The aim of the study was to characterize and compare films made of cellulose nanocrystals (CNC), nano-fibrils (CNF), and bacterial nanocellulose (BNC) in combination with chitosan and alginate in terms of applicability for potential food packaging applications. In total, 25 different formulations were made and evaluated, and seven biopolymer films with the best mechanical performance (tensile strength, strain)—alginate, alginate with 5% CNC, chitosan, chitosan with 3% CNC, BNC with and without glycerol, and CNF with glycerol—were selected and investigated regarding morphology (SEM), density, contact angle, surface energy, water absorption, and oxygen and water barrier properties. Studies revealed that polysaccharide-based films with added CNC are the most suitable for packaging purposes, and better dispersing of nanocellulose in chitosan than in alginate was observed. Results showed an increase in hydrophobicity (increase of contact angle and reduced moisture absorption) of chitosan and alginate films with the addition of CNC, and chitosan with 3% CNC had the highest contact angle, 108 ± 2, and 15% lower moisture absorption compared to pure chitosan. Overall, the ability of nanocellulose additives to preserve the structure and function of chitosan and alginate materials in a humid environment was convincingly demonstrated. Barrier properties were improved by combining the biopolymers, and water vapor transmission rate (WVTR) was reduced by 15–45% and oxygen permeability (OTR) up to 45% by adding nanocellulose compared to single biopolymer formulations. It was concluded that with a good oxygen barrier, a water barrier that is comparable to PLA, and good mechanical properties, biopolymer films would be a good alternative to conventional plastic packaging used for ready-to-eat foods with short storage time.

This study investigated the effect of hemp fiber pretreatments (water and sodium hydroxide) combined with silane treatment, first on the fiber properties (microscale) and then on polylactide (PLA) composite properties (macroscale). At the microscale, Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy investigations highlighted structural alterations in the fibers, with the removal of targeted components and rearrangement in the cell wall. These structural changes influenced unitary fiber properties. At the macroscale, both pretreatments increased the composites’ tensile properties, despite their negative impact on fiber performance. Additionally, silane treatment improved composite performance thanks to higher performance of the fibers themselves and improved fiber compatibility with the PLA matrix brought on by the silane couplings. PLA composites reinforced by 30 wt.% alkali and silane treated hemp fibers exhibited the highest tensile strength (62 MPa), flexural strength (113 MPa), and Young’s modulus (7.6 GPa). Overall, the paper demonstrates the applicability of locally grown, frost-retted hemp fibers for the development of bio-based composites with low density (1.13 to 1.23 g cm−3).

Cereal straw and bagasse are presently the leading non-wood plants used in production of paper, though many fast-growing perennial plants have been studied for their suitability for paper manufacturing, too. In the present study the use of Japanese knotweed, as one of the most invasive alien plant species in Slovenia, as alternative raw material for papermaking is demonstreted. Paper was made of 55% Japanese knotweed and sulfate cellulose produced from 60% eucalyptus and 40% conifer fiber. The paper with the basic weight of 90 g/m 2 was manufactured on the pilot paper machine at the Pulp and Paper Institute. Among printability characteristics paper brightness, colour, yellowness, roughness, air permeability, specular gloss, print penetration, picking, and print unevenness were determined. The preliminary research has shown, that Japanese knotweed, as a cheap local raw material, could be used in paper making industry, though the fiber processing and paper making process must be improved in order to obtain good printability.

Fountain solution induced mottling in offset printing manifests as non-homogenous printing area with optical variation has several influencing factors. One mechanism is that the fountain solution from the previous printing unit has no time to absorb into the coating before ink transfer or the ink cannot emulsify the water and stays on top of the ink surface as an additional hydrophilic layer. In paper coating development, the paper chemistry influences the surface chemistry features of the ink-paper coating interaction and can cause water repellency. Porosity and the absorbing capacity of paper and its coating is of great importance to avoid press related problems. In this paper, we have examined paper substrates which were reported to cause wet repellence mottling and tested their porosity ratio of micro and macro pores and their water/ink absorption properties. The micro macro porosity was determined by using easy and low-cost proprietary technique for the porosity ratio determination. We have measured ink stabilization values, penetration dynamics, wet repellence mottling and micro and macro porosity on paper samples printed with laboratory sheet-fed offset printing. We have found that the lower number of macropores and non-optimal micro and macropore distribution influenced the occurrence of water induced wet repellence and lowered the optical homogeneity of the samples.

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Bacterial nanocellulose (BNC) has gained a lot of attention in recent years due to its nano-size-derived properties. Although it is essentially chemically similar to plant-derived cellulose, it has smaller size and is enriched in free hydroxyl groups, which greatly improve mechanical properties of reinforced paper. However, although BNC has some unique features, it comes at a high price. In this paper, we introduce a new solution for BNC production. We have isolated bacterial nanocellulose directly from agro-industrial waste—mother of vinegar—and used it in the production of paper sheets. We show here that paper sheets made with the addition of only 10% bacte-rial nanocellulose from mother of vinegar substantially improved basic mechanical as well as printing properties of paper.

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Paper surface efficiency was developed by Preucil and was intended to define the colourimetry and geometrical part of the light reflection with paper surface values. The surface characteristics of paper, primarily its roughness and absorptivity affect colour reproduction beside the ink pigments or dye. Rougher paper surfaces scatter the light in a more non-uniform manner while paper absorption may cause ink vehicle absorption and thus decreasing gloss, or it may absorb both vehicles and pigment-producing an unexpected colour shift. The formula was upgraded with paper whiteness values as the basic formula did not explain the whole phenomena. These paper properties were the foundation of the paper standardisation for standardised printing. On the other hand, during inkjet printing, a limited amount of liquid is deposited onto a paper surface. When the droplet hits the surface, it starts to spread and wet the surface depending on the ink and paper properties and had different colourant deposition from the formulas used mainly for offset printing inks. In this paper, we have researched the modified surface efficiency formula applied to inkjet printing (HP PageWide Pro 477dw) on invasive and agro-residue papers with specific non-white paper shades. We have measured the dynamic liquid penetration using ultrasound measurement to model the surface behaviour of the inks and measured CIE LCH values of the samples and calculated the CIE ΔE00 colour differences and the influence of paper surface efficiency and paper shade influence on the colour reproduction. The results indicate that using recalculated Cobb Absorption values gives good negative linear correlation with the original formula regarding the magnitude of colour difference.