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The word “antisocial” appears to well describe some aspects that have been observed when nanofibrillated cellulose (NFC) has been added to papermaking fiber suspensions, in combination with some chemical additives that are commonly used in that process. The analogies of folded hands or a clenched fist can be used to convey a hypothesis of an inability of certain cellulosic fibrils to become engaged in a microscopic three-dimensional structure, which appears to be essential for the development of paper strength. Though this editorial points to some important drawbacks of NFC as an additive for conventional papermaking, it also sheds more light on the wisdom of conventional pulp refining technology. One can envision refining partly as a way to activate cellulosic nanofibrils at the fiber surfaces such that they are ready to intertwine with each other efficiently at a nano scale during the formation of the sheet. In this way they can achieve a favorable combination of dewatering rate, efficient of retention of the fibrillated matter, and notable increases in strength properties.

Composites, which have become very common in mass-produced items, have the potential to outperform similar materials made from any one of their individual components. This tutorial review article considers published studies that shine a light on what is required for such structures to earn the name “sustainable”. The focus is on a series of questions that deal with such issues as the carbon footprint, other life-cycle impacts, durability, recyclability without major loss of value, reusability of major parts, and the practical likelihood of various end-of-life options. To achieve the needed broader impacts of limited research dollars, it is important that researchers choose their research topics carefully. Among a great many possible options for preparing truly eco-friendly composite materials, it will be important to focus attention on the much smaller subset of technologies that have a high probability of commercial success and large-scale implementation.

The pulp and paper industry is highly energy-intensive. In mills that use chemical pulping, roughly half of the higher heating value of the cellulosic material used to manufacture the product typically is incinerated to generate steam and electricity that is needed to run the processes. Additional energy, much of it non-renewable, needs to be purchased. This review considers publications describing steps that pulp and paper facilities can take to operate more efficiently. Savings can be achieved, for instance, by minimizing unnecessary losses in exergy, which can be defined as the energy content relative to a standard ambient condition. Throughout the long series of unit operations comprising the conversion of wood material to sheets of paper, there are large opportunities to more closely approach a hypothetical ideal performance by following established best-practices.

Size presses on paper machines are used to apply a solution of a polymer – usually starch – to the surface of the sheet and thereby to increase the stiffness, surface strength, and printing quality of the product. This article reviews publications dealing with the size press equipment, the materials, and factors affecting both the operating efficiency and attributes of the resulting paper. The emergence of film-press equipment (e.g. blade-metering size presses) in the 1980s has greatly decreased the frequency of web breaks and increased productivity. Starch technology at the size press, though relatively mature, continues to evolve. By adjustment of starch attributes, solids levels, and incorporating other additives, modern papermakers can tune size press outcomes to meet a range of paper product requirements, including strength, hydrophobicity, and the reduction of air permeability. By application of various synthetic polymers, mineral particles, and even nanocellulose in combination with starch or other base polymers, there is potential to extend the technology to meet a range of future needs for paper products.

Barrier films that are used on packages play an important role, especially in the protection of food products. Research is being carried out at an accelerating pace to replace petroleum-based plastic films, which do not biodegrade and are difficult to recycle. This review article considers publications related to the use of polyelectrolyte complexes (PECs) in barrier films as a strategy to decrease the permeation of oxygen and other substances into and out from packages. Research progress has been achieved in using combinations of positively and negatively charged polymers, sometimes together with platy mineral particles, as a way to restrict diffusion through packaging materials. In principle, the ionic bonds within PECs contribute to a relatively high cohesive energy density within such a barrier film, which can resist diffusion of various gases and greasy substances. Resistance to water vapor, as well as aqueous substances, represent important challenges for barrier concepts that depend on ionic bond contributions. Factors affecting barrier performance of PEC-based films are discussed in light of research findings.

This review article considers the formulation of a broad range of coatings designed for the protection and changing the appearance of wood surfaces. Findings from the literature are considered from the standpoint of the main chemical components, how they can be formulated into a spreadable product, the events leading to curing, and factors affecting the performance of the resulting coating layers on wood surfaces. A series of hypotheses are considered, relating to the mechanisms underlying wood coating products and their usage. Special attention is paid to the topics of adhesion at the coating-wood interface, the development of film strength and hardness, and challenges related to the past and continuing development of waterborne coating formulations. The modern technologist seeking to coat wood has many options to choose from, and there has been a need to make current knowledge related to the field more available to the wider scientific community.

Family groups in the ancient cultures of China, Korea, and Japan have toiled for generations in an effort to out-compete their neighbors in the pursuit of handmade paper products having better strength performance, in addition to flatness, uniform appearance, and other desirable attributes. Study of the history of the papermaking craft reveals a remarkable ability of ancient peoples to discover advantageous ways to prepare the cellulosic pulp, to improve its brightness, and to form uniform and strong paper sheets. But though the ancients knew how to “beat” the pulp to improve its bonding ability, there is no evidence of any of them having attempted to greatly “over-beat” some of the fiber, thus making nanocellulose, for potential addition to the fiber mixture. Why not? In this editorial, it is proposed that the ancients may have discovered that adding very highly fibrillated cellulose material to paper was not a good idea.

This editorial considers three groups of individuals and how they often find themselves following common ways of thinking. Artists, especially those who become well known, are hard workers and somewhat stubborn. Once they have found a type of paper that works well for them, they tend to develop loyalty to it, regardless of what the label on the ream wrap may say. Papermakers, ancient and modern, likewise have tended to stick with practices that are convenient to them at the moment, whether or not they contribute to archival quality. Fortunately, the transition to alkaline papermaking practices means that modern printing papers tend to last a lot longer. Increasing knowledge of the importance of acid-free paper, as well as the principles of sustainability, are making positive contributions to our ongoing cultural heritage, at least to the part of that heritage that is related to cellulosic materials.

A sustainable packaging system with excellent liquid- and gas-barrier properties and enhanced strength properties was highlighted by a composite coating containing a mixture of cellulose nanocrystals (CNC), a high-aspect ratio nano-filler montmorillonite clay, an amphiphilic binder soy protein, and a surface-active agent alkyl ketene dimer. They were tested on various surfaces of commercially available packaging papers and compared with the appropriate control (i.e., CNC-only coating) to determine surface morphology, chemical composition, barrier, and mechanical properties. Scanning electron microscopy image analysis showed a compact matrix whose defects (cracks) were significantly attenuated compared to the control while FTIR showed fewer exposed hydroxyl (–OH) groups. The compact structure and reduced proportion of –OH groups are attributed to the plate-like structure, high aspect ratio of clay, and uniform distribution of additives to help inhibit gas, moisture, water, oil, and grease permeation. The base paper used also had a significant impact on how coatings interacted with various fluids. Overall, sustainable CNC-composite barrier coatings with relatively low-cost additives were fabricated and showed improved barrier and strength characteristics with a strong potential as barrier coatings for packaging. Graphical Abstract

Size presses on paper machines are used to apply a solution of a polymer – usually starch – to the surface of the sheet and thereby to increase the stiffness, surface strength, and printing quality of the product. This article reviews publications dealing with the size press equipment, the materials, and factors affecting both the operating efficiency and attributes of the resulting paper. The emergence of film-press equipment (e.g. blade-metering size presses) in the 1980s has greatly decreased the frequency of web breaks and increased productivity. Starch technology at the size press, though relatively mature, continues to evolve. By adjustment of starch attributes, solids levels, and incorporating other additives, modern papermakers can tune size press outcomes to meet a range of paper product requirements, including strength, hydrophobicity, and the reduction of air permeability. By application of various synthetic polymers, mineral particles, and even nanocellulose in combination with starch or other base polymers, there is potential to extend the technology to meet a range of future needs for paper products.