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Marine propellers operate under severe service conditions and experience various corrosion forms. Electrochemical, mechanical, and biological corrosion are the three main common types of corrosion that occur on marine propellers. Electrolysis (electrolytic corrosion), being one of the electrochemical corrosion forms, has been extensively observed on marine propellers. It is the forced introduction of an external current in metals when submerged in seawater. However, it has rarely been studied for marine propellers, mostly on underground pipelines. This paper investigates the effect of electrolysis on a chromium-containing coating on copper substrate by studying the surface and cross-sectional microstructure of the substrate. It is likely that cathodic disbondment caused by high alkalinity and hydrogen evolution at the defect location were the primary reasons contributing to the failure of the coating, and the silver-colored layer deposition around the delaminated area is the corrosion product of copper–chromium oxide. The purpose of this study is to understand the electrolysis corrosion mechanism on Cu substrate and to develop a highly effective anticorrosion coating for marine propellers. [ABSTRACT FROM AUTHOR]

Marine propellers work under severe service conditions, where they commonly suffer from mechanical, electrochemical, and biological corrosion damage. The major mechanical corrosion involves cavitation, erosion, and impingement corrosion. On the other hand, the major electrochemical corrosion involves galvanic corrosion and electrolysis. As a result, consideration of both desired mechanical and electrochemical properties is necessary when designing a marine propeller coating. In this study, a PVB (polyvinyl butyral) and an epoxy coating were formulated without corrosion inhibitors to investigate the desired coating properties for marine propeller applications. The two coatings were compared with a Cr-containing commercial marine propeller coating to investigate the advantages and disadvantages of using PVB and epoxy for marine propeller coatings. It was found that it is desirable for marine propeller coatings to be flexible to avoid cracking and flaking; to be able to withstand high pH in order to resist cathodic disbondment (electrolysis); to have adequate primer–substrate adhesion; and, ideally, to be able to self-heal when the coating is damaged (cavitation). It was found that the PVB-ZO coating has more desirable properties, and introducing self-healing properties could be one of the options for further optimization in the future. [ABSTRACT FROM AUTHOR]

Biofouling is the buildup of marine organisms on a submerged material. This research tests the efficacy of phosphonium ion gels comprising phosphonium monomers ([P444VB][AOT] and [P888VB][AOT]) and free ionic liquid ([P4448][AOT], [P88814][AOT]) (10 to 50 wt%), varying copper(II) oxide biocide concentrations (0 to 2 wt%), and the docusate anion [AOT]− for added hydrophobicity. The efficacy of these formulations was tested using a seachest simulator protected from light and tidal currents in New Zealand coastal waters over the summer and autumn periods. Anti-fouling performance was correlated with the hydrophobicity of the surface (water contact angle: 14–131°) and biocide concentration. Formulations with higher hydrophobicity (i.e., less free ionic liquid and longer alkyl chain substituents) displayed superior anti-fouling performance. The presence of the copper(II) biocide negatively affected anti-fouling performance via significant increases to hydrophilicity. No correlation was observed between antimicrobial activity and anti-fouling performance. Overall, phosphonium ion gels show potential for combining anti-fouling and foul release properties. [ABSTRACT FROM AUTHOR]

Increasing importance is being placed on sustainability worldwide to limit climate change's effects. In New Zealand, a sizeable increase in demand for housing is driving a residential construction boom, with new dwelling consents increasing yearly for the last decade. The New Zealand Government's commitment to sustainability has become legislation through the Climate Change Response (Zero Carbon) Amendment Act 2019. Therefore, the next stage is how the construction industry can limit and reduce its carbon emissions through one of the strategies, namely material choice. This study was intended to examine the influence of various building materials on climate change and to identify how more sustainable home construction and design in New Zealand may contribute to the government's 2050 emissions reduction targets. A life-cycle assessment (LCA) was used in this study to investigate the global warming potential (GWP) produced by five case study houses and various material options for building envelope components. The study focused on the environmental impact of materials with high usage in industry and potential new materials that have shown an ability to conform to the New Zealand Building Code standards. It was found that case study House 1 (with timber flooring founded on senton piles with concrete footings, a timber frame, plywood wall cladding, and metal roof cladding) and House 2 (with a concrete waffle slab, a light steel frame, masonry wall cladding, and metal roof cladding) had the lowest GWP emissions compared to the other case study houses, with 631.13 and 633.16 kg CO2eq/m2, respectively. However, it should be noted that all the case study houses were not similar in size and design. In addition, the study investigated the different building envelope material options for the foundation, wall cladding, framing, and roof cladding. The study found that some new materials or materials that are not common in New Zealand could be used as an option for the housing envelope by having lower carbon emissions, such as 3D-printed concrete blocks compared with brick and concrete masonry for wall cladding systems. [ABSTRACT FROM AUTHOR]

Aims: To determine the antimicrobial potency of a surface‐anchored quaternary ammonium salt (SAQAS)‐based biocide during in vitro wet and dry fomite assays and to determine the mechanism of killing bacteria on the surface. Methods and Results: Wet and dry fomite assays were established in vitro for a commercially available biocide (SAQAS‐A) applied to glass and low‐density polyethylene (LDPE) surfaces. Both wet and dry fomite tests showed the active killing of Gram‐positive and Gram‐negative bacteria but not endospores. Assays measuring membrane permeability (ATP and DNA release), bacterial membrane potential and bacterial ROS production were correlated with the time‐to‐kill profiles to show SAQAS‐A activity in suspension and applied to a surface. Conclusions: SAQAS‐A is an effective biocide against model strains of vegetative bacteria. The killing mechanism for SAQAS‐A observed minimal membrane depolarization, a surge in ROS production and assessment of membrane permeability supported the puncture of cells in both suspension and surface attachment, leading to cell death. Significance and Impact of the study: SAQAS represents effective surface biocides against single challenges with bacteria through a mechanical killing ability that supports real‐world application if their durability can be demonstrated to maintain residual activity. [ABSTRACT FROM AUTHOR]

This research presents a partial biodegradable polymeric blend aimed for large-scale fused deposition modeling (FDM). The literature reports partial biodegradable blends with high contents of fossil fuel-based polymers (>20%) that make them unfriendly to the ecosystem. Furthermore, the reported polymer systems neither present good mechanical strength nor have been investigated in vulnerable environments that results in biodegradation. This research, as a continuity of previous work, presents the stability against biodegradability of a partial biodegradable blend prepared with polylactic acid (PLA) and polypropylene (PP). The blend is designed with intended excess physical interlocking and sufficient chemical grafting, which has only been investigated for thermal and hydrolytic degradation before by the same authors. The research presents, for the first time, ANOVA analysis for the statistical evaluation of endurance against biodegradability. The statistical results are complemented with thermochemical and visual analysis. Fourier transform infrared spectroscopy (FTIR) determines the signs of intermolecular interactions that are further confirmed by differential scanning calorimetry (DSC). The thermochemical interactions observed in FTIR and DSC are validated with thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) is also used as a visual technique to affirm the physical interlocking. It is concluded that the blend exhibits high stability against soil biodegradation in terms of high mechanical strength and high mass retention percentage. [ABSTRACT FROM AUTHOR]

This research undertakes a Life Cycle Analysis (LCA) to determine the climate change potential of a typical newly built steel detached dwelling in Palmerston North, New Zealand (NZ) and assesses its results concerning the 2 °C and 1.5 °C 2050 Paris Agreement targets. The proposed, upcoming policy and actions of the NZ government relating to its residential building and construction sector, which are set with an overarching aim to allow NZ to progress towards meeting the 2050 Paris Agreement targets, are also discussed in this paper. The results of the LCA demonstrate that the projected stock of steel-framed detached houses significantly exceeds the calculated climate budget and eventual 2050 Paris Agreement targets. For both the 2 °C and 1.5 °C scenarios, the magnitude of exceedance of the climate budget is 5.2 and 7.3 times more than the acceptable limit, correspondingly. These findings suggest that the sector will need to undergo a significant transition in order to fulfil the 2050 Paris Agreement targets. In the meanwhile, the sector's upcoming policies and regulations must be achievable while progressing toward achieving net-zero carbon emissions. [ABSTRACT FROM AUTHOR]

In this work silicon nitride (Si3N4) fibres, with diameters D50 = 300 nm, were successfully functionalised with a monolayer of γ-glycidoxypropyl trimethoxysilane (GPS) coupling agent. The surface modification was used as a method to enhance the dispersion and interfacial adhesion of the fibres in epoxy polymer composites. It is well known that strong interfacial adhesion between dispersed inorganic fibres and a polymer matrix improves the mechanical properties of the composite by providing an effective stress-transfer pathway between the matrix and the fibres. The functionalised Si3N4 fibres were dispersed into a commercial epoxy resin via tumble-mill mixing and ultra-sonication. Setting was initiated via addition of a poly-amine hardener and the composites were cured at room temperature for 24 hours. The fractured surfaces of the cured composite materials were analysed via SEM imaging and the mechanical properties of the composites were tested. The GPS-Si3N4 composites were shown to have improved bonding at the interface, which resulted in enhanced mechanical properties compared to the unfunctionalised Si3N4 composites, with improved tensile strengths and hardness values. This study shows the importance of achieving a strong interphase region between the surface of a fibre and the polymer matrix in fibre-reinforced polymer composites. [ABSTRACT FROM AUTHOR]

Fire performance of water-based plaster systems containing acrylic copolymer binder and non-flammable mineral and ceramic fillers intended for decorative coating application was determined by cone calorimetric method. The coatings were applied on common building substrate materials used in construction sector, namely, Medium Density Fibre (MDF) boards, Gypsum Boards (GIB) and Stainless Steel (SS), and the different plaster finishes attempted on these substrates were Tierrafino, Suave and Bone China respectively. Group numbers of the different test samples were also evaluated following the Kokkala method. Based on various measurements, especially heat release, smoke evolution, mass loss data and the Group number estimates, it is evident that these organic fire retardant free coatings can offer good fire safety if applied on appropriate substrates like GIB or SS. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ultra-high surface area silica, UHSAS (N 2 BET surface area:>700 m 2 g −1 ) was obtained from expanded perlite (EP) by a two-step process. In the first step, a hydrothermal process using aqueous sodium hydroxide (at 70 °C for 24 h) was employed to convert EP into an ordered intermediate zeolitic phase. The materials and the process dynamics were examined by various analytical techniques to elucidate the material transformation mechanism involved and to optimize the silica surface area. The structural details of conversion of EP to high surface silica has been identified by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Solid State Nuclear Magnetic Resonance (SSNMR). These analyses have confirmed that the conversion includes an intermediate zeolite phase, which is predominantly NaP1 type zeolite. In the next stage, this intermediate NaP1 type zeolite was converted to amorphous high surface-area silica by hydrochloric acid treatment. Amorphous high-surface area silica was also recovered from the supernatant solution obtained from hydrothermal process by hydrochloric acid treatment. The overall process of silica extraction from EP was optimized to achieve the UHSAS products. [ABSTRACT FROM AUTHOR]

The development of a sustained-release biocide system, involving an anchored quaternary ammonium salt (AQAS) embedded in expanded perlite (EP) substrate, is reported. Scanning electron microscopy (SEM) images reveal the well-defined honeycomb cells that are a feature of EP. These honeycomb cells exhibit a variety of polygon shapes, which are filled with the AQAS molecules as evidenced by SEM data. The aqueous leaching of the AQAS from the EP honeycomb cells is monitored by the Fourier transform infrared CH stretching absorbance maxima at 2920 and 2850 cm -1 . Solid-state NMR data indicate the formation of three dominant oligomeric forms of the AQAS biocide molecules formed within the EP network by condensation reactions at curing temperatures (160 °C). The various oligomeric species involve different numbers of SiO chains bonded to a central Si atom within the AQAS anchoring groups. Assays confirm the potency of the AQAS oligomers against Staphylococcus aureus and Escherichia coli bacteria.