The primary aim of modern biorefineries is the efficient conversion of lignocellulosic materials into valuable products. Sugars and oils can be converted into valuable chemicals, but processing of lignin is still a challenge. A vast amount of lignin is incinerated to produce process steam and energy, and only a very small part is used for the production of value-added products. Technical lignins are isolated as by-streams in lignocellulosic refineries, e.g., as kraft, soda, organosolv, and hydrolysis lignins, as well as lignosulphonates. They have a modified structure and contain impurities that are dependent on the processing method. The structure and the composition of technical lignins restrict their subsequent applications. This paper reviews limiting factors in utilization of technical lignins. Four major classes of problems are identified, and approaches to overcoming these problems are suggested.

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aElongation at failure is an important but underrated functional property of paper. Traditionally, elongation has been of specific importance for sack and bag paper grades. Mechanical treatments at high consistency are known to induce fibre deformations that contribute to the elongation of paper. However, it is not clear to what extent different fibre deformations can improve the elongation of paper. The aim of this work was to investigate the influence of three mechanical treatments on fibre and paper properties. The wing defibrator, the E-compactor, and the Valley beater were used for treating chemical softwood pulp. It was found that the type and intensity of mechanical treatments significantly affect the formation of fibre deformations, and thus the resulting properties of paper. The combination of high-consistency wing defibrator treatment and subsequent low-consistency valley beating provided paper with high elongation potential and good strength properties without impairing the dewatering properties.

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Paper and paperboard are widely used in various types of packaging. Paper-based packaging is a recyclable, biodegradable, renewable and sustainable product, which gives it certain advantages over most plastic-based packaging materials. Although paper-based packaging, in some areas, lacks attractiveness in terms of visual appearance, 3D forming is an important method for producing advanced shapes from paper and paperboard, suitable, for instance, for modified atmosphere packaging. That said, very little is known about the deformations experienced by paper-based materials in 3D forming. Understanding the role played by the mechanical properties of paper and paperboard in the 3D forming process is key to improving performance. This paper presents experimental results obtained using three different forming devices designed to be used with paper-based materials and links the formability data with specific mechanical properties of the paperboard samples. Paperboard properties that were found to correlate with formability were as follows: compressive strength and strain, tensile strain, paper-to-metal friction and out-of-plane stiffness. The requirements for formability are different for the fixed blank forming process and sliding blank forming process.

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Heat sealing behavior of mono-polyolefins and paper-based materials is drastically different from conventional multilayer plastic laminates. This paper presents the effect of sealing conditions on Hot-Tack and Cold-Tack for an oriented polypropylene (OPP)-based polyolefin laminate with either polyethylene (PE) or cast polypropylene (CPP) sealing layer and two different barrier paper materials carrying a thin acrylic copolymer sealing layer. The investigations include pressure, temperature, time, jaw pattern, and climate conditions (moisture). It is shown that the monopolyolefins reach comparable Hot-Tack and Cold-Tack ranges compared with the reference polyethylene terephthalate (PET)-aluminum (Al)-PE laminate. The CPP laminate exhibits a narrow sealing window near the range in which shrinkage is observed. While for the polyolefins temperature plays the main role, the sealing of paper materials turned out to be dependent on pressure, time, and moisture content in paper. Due to a rupture through the polymer thin coating, the Cold-Tack is dominated by a delamination of paper and coating. Consequently, the Cold-Tack is drastically lower than with PETAl -PE laminate. Monopolypropylene films exhibit extremely narrow sealing window, which shall be taken into the design consideration of bag formfill-seal (FFS) machines. Polymer coated paper can be potentially used at high-speed FFS; however, special attention shall be paid to moisture content control and filling.

Production of paper-based packaging is growing at the present moment and has great future prospects. However, the development of new packaging concepts is creating a demand for an improvement in the mechanical properties of paper. Extensibility is one of these properties. Highly extensible papers have the potential to replace certain kinds of plastics used in packaging. Extensibility is also important for the sack and bag paper grades and for runnability in any converting process. This paper reviews the factors that affect the extensibility of fibres and paper, and discusses opportunities for improving the straining potential of paper and paper-like fibre networks. It is possible to classify factors that affect extensibility into three main categories: fibre structure, interfibre bonding, and structure of the fibre network. Extensibility is also affected by the straining situation and the phase state of the polymers in the cell wall. By understanding the basic phenomena related to the elongation, and by combining different methods affecting the deformability of fibre network, extensibility of paper can be raised to a higher level.