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Thermal Pretreatment (thermal + pretreatment)
Selected AbstractsEffect of Molecular Weight on Photoinduced Birefringence in a Chiral Liquid Crystalline Azodye PolymerMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2006Mikhail Kozlovsky Abstract Summary: The evolution of the photoinduced birefringence in thin films of narrow polymer fractions is studied and compared with the behavior of the non-fractionated polymer. The ,nind value decreases by increasing the degree of polymerization () within the oligomeric range but becomes independent of molecular weight starting from a of ,70. Thermal pretreatment of the films results in higher photoinduced birefringence. The films show good stability of the photorecording. Birefringence induced after 10 min, ,nind(600) and its growth rate at the same moment versus molecular weight. [source] Ultrastructural and Changes in Pectin Composition of Sweet Cherry from the Application of Prefreezing TreatmentsJOURNAL OF FOOD SCIENCE, Issue 9 2005Jesus Alonso ABSTRACT: Thermal and calcium pretreatments applied to preserve the sweet cherry texture by the freezing/thawing process produced biochemical changes in the pectic substances and ultrastructural alterations to the cells and tissues, which were visible under scanning electron microscopy. Partial dehydration of the epidermic tissue caused by calcium (100 mM CaCl2) and thermal (50 °C/10 min) pretreatment attenuated the surface damage produced by freezing. However, pretreatment at 70 °C/2 min caused partial destruction of the epidermic tissue and plasmolysis of the parenchymatic cells. After freezing, the cell walls in the parenchymatic tissue of the fruits pretreated with 100 mM CaCl2 exhibited swelling as a result of gelling of the cell-wall pectic material. Thermal pretreatments increased the ethylenediaminetetraacetic acid (EDTA)-soluble pectin fraction and reduced the degree of pectin esterification. Thermal treatments at 70 °C, without immersion in calcium, reduced the water- and pectinase-soluble pectin fractions, whereas immersion in calcium prevented depolymerization of these fractions. Immersion in 100 mM CaCl2 increased the water-soluble pectin fraction. [source] Formation of diffusion-hindering interlayers in metals in contact by dedicated thermal treatmentCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1-2 2005D. C. Meyer Abstract Thermal evolution of the structure of Fe/Al multilayers (MLs) with nominal composition 5*(5 nm Al / 5 nm Fe) prepared by crossed-beam pulsed laser deposition is studied by wide-angle X-ray scattering and X-ray reflectometry after different temperature-time procedures of thermal treatments under high-vacuum conditions. In comparison to direct thermal annealing at temperatures of 250 °C and 275 °C, respectively, which results in nearly complete mixing of the MLs and formation of the FeAl intermetallic compound, quite different behaviour was found after dedicated thermal pretreatment. Annealing at successive growing temperatures before final annealing at temperatures mentioned, resulted in conservation of pronounced multilayer structure. From the results it is generalised, that also in the case of ML systems, the tendency of mixing a dedicated tuning of interface characteristics by thermal treatment allows for formation of diffusion-hindering interlayers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Dye diffusion and the phenomenon of barriness on polyamide fabricsCOLORATION TECHNOLOGY, Issue 2 2004L Razafimahefa Dyed polyamide fabrics tend to exhibit barriness, particularly when acid dyes of good wet fastness are used. The causes of this phenomenon have been investigated by studying the diffusion kinetics of the dyeing process. The conditions used in the pretreatment of the yarn have been considered, in particular the effect of mechanical and thermal conditions during thermal pretreatment. It has been demonstrated that barriness is dependent only on the kinetics of diffusion. If drawing is increased, the rate of dye diffusion is reduced, whereas an increase in the texturising temperature tends to increase it. The influence of dye diffusion decreases as the dyeing temperature rises. The traditional practice of dyers to attempt to reduce barriness by raising the dyebath temperature very slowly therefore makes matters worse. To reduce barring it would be preferable to introduce the dyestuff to the dyebath only once the dyeing temperature has been reached. [source] EFFECTS OF THERMAL AND ELECTROTHERMAL PRETREATMENTS ON HOT AIR DRYING RATE OF VEGETABLE TISSUEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2000WEI-CHI WANG ABSTRACT Cylindrical samples of carrot, potato and yam were dried in a hot-air dehydrator after preheating to 50C or 80C by three different heating methods (conventional, microwave and ohmic). The results showed that enhancement of drying rate increased with pretreatment temperature. Ohmic pretreatment increased the drying rate more than conventional and microwave heating. Desorption isotherms showed that in the low aw range, desorption data of preheated and raw materials were similar. However, the isotherms of preheated samples shifted when aw was high, which indicated that thermal pretreatments altered the structure, and apparently, the water distribution within these materials. For all samples, ohmic pretreatment showed stronger influences on isotherms than microwave heating, while the pretreatment effect of conventional heating was only observed for potato tissue. [source] | ||||||||||