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Journal of Thermal Analysis and Calorimetry
Authors: Maria Villanueva, I. Fraga, J. Rodríguez-Añón, J. Proupín-Castiñeiras, and J. Martín

Abstract  

The diffusive, calorimetric and thermal degradation behavior of different epoxy-amine systems was investigated during water sorption at different temperatures (23, 40 and 70°C). Experimental results showed that the water absorption at these temperatures fitted well to Fick’s law. Influence of water immersion during different periods of time on the glass transition temperatures was studied by differential scanning calorimetry. Thermal degradation of saturated samples was studied by thermogravimetric analysis. Dependence on the selected curing cycle was also checked.

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The diffusive and dynamic mechanical behavior of the DGEBA/1,3-BAC epoxy resin system was studied during water absorption. The diffusion of water was investigated at 100% relative humidity, by immersion of specimens in water at 60, 80 and 100°C. In all absorption experiments, water diffusion followed Fick's law. Diffusion coefficients and saturated water concentrations are given for these temperatures. The activation energy for diffusion was determined from the relationship between the diffusion coefficient and the reciprocal of the absolute temperature. The value obtained was 31.2 kJ mol−1. Dynamic mechanical analysis of samples immersed in 100°C water and with various water contents showed both a shift of Tg, defined by thetanδ peak, to lower temperatures and a slight decrease in the dynamic modulus in the presence of water. These effects are probably a result of plasticization.

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Damaged starch, protein and arabinoxylan (AX) content and composition have been related to water absorption (WA) in a large set of samples. We tested 20 modern bread wheat cultivars bred in Hungary, 20 old Hungarian landraces, and 17 cultivars with special biochemical/functional characteristics from all around the world, this last set for international comparison. Grain was field grown in the 2011 and 2012 harvest seasons. Alinear mathematical model has been developed to estimate WA from protein content, starch damage, AX content and the relative amount of soluble proteins with strong correlation (r2 = 0.65) between measured and estimated data. The introduction of a new parameter, related to the cultivar dependent quantitative composition of soluble proteins and determined by lab-on-a-chip (LOC) analysis, largely improved the predictability of WA. Based on the large variation among the level of AX and certain soluble protein components in wheat flour and their significant contribution toWA determination, it was concluded, that these properties could be appropriate target traits to alter them during wheat breeding programs to improve the WA of wheat flour.

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. , Hamard , E. , Cothenet A. Measuring the water absorption of recycled aggregates, what is the best practice for concrete production? Construction and Building Materials , Vol. 123 , 2016 , pp. 690 – 703

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. Zhang Z. Y. Richardson M. O. W. Effect of water, absorption on the mechanical properties of hemp fiber reinforced unsaturated polyester

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Pollack Periodica
Authors: Julia Cigasova, Nadezda Stevulova, Ivana Schwarzova, and Jozef Junak

2116 2123 Dhakal H. N., Zhang Z. Y., Richardson M. O. W. Effect of water absorption on the mechanical properties of hemp fiber reinforced unsaturated polyester composites

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Pollack Periodica
Authors: Yahya Fall, Mimoun Chourak, Seif-Eddine Cherif, Mahjoub Himi, and Mohammed Rougui

. , Stevulova N. , Terpakova E. Influence of water absorption on the selected properties of hemp hurds composites , Pollack Periodica , Vol. 10 , No. 1 , 2015 , pp. 123 ‒ 132 . [4

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(Building physical formulae and tables) 1997 Juhász, P., K. Kopecskó 2012: Changes of color and water-absorption of Hungarian

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Acta Alimentaria
Authors: O. Velasco-González, S. Echavarría-Almeida, A. Pajarito, and E. San Martín-Martinez

Mullin, W.J. & Xu, W. (2001): Study of soybean seed coat components and their relationship to water absorption. J. agric. Fd Chem. , 49 , 5331

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. Z. Karaca 2010 Water absorption and dehydration of natural stones versus time Construction and Building Materials 24 786 790

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