Moisture absorption and diffusivity of epoxy filled layered-structure nanocomposite

This paper studies moisture absorption and diffusivity of epoxy reinforced layered structure nanocomposites and its effect on fracture toughness. Two different types of layered fillers employed in the study were clay and graphene platelets, in which both surface layers were unmodified and modified by characterized by swelling analysis and fracture toughness measurement. The outcomes surfactant. The nanocomposites were showed that the moisture absorption and diffusivity decreased with the addition of layered fillers. It was found that the modified graphene platelets and clay outperformed the unmodified layers and neat epoxy in terms of reduction of moisture absorption and diffusivity. The modified graphene platelets reduced the moisture uptake and diffusivity about 30% and 33%, respectively compare to neat epoxy, thus indicates its outstanding performance in barrier applications. However, once the nanocomposites were swelling in the water for 5 days, it is noticed that the fracture toughness of nanocomposites were reduced significantly about 35% in average. Nevertheless, the modified graphene platelets still display the better performance compare to the other samples although there was reduction of fracture toughness

Experimental investigation on performance of fabrics for indirect evaporative cooling applications

© 2016 Indirect evaporative cooling, by using water evaporation to absorb heat to lower the air temperature without adding moisture, is an extremely low energy and environmentally friendly cooling principle. The properties of the wet channel surface in an indirect evaporating cooler, i.e. its moisture wicking ability, diffusivity and evaporation ability, can greatly affect cooling efficiency and performance. Irregular fibres help to divert moisture and enlarge the wetted area, thus promoting evaporation. A range of fabrics (textiles) weaved from various fibres were experimentally tested and compared to Kraft paper, which has been conventionally used as a wet surface medium in evaporative coolers. It was found that most of the textile fabrics have superior properties in moisture wicking ability, diffusivity and evaporation ability. Compared with Kraft paper, the wicking ability of some fabrics was found to be 171%–182% higher, the diffusion ability 298%–396% higher and evaporation ability 77%–93% higher. A general assessment concerning both the moisture transfer and mechanical properties found that two of the fabrics were most suitable for indirective evaporative cooling applications

Processibility of corn protein blends and resulting properties of the extrudates

During the last decade, the global biofuels industry has experienced exponential growth. By-products such as high protein corn gluten meal (CGM) and high fibre distillers dried grains with solubles (DDGS) have grown in parallel. CGM has been shown to be suitable as a biopolymer; the high fibre content of DDGS reduces its effectiveness, although it is considerably cheaper. In this study, the processing behaviour of CGM and DDGS blends were evaluated and resulting extrudate properties were determined. Prior to processing, urea was used as a denaturant. DDGS:CGM ratios of 0, 33, 50, 66 and 100% were processed in a single screw extruder, which solely used dissipative heating, with a 2 mm circular die. Resulting screw speeds ranged from 216 to 228 rpm, and die exit temperatures ranged from 96 to 150oC. Blends containing DDGS were less uniformly consolidated and resulted in more dissipative heating. Blends showed multiple glass transitions, which is characteristic of mechanically compatible blends. Transmission electron microscopy revealed phase separation on a micro-scale, although distinct CGM or DDGS phases could not be identified. On a macro-scale, optical microscopy suggested that CGM-rich blends were better consolidated, supported by visual observations of a more continuous extrudate formed during extrusion. As with all biological materials, the extruded blends exhibited sorption behaviour over time, the magnitude of which varied according to blend ratio. EMC values ranged from approximately 0% to nearly 50%, depending upon the humidity level and blend ratio. Nonlinear regression was successfully used to model the effects of relative humidity and blend ratio on the equilibrium moisture contents, with a coefficient of determination of 99%. Future work should aim to also characterize the mechanical properties of these blends to assess their suitability as either bioplastic feedstock or pelletized livestock feed

Hot-pressing process modeling for medium density fiberboard (MDF)

In this paper we present a numerical solution for the mathematical modeling of the hot-pressing process applied to medium density fiberboard. The model is based in the work of Humphrey[82], Humphrey and Bolton[89] and Carvalho and Costa[98], with some modifications and extensions in order to take into account mainly the convective effects on the phase change term and also a conservative numerical treatment of the resulting system of partial differential equations.Comment: LaTeX, 11 figures. Added references. Fixed some errors. To appear in International Journal of Mathematics and Mathematical Sciences, http://jam.hindawi.co

Maturity effects in concrete dams

Model equations for determining the coupled heat, moisture and maturity changes within a concrete block are introduced and briefly examined. Preliminary results are obtained for the heat exchange between concrete slabs in contact driven by maturity differences

Variation in the impact of stem scar and cuticle on water loss in highbush blueberry fruit argue for the use of water permeance as a selection criterion in breeding

The role of fruit scar on water loss from fresh harvested, fully blue highbush blueberry (Vaccinium corymbosum L.) fruit was studied on three germplasm lines from each of three half-sib families at University of Talca, Chile. The stem scar of half of the harvested fruit was sealed using nail polish and weight loss of sealed and non-sealed fruit determined daily at 20 °C (5 d storage) and bi-weekly at 0 °C (15 d storage). Fruit firmness was determined at the end of the storage period. The stem scar accounted for approximately 40% of the moisture lost at 20 °C, but percentages varied considerably between lines. While the stem scar covered 0.19% to 0.74% of the fruit surface area, its rate of transpiration was 170-times higher than for the cuticle at 20 °C. The larger the fruit scar area, the greater was the absolute rate of water loss, but scar size scar did not affect the rate of weight loss expressed on a per gram fruit basis. Higher levels of water loss were associated with a greater loss in firmness; fruit having a large scar had a greater rate of water loss and were less firm than those having medium or small scars. The water permeance of the fruit cuticle varied two-fold and the apparent permeance of the scar varied three-fold among the 9 lines evaluated when held at 20 °C. Interestingly, one line exhibited a 75% lower rate of water loss from its stem scar than the other lines than would be predicted based on its scar diameter. Storage at 0 °C reduced the rate of water loss by 90% but the cuticle permeance was not affected by temperature. Sealing the stem scar increased fruit firmness retention at 0 °C and 20 °C, but provided less benefit at 0 °C vs. 20 °C. The highly variable nature of water loss through the stem scar and the cuticle in this study suggests that large gains in reductions in water loss are possible for the highbush blueberry once the mechanisms for transpiration are better understood.In Chile, this work was supported by the National Commission for Scientific and Technological ResearchCONICYT (FONDECYT11130539) and the Universidad de Talca (research programs “Adaptation of Agriculture to Climate Change (A2C2)”, “Fondo Proyectos de Investigación” and “Núcleo Científico Multidisciplinario”). In the United States this work was partially supported by the “2015 Fulbright Specialist Program”, Project 6365. In Spain this work was partially supported by “Fundación Carolina” and “Programa de Doctorado en Ciencia y Tecnología Agraria y Alimentaria”, Universitat de Lleida