Effects of Current Annealing on Thermal Conductivity of Carbon Nanotubes

This work documents the annealing effect on the thermal conductivity of nanotube film (CNTB) and carbon nanotube fiber (CNTF). The thermal properties of carbon nanotube samples are measured by using the transient electro-thermal (TET) technique, and the experimental phenomena are analyzed based on numerical simulation. During the current annealing treatment, CNTB1 always maintains the negative temperature coefficient of resistance (TCR), and its thermal diffusivity increases gradually. When the annealing current is 200 mA, it increases by 33.62%. However, with the increase of annealing current, the TCR of CNTB2 changes from positive to negative. The disparity between CNTB2 and CNTB1 suggests that they have different physical properties and even structures along their lengths. The high-level thermal diffusivity of CNTB2 and CNTF are 2.28–2.46 times and 1.65–3.85 times higher than the lower one. The results show that the decrease of the thermal diffusivity for CNTB2 and CNTF is mainly caused by enhanced Umklapp scattering, the high thermal resistance and torsional sliding during high temperature heating.

Effects of In-Process Temperatures and Blending Polymers on Acrylonitrile Butadiene Styrene Blends

Acrylonitrile butadiene styrene (ABS) is a renowned commodity polymer for additive manufacturing, particularly fused deposition modelling (FDM). The recent large-scale applications of 3D-printed ABS require stable mechanical properties than ever needed. However, thermochemical scission of butadiene bonds is one of the contemporary challenges affecting the overall ABS stability. In this regard, literature reports melt-blending of ABS with different polymers with high thermal resistance. However, the comparison for the effects of different polymers on tensile strength of 3D-printed ABS blends was not yet reported. Furthermore, the cumulative studies comprising both blended polymers and in-process thermal variables for FDM were not yet presented as well. This research, for the first time, presents the statistical comparison of tensile properties for the added polymers and in-process thermal variables (printing temperature and build surface temperature). The research presents Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) to explain the thermochemical reasons behind achieved mechanical properties. Overall, ABS blend with PP shows high tensile strength (≈31 MPa) at different combinations of in-process parameters. Furthermore, some commonalities among both blends are noted, i.e., the tensile strength improves with increase of surface (bed) and printing temperature.

Investigation of Bath/Freeze Lining Interface Temperature Based on the Rheology of the Slag

Freeze lining is a solidified layer of slag formed on the inner side of a water-cooled pyrometallurgical reactor, which protects the reactor walls from thermal, physical, and chemical attacks. Because of the freeze lining's high thermal resistance, the reactor heat losses strongly depend on the freeze lining thickness. In a batch process such as slag fuming, the conditions change with time, affecting the freeze lining thickness. Determining the freeze lining thickness is challenging as it cannot be measured directly. In this study, a conceptual framework based on the morphology and microstructure of freeze lining and the rheology of the slag is discussed and experimentally evaluated to determine the freeze lining thickness. It was found that the bath/freeze lining interface lies just below critical viscosity temperature. The growth of the freeze lining is primarily controlled by the mechanical and thermal degradation of the crystals forming at the interface. The bath/freeze lining interface temperature for the measured slag lies in the range of 1035–1070°C.

In situ U g-value measurement on three different glazing types

This study presents in situ monitoring data of three different glazing systems over a period of one year. An insulated glass unit (IGU), a Vacuum Insulated Glass hybrid unit (VIG-hybrid) and an opaque architectural insulation module (AIM) were monitored under the equivalent environmental condition in this study. Different issues were observed and analyzed. It was found that the Ug-value cited by the manufacturers agrees with the Ug-values derived from the measured data, to within less than 5 % for the IGU and the VIG-hybrid. The consistency of the Ug-value of each glazing types one year after the start of monitoring was validated for similar environmental conditions. Depending on the magnitude of the resistance to heat flow, an increasing Ug-value was observed for a higher temperature difference between the inside and outside environments. The effect is much more significant for the glazing type with the largest Ug-value (IGU) and less significant for the glazing types with a high thermal resistance (VIG-hybrid, AIM).

Thermal stable and proteinase-K resistant insecticidal toxins produced by Photorhabdus luminescens

Photorhabdus is lives in a mutualistic association with nematodes from the family Heterorhabditis. Bacteria of the Photorhabdus can survive independently and cause toxicity in a larger variety of insects. In the present study, insecticidal activity of non-portentous heat-stable metabolites of Photorhabdus luminescens was evaluated against Galleria mellonella. For this purpose, the culture extract of P. luminescens was injected into the G. mellonella larvae, which killed almost 90% of larvae within 48 h. The extract showed 100% insecticidal activity after heat treatment of 70 C for 30 min and even 60% and 40% activity lasted at 80 C and 90 C respectively. The extract also showed a high degree of thermal stability and was 100% actives after 60 min at 70 C. In addition, insecticidal activity was preserved up to 100% after all proteinase-K treatments (0 ?g/mL to 50 ?g/mL). The results revealed that the extracts were non-portentous and showed high thermal resistance and stability. Keywords: Photorhabdus, insecticidal activity, toxins, heat stable non-proteinaceous

Development of Polystyrene Foam Plates and Sprayed Concrete for Three-Layer Products and Structures

Energy saving is one of today’s biggest challenges. Since the construction industry is very energy intensive, there is a question of drastic reduction of energy consumption in all types of buildings. There are different approaches to this issue, but ultimately there is a need to create materials that have high thermal resistance.

Applied Rheology as Tool for the Assessment of Chitosan Hydrogels for Regenerative Medicine

The regeneration of soft tissues that connect, support or surround other tissues is of great interest. In this sense, hydrogels have great potential as scaffolds for their regeneration. Among the different raw materials, chitosan stands out for being highly biocompatible, which, together with its biodegradability and structure, makes it a great alternative for the manufacture of hydrogels. Therefore, the aim of this work was to develop and characterize chitosan hydrogels. To this end, the most important parameters of their processing, i.e., agitation time, pH, gelation temperature and concentration of the biopolymer used were rheologically evaluated. The results show that the agitation time does not have a significant influence on hydrogels, whereas a change in pH (from 3.2 to 7) is a key factor for their formation. Furthermore, a low gelation temperature (4 °C) favors the formation of the hydrogel, showing better mechanical properties. Finally, there is a percentage of biopolymer saturation, from which the properties of the hydrogels are not further improved (1.5 wt.%). This work addresses the development of hydrogels with high thermal resistance, which allows their use as scaffolds without damaging their mechanical properties.

Characterization of the Hygrothermal Properties of Wood Fibre Insulaton Board

High thermal resistance building envelopes comprising wood fibre insulation board (WFIB) contribute to a reduction in building energy consumption associated with unwanted heat losses and gains. The longterm performance and durability of the WFIB material may perform differently than expected due to the temperature and moisture dependent material characteristics, including moisture sorption, vapour permeance, and thermal conductivity. This research investigated the characterization of hygrothermal properties of WFIB at temperatures and relative humidities expected for a Canadian climate. The hygrothermal characteristics of WFIB were determined to have a range of values as a result of the variable nature of wood fibre materials with temperature and moisture, and the variability of WFIB materials amongst manufactured products. The variabilities of these hygrothermal properties are expected to impact the materials overall moisture storage at various in-situ temperature and relative humidity conditions, and the materials ability to transport moisture at various in-situ temperature and relative humidity conditions. Additionally, the thermal performance of WFIB is expected to vary with in-situ temperature and relative humidity conditions, with increased thermal losses/gains with increasing temperature and increasing relative humidities.

Characterization of the Hygrothermal Properties of Wood Fibre Insulaton Board

High thermal resistance building envelopes comprising wood fibre insulation board (WFIB) contribute to a reduction in building energy consumption associated with unwanted heat losses and gains. The longterm performance and durability of the WFIB material may perform differently than expected due to the temperature and moisture dependent material characteristics, including moisture sorption, vapour permeance, and thermal conductivity. This research investigated the characterization of hygrothermal properties of WFIB at temperatures and relative humidities expected for a Canadian climate. The hygrothermal characteristics of WFIB were determined to have a range of values as a result of the variable nature of wood fibre materials with temperature and moisture, and the variability of WFIB materials amongst manufactured products. The variabilities of these hygrothermal properties are expected to impact the materials overall moisture storage at various in-situ temperature and relative humidity conditions, and the materials ability to transport moisture at various in-situ temperature and relative humidity conditions. Additionally, the thermal performance of WFIB is expected to vary with in-situ temperature and relative humidity conditions, with increased thermal losses/gains with increasing temperature and increasing relative humidities.