Patrik Ahvenainen

Aalto University · Department of Bioproducts and Biosystems

Cellulose crystallinity assessment is important for optimizing the yield of cellulose products, such as bioethanol. X-ray diffraction is often used for this purpose for its perceived robustness and availability. In this work, the five most common analysis methods (the Segal peak height method and those based on peak fitting and/or amorphous standar...

Background Biological materials have a complex, hierarchical structure, with vital structural features present at all size scales, from the nanoscale to the macroscale. A method that can connect information at multiple length scales has great potential to reveal novel information. This article presents one such method with an application to the bam...

Bamboo is an underutilized resource widely available in countries with rapidly developing economies. Structural bamboo products, analogous to wood products, allow flexibility in the shape and dimensions of bamboo structural members. Here, the ultrastructure, microstructure, cell wall properties and flexural properties of three species of bamboo (Mo...

Balsa, with its low density and relatively high mechanical properties, is frequently used as the core in structural sandwich panels, in applications ranging from wind turbine blades to racing yachts. Here, both the cellular and cell wall structure of balsa are described, to enable multi-scale modeling and an improved understanding of its mechanical...

In this paper we present a fast model system for monitoring the recrystallization of quench-cooled amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering. The use of these two methods enables comparison between surface and bulk crystallization. Non-ordered mesoporous silica micro-particles were added to the system in order to al...

Plant-based cellulosic materials are intriguing building blocks for functional materials, and sustainable nanocellulose production strategies have been intensively explored. Most of the existing strategies, however, suffer from the fact that highly energy-intensive fiber fibrillation yields a nanocellulose gel containing more than 95% water. We sho...

The structure of hardwoods representing eight tropical and five temperate species was characterized from the atomistic level up to the cellular level using X-ray scattering, X-ray microtomography and light microscopy. The species were chosen for this study based on their popularity as tonewoods. The ultrastructure of wood cell walls, including crys...

In the original publication of the article, the acknowledgment missed one of the funding agencies. The correct acknowledgement should be.

We followed the cellulose structure formation induced by water diffusion into Lyocell dopes based on both N-Methylmorpholine N-oxide (NMMO) and 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc], by using scanning simultaneous small- and wide-angle scattering (SAXS-WAXS) experiment along the diffusion gradient. The water content at each point wa...

This paper discusses the influence of reactor design and initial consistency when partially hydrolyzing microcrystalline cellulose (MCC) in supercritical water. Experiments conducted on two pilot reactors located in Finland and in Spain showed that stopping the reaction using depressurization instead of quenching, combined with a sufficiently high...

The levelling-off degree of polymerization (LODP) is typically considered an apodictic number of each cellulosic source that relates to the length of its cellulose crystallites. In this study, we have performed hydrothermal and alkaline treatments on bleached birch kraft pulp to adjust the xylan content, and the resulting pulps have been subjected...

Many endangered tropical hardwoods are commonly used in electric guitars. In order to find alternative woods, the current electric guitar woods need to be studied and classified as most research in this field has focused on acoustic instruments. Classification was done based on luthier literature, woods used in commercially available electric guita...

Hydrothermal treatments of birch wood and kraft pulp were compared for their ability to extract the xylan and produce viscose-grade pulp. Water post-hydrolysis of kraft pulp produced a high-purity cellulosic pulp with lower viscosity but higher cellulose yield than traditional pre-hydrolysis kraft pulping of wood. Post-hydrolysis of pulp also incre...

The poster outlines some of the goals of the two-year post-doctoral research project funded by the Kone foundation. The aim of the project is to study the structure of wood used in electric guitars and to find alternative wood species that could be used in favor of the threatened wood species. The challenge is how the wood structure relates to the...

Quite recently, the Ioncell-F process, a novel and promising Lyocell fibre process, has been developed. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) utilized in this process, was identified as an excellent cellulose solvent for dry-jet wet fibre spinning. Fibres spun from cellulose-[DBNH]OAc solution have shown excellent...

Background Lignocellulose from fast growing hardwood species is a preferred source of polysaccharides for advanced biofuels and “green” chemicals. However, the extensive acetylation of hardwood xylan hinders lignocellulose saccharification by obstructing enzymatic xylan hydrolysis and causing inhibitory acetic acid concentrations during microbial s...

Combining X-ray scattering and tomography modalities in one in-house set-up allows new kind of information to be studied in hierarchical samples such as plants. As a proof-of-concept tissue-specific scattering patterns of Moso bamboo was obtained. The method requires very little sample preparation. Scattering-contrast tomography was done for one sl...

This work discusses the suitability of supercritical water treatment (SCWT) for depolymerising microcrystalline cellulose in a controlled way. The SCWT partially hydrolysed cellulose down to a mixture of three valuable products: water-insoluble low-molecular-weight cellulose (WI-LMWC) precipitate, water-soluble low-molecular-weight cellulose (WS-LM...

Composite fibres that contain cellulose and lignin were produced from ionic liquid solutions by dry-jet wet spinning. Eucalyptus dissolving pulp and organosolv/kraft lignin blends in different ratios were dissolved in the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate to prepare a spinning dope from which composite fibres were spun success...

The mechanical performance of materials reinforced by cellulose nanofibrils is highly affected by the orientation of these fibrils. This paper investigates the nanofibril orientation distribution of films of partly oriented cellulose nanofibrils. Stripes of hydrogel films were subjected to different amount of strain and, after drying, examined with...

Cellulose is the most abundant biopolymer on Earth and hence it has enormous potential as a source of renewable energy. The nanoscale properties of cellulose are also import for the wood and papermaking industries. The atomic level structure of naturally occurring cellulose Iβ allomorph is well known [1] and this atomistic model is employed in this...

The purpose of the poster is to visualize how the scattering intensities are affected by the size of the average size of the cellulose crystallites, using both experimental and ideal, atomistic models. The poster won the best poster prize award.

The nanoscale parameters of weakly scattering Arabidopsis thaliana stems were analyzed by wide-angle X-ray scattering.

Cutting tools leave characteristic marks that can connect a set of toolmarks to an individual tool. When the depth resolution of an optical microscope is insufficient, more advanced three-dimensional (3D) imaging methods such as Scanning White Light Interferometry (SWLI) and confocal microscopy are required. We cut ten copper wires (2.1+/-0.1 mm di...

Scanning White Light Interferometry provides sub-micron depth resolution and is therefore an ideal data acquisition method for forensic toolmark comparison in which such resolution is required. We imaged toolmarks made on ten copper wires with a preselected part of the jaws of a pair of diagonal cutting pliers. The common pattern found in the surfa...