Elastic Paper with Mechanically Switchable Fiber and Pore Structure

具有机械可转换纤维和孔结构的弹性纸

• 批准号: 405549418
• 负责人: Professor Dr. Matthias Rehahn
• 金额: --
• 依托单位: Helmholtz-Zentrum hereon GmbH
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405549418?language=en
• 关键词: Elastic; Paper; Mechanically; Switchable; Fiber

The aim of the project is to develop papers that can be reversibly stretched by more than 100%. With increasing elongation, a higher order of fiber alignment should result in an increasing orientation of the pore structure of the sheet. Deformation and preferential orientation, driven by entropy elasticity, on the one hand should immediately regress when the applied tensile, compressive or shear stress ends. On the other hand, elastic papers are to be developed, which initially retain a distinct state of elongation/compression without application of force and only return to an initial, permanent shape after application of a stimulus from this temporary deformation (i.e. shape-memory papers).With regard to their chemical and physical properties, the fibers of the desired elastic paper should be similar to those of conventional papers, hence, the only difference will be an elastic deformability of the novel paper. Likewise, its production should be based on well-known components and processes of paper making technology. The main challenge is to prevent the otherwise common direct linking of the pulp fibers by means of hydrogen bonding, and instead to achieve their cohesion indirectly via elastomeric, highly deformable colloidal particles in between the fibers.On the one hand, a major challenge is to build up the colloid particles with respect to suitable size, elasticity, deformation/relaxation characteristics and chemical structure (sufficient number of cationic functionalities on the shell). On the other hand, the fibers should be equipped with a chemical structure for preferential formation of the ionic bonds (e.g. attachment of anionic groups).Finally, it is necessary to develop a method of mixing the likewise electrostatically stabilized suspensions of the cationic elastomer particles with the anionic pulp fibers and converting them into homogeneous papers while forming the fiber-bridging ionic bonds between the particles and the surface of the fibers.In the later stage of the project, additional colloid particles are to be produced, which exhibit stretch crystallization or glass transition temperatures near room temperature. By this, elastic shape memory papers can be generated. Furthermore, it should be validated whether elastic papers with preferential orientation of the fibers can be developed for anisotropic extensibilities. Perspectively, a fundamental understanding as well as in ideal case the modeling of the structure-property relationship will be developed. Thereby, the variability of the hierarchical pore structure and its orientation during stretching is of particular importance.

该项目的目标是开发出可逆拉伸超过100%的纸张。随着伸长率的增加，纤维排列的阶数越高，片材的孔结构的取向就会越大。一方面，在外加拉应力、压应力或剪应力结束时，变形和择优取向在熵弹性的驱动下应立即回归。另一方面，要开发弹性纸，它最初在不加力的情况下保持明显的伸长/压缩状态，并且只有在施加来自这种暂时变形的刺激后才返回初始的、永久的形状(即形状记忆纸)。就其化学和物理特性而言，所需的弹性纸的纤维应该与传统纸的纤维相似，因此，唯一的区别将是新型纸的弹性变形性。同样，它的生产应该以造纸技术的知名组件和工艺为基础。主要的挑战是防止纸浆纤维之间通过氢键直接连接，而是通过纤维之间弹性的、高度变形的胶体颗粒间接实现它们的粘合。一方面，主要的挑战是建立关于合适的尺寸、弹性、变形/松弛特性和化学结构(壳层上有足够数量的阳离子官能团)的胶体颗粒。另一方面，纤维应该具有优先形成离子键的化学结构(例如，阴离子基团的附着)。最后，有必要开发一种方法，将同样静电稳定的阳离子弹性体颗粒悬浮液与阴离子纸浆纤维混合，并将其转变为均匀的纸张，同时在颗粒与纤维表面之间形成纤维桥离子键。在项目的后期阶段，将产生更多的胶体颗粒，其拉伸结晶或玻璃化转变温度接近室温。由此，可以产生弹性形状记忆纸。此外，还应验证是否可以为各向异性延伸性开发出具有纤维择优取向的弹性纸。从长远来看，将建立一个基本的理解，以及在理想情况下的结构-性质关系的建模。因此，拉伸过程中分级孔结构及其取向的可变性尤为重要。