In 1628, the Swedish warship Vasa capsized on her maiden voyage and sank in the Stockholm harbor. The ship was recovered in 1961 and, after polyethylene glycol (PEG) impregnation, it was displayed in the Vasa museum. Chemical investigations of the Vasa were undertaken in 2000, and extensive holocellulose degradation was reported at numerous locations in the hull. We have now studied the longitudinal tensile strength of Vasa oak as a function of distance from the surface. The PEG-content, wood density, and cellulose microfibril angle were determined. The molar mass distribution of holocellulose was determined as well as the acid and iron content. A good correlation was found between the tensile strength of the Vasa oak and the average molecular weight of the holocellulose, where the load-bearing cellulose microfibril is the critical constituent. The mean tensile strength is reduced by approximately 40%, and the most affected areas show a reduction of up to 80%. A methodology is developed where variations in density, cellulose microfibril angle, and PEG content are taken into account, so that cell wall effects can be evaluated in wood samples with different rate of impregnation and morphologies.

In the global pursuit for sustainable packaging solutions, usage of different paper raw material is one of the key components to fulfil the goal. Moulded fibre products allow usage of different fibre raw material, although for today, with some restrictions. For example, recycled fibre is of varying quality and can be a challenging material to use for thermoformed wet moulding applications. Further, CTMP strength potential should be further utilized for this application. In both cases, the stock preparation is crucial. The relationship between fibre type, stock preparation, processing and performance needs to be investigated to define how to best produce high-quality wet moulded fibre products using a specific fibre type. To be able to study this a laboratory equipment for manufacturing of high-quality wet moulded fibre products has been set up. Moreover, two test methods to evaluate properties important for trays have been developed; one to evaluate how much load the tray can take and one to evaluate how much the tray will warp during handling. Together with an optimised stock preparation for different fibre raw materials studies can be performed, which aim at increased usage of fibre qualities such as recycled fibre or CTMP for high-quality moulded fibre products. 

This paper presents a novel approach to reduce the water vapor transmission rate (WVTR) and water absorbance of wheat gluten/paperboard laminates by introducing a hydrophobic component (oleic acid (OA)) into the hydrophilic plasticizer (glycerol). Whereas the paperboard showed immeasurably high WVTR, the laminate with gluten/glycerol yielded finite values. More importantly, by incorporating 75 wt.% OA into the plasticizer, the WVTR and water absorbance were reduced by, respectively, a factor of three and 1.5-2. Of particular interest was that the mechanical properties were not changing dramatically between 0 and 50 wt.% OA. The results showed clear benefits of combining a gluten film with paperboard. Whereas the paperboard provided toughness, the WG layer contributed with improved moisture barrier properties. In addition, WVTR indicated that the paperboard reduced the swelling of the outer gluten/glycerol layer in moist conditions; a free standing gluten/glycerol film would yield infinite, rather than finite, WVTR values. 

In this study the effect of the mercerization degree on the water retention value (WRV) and tensile properties of compression molded sulphite dissolving pulp was evaluated. The pulp was treated with 9, 10, or 11 % aqueous NaOH solution for 1 h before compression molding. To study the time dependence of mercerization the pulp was treated with 12 wt% aqueous NaOH for 1, 6 or 48 h. The cellulose I and II contents of the biocomposites were determined by solid state cross polarization/magic angle spinning carbon 13 nuclear magnetic resonance (CP/MAS 13C NMR) spectroscopy. By spectral fitting of the C6 and C1 region the cellulose I and II content, respectively, could be determined. Mercerization decreased the total crystallinity (sum of cellulose I and cellulose II content) and it was not possible to convert all cellulose I to cellulose II in the NaOH range investigated. Neither increased the conversion significantly with 12 wt% NaOH at longer treatment times. The slowdown of the cellulose I conversion was suggested as being the result from the formation of cellulose II as a consequence of coalescence of anti-parallel surfaces of neighboring fibrils (Blackwell et al. in Tappi 61:71-72, 1978; Revol and Goring in J Appl Polym Sci 26:1275-1282, 1981; Okano and Sarko in J Appl Polym Sci 30:325-332, 1985). Compression molding of the partially mercerized dissolving pulps yielded biocomposites with tensile properties that could be correlated to the decrease in cellulose I content in the pulps. Mercerization introduces cellulose II and disordered cellulose and lowered the total crystallinity reflected as higher water sensitivity (higher WRV values) and poorer stiffness of the mercerized biocomposites.

Laboratory paper coatings of simple composition, comprising only a single spherical plastic pigment and binder type, were analysed in terms of water-based inkjet print quality. Optical density and gamut of dye colours decreased with increasing pigment size, and followed the binder hierarchy from polyvinyl alcohol (best) to carboxymethyl cellulose to styrene-butadiene latex (worst). For the larger pigment size, density and gamut also decreased with decreasing binder content and increasing coat weight. Colour-colour sharpness was evaluated using four measures of line bleeding, of which mean line width and blurriness were found to be the most useful and well correlated. Both bleeding measures, while following the same binder chemistry hierarchy mentioned above, now worsened with decreasing pigment particle size. This tallies with expectations from capillarity and light scattering, e.g. increasing particle size (in the range studied) increases both liquid penetration rate and opacity, thus resulting in decreased colour richness but increased sharpness.

All-cellulose composites are commonly prepared using cellulose solvents. In this study, moldable all-cellulose I wood fiber materials of high cellulose purity (97%) were successfully compression molded. Water is the only processing aid. The material is interesting as a “green” biocomposite for industrial applications. Dissolving wood fiber pulps (Eucalyptus hardwood and conifer softwood) are used and the influence of pulp origin, beating and pressing temperature (20–180 °C) on supramolecular cellulose nanostructure is studied by solid state CP/MAS 13C NMR. Average molar mass is determined by SEC to assess process degradation effects. Mechanical properties are determined in tensile tests. High-density composites were obtained with a Young’s modulus of up to 13 GPa. In addition, nanoscale cellulose fibril aggregation was confirmed due to processing, and resulted in a less moisture sensitive material.

Polycondensations of cis-9,10-epoxy-18-hydroxyoctadecanoic acid, isolated from birch outer bark, were performed at 75°C in toluene as solvent and at 85°C In bulk using immobilized Candida antarctica lipase B as catalyst. The polycondensation performed in toluene in presence of molecular sieves gave a polyester with DP 50 after 24 h. The same DP was obtained at much shorter reaction time (3 h) by bulk polymerization in an open vial without any drying agent present.

In this study we report polycondensation and co-polymerization of cis-9,10-epoxy-18-hydroxyoctadecanoic acid (1) isolated from birch outer bark using immobilized Candida antarctica lipase B (Novozyme 435) as catalyst to give epoxy activated straight chain polyesters and cyclic macromonomers.

Biomimetic approaches involving environmentally-friendly synthetic pathways provide an opportunity to elaborate novel high-performance biocomposites. Here we have developed a low-energy biosynthetic system for the production of a high-strength composite material consisting of self-assembled and nanostructured cellulosic nanofibers. This biocomposite is analogous to natural composite materials with high strength and hierarchical organization such as wood or tendon. It was generated by growing the bacterium Acetobacter, which naturally produces cellulosic nanofibers, in the presence of hydroxyethylcellulose (HEC). Individual cellulose fibrils were coated by HEC and exhibited a smaller lateral dimension than pure bacterial cellulose (BC) fibrils. They self-assembled to form compartmentalized nanofibers and larger cellulose fibril aggregates compared to pure BC. The tensile strength of nanocomposite films prepared from the compartmentalized cellulosic nanofibers was 20% higher than that of pure BC sheets and wood cellulose nanopapers, and 60% higher than that of conventional BC/HEC blends, while no strain-to-failure decrease was observed. The thin nanoscale coating consisting of hydrated HEC significantly increased the mechanical performance of the nanocomposite films by provoking compartmentalization of individual fibrils.