Control of Protective Coating Performance Aspects Through Manipulation of Polymer Fragility

液体应用，在环境条件下应用的高性能保护涂层必须经过成膜，以提供连贯，粘附和功能的涂层，以提供必要的性能。薄膜形成的速度和程度在过程（被涂物品处理或储存的速度）和涂层性能（已开发的特性）方面都是最重要的。确保涂层具有可行的容器寿命，在经济的时间范围内干燥，并且在投入使用时涂层性能足够是成功成膜的重要组成部分。双组分热固性环氧胺配方代表了大多数需要防腐或耐化学性的环境固化涂层技术。在环境固化条件下，在玻璃化到玻璃态之前，聚合物粘合剂中所有反应基团的完全转化很少实现，并且经过一段时间的扩散控制过程后，反应基本上停止。因此，涂层必须经常在未固化状态下达到必要的性能。为了提高应用效率和最终性能之间的理想平衡，需要更好地了解固化温度、反应基团转化程度、聚合物结构选择和聚合物玻璃化转变（Tg）对涂膜性能之间的相互关系，以指导涂膜配方的设计。聚合物玻璃脆性的概念与聚合物迁移率随温度变化的程度有关，温度接近Tg。“脆弱”系统被描述为聚合物迁移率的大变化接近Tg（伴随着大热容变化），而“强”系统具有较低的迁移率（和较低的热容变化）。易碎性量化了材料从液体转变为固体的速度，并与聚合物段的填充效率有关，而聚合物段的填充效率又被认为与各种关键性能标准（特别相关的是机械性能和分子扩散屏障性能）相关。通过选择反应性组分，操纵聚合物易损性可能因此为操纵干燥过程和最终涂层性能标准提供了一条途径。我们建议检查假设，聚合物的脆弱性可以通过聚合物结构带来的选择反应组分操纵。主要的环氧胺粘合剂组分和其他常见的活性添加剂在现代环氧胺涂料配方中使用的影响，包括叔胺促进剂。使用模型公式，将探索应用最先进的调制DSC方法来解释复杂的玻璃过渡区域。对起始材料和相应的完全固化薄膜热容量变化的评估将有助于确定脆性的差异。红外技术的应用将量化反应转化，并允许探索聚合物结构，转化和脆弱性之间的关系。将探讨聚合物脆性对关键薄膜性能属性的影响。主要是干燥过程，但也与通过正电子湮没光谱（PALS）或动态蒸汽吸收（DVS）的固化膜的膜间扩散分子传输特性有关，以及使用动态力学分析（DMA）的聚合物膜老化过程。

Liquid applied, high performance protective coatings applied under ambient conditions must undergo film formation to deliver a coherent, adherent and functioning coating film to deliver the necessary performance. The rate and extent of film formation is of the highest importance both in terms of the process (how quickly a coated article can be handled or stored) and also in terms of coating performance (what properties have developed). Ensuring the coating has a workable pot-life, is dried in an economic timeframe and that coating performance is adequate when placed into service are vital components of successful film formation. Two component thermosetting epoxy-amine formulations represent the majority of ambient cured coating technology where corrosion protection or chemical resistance is required. Complete conversion of all reactive groups in the polymer binder is rarely achieved under ambient curing conditions before vitrification to the glassy state occurs and, following a period of diffusion controlled processes, reaction essentially stops. Consequently the coating must often achieve necessary performance in an under-cured state.In order to improve the desired balance of application productivity alongside final performance properties, greater understanding of the inter-relationships between cure temperature, extent of conversion of reactive groups, choice of polymer architecture and polymer glass transition (Tg) on coating film performance is required to guide design of coating formulations.The concept of polymer glass fragility is associated with the extent that polymer mobility changes with temperature close to Tg. "Fragile" systems are described as those that have large changes in polymer mobility close to Tg (accompanied by large heat capacity change) whereas "strong" systems have lower mobility (and lower change in heat capacity). Fragility quantifies how quick a material changes from liquid to solid and is related to polymer segment packing efficiency which, in turn, is believed correlated with various key performance criteria (of particular relevance is mechanical properties and molecular diffusion barrier properties). Through choice of reactive components, manipulation of polymer fragility may thus provide a route to manipulate both drying processes and final coating performance criteria.We propose to examine the hypothesis that polymer fragility can be manipulated through polymer architecture brought about through choice of reactive components. Influence of main epoxy-amine binder components and other common reactive additives used in modern epoxy-amine coating formulations including tertiary amine accelerators will be explored.Using model formulations, application of state-of-the-art Modulated DSC methodology will be explored to interpret complex glass transitions regions. Assessment of changes in heat capacity of starting materials and corresponding fully cured films will allow determination of differences in fragility. Application of Infra-Red techniques will quantify reaction conversion and allow relationships between polymer architecture, conversion and fragility to be explored.The implications of polymer fragility on key film performance attributes will be explored. Primarily drying processes, but also those associated with through-film diffusional molecular transport properties of cured films using Positron Annihilation Spectroscopy (PALS) or Dynamic Vapour Sorption (DVS) and polymer film aging processes using Dynamic Mechanical Analysis (DMA).