title: Platinum(II), palladium(II) and gold(III) complexes containing 1,1,4-trisubstituted thiosemicarbazide dianion ligands

authors: Henderson, William

subjects: chemistry

abstract: Reactions of cis-[PtCl₂(PPh₃)₂] or [PdCl₂(PPh₃)₂] with Ph₂N---NHC(S)NHPh and excess triethylamine, in refluxing methanol gave the complexes [M{SC(=NPh)NNPh₂}(PPh₃)₂] containing thiosemicarbazide dianion ligands. An analogous gold(III) complex containing the cyclo-aurated anilinopyridine ligand was also synthesised. A single crystal X-ray diffraction study was carried out on the complex [Pt{SC(=NPh)NNPh₂}(PPh₃)₂] which confirmed the bonding of the thiosemicarbazide dianion ligand via sulfur and the nitrogen bearing the NPh₂ substituent. In contrast, reaction of Ph₂N---NHC(S)NHMe with cis-[PtCl₂(PPh₃)₂] and excess triethylamine gave the complex [Pt{SC(=NNPh₂)NMe}(PPh₃)₂], containing a Pt---NMe group, characterized spectroscopically.

text: Platinum(II), palladium(II) and gold(III) complexes containing 1,1,4-trisubstituted thiosemicarbazide dianion ligands Reactions of cis-[PtCl₂(PPh₃)₂] or [PdCl₂(PPh₃)₂] with Ph₂N---NHC(S)NHPh and excess triethylamine, in refluxing methanol gave the complexes [M{SC(=NPh)NNPh₂}(PPh₃)₂] containing thiosemicarbazide dianion ligands. An analogous gold(III) complex containing the cyclo-aurated anilinopyridine ligand was also synthesised. A single crystal X-ray diffraction study was carried out on the complex [Pt{SC(=NPh)NNPh₂}(PPh₃)₂] which confirmed the bonding of the thiosemicarbazide dianion ligand via sulfur and the nitrogen bearing the NPh₂ substituent. In contrast, reaction of Ph₂N---NHC(S)NHMe with cis-[PtCl₂(PPh₃)₂] and excess triethylamine gave the complex [Pt{SC(=NNPh₂)NMe}(PPh₃)₂], containing a Pt---NMe group, characterized spectroscopically.

year: 2003

title: The viability of waste copper chromium and arsenic treated timber reinforced polypropylene as a sustainable building material

authors: Nelson, Jacob Martin Bruton

subjects: Natural fibre composites

abstract: The aim of this thesis was to investigate the viability of wood-plastic composites (WPCs) produced from wood flour and fibre derived from waste copper chromium and arsenic (CCA) treated timber for use as a sustainable material in the construction sector.

The research included an assessment of mechanical properties and the leaching of heavy metals from the wood-plastic composites, and the results were compared to material requirements in the building sector provided through literature and New Zealand building standards. Mechanical and chemical methods were used to prepare wood flour and fibre samples from waste CCA treated timber for use in wood-plastic composites. Composites were produced through compounding using a twin screw extruder or a custom sigma blade compounder and then injection moulded for material testing. Composites produced using an extruder with 40 wt.% bleached fibres and 4 wt.% MAPP, increased tensile strength (TM) from 18.5 MPa for the polypropylene used for the matrix to 27.6 MPa; Young's modulus (YM) was increased from 0.84 GPa to 2.33 GPa.

Comparison of mechanical performance with commercial WPC properties suggests that waste CCA treated timber could be used as a raw material to produce WPC for semi-structural applications. The modulus (2.33 GPa, in the highest performing composites) was roughly three times lower than commonly used commercial timbers used in structural applications. The creep performance was not measured for a time frame long enough to be indicative of the 50 years required for structural application. Therefore, further research is required to investigate whether the low modulus and creep performance of the WPC is acceptable for a structural material in the construction sector.

One of the largest concerns with using waste CCA treated timber as a reinforcement material in WPC was the inclusion of heavy metals and the potential for leaching. Arsenic was considered the most toxic of the heavy metals in the CCA treated timber. Processing of the waste CCA treated timber to obtain fibre was found to reduce arsenic concentration by up to 99.94 % in the best scenario. Furthermore, arsenic in leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing wood flour composites to digested and bleached fibre composites. The concentration of copper, chromium, and arsenic in leachate from composites produced with chemically obtained fibre was found to be significantly lower than the maximum allowable drinking levels in New Zealand. Therefore, indicating the application of composites produced with wood fibre from waste CCA treated timber can be regarded as safe even in scenarios that involve human contact with the material.

A life cycle analysis study found that the use of an alkali digestion process to obtain fibre significantly increased the environmental impact compared to the processing required to obtain wood flour. In a study of a potential commercial scale process, ultrasonic treatment and hydrogen peroxide bleaching as secondary fibre treatments were the largest contributors to environmental impact in the preparation of wood fibre. Thus, the results suggest that chemical treatments should only be employed to produce wood fibre when the highest mechanical performance or lowest leaching levels are required for the application of the wood-plastic composites.

text: The viability of waste copper chromium and arsenic treated timber reinforced polypropylene as a sustainable building material The aim of this thesis was to investigate the viability of wood-plastic composites (WPCs) produced from wood flour and fibre derived from waste copper chromium and arsenic (CCA) treated timber for use as a sustainable material in the construction sector.

The research included an assessment of mechanical properties and the leaching of heavy metals from the wood-plastic composites, and the results were compared to material requirements in the building sector provided through literature and New Zealand building standards. Mechanical and chemical methods were used to prepare wood flour and fibre samples from waste CCA treated timber for use in wood-plastic composites. Composites were produced through compounding using a twin screw extruder or a custom sigma blade compounder and then injection moulded for material testing. Composites produced using an extruder with 40 wt.% bleached fibres and 4 wt.% MAPP, increased tensile strength (TM) from 18.5 MPa for the polypropylene used for the matrix to 27.6 MPa; Young's modulus (YM) was increased from 0.84 GPa to 2.33 GPa.

Comparison of mechanical performance with commercial WPC properties suggests that waste CCA treated timber could be used as a raw material to produce WPC for semi-structural applications. The modulus (2.33 GPa, in the highest performing composites) was roughly three times lower than commonly used commercial timbers used in structural applications. The creep performance was not measured for a time frame long enough to be indicative of the 50 years required for structural application. Therefore, further research is required to investigate whether the low modulus and creep performance of the WPC is acceptable for a structural material in the construction sector.

One of the largest concerns with using waste CCA treated timber as a reinforcement material in WPC was the inclusion of heavy metals and the potential for leaching. Arsenic was considered the most toxic of the heavy metals in the CCA treated timber. Processing of the waste CCA treated timber to obtain fibre was found to reduce arsenic concentration by up to 99.94 % in the best scenario. Furthermore, arsenic in leachate from composites was found to decrease from 41.29 to 0.07 ppb when comparing wood flour composites to digested and bleached fibre composites. The concentration of copper, chromium, and arsenic in leachate from composites produced with chemically obtained fibre was found to be significantly lower than the maximum allowable drinking levels in New Zealand. Therefore, indicating the application of composites produced with wood fibre from waste CCA treated timber can be regarded as safe even in scenarios that involve human contact with the material.

A life cycle analysis study found that the use of an alkali digestion process to obtain fibre significantly increased the environmental impact compared to the processing required to obtain wood flour. In a study of a potential commercial scale process, ultrasonic treatment and hydrogen peroxide bleaching as secondary fibre treatments were the largest contributors to environmental impact in the preparation of wood fibre. Thus, the results suggest that chemical treatments should only be employed to produce wood fibre when the highest mechanical performance or lowest leaching levels are required for the application of the wood-plastic composites.

year: 2022

title: Indigenous knowledge, methodology and mayhem: What is the role of methodology in producing indigenous insights? A discussion from Mātauranga Māori

authors: Smith, Linda Tuhiwai

abstract: The emergence of an academic discourse called Indigenous knowledge internationally, and mātauranga Māori in Aotearoa New Zealand, presents some substantive challenges to concepts of knowing and being, of knowledge creation, knowledge work and the making of meaning. These challenges engage us across philosophical, disciplinary, institutional, inter-generational, territorial and community boundaries, presenting an opportunity to imagine this field anew, and the theories and methodologies that inform contemporary Māori or Indigenous Studies. This article raises some discussion about ‘research methodologies’ being used when discussing mātauranga Māori and Indigenous knowledge (hereafter referred to as IK mātauranga). Research methodologies are often associated with specific disciplines of knowledge and viewed as the primary if not singular way in which knowledge is generated. Arguably, IK mātauranga occupies a different knowledge space from traditional academic disciplines, including their transdisciplinary interstices. This article speaks to a gnawing sense that mayhem is at play, as the academic work around IK mātauranga begins to consolidate and become institutionalised away from its indigenous communities and contexts, where it began and where it still informs identities, ways of living and being.

text: Indigenous knowledge, methodology and mayhem: What is the role of methodology in producing indigenous insights? A discussion from Mātauranga Māori The emergence of an academic discourse called Indigenous knowledge internationally, and mātauranga Māori in Aotearoa New Zealand, presents some substantive challenges to concepts of knowing and being, of knowledge creation, knowledge work and the making of meaning. These challenges engage us across philosophical, disciplinary, institutional, inter-generational, territorial and community boundaries, presenting an opportunity to imagine this field anew, and the theories and methodologies that inform contemporary Māori or Indigenous Studies. This article raises some discussion about ‘research methodologies’ being used when discussing mātauranga Māori and Indigenous knowledge (hereafter referred to as IK mātauranga). Research methodologies are often associated with specific disciplines of knowledge and viewed as the primary if not singular way in which knowledge is generated. Arguably, IK mātauranga occupies a different knowledge space from traditional academic disciplines, including their transdisciplinary interstices. This article speaks to a gnawing sense that mayhem is at play, as the academic work around IK mātauranga begins to consolidate and become institutionalised away from its indigenous communities and contexts, where it began and where it still informs identities, ways of living and being.

year: 2016