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Investigation on asphalt’s wax-induced phase separation behavior and its impact on rheological properties
Published in Sandra Erkens, Xueyan Liu, Kumar Anupam, Yiqiu Tan, Functional Pavement Design, 2016
M. Gong, H. Yao, T. Pauli, Z. Yao, J. Yang
H-NMR result indicates that bee structure may consist of alkane molecules with long chain and short/fewer branches. Research shows that there is surface freezing phenomenon in molten normal alkane (Ocko et al. 1997). As the temperature goes down, these alkane molecules will form an elastic crystal embedded in the viscoelastic matrix. Since properties (viscoelasticity and Poisson’s ratio) of wax crystal layer and matrix are different, this mismatch would induce compression stress on the elastic crystal. Then the wax crystal may undergo a diffusion induced wrinkling process through relaxation of the curvature elasticity (Safran, 1999; Vandeparre, 2008; Chung, 2009; Huang, 2013; Na et al. 2015).
Optimization of freezing parameters for freeze-drying mango (Mangifera indica L.) slices
Published in Drying Technology, 2018
Natalia A. Salazar, Catalina Alvarez, Carlos E. Orrego
The temperature history of the freezing data of the assays can be used to determine the initial freezing temperature of MS, recording the rise in each sample temperature after its initial supercooling point. From this information, the average initial freezing temperature of MS was ca. −1.9 ± 0.1°C. The MS were frozen by contact with the refrigerated steel plate of the lyophilizer. Except for the assays with T = 0°C, when the sample reached T, the lower surface of MS was at least partially frozen when the VISF treatments were applied. The surface freezing is caused by the thermal demand of the sudden superficial water crystallization, which in turn is owed to the pressure differential between chamber pressure and supercooled water and/or surface ice. The effect of VISF in water solutions is the local and well-arranged surface freezing which leads to the formation of an ordered structure that allows faster sublimation during freeze-drying. Despite the presence of a solid phase (MS are a solid material, and the VISF application was done when part of its water was frozen), the use of VISF in solid samples like MS also ordered the surface structure and allowed to obtain a more dried product. This driven force is weakened as sample temperature is lower and chamber pressure is higher. That could explain the higher values of DMS final moisture content predicted by the model for P = 900 mtorr (Fig. 4).