论文标题
热和机械恢复对巧克力流变行为的影响
Effect of Thermal and Mechanical Rejuvenation on Rheological Behavior of Chocolate
论文作者
论文摘要
已知巧克力在温度升高以及变形场的应用下会经历固液过渡。从熔融状态（或热恢复活力）突然降低温度后，巧克力的流变特性会在等热条件下经历时间的变化，这种行为使人联想到聚合物玻璃中的身体衰老。再一次，在停止剪切流（或机械恢复活力）之后，巧克力显示了流变特性的时间演变，这种行为类似于软玻璃材料中的物理老化。在这项工作中，我们评估了三种流变特性，即动态模量，放松时间光谱和巧克力的特征放松时间，并比较了它们在热和机械恢复后的演变。我们观察到，机械恢复后的流变特性的演变与热恢复的变化明显不同，其中，在前一种情况下，演变更逐渐。一方面，这项工作为剪切方式如何影响巧克力的流变行为提供了独特的见解。另一方面，这项工作清楚地表明，与热恢复活力相比，机械恢复后巧克力探索了能量景观的不同部分。
Chocolate is known to undergo solid-liquid transition upon an increase in temperature as well as under application of deformation field. Upon sudden reduction in temperature from a molten state (or thermal rejuvenation), rheological properties of chocolate undergo evolution as a function of time under isothermal conditions, a behavior reminiscent of physical aging in polymeric glasses. Then again, subsequent to cessation of shear flow (or mechanical rejuvenation), chocolate shows temporal evolution of the rheological properties, a behavior similar to physical aging in soft glassy materials. In this work, we evaluate three rheological properties, namely, dynamic moduli, relaxation time spectrum and characteristic relaxation time of chocolate, and compare their evolution after thermal as well as mechanical rejuvenation. We observe that the evolution of the rheological properties subsequent to mechanical rejuvenation is distinctly different from that of thermal rejuvenation, wherein the evolution is more gradual in the former case. On the one hand, this work provides unique insights into how shear affects the rheological behavior of chocolate. On the other hand, this work clearly suggests that chocolate explores different sections of the energy landscape after mechanical rejuvenation compared to that of thermal rejuvenation.
