Improving the material efficiency of furnishes in papermaking by stratification and chemical modifications: Dissertation

The material efficiency is the key word of today's industry. This is also the case in papermaking, but proper tools have been missing. An extensive research on modifying fibre's surface chemistry and paper's structure was conducted in order to find the tools. Selective removal of carbohydrates by enzymatic treatments, spray application of various biopolymers, and furnish stratification were evaluated as the strategies for increasing the material efficiency in the context of the modern papermaking process. The effects of the aforementioned treatments were evaluated by complex studies of dewatering characteristics, wet and dry strength properties, and basic properties of the resulting paper samples. Enzymatic methods showed potential to intensify the water removal processes. The surface chemical modifications have potential to improve the strength of wet and dry paper. This is an essential requirement for reducing the raw material costs, either by reducing basis weight or by increasing the filler content. Stratification brings further freedom to tailor the surface properties independently of the central layer properties. Overall, these studies indicate that when aiming at reduced material and energy consumption, no single method is able to fulfil the partly conflicting demands. But by combining several unconventional techniques such as enzymatic treatment, spraying of chemicals and furnish stratification, the material efficiency of fibre could substantially be improved