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This research investigated the influence of the layered structure of paper on its selected strength properties. Two types of cellulose pulp were used: unbleached kraft pine pulp (UBSK) and unrefined bleached birch kraft pulp (BHK). Multi-ply papers were obtained from layers of appropriate grammage formed separately and bonded in a wet state. Paper layers were formed from primary pulps (UBSK and BHK) or their mixtures (three-ply UBSK-BHK paper and three-ply UBSK-BHK-UBSK paper), from which various variants of laboratory paper samples were made. This work focused on three-layer papers. The obtained laboratory sheets were analysed for changes in tear resistance, tensile strength, bursting strength, short span compression strength (SCT), and corrugating medium test (CMT). In most cases, three-layer structures were characterised by higher strength parameters than single-layer papers. The tear strength and SCT of papers consisting of three layers formed from both mixed pulps were slightly lower than those of solid papers. The results demonstrate the feasibility of producing three-ply paper with significantly reduced variability in parameters such as elongation and bursting strength, which are inherently subject to high variability.

The potential of paper and paperboard as fiber-based materials capable of replacing conventional polymer-based materials has been widely investigated and evaluated. Due to paper’s limited extensibility and inherent heterogeneity, local structural variations lead to unpredictable local mechanical behavior and instability during processing, such as mechanical forming. To gain a deeper understanding of the impact of mechanical behavior and heterogeneity on the paper forming process, the Finite Element Method (FEM) coupled with continuum modeling is being explored as a potential approach to enhance comprehension. To achieve this goal, utilizing experimentally derived material parameters alongside stochastic finite element methods allows for more precise modeling of material behavior, considering the local material properties. This work first introduces the approach of modeling heterogeneity or local material structure within continuum models, such as the Stochastic Finite Element Method (SFEM). A fundamental challenge lies in accurately measuring these local material properties. Experimental investigations are being conducted to numerically simulate mechanical behavior. An overview is provided of experimental methods for material characterization, as found in literature, with a specific focus on measuring local mechanical material structure. By doing so, it enables the characterization of the global material structure and mechanical behavior of paper and paperboard.

The primary aim of this research was to explore the feasibility of producing environmentally friendly composite materials by employing diverse hybrid matrices consisting of dammar natural resin, supplemented with small proportions of two synthetic resins: one epoxy and the other acrylic. A blend of paper and chicken feathers served as the reinforcing elements. The fabrication of these composite materials utilized a hand layup technique. Targeted for applications in the furniture industry or interior design, their mechanical properties were assessed through various tests. Specimens were obtained from the manufactured samples and subjected to evaluations for tensile strength, compression, flexure, vibrations, Shore hardness, and water absorption. Results indicated that irrespective of the testing method employed, the mechanical strength properties exhibited a decline with an increase in the percentage of dammar in the hybrid resins, whereas the elasticity properties demonstrated an increase with this percentage.

Hemp hurd fiber, a low-value waste stream from the hemp industry, has potential downstream applications as an alternative to non-renewable plastics for single-use food service ware and packaging applications. Packaging paper substrates made from chemically pulped hemp hurd, mixed in varying ratios with bleached thermomechanical radiata pine pulp were developed and tested. Handsheets were characterized using several mechanical property tests including tensile strength, tearing resistance, burst strength, short-span compression, ring crush, together with Gurley air resistance, contact angle, and Cobb60 tests. Generally, addition of hemp hurd fibers significantly improved handsheet mechanical properties. Hot-pressing of the handsheets so as to approximate molded fiber thermoforming further enhanced their performance, with pure hemp hurd handsheets having the highest mechanical properties and barrier performance. A prototype was successfully thermoformed from hemp fiber, demonstrating overall feasibility of this fibre source for molded fibre objects.

Flow and spontaneous imbibition phenomena in porous media are important for various industrial applications, including printing and medical lateral flow assays. Their quantitative characterization is important to better understand and select the appropriate raw materials. However, standard methods often require time-consuming tests, and/or expensive equipment. Different time scales must be considered, limiting the range of possible characterization tools. A novel experimental approach based on image analysis for characterizing spontaneous imbibition processes is presented. Hence, ultra-fast diffusion may be quantitatively characterized. Models are issued from the literature to consider physical phenomena at small (milliseconds) and medium range (seconds) of time scales. The obtained experimental data fit with theoretical results, providing valuable insights into the understanding of fluid flow behavior at different time scales. Furthermore, the identification of some physical properties for either the fluid, or the substrate, based on the theoretical models are possible, as the contact angle, which remains to be otherwise challenging. This study contributes to bridging the gap between spontaneous imbibition and capillary phenomena at different time scales, their modeling, and a characterization of material and/or fluid properties paving the way for enhanced understanding and control of fluid behavior in porous media. Different papers are considered to illustrate the method. [ABSTRACT FROM AUTHOR]