Understanding Predicting the Failure of Cellulosic Materials

Nowadays, our world is dominated by smart technologies, which massively influence our daily life. However, there is a natural and sustainable resource that has improved our way of living for a much longer time. Throughout history, wood has been an important construction material. Separating wood into its smallest fragments cellulosic fibers and treating them, leads to products which are connected to our everyday needs: paper, having transferred the written word through time, is a classic in many forms, and paperboard as a reliable packaging material ensures the comfort of online shopping and food delivery. Though the applications differ widely, the base material is always the same. A cellulosic fiber has a complex hierarchical structure, which consists of several layers. The fiber shape can be imagined as a hollow cylindrical tube with pointed ends. While a tree trunk is massive, single cellulosic fibers are delicate. With 1-5 millimeters in length and a diameter of tens of micrometer (thinner than a single hair), handling of single cellulosic fibers is not easy. Such fibers are processed in the pulp and paper industrial sector to create complex fiber networks for various paper and paperboard applications. The strength of these networks is dominated by the fiber-fiber bonding and the mechanical behavior of the single cellulose fibers. Therefore, in modeling and simulation approaches of such fiber networks input parameter of the single fiber level is desperately needed and difficult to collect. Within this project, we aim to improve the understanding of the mechanical behavior of cellulose fiber networks by studying the fiber-fiber bonding and the single fiber mechanics on the microscale. The resulting mechanical parameters will be implemented in a multiscale modelling approach by our German colleagues at University of Wuppertal to predict the failure of paper-based products. To achieve this, we will combine state-of-the-art experimental methods to describe the mechanics of the fiber and fiber-fiber bonds and advanced modelling schemes.