Composite films from spruce galactoglucomannans with microfibrillated spruce wood cellulose

Two future wood biorefinery products, spruce galactoglucomannans (GGM) and microfibrillated spruce wood cellulose (MFC), were mixed to form composite films. The films were plasticized with different amounts of glycerol, and the preparation of films was successful even with low glycerol contents. The film properties were studied using optical microscopy and scanning electron microscopy, x-ray diffraction, water sorption, dielectric analysis, moisture scanning dynamic mechanical analysis, and tensile testing. The addition of MFC clearly affected the properties of the films by decreasing the moisture uptake and increasing the relative humidity of softening of the films and by increasing the glass transition temperature, tensile strength, and Young’s modulus of the films. The effect of MFC addition on the tensile properties of films was emphasized at low glycerol contents. The addition of MFC did not affect the degree of crystallinity of GGM in the films, which was between 20 and 25%. MFC can be efficiently used as reinforcement of GGM films to form wood-based composite materials and to prepare GGM-based films and coatings with low plasticizer content.     

Microwave-assisted extraction of high-molecular-weight hemicelluloses from spruce wood

Microwave-assisted extraction (MAE) at atmospheric pressure has been demonstrated as an efficient technology for the extraction of polymeric hemicelluloses from spruce sawdust. This technology was shown to be more efficient than conventional extraction. MAE leads to a high solubilization of wood and a selective extraction of hemicellulose polymers with high molecular weights. To optimize MAE, different treatment powers (125–573 W) of presoaked spruce sawdust in water and 1 M sodium hydroxide solution for a period of 60 min were tested. The yield of hemicellulose extraction increased with the microwave power in both mediums, but with a clear advantage for presoaked samples in basic medium. The characterization of extracted hemicelluloses has shown high extraction selectivity depending on the medium of impregnation of sawdust before MAE: High-molecular-mass acetylated galactoglucomannans (M_w ∼ 41 kDa) were isolated after presoaking in water and higher molecular mass arabinoglucoronoxylans (M_w ∼ 66 kDa) in basic medium.     

Preservation of beech and spruce wood by allyl alcohol-based copolymers

Allyl alcohol (AA), acrylonitrile (AN), methyl methacrylate (MMA), monomers and monomer mixtures AA+AN, AA+MMA were used to conserve and consolidate Beech and Spruce. After impregnation, copolymerisation and polymerisation were accomplished by gamma irradiation. The fine structure of wood+polymer(copolymer) composites was investigated by Scanning Electron Microscopy (SEM). It was observed that copolymer obtained from AA+MMA monomer mixture showed the optimum compatibility. The compressional strength and Brinell Hardness Numbers determined for untreated and treated wood samples indicated that the mechanical strength of wood+copolymer composites was increased. It was found that the mechanical strength of the wood samples containing the AA+MMA copolymer was higher than the others. In the presence of P(AA/MMA), at highest conversion, the compressive strength perpendicular to the fibres in Beech and Spruce increased approximately 100 times. The water uptake capacity of wood+copolymer composites was observed to decrease by more than 50% relative to the original samples, and biodegradation did not take place.     

Thermogravimetry as a possible tool for determining modification degree of thermally treated Norway spruce wood

Thermal treatment is one of environmental friendly wood modification processes, developed in order to improve wood’s natural durability and dimensional stability. Beside wood species, mainly isothermal temperature of heat-treatment and process duration affect these properties, which also correlate with the mass losses caused by the treatment. However, there is a lack of suitable external quality control methods. In this work thermogravimetry as a potential method for determining the degree of thermal modification is presented. Several calibration curves, representing the mass losses in a certain temperature range (the values obtained from the TG curves) compared to weight losses caused by previous heat-treatment (known values), were established for spruce wood samples modified at different isothermal temperatures (from 170 to 220 °C). Linear plot and good correlation factors (R ² = 0.95 and 0.96) were obtained for the TG mass losses from 130 to 280 °C and from 130 to 300 °C, both under nitrogen atmosphere. The predominant cause of mass loss in this temperature region was depolymerisation and thermal decomposition of hemicelluloses residues. Lower correlation factors were obtained under the air atmosphere and in the wider temperature range, respectively.     

Analysis of galactoglucomannans from spruce wood by capillary electrophoresis

The aim of this study was to setup a method for detection and quantification of monosaccharide components in technical galactoglucomannas (T-GGM) from spruce wood using capillary zone electrophoresis (CZE). CZE technique was optimised regarding borate buffer concentrations, EOF modifier application, and system pH. Aqueous solution of T-GGM was chemically hydrolysed by sulphuric acid, in an autoclave. In this way obtained monosaccharides were derivatized with 4-amino benzoic acid ethyl ester via reductive amination using sodium cyanoborohydride. The results of the optimisation procedure showed that the borate buffers at lowest concentrations (100 and 200 mM) with acetonitrile addition as EOF modifier gave the optimal measurement results, as it showed sufficient separation at relatively short migration times. The amounts of single monosaccharide components in the T-GGM samples obtained by the optimised CZE procedure were practically the same in comparison to the results of the well established HPLC-anion exchange chromatography. On the basis of this research, it was concluded that the capillary zone electrophoresis is an efficient analytical procedure for the characterisation of galactoglucomannans derived from softwoods.     

Nitration of lignin isolated from spruce wood by mechanical grinding

Summary 1. The nitration of spruce lignin obtained by mechanical grinding has been carried out with nitric acid in an anhydrous medium under heterogeneous and homogeneous conditions. Fractionation of the nitrolignin has been carried out and the elementary and functional composition of the fractions has been determined; the mean semi-empirical formulas of the C₉ structures have been calculated for both fractions. It has been shown that, depending on the nitration conditions, from one to two nitro groups enter the C₆-C₃ structural element of nitrolignin and, with an excess of HNO₃, nitrate groups as well.The fall in the content of OCH₃ groups corresponds to the content of phenolic hydroxyl groups in the initial MGL and can be explained by the demethylation of the guaiacyl structures of the lignin on nitration.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 1, pp. 58–65, 1966     

Calculation of charring rate and char depth of spruce and pine wood from mass loss

Journal of Thermal Analysis and Calorimetry - A charring rate is a key parameter for the calculation of fire resistance of timber structures and for fire investigation. Charring rates are...     

Comparison of steam pretreatment of eucalyptus,aspen, and spruce wood chips and their enzymatic hydrolysis

Applied Biochemistry and Biotechnology - Enzymatic hydrolysis of SO2-impregnated, steam-explodedEucalyptus viminalis was carried out at increasing substrate concentrations and enzyme loadings. When...     

A comparative CP/MAS 13C-NMR study of cellulose structure in spruce wood and kraft pulp

CP/MAS ¹³C-NMR spectroscopy in combination with spectral fitting was used to study the supermolecular structure of the cellulose fibril in spruce wood and spruce kraft pulp. During pulping, structures contributing to inaccessible surfaces in the wood cellulose are converted to the cellulose I allomorph, that is, the degree of order is increased. This increase is also accompanied by a conversion of cellulose I to cellulose I. Cellulose from wood composed of different cell types, that is, compression wood, juvenile wood, earlywood, latewood and normal wood exhibited a similar supermolecular structure. Assignments were made for signals from hemicellulose which contribute significantly to the spectral C-4 region (80–86 ppm) in kraft pulp spectra but substantially less to the corresponding region in wood spectra.     

Radionuclide-rich spruce twigs and needles as analytical reference materials

Black spruce /Picea mariana/ twigs and needles have been collected from a uraniferous area of northern Saskatchewan and characterized for their content of some radionuclides and trace elements in an interlaboratory program. These materials, rich in uranium, are available as reference materials, for estimating accuracy in the analysis of vegetation, from the Canadian Certified Reference Materials Project in Ottawa, Canada.     

Fia-spectrophotometric determination of thiamine after UV-irradiation

The determination of thiamine was carried out by UV-photodegradation in a single-line flow-injection assembly. The UV-photodegradation of thiamine was carried out in the coil of the injection valve, constituted of a PTFE tubing, half of its length being helically coiled around a UV lamp. A peak with two adjoining maxima was produced by injection, corresponding to the absorbance of the irradiated and non-irradiated sample. The analytical parameter is the difference between the two peaks, measured at 264 nm. The calibration graph is linear over the 1.2–30 μg/ml range of thiamine hydrochloride in 0.1M HCl. The influence of certain admixed substances was studied and the method was tested for the determination of thiamine in tablets.     

Quaternized wood as sorbent for hexavalent chromium

The potential of quaternized wood (QW) chips in removing hexavalent chromium from synthetic solution and chrome waste under both batch and continuous-flow conditions was investigated. Sorption was found to be dependent on pH, metal concentration, and temperature. QW chips provide higher sorption capacity and wider pH range compared with untreated wood chips. The equilibrium data could be fitted into the Langmuir isotherm model, and maximum sorption capacities were calculated to be 27.03 and 25.77 mg/g in synthetic chromate solution and chrome waste, respectively. The presence of sulfate in high concentration appeared to suppress the uptake of chromium by QW chips. Column studies showed that bed depth influenced the breakthrough time greatly whereas flow rate of influent had little effect on its sorption on the column.     

PVC/MBS共混物的紫外光交联及光氧化反应

PVC及其共混物应用广泛,MBS作为PVC制品的透明抗冲改性剂,在提高PVC抗冲性能的同时,必然影响PVC在紫外光照下发生的光化学反应过程,我们用紫外可见光研究了MBS对PVC紫外光解脱HCl动力学,发现MBS对PVC光解脱HCl有抑制作用,本文利用FTIR光谱研究PVC／MBS共混体系中,MBS对PVC光氧化、光交联及光降解过程的影响。