No abstract

Hydrothermal treatments (HTT) are used in the biorefineries to effectively valorize carbohydrate fractions and their products. However, lignin is often marginalized as a secondary component. Herein, we propose a new biorefinery approach focused on lignin valorization. We demonstrate that high-value lignins can be extracted using a simple, green and affordable process consisting of an optimized HTT followed by lignin extraction with aqueous acetone under ambient conditions. Significantly, the chemical structure and molecular mass of the lignin can be tailored by the selection of the process variables while maintaining a high yield, in the range of ~ 60-90%. For example, the average molecular mass (Mw) of the isolated lignins is in the range between 2.5 and 5 kDa while the amount of -O-4 linkages is 4-28 per 100 Ar.The extracted lignins are further used to generate micro and nanoparticles by using an aerosol flow system. The introduced lignin profiling affords control of particle properties, including average size and distribution, surface energy and wettability. Overall, the suggested approach allows to customize lignin products while achieving a 58% reduction in the lignin particles production costs compared to the lowest prime figures reported so far.

Cellulose-lignin composite fibres as precursors for carbon fibres. Part 1 -Manufacturing and properties of precursor fibres Mikaela Trogen (Conceptualization) (Investigation) (Formal analysis) (Visualization) (Writing -original draft), Nguyen-Duc Le (Resources) (Writing -review and editing), Daisuke Sawada (Investigation) (Formal analysis) (Visualization) (Writing -review and editing), Chamseddine Guizani (Formal analysis) (Writing -review and editing), Tainise Vergara Lourençon (Investigation) (Formal analysis) (Writing -review and editing), Leena Pitkänen (Investigation) (Formal analysis) (Writing -review and editing), Herbert Sixta (Resources) (Supervision), Riddhi Shah (Investigation) (Writingreview and editing), Hugh O'Neill (Resources) (Writing -review and editing), Mikhail Balakshin (Resources) (Writing -review and editing), Nolene Byrne (Resources) (Supervision) (Writing -review and editing), Michael Hummel (Supervision) (Funding acquisition) (Conceptualization) (Resources) (Writing -review and editing)

The substitution of phenol by lignin in phenol-formaldehyde (PF) resins is one of the most promising end uses of lignin valorization. Lignin from grasses and softwood has been the focus of the studies in this field as they present a higher number of theoretical reactive sites for resin synthesis. Herein we examined the composition and chemical reactivity of “less-reactive” hardwood lignin fractions and their performance in PF resins, synthesized by substituting 50 wt% of the phenol with lignin. Before resin synthesis, the samples were hydroxymethylated and the maximum formaldehyde consumption was recorded. By doing so, we observed that hardwood fractions consumed formaldehyde close to the theoretical calculation, whereas the reference softwood lignin consumed only about ¼ of the theoretical value. In the resin synthesis, we added formaldehyde to the formulation according to the measured maximum formaldehyde consumption. Thus, low values of free formaldehyde in lignin-PF (LPF) resins were achieved (<0.23%). Moreover, the resin bonding strength displayed similar performance irrespective of whether the LPF resins were made with softwood or hardwood lignin (range of 3.4–4.8 N mm−2 at 150°C and 45–480 s of press time). Furthermore, we concluded that hardwood kraft lignins present no disadvantage compared to softwood lignins in PF resin applications, which have significant practical implications.

This study aimed to characterise wood discolouration of three Brazilian eucalypt species exposed to the action of natural weathering in two distinct places. To achieve this, tests were performed at an exposed outdoor site and under a forest canopy; both located in the state of Rio Grande do Sul, Brazil. Colorimetric measurements were performed every 45 days during the period of 1 year in order to obtain the parameters L*, a*, b*, C* and h*. The main results showed significant darkening in the first 4 months and subsequently increased the greyish colour. Colour variations were observed between species, field and exposure time in service.

No abstract

In this study, a new simple method for chemical modification of wood from fast-growing Eucalyptus saligna (blue gum) was tested by a two-step treatment with methacryloyl chloride. The wood samples were submerged in a solution of 10 % methacryloyl chloride in dichloromethane for 15 h and then exposed to three temperatures: air dried, 50 and 100°C for 2 h. The chemical modifications of the wood were examined by ATR-IR and 13 C CP/MAS solid-state NMR; quantitative chemical composition of wood samples by means of wet chemical quantification, HPLC, TGA; colorimetric evaluation by CIELAB method and UV-Vis spectroscopy. Water uptake tests were also performed. A partial substitution of the hydroxyl by methacrylate groups on the cell wall of blue gum wood was observed, and also loss of a hemicelluloses fraction after the treatments. The colour change increased with increasing temperature in the second step of the treatment. Dimensional stability and water repellence were improved by 40-50 and 60-75 %, respectively.

No abstract