Modelling the impact of processing conditions on the kinetics of self assembly of soft multicomponent materials: effects of shear flow

模拟加工条件对软质多组分材料自组装动力学的影响：剪切流的影响

• 批准号: 341652-2007
• 负责人: Mazzanti, Gianfranco
• 金额: $ 2.16万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=482215
• 关键词: Modelling; impact; processing; conditions; kinetics

I aim at developing conceptual and mathematical models for the thermodynamic and momentum, heat and mass transfer mechanisms that determine the self-assembly of edible multicomponent systems subject to different external fields (temperature profiles, shear and extensional flow, etc.). Shear flow is used very empirically in industry to obtain desired structural properties, but little fundamental knowledge exists. This application focuses on crystallization of multicomponent lipid systems prepared with pure components. This will somewhat simplify the complexity from the multicomponent nature and the polymorphism of these materials: even a pure component can form different solid phases. Studies at high temperature will look at the initial steps when the particles are nanometres in size, because they are crucial to the spatial distribution of particles, that will impact all the crystallization mechanisms occurring at later stages. Studies at lower temperatures will include polymorphic transformations. Models based on fundamental mechanisms and amenable to work under flow and variable temperature are required. Yet, the few models used in the literature do not have that flexibility. I recently developed a successful model for the crystallization of palm oil and milk fat under shear (e.g. Phys. Rev. E. 71, 041607, 2005), and propose to examine the hypotheses proposed with that model: impact of particle segregation on growth/nucleation ratios, acceleration of polymorphic transformations by secondary nucleation of undercooled liquid, and layered crystallization. To examine these hypotheses we require measurements that integrate several methods to provide quantitative phase distribution, particle characteristics and mechanical properties in-situ and in real time. We will combine NMR, rheology and synchrotron XRD. Done simultaneously these measurements will mean a breakthrough in the study crystallization kinetics of multi-phase systems. The findings will be very useful for aggregation processes in other materials as well since the lipid molecules have sizes between large polymers and small compounds.

我的目标是开发热力学和动量，传热和传质机制的概念和数学模型，这些模型决定了受不同外部场（温度分布，剪切和拉伸流等）影响的可食用多组分系统的自组装。工业上非常经验地使用剪切流来获得所需的结构性能，但缺乏基础知识。本应用着重于用纯组分制备的多组分脂质体系的结晶。这将在一定程度上简化这些材料的多组分性质和多态性的复杂性：即使是纯组分也可以形成不同的固相。高温下的研究将着眼于颗粒尺寸为纳米级时的初始步骤，因为它们对颗粒的空间分布至关重要，这将影响后期发生的所有结晶机制。低温下的研究将包括多态转变。需要基于基本机理的模型，并能在流动和变温条件下工作。然而，文献中使用的少数模型不具有这种灵活性。我最近开发了一个成功的模型，用于剪切下棕榈油和乳脂的结晶(例如Phys。Rev. E. 71, 041607, 2005)，并建议检验该模型提出的假设：颗粒偏析对生长/成核比的影响，过冷液体的二次成核加速多晶转变，分层结晶。为了检验这些假设，我们需要结合几种方法进行测量，以提供实时的定量相分布、颗粒特征和力学性能。我们将结合核磁共振，流变学和同步加速器XRD。同时进行这些测量将意味着多相体系结晶动力学研究的突破。由于脂质分子的大小介于大聚合物和小化合物之间，这一发现将对其他材料的聚集过程非常有用。