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Aqueous foams consist of air bubbles stabilized in a fluid medium. Surface active agents adsorbed at the air/liquid interface may enhance foam stability by modifying the interfacial energy at the air/liquid interface. In addition, they affect the interfacial and bulk viscoelasticity as well as the capillary pressure across the plateau borders. The diffusion and adsorption kinetics of surface active agents in the foam and at interfaces impact the foamability to given extent. The foam dynamics (foamability, foam stability), in turn, is closely related to parameters that are used to define the physical chemistry of foams. We incorporated cellulosic fibers (wood fibers and cellulose nanofibrils) in surfactant-stabilized foams, producing bio-based systems that we expect to have a wide range of applications. The physical chemistry of the air/liquid interface in such foams was altered by the presence of various surfactant types (anionic, cationic and nonionic). The synergistic role of natural wood fibers and surfactants in foam generation and stabilization processes was evaluated as a function of surfactant concentration. Here we discuss the effect on foam dynamics of added wood fibers and cellulose nanofibrils, which were used as rheology modifier.

According to an example aspect of the present invention, there is provided bio-based mineral oil barrier coatings and films usable for decreasing mineral oil migration, for example in food packaging materials, and thus improving the safety of the materials facing the mineral oil containing environment.Patent family as of 17.12.2021EP3411231 A1 20181212 EP20170747055 20170203 EP3411231 A4 20190904 EP20170747055 20170203 FI127441 B 20180615 FI20160005075 20160203 FI20165075 A 20170804 FI20160005075 20160203 US2019001647 AA 20190103 US20170063300 20170203 WO17134345 A1 20170810 WO2017FI50058 20170203Link to current patent family on right

Trees are a tremendous source of renewable materials comprising mainly cellulose, hemicellulose and lignin. Hemicelluloses are a complex component of wood cell wall that contribute to the strong network with cellulose fibrils. The structure of the hemicellulose grades depends on the plant species and extraction method. While cellulose is, and has been, of scientific and industrial interest, wood-based hemicelluloses, xylan being the principle type of them, have had very limited use in industrial applications. So far, the main attention of hemicelluloses has been as a raw material for biobased chemicals. In materials technology applications, investigations have been directed in modification of the wood-based hemicelluloses to tune their water-solubility, functionality, film formation, among others. In addition to solid structures such as films, hemicelluloses are suggested as interfacial stabilizers. In this contribution etherified and oxidized hemicellulose grades are suggested for applied materials science purposes. The surface activity and interfacial stabilization capability of hardwood and softwood hemicellulose ethers is contrasted to their structural features. Oxidized xylan grades are presented as a novel material for functional hemicellulose films.

Several standard or material specific methods for grease barrier testing are being used. Results are expressed either as the time in which a test liquid has penetrated through a packaging material or as the amount of liquid which has penetrated through the material during a certain time period. However, such tests are not accurate, and there was a need for a new and more quantitative test method. A new test method developed by integrating two previous standard methods will be presented. Dyed oil or grease is placed on the food contact side of the sample under a specific weight. The reverse side is then scanned after pre-selected time intervals. This method combines visual data with a numerical result obtained by image analyses. Likewise, there are several methods for testing mineral oil hydrocarbon (MOH) barrier of packaging materials. Such mineral oil residues in food have raised concern as potential genotoxic carcinogens during the recent years, especially in Europe. These contaminants may originate from printing ink residues from recycled paperboard, certain additives, processing aids, and lubricants. A test method for MOH barrier will be presented in which the mineral oils are introduced to the test system in the gas phase. The amount of MOH diffused through a packaging material and absorbed into a food simulant is determined by gas chromatography. Focus was on compounds of relevant molecular weight, and using equipment and materials which are commercially available.

A method for testing the mineral oil barrier properties of packaging materials has been developed as a response for the concerns on contamination of food by mineral oil compounds. The aim was to provide an efficient tool to evaluate packaging materials with respect to this. The method is a modification of the so-called cup test using model compounds comparable with mineral oil components with different length and configuration of the hydrocarbon chain. The model compounds are introduced in the gas phase as penetrants. The absorbed amounts, which have migrated through the barrier, are analysed from a food simulant or powdered sugar. The method has been validated for coated and non-coated boards. Compared with folding boxboard without polymer coating, polyethylene terephthalate-coated board reduces the amount of the C16 compound in food simulant after 7-day tests by a factor of 30. An extended migration model describing sorption mechanisms to both food simulant and fibres in the packing material has been developed. The model simulations for folding boxboard indicate that fibres absorb a significant proportion of the compounds when molecular weight increases. This retards the migration significantly compared with the speed expected by diffusion mechanism only.

We suggest an approach for high-resolution chemical mapping by Atomic Force Microscopy (AFM) to reveal submicron hierarchy of films from renewable components. The chemical mapping is demonstrated for films that are constructed of cellulose nanofibrils, hydroxypropylated hemicelluloses and sorbitol. Distribution of the components depending on the precursor dispersion composition and the source of the cellulose nanofibrils or hemicellulose additive (softwood vs. hardwood) were investigated. The difference in adhesion between the film components and the AFM tip enables qualitative mapping of the components in the film. We correlate the submicron organization of the films to their mechanical and barrier performance. Furthermore, quantitative mapping of hydroxypropylated hemicellulose additive with varying degree of substitution will be discussed and the potential to probe functional cellulose surfaces with respect to degree of functionality will be assessed.

Recently, mineral oil (MO) residues in food have raised concern because there is a potential risk that consumers are exposed to a range of MO hydrocarbons (MOH) via food (1). The European Food Safety Authority (EFSA) published an opinion on mineral oil in 2012 (1). Concern was in particular expressed for the MO aromatic hydrocarbons (MOAH), because EFSA assumed the presence of genotoxic carcinogens. Potential background exposure to saturated MO hydrocarbons (MOSH) via food was also considered a concern. MOH contamination of food may be caused by printing ink residues found in packages from recycled paperboard but originates also from certain additives, processing aids, and lubricants. As a result of the concerns, an ordinance for food and food packaging is under preparation in Germany. The ordinance will set limits for MOSH and MOAH in food and food contact materials manufactured using recycled paper pulp, to protect consumers from potential health risks (2). The crucial question is whether MOH compounds can penetrate through barriers at the food contact side of the recycled packages or indirectly through inner packages of virgin paperboard into into the food. Several methods to test the food contact materials for MOH transmission have been introduced (3,4) including the use of test packs with layers of donor paper, a spacer paper, the tested barrier layer and a receptor. An alternative method is the permeation cell method. A third alternative uses test cups for hexane vapour transmission rates measurements. The objectives of this work is to develop a reproducible barrier test method where the mineral oils are introduced to the test system in the gas phase. The focus is on using surrogate compounds of a relevant molecular weight range for the drafted German ordinance. Finally, the equipment and materials used should be commercially available. In the new approach, the selected surrogate compounds representing MOH were introduced in the gas phase by saturating a closed space with them. Inside the closed space a fixed amount of food simulant, typically modified polyphenylene oxide TenaxTM, was placed into commercial test cups. The materials tested for their barrier properties were fitted into the lid of the test cups. After the test period, the cups were removed from the closed space and the food simulant was extracted. Finally, the content of the surrogate compounds in the extract was determined by gas chromatography and the transmission rates were calculated. Boards with different barrier coatings were tested with this new method and theoretical diffusion constants were determined using a physical model for the experimental setup.

Biomass is a promising alternative for the production of energy, novel materials, chemicals, and other valuable products. A certain degree of processing is required to achieve those results. Hydrothermal processes offer a unique way to obtain a wide range of biorefinery products. They can be considered as environmentally friendly processes, using solely water at different temperatures as a process medium to convert abundant and inexpensive biomass into products. We provide a short overview on hydrothermal processes that use water in its liquid state, including hot water extraction, pressurized hot water extraction, liquid hot water pretreatment, hydrothermal carbonization, and hydrothermal liquefaction. We also provide examples of current research and real-world findings. We then present a novel hydrothermal biorefinery concept for sequencing these single processes, giving concrete examples of possible raw materials and products. Sequencing gives new possibilities for biorefineries to exploit all the biomass components as valuable products with zero losses. The added value comes from the increased efficiency of the bio-based products' value chain, by reducing losses and generating higher-value products and services.

There is an increasing interest in renewable raw materials in all industries and adhesive industry is no exception. With the continuous development of biorefineries, the selection of bio-based materials is growing. The objective of this Thesis was to determine whether tannins from the bark of Finnish softwood could be added to that selection in regards to hot melt adhesive formulation. More precisely, whether tannins would be compatible with established materials, and whether tannins would be compatible with cellulose derivatives. This work functions as a laboratory scale proof of concept. The theoretical part of this Thesis introduces how adhesives work, what are hot melt adhesives and how adhesives are tested, before presenting some sustainable materials and tannins in particular. Hot melt adhesives have three primary components, polymer, tackifier and wax, and the properties of the adhesive can be adjusted by component selection and ratio. Hot melt adhesives are mostly used in packaging industry and thus this Thesis focuses on using folding boxboard. Phenolic tackifiers are industrially available and lignin has been proven to function as tackifier with cellulose derivatives. Due to these facts, hypothesis was that tannins should function as tackifiers due to their phenolic nature, especially with cellulose derivatives. Tannins used in this Thesis are extracted from the bark of Finnish softwood. It was discovered that mixture of tannins and poly(DL-lactide-co-ε-caprolactone) was a potential hot melt adhesive. This formulation was developed by screening mixtures of crude spruce tannin with 7 different polymers and 5 different waxes. Screening of the adhesive capabilities of different combinations was done by manual testing, and the peel strength of the most promising formulations was measured. The copolymer can be used as a hot melt adhesive by itself, but the processability and adhesion towards uncoated boxboard increased with tannins. In contrast to expectations, adhesive capabilities with the tested cellulose esters were weak. Next steps should be development of a better mixing mechanism as the tannin-copolymer mixture was not fully homogenous. There should also be research into how the parameters of the copolymer affect the adhesive capabilities of the hot melt adhesive, and whether changing these parameters could be used to enhance the adhesive. Compatibility with other materials should still also be tested with tannins.