Lignocellulose biomass has a tremendous potential as renewable biomaterials for fostering the “bio-based society” and circular bioeconomy paradigm. It requires efficient use and breakdown of fiber ...cell walls containing mainly cellulose, hemicellulose and lignin biopolymers. Despite their great importance, there is an extensive debate on the true structure of fiber walls and knowledge on the macromolecular nano-organization is limited and remains elusive in 3D. We employed dual-axis electron tomography that allows visualization of previously unseen 3D macromolecular organization/biopolymeric nano-architecture of the secondary S2 layer of Norway spruce fiber wall. Unprecedented 3D nano-structural details with novel insights into cellulose microfibrils (~ 2 nm diameter), macrofibrils, nano-pore network and cell wall chemistry (volume %) across the S2 were explored and quantified including simulation of structure related permeability. Matrix polymer association with cellulose varied between microfibrils and macrofibrils with lignin directly associated with MFs. Simulated bio-nano-mechanical properties revealed stress distribution within the S2 and showed similar properties between the idealized 3D model and the native S2 (actual tomogram). Present work has great potential for significant advancements in lignocellulose research on nano-scale understanding of cell wall assembly/disassembly processes leading to more efficient industrial processes of functionalization, valorization and target modification technologies.
Bio-based adhesives have gained considerable attention in the last years as more sustainable and healthier alternatives to the formaldehyde-based adhesives used today in wood-based panel ...manufacturing. In this study, dialdehyde starch (DAS) with various aldehyde contents was prepared by using sodium metaperiodate as an oxidizing agent. Characterizations were performed by employing Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and thermal stability analysis. Different adhesive compositions were used for making medium-density fiberboard (MDF) panels. They were based on DAS (12 wt% based on fiber), emulsifiable diphenylmethane diisocyanate (eMDI, 2-4 wt% based on DAS), and microfibrillated cellulose (MFC, 0.5-1.0 wt% based on DAS). Fibers and the adhesive components were mixed with a combination of dry mixing and wet spraying. The physical and mechanical properties of MDF panels bonded with different DAS-based adhesives were compared with those of melamine urea-formaldehyde (MUF) adhesive and sole eMDI. The results showed that the MDF panels made with DAS-MFC-eMDI of 99.52% bio-based content showed comparable properties to standard panels with a commercial MUF adhesive. It was implied that DAS in the presence of small amount of eMDI can create strong bonds with wood fibers, while an additional positive effect on bonding was due to the contact surface enlargement of MFC.
Dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD, brushite) crystals were synthesised within Scots pine sapwood via a wet-chemistry route from aqueous solutions of Ca(CH3COO)2 and NH4H2PO4 salts. ...SEM/EDS analysis was used to assess the saturation of the wood cell lumina and cell wall as well as morphological features and elemental composition of the co-precipitated mineral. Brushite mineral crystallization and crystallite growth within the wood matrix was studied by in situ XRD. The chemical composition of the mineral before and after the dissolution was evaluated using FTIR spectroscopy. The overall impact of brushite on the thermal behaviour of wood was studied by TGA/DSC and TGA/DTA/MS analysis under oxidative and pyrolytic conditions. Bending and compression strength perpendicular and parallel to the fibre directions as well as bending strengths in longitudinal and transverse directions of the mineralised wood were also evaluated. Results indicate the viability of the wet-chemistry processing route for wood reinforcement with crystalline calcium phosphate (CaP)-based minerals, and imply a potential in producing hybrid bio-based materials that could be attractive in the construction sector as an environmentally friendly building material.
In the present work, gadolinium substitution effects on the properties of yttrium manganite Y
Gd
Mn
Fe
O
(x from 0 to 1 with a step of 0.2) synthesized by an aqueous sol-gel method have been ...investigated. Partial substitution of Mn
by
Fe
in the manganite was also performed in order to investigate deeper the structural properties of synthesized compounds applying Mössbauer spectroscopy. It was demonstrated that substitution of Y
by Gd
ions leads to the changes of structural, magnetic and morphological properties of investigated system. The crystal structure gradually transformed from hexagonal to orthorhombic with an increase of Gd
content in the crystal lattice. The mixed phase was obtained when x = 0.6, whereas other compounds were determined to be monophasic. Magnetization measurements revealed paramagnetic behavior of all specimens, however magnetization values were found to be dependent on chemical composition of the samples. Solid solutions with orthorhombic structure revealed higher magnetization values compared to those of hexagonal samples. The highest magnetization was observed for pure GdMn
Fe
O
. Structural properties were investigated by powder X-ray diffraction, Mössbauer, FTIR and Raman spectroscopies. Morphological features of the synthesized specimens were studied by scanning electron microscopy (SEM).
Key message
Increasing environmental pressures appearing over the last few years have led to important changes in the field of wood protection. In this context
,
new technologies
,
based either on ...thermal or chemical modifications
,
suggest increasing interest in prospect of programmed ban of biocide products
.
•
Context
The evolution of the regulations on the use of biocide products has led to important changes in the field of wood preservation, leading to an increasing interest for non-biocide treatments like thermal or chemical modifications to face to the programmed ban of biocide products.
•
Aims
The paper reviews the different non-biocide alternatives developed currently on an industrial scale, highlighting their main characteristics and applications.
•
Results
Different treatments have been developed on an industrial scale involving mainly thermal modifications and acetylation, furfurylation and DMDHEU constituting already available solutions.
•
Conclusion
Different non-biocide alternatives already exist and will become more important in the next decades due to the increasing legislative pressure driven by environmental considerations.
This review article introduces recent scientific and technical reports due to near infrared spectroscopy (NIRS) at wood science and technology, most of which was published between 2006 and 2013. Many ...researchers reported that NIR technique was useful to detect multi traits of chemical, physical, mechanical and anatomical properties of wood materials although it was widely used in a state where characteristic cellular structure was retained. However, we should be sensitive and careful for application of NIRS, when spectra coupled with chemometrics presents unexpected good results (especially, for mechanical physical and anatomical properties). The real application for on-line or at-line monitoring in wood industry is desired as next step. Basic spectroscopic research for wooden material is also progressed. It should be a powerful and meaningful analytical spectroscopic tool.
Textured WO 3 and WO 3 Raudoniene, J.; Laurikenas, Andrius; Kaba, Meriyam M. ...
Thin solid films,
2018, Volume:
653
Journal Article
Peer reviewed
Tungsten trioxide (WO 3 ) and molybdenum-doped tungsten trioxide (WO 3 :Mo) films were deposited on stainless steel surface by a chemical aqueous solution approach using dip-coating technique. The ...deposited 5, 10 and 15-layer films were homogeneous and continuous. The surface morphology and crystallinity of the produced films were dependent on the metal cation species and concentration of PVA in the solution. FE-SEM analysis revealed the formation of textured WO 3 film surfaces having spike-like nanostructures. The values of the static water contact angle measured on the film surface showed that deposited WO 3 films can exhibit both hydrophilic and hydrophobic nature, while WO 3 :Mo films showed hydrophilic behavior. Tribological properties of the deposited films were evaluated in deionized water. All three coatings retained a lubricating layer much better than original steel, demonstrating major reduction in friction and wear. Particularly effective were PVA-free WO 3 films, whose friction coefficient stayed under 0.2 for over 2000 cycles. Excellent tribological, hydrophobic and hydrophilic properties along with simple deposition methods suggest very promising potential of WO 3 and WO 3 :Mo coatings in industrial applications.
Wood science covers in particular the areas of the formation and composition as well as the chemical, biological and physical-mechanical properties of wood. First comprehensive studies have already ...been published in the last century. Detailed knowledge of wood is required for the processing of wood, the production of wood-based materials, and the utilization of wood and wood-based materials as buildings and various other products such as furniture. This review gives a brief overview on the progress in wood chemistry, wood biology (including photosynthesis and biodeterioration), and physical-mechanical properties of wood and wood-based materials. These fundamentals are also essential for understanding technological processes and product development.
Changes in both formaldehyde legislations and voluntary requirements (
e.g.
Germany RAL) are currently the driving factors behind research on alternatives to amino-based adhesives; moreover, consumer ...interest in healthy and sustainable products is increasing in bio-based adhesives. Sources of formaldehyde emissions in wood-based panels as well as different emission test methods have been discussed, and the main focus of this review is on the research conducted on sustainable bio-based adhesive systems for wood panels. Lignin, tannin, protein, and starch have been evaluated as both raw materials and adhesive alternatives to existing amino-based thermosetting adhesives. Adhesion improving modifications of these bio-based raw materials as well as the available and experimental crosslinkers have also been taken into account.
Stricter legislation on formaldehyde emissions as well as growing consumer interest in sustainable raw materials and products are the main driving factors behind research on bio-based adhesives, as alternatives to amino-based ones, for wood panels.
The quality of wood powders depends on the size reduction technology used to produce them. The pre-drying, chipping, and conventional (impact and attritional) size reduction steps, commonly employed ...in industry, act to degrade wood and diminish its full potential as a renewable feedstock. In this study, the effect of using a new green (i.e. freshly harvested) milling technology, the multi-blade shaft mill (MBSM), on wood powder properties was investigated. Particle size distribution (PSD) and shape properties were measured by two-dimensional image analysis and surface area analysis was performed. The results showed that the MBSM can produce much finer powders compared to hammer milling, with particles demonstrating unique morphology and high specific surface area. Green wood milling yielded particles with the highest sphericity (0.64), aspect ratio (0.58), and micropore diameter (4.5 nm). Finer particles with spherical shapes enhanced the bulk density. Moreover, mill settings permit tailor-made powders according to the desired PSD.
PDF
