton species are sensitive to changes in water quality and fish introductions.

text: Effects of introduced fish on zooplankton – fact sheet Zooplankton are small animals that feed on algae and bacteria in lakes, and are in turn food for small fish. Three major zooplankton groups exist in lakes; the cladocerans and copepods, which are both small crustaceans, and the rotifers (Figure 1). Like other animals, many zooplankton species have naturally distinct geographies, meaning New Zealand has species that are not known from other parts of the world. Many zooplankton species are sensitive to changes in water quality and fish introductions.

year: 2015

title: Māori, Tongan and Chinese households: Medications and elder care

authors: Nikora, Linda Waimarie

subjects: medications

abstract: Research reveals that medicines are frequently not taken as intended, stockpiled for future use, discontinued when symptoms fade or passed to others. Medications are material objects with therapeutic uses that enter into and take on meaning within people’s lives. In this way they are culturally embedded phenomena that carry meanings and shape social relationships and practices. The symbolic meanings given to medications and cultural relations are important for understanding variations in medication practices. Households with elders often contain more medications and have more complex age-related medical conditions. In households where members are engaged in the reciprocation of care among two or three generations, medications within and between these relationships take on a range of dynamic meanings. In this paper, we explore how interactions between household members affect medicines-taking practices of elders and their families from three cultural groups: Māori, Tongan and Chinese. This research was funded by the Health Research Council of New Zealand and the Marsden Fund of the Royal Society of New Zealand.

text: Māori, Tongan and Chinese households: Medications and elder care Research reveals that medicines are frequently not taken as intended, stockpiled for future use, discontinued when symptoms fade or passed to others. Medications are material objects with therapeutic uses that enter into and take on meaning within people’s lives. In this way they are culturally embedded phenomena that carry meanings and shape social relationships and practices. The symbolic meanings given to medications and cultural relations are important for understanding variations in medication practices. Households with elders often contain more medications and have more complex age-related medical conditions. In households where members are engaged in the reciprocation of care among two or three generations, medications within and between these relationships take on a range of dynamic meanings. In this paper, we explore how interactions between household members affect medicines-taking practices of elders and their families from three cultural groups: Māori, Tongan and Chinese. This research was funded by the Health Research Council of New Zealand and the Marsden Fund of the Royal Society of New Zealand.

year: 2010