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: Seismically-induced down-sagging structures in tephra layers (tephra-seismites) preserved in lakes since 17.5 cal ka, Hamilton lowlands, New Zealand

authors: Kluger, Max O.

abstract: We analysed numerous soft-sediment deformation structures (SSDSs) identified in seven unconsolidated, up to 8-cmthick, siliceous tephra layers that had been deposited in ~35 riverine-phytogenic lakeswithin the Hamilton lowlands, northern North Island, New Zealand, since 17.5 calendar (cal) ka BP. Based on sediment/tephra descriptions and X-ray computed tomography scanning of cores taken from ten lakes, we classified these SSDSs into elongated load structures (i.e., down-sagging structures) of different dimensions, ranging from millimetre- to decimetre-scale and centimetre-long dykes. Down-sagging structures were commonly manifested as intrusions of internal tephra beds of very fine to medium sand into underlying organic lake sediments.
The tephra layers commonly exhibited an upper silt bed, which was not directly affected by deformation. Dry bulk density and grain size distribution analyses of both the organic lake sediment and the internal tephra beds provided evidence for the deformation mechanism of down-sagging structures and their driving force:
the organic lake sediment and the upper silt bed are less liquefiable, whereas the very fine to medium sand internal tephra beds are liquefiable. The tephra layers and encapsulating organic lake sediments formed three layer (a–b–a) density systems, where ‘a’ denotes the sediment unit of lower density. We infer that downward directed deformation was favoured by the a–b–a density system with the upper, less-liquefiable, silt bed within the tephra layer preventing upward intrusion during the liquefaction process. The spatial distribution and ages of SSDSs within the lakes provided some evidence that liquefaction of the older tephra layers, i.e., Rerewhakaaitu, Rotorua, and Waiohau tephras, deposited 17.5, 15.6, and 14 cal ka BP, respectively, was triggered by a seismic source to the northeast of the Hamilton lowlands (i.e., Kerepehi and/or Te Puninga faults). In contrast, the liquefaction of the younger tephra layers, i.e., Opepe, Mamaku, and Tuhua tephras, deposited 10.0, 8.0, and 7.6 cal ka BP, respectively, may have been triggered by movement on local faults within the Hamilton lowlands, namely the Hamilton Basin faults, or by distant faulting at the Hikurangi subduction margin east of North Island.

text: Seismically-induced down-sagging structures in tephra layers (tephra-seismites) preserved in lakes since 17.5 cal ka, Hamilton lowlands, New Zealand We analysed numerous soft-sediment deformation structures (SSDSs) identified in seven unconsolidated, up to 8-cmthick, siliceous tephra layers that had been deposited in ~35 riverine-phytogenic lakeswithin the Hamilton lowlands, northern North Island, New Zealand, since 17.5 calendar (cal) ka BP. Based on sediment/tephra descriptions and X-ray computed tomography scanning of cores taken from ten lakes, we classified these SSDSs into elongated load structures (i.e., down-sagging structures) of different dimensions, ranging from millimetre- to decimetre-scale and centimetre-long dykes. Down-sagging structures were commonly manifested as intrusions of internal tephra beds of very fine to medium sand into underlying organic lake sediments.
The tephra layers commonly exhibited an upper silt bed, which was not directly affected by deformation. Dry bulk density and grain size distribution analyses of both the organic lake sediment and the internal tephra beds provided evidence for the deformation mechanism of down-sagging structures and their driving force:
the organic lake sediment and the upper silt bed are less liquefiable, whereas the very fine to medium sand internal tephra beds are liquefiable. The tephra layers and encapsulating organic lake sediments formed three layer (a–b–a) density systems, where ‘a’ denotes the sediment unit of lower density. We infer that downward directed deformation was favoured by the a–b–a density system with the upper, less-liquefiable, silt bed within the tephra layer preventing upward intrusion during the liquefaction process. The spatial distribution and ages of SSDSs within the lakes provided some evidence that liquefaction of the older tephra layers, i.e., Rerewhakaaitu, Rotorua, and Waiohau tephras, deposited 17.5, 15.6, and 14 cal ka BP, respectively, was triggered by a seismic source to the northeast of the Hamilton lowlands (i.e., Kerepehi and/or Te Puninga faults). In contrast, the liquefaction of the younger tephra layers, i.e., Opepe, Mamaku, and Tuhua tephras, deposited 10.0, 8.0, and 7.6 cal ka BP, respectively, may have been triggered by movement on local faults within the Hamilton lowlands, namely the Hamilton Basin faults, or by distant faulting at the Hikurangi subduction margin east of North Island.

year: 2023-03

title: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education

authors: Rawiri, Casey

subjects: social support

abstract: The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

text: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

year: 2007