Analytical pyrolysis as a direct method to determine the lignin content in wood. Part 2: evaluation of the common model and the influence of compression wood

In Part 1, a method for the quantification of the lignin content (Py-lignin) of Maritime pine and spruce wood samples directly from the pyrograms was presented (A. Alves, M. Schwanninger, H. Pereira, J. Rodrigues, J. Anal. Appl. Pyrol. 76 (2006a) 209). The good correlation found between the Py-lignin and Klason lignin content gave a common model to both species. In this work different larch species (Larix sp.) as well as varieties of European larch were used to evaluate this common model, revealing only small differences between the measured and the predicted Klason lignin contents. Compression wood was included due to the difference in lignin composition and content compared to normal wood. As the influence of compression wood was small a so-called ‘‘softwood model’’ including all samples was calculated (Py-lignin = 0.7325 Klason lignin + 3.9195, R2 = 0.94). This can be used for pine, larch, and spruce wood with the limitation of the highest and lowest values where the species-specific models lead to better results, although more than 95% of the differences between the species-specific models and the ‘‘softwood model’’ lie within 0.3%. It is expected that this model can predict the Klason lignin content of other softwoods

Biotehnološka razgradnja i molekularni mehanizmi razgradnje drveta pomoću selektivnih gljiva, uzročnika bijele truleži

Microbial mechanisms of lignin degradation may be utilised for solid-state fermentations other than biopulping, during which the selective conversion of lignin is required. The current paper reviews current work into selective lignin conversion, with emphasis on the contributions made by our research group, which consists of researchers from five different laboratories. Three of them cooperate within Wood K plus. The recent research of this group has focussed on fermentations utilising the unique metabolism of selective white-rot fungi to modify wood surfaces during relatively short fermentation times of less than one week and on research into the molecular mechanisms causing these modifications. Lignin degradation by selective fungi (e.g. Ceriporiopsis subvermispora and species of the genus Phlebia) on the wood surfaces was significant after three days. After seven days the overall lignin content of spruce wood shavings was reduced by more than 3.5 %. Lignin loss was accompanied by an increase of extractable substances. To evaluate small changes and to trace the fungal modification processes, Fourier transform infrared spectroscopic (FTIR) techniques and electron paramagnetic resonance (EPR) spectroscopy were applied and adapted. The spectra recorded in the near infrared region (FT-NIR) turned out to be very useful for kinetic studies of the biopulping/biomodification processes and a good method to evaluate the capabilities of fungi to modify wood surfaces within this short period.Mikrobiološki mehanizmi razgradnje lignina, osim biološke proizvodnje pulpe tijekom koje dolazi do selektivne pretvorbe lignina, mogu se primijeniti tijekom fermentacije na krutoj podlozi. U ovom je revijalnom prikazu dan pregled istraživanja selektivne pretvorbe lignina, a osobito rad znanstvenoga tima, koji se sastoji od istraživača iz pet raznih laboratorija. Troje istraživaa surađuju u centru Wood K plus. Istraživanja te skupine bila su usmjerena na fermentaciju primjenom jedinstvenog metabolizma selektivne gljive, uzročnika bijele truleži, u razgradnji površine drveta tijekom relativno kratkog vremena fermentacije (manje od tjedan dana) i na istraživanje molekularnih mehanizama koji uzrokuju te promjene. Razgradnja lignina s pomoću selektivnih gljiva (npr. Ceriporiopsis subvermispora i vrste roda Phlebia) na površini drveta bila je značajna nakon tri dana. Nakon sedam dana ukupni udjel lignina u piljevini drva smreke smanjen je za više od 3,5 %. Gubitak lignina praćen je povećanjem količine ekstraktibilnih tvari. Da bi se pratio proces modifikacije s pomoću gljiva, primijenjene su prilagođene metode Fourier transformacijske infracrvene spektroskopije (FTIR) i elektronske paramagnetske rezonancije (EPR). Spektar snimljen blizu infracrvenog područja (FT-NIR) bio je vrlo koristan za istraživanje kinetike biološke proizvodnje pulpe odnosno procesa biomodifikacije i dobra je metoda za procjenu sposobnosti gljiva da u vrlo kratkom vremenskom roku razgrađuju površinu drveta

FIBRILLATION OF FLAX AND WHEAT STRAW CELLULOSE: EFFECTS ON THERMAL, MORPHOLOGICAL, AND VISCOELASTIC PROPERTIES OF POLY(VINYLALCOHOL)/FIBRE COMPOSITES

Nano-fibrillated cellulose was produced from flax and wheat straw cellulose pulps by high pressure disintegration. The reinforcing potential of both disintegrated nano-celluloses in a polyvinyl-alcohol matrix was evaluated. Disintegration of wheat straw was significantly more time and energy consuming. Disintegration did not lead to distinct changes in the degree of polymerization; however, the fibre diameter reduction was more than a hundredfold, creating a nano-fibrillated cellulose network, as shown through field-emission-scanning electron microscopy. Composite films were prepared from polyvinyl alcohol and filled with nano-fibrillated celluloses up to 40% mass fractions. Nano-fibrillated flax showed better dispersion in the polyvinyl alcohol matrix, compared to nano-fibrillated wheat straw. Dynamic mechanical analysis of composites revealed that the glass transition and rubbery region increased more strongly with included flax nano-fibrils. Intermolecular interactions between cellulose fibrils and polyvinyl alcohol matrix were shown through differential scanning calorimetry and attenuated total reflection-Fourier transform infrared spectroscopy. The selection of appropriate raw cellulose material for high pressure disintegration was an indispensable factor for the processing of nano-fibrillated cellulose, which is essential for the functional optimization of products

Biotehnološka razgradnja i molekularni mehanizmi razgradnje drveta pomoću selektivnih gljiva, uzročnika bijele truleži

Microbial mechanisms of lignin degradation may be utilised for solid-state fermentations other than biopulping, during which the selective conversion of lignin is required. The current paper reviews current work into selective lignin conversion, with emphasis on the contributions made by our research group, which consists of researchers from five different laboratories. Three of them cooperate within Wood K plus. The recent research of this group has focussed on fermentations utilising the unique metabolism of selective white-rot fungi to modify wood surfaces during relatively short fermentation times of less than one week and on research into the molecular mechanisms causing these modifications. Lignin degradation by selective fungi (e.g. Ceriporiopsis subvermispora and species of the genus Phlebia) on the wood surfaces was significant after three days. After seven days the overall lignin content of spruce wood shavings was reduced by more than 3.5 %. Lignin loss was accompanied by an increase of extractable substances. To evaluate small changes and to trace the fungal modification processes, Fourier transform infrared spectroscopic (FTIR) techniques and electron paramagnetic resonance (EPR) spectroscopy were applied and adapted. The spectra recorded in the near infrared region (FT-NIR) turned out to be very useful for kinetic studies of the biopulping/biomodification processes and a good method to evaluate the capabilities of fungi to modify wood surfaces within this short period.Mikrobiološki mehanizmi razgradnje lignina, osim biološke proizvodnje pulpe tijekom koje dolazi do selektivne pretvorbe lignina, mogu se primijeniti tijekom fermentacije na krutoj podlozi. U ovom je revijalnom prikazu dan pregled istraživanja selektivne pretvorbe lignina, a osobito rad znanstvenoga tima, koji se sastoji od istraživača iz pet raznih laboratorija. Troje istraživaa surađuju u centru Wood K plus. Istraživanja te skupine bila su usmjerena na fermentaciju primjenom jedinstvenog metabolizma selektivne gljive, uzročnika bijele truleži, u razgradnji površine drveta tijekom relativno kratkog vremena fermentacije (manje od tjedan dana) i na istraživanje molekularnih mehanizama koji uzrokuju te promjene. Razgradnja lignina s pomoću selektivnih gljiva (npr. Ceriporiopsis subvermispora i vrste roda Phlebia) na površini drveta bila je značajna nakon tri dana. Nakon sedam dana ukupni udjel lignina u piljevini drva smreke smanjen je za više od 3,5 %. Gubitak lignina praćen je povećanjem količine ekstraktibilnih tvari. Da bi se pratio proces modifikacije s pomoću gljiva, primijenjene su prilagođene metode Fourier transformacijske infracrvene spektroskopije (FTIR) i elektronske paramagnetske rezonancije (EPR). Spektar snimljen blizu infracrvenog područja (FT-NIR) bio je vrlo koristan za istraživanje kinetike biološke proizvodnje pulpe odnosno procesa biomodifikacije i dobra je metoda za procjenu sposobnosti gljiva da u vrlo kratkom vremenskom roku razgrađuju površinu drveta

Chemical Imaging of Poplar Wood Cell Walls by Confocal Raman Microscopy

Confocal Raman microscopy was used to illustrate changes of molecular composition in secondary plant cell wall tissues of poplar (Populus nigra × Populus deltoids) wood. Two-dimensional spectral maps were acquired and chemical images calculated by integrating the intensity of characteristic spectral bands. This enabled direct visualization of the spatial variation of the lignin content without any chemical treatment or staining of the cell wall. A small (0.5 μm) lignified border toward the lumen was observed in the gelatinous layer of poplar tension wood. The variable orientation of the cellulose was also characterized, leading to visualization of the S1 layer with dimensions smaller than 0.5 μm. Scanning Raman microscopy was thus shown to be a powerful, nondestructive tool for imaging changes in molecular cell wall organization with high spatial resolution

Analytical pyrolisis as a direct method to determine the lignin content in wood. Evaluation of species-specific differences in softwood lignin composition using principal component analysis

Both the genetics and the environment determine the chemical composition of wood. To assess the chemical composition analytical pyrolysis is being increasingly used. Each single pyrogram is a fingerprint of the chemical composition that should reflect tissue, species, and site related information although hidden in an amount of data. Principal component analysis was applied to evaluate the pyrolysis results with respect to differences in lignin composition using G- and H-lignin-derived peaks from the pyrograms. The three species: pine, spruce and larch were separated in the first principal scores plot and the corresponding loadings plot revealed that it is vanillin (G 9) and G–C C C (G 11) on one hand and isoeugenol (G 8) and dihydroconiferyl alcohol (G 19) on the other hand that separate spruce and larch from pine. Beside others G 9 plus G 11 and G 8 plus G 19 separate spruce form larch as well as Vaquey pine from Blagon pine. In addition an investigation of the different tissues – normal wood and reaction wood – and the discussion of these results together with the loadings helped to reveal the differences in lignin composition between the species, tissues, and two sites. It was shown that analytical pyrolysis combined with principal component analysis could be useful for the identification of species and their origi