Research Articles

Few studies have been conducted about relation between cellulose para-meters and biomechanical properties of wood in tropical angiosperms species. For this purpose, on 13 trees from 3 species of French Guyana tropical rainforest in a clear active process of restoring verticality, i) growth strains were measured in situ in order to determine the occurrence of tension wood within samples and ii) cellulose structural parameters were estimated on all the samples using X-ray diffraction method. Crystallite size was estimated from the full-width at half-maximum of the Miller index (002) arc diffraction and angle T was measured following Cave’s method. Relationships between these parameters and growth stresses were good and the variations between normal and tension wood were significant, i.e. a lower angle T and a larger crystallite size in tension wood. In order to have a good estimation of the microfibril angle in the main layer of the secondary wall for each species, an experimental calibration was done between angle T and microfibril angle observed with scanning electron microscopy.

Scale formation in the digester during kraft pulping represents a great problem in pulp mills. Scaling reduces pulping control and efficiency, increasing energy costs and leading to cleaning breakdowns, with subsequent losses in productivity. The kraft process promotes CaCO3 scaling due to high calcium ion and carbonate concentrations, as well as high alkalinity and temperature levels, which increase the speed with which liquors reach a state of supersaturation. This work examines the action of diethylene triamine penta(methylene phosphonic acid) (DTPMPA), either alone or combined with commercial anti-scaling agents, as an inhibitor of calcium carbonate precipitation in the kraft pulping of Pinus taeda. The theoretical amount of calcium deposited in the digester was obtained by mass balance. Soluble calcium was stable throughout cooking when using the phosphonates alone or combined with anti-scaling agents. When adding only DTPMPA, calcium stays in the pulp, rather than forming deposits.

In this study, clove bud oil, which was cultivated in the Mediterranean region of Turkey, was provided from a private essential oil company in Turkey. Essential oil from clove (Syzygium aromaticum L.) was obtained from steam-distillation method, and its chemical composition was analyzed by GC and GC-MS. The results showed that the essential oils mainly contained about 87.00% eugenol, 8.01% eugenyl acetate and 3.56% β-Caryophyllene. The chemical composition of the Turkish clove bud oil was comparable to those of trees naturally grown in their native regions.

In this work two types of lignin-novolac resins have been formulated, partially substituting phenol by softwood ammonium lignosulfonate as filler or extender (methylolated) to study the viability of that substitution when resins will be employed as adhesives in textile felts. A commercial novolac resin was used as reference. Free phenol, free formaldehyde, water content, softening point, and flow distance values were determined in all cases to verify whether the material fulfills specifications. In addition, FTIR and NMR spectroscopic techniques were employed for the characterization of three resins samples tested to discuss their structural differences and similarities. The results obtained have shown that the substitution proposed is feasible from the point of view of the resins synthesis to get the pre-polymer.

Wood cell wall polysaccharides can be probed with monoclonal antibodies and carbohydrate-binding modules (CBMs). Binding of monoclonal antibodies to β-1-4-xylan, β-1-4-mannan, β-1-3-glucan, and α-1-5-arabinan structures were observed in native Sitka spruce (Picea sitchensis (Bong.) Carrière) wood cell walls. Furthermore CBMs of different families, differing in their affinities for crystalline cellulose (3a) and amorphous cellulose (17 and 28), were shown to bind to the native wood cell walls with varying intensities. Resin channel forming cells exhibited an increased β-1-4-xylan and a decreased β-1-4-mannan content. Focusing on severe compression wood (CW) tracheids, β-1-3-glucan was found towards the cell lumen. In contrast, α-1-5-arabinan structures were present in the intercellular spaces between the round tracheids in severe CW, highlighting the importance of this polymer in cell adhesion.

In NaHSO3-solutions of coniferaldehyde and its methyl ether (models for lignin chromophores of the cinnamaldehyde type) a dynamic equilibrium between the aldehydes and their hydrogen sulfite adducts is set up. A comparatively slow addition of hydrogen sulfite to the double bond leading to 1,3-disulfonic acid derivatives occurs; coniferaldehyde reacts slower than its methyl ether. In Na2SO3-solution both aldehydes are rapidly converted to 1,3-disulfonic acid derivatives. The results suggest that in both NaHSO3-solution and Na2SO3-solution the free cinnamaldehydes and sulfite ion are the reactants in the formation of disulfonic acid derivatives. Alkaline treatment of the 1,3-disulfonic acids leads to regeneration of the cinnamaldehydes. On prolonged storage in Na2SO3-solution, the 1,3-disulfonic acid derivative of the methyl ether of coniferaldehyde undergoes reactions leading to colored products and regeneration of the cinnamaldehyde on alkaline treatment fails. A model compound representative of lignin chromophores of enone type (trans-3,3’,4,4’-tetramethoxychalcone) rapidly undergoes addition to the double bond with formation of a sulfonic acid derivative in Na2SO3-solution. Treatment of a second model of enone type, 2,6-dimethoxy-p-quinone, with NaHSO3/Na2SO3-solution results in formation of a sulfonic acid derivative. The reactions of lignin chromophores of the enone and enal types with hydrogen sulfite/sulfite are discussed.

In this work we examined the morphological and chemical characteristics of the fibrous strands of oil palm empty-fruit-bunch which were left behind after being stripped of their fruits used for oil production. The empty-fruit-bunches were mechanically loosened to yield the fibrous strands, which can be used in paper and board making. We found that the fibrous strands had unique structure by having several large-diameter, long vessel elements in their core region, surrounded by vascular fibers. They had numerous silica-bodies attached to craters on their surfaces; the craters were perforated at the bottom. Many other minerals were also present in the strands. Our microscopic observations suggested that the silica-bodies are connected to a network of siliceous pathway within the fibrous matrix, and minerals tend to concentrate adjacent to the silica-bodies. Our findings could be useful in identifying suitable techniques for processing the oil palm fiber strands into value-added products.

The influences of flax lignin and phenolic compounds obtained from spruce bark on the development of Lycopersicon esculentum plantlets were evaluated. Depending on the applied treatment and the concentrations used, the natural aromatic compounds had stimulatory effects on the germination capacity and the plantlets height and leaf area. The influence of lignin on Lycopersicon esculentum was lower compared to the phenolic extract.

The aim of this work was to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of hemp nanofibers, using inverse gas chromatography (IGC), and to investigate the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Bio-nanocomposite materials were prepared from poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) as the matrix, and the cellulose nanofibers extracted from hemp fiber by chemo-mechanical treatments. Cellulose fibrils have a high density of –OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. The IGC results indicated that styrene maleic anhydride coated and ethylene-acrylic acid coated fibers improved their potential to interact with both acidic and basic resins. From transmission electron microscopy (TEM), it was shown that the nanofibers were partially dispersed in the polymer matrix. The mechanical properties of the nanocomposites were lower than those predicted by theoretical calculations for both nanofiber-reinforced biopolymers.

Rice straw (RS) is one of the most abundant lignocellulosic waste by-products worldwide and provides an alternative substrate to produce useful chemicals such as bioethanol and lactic acid. However, higher enzyme loadings are needed to obtain a higher product yield, which makes the large-scale utilization economically difficult. The presence of non-ionic surfactants and poly(ethylene glycol) (PEG) during the enzymatic hydrolysis of lignocellulosics has been found to increase the conversion of cellulose into fermentable sugars. We have found that adding 0.2g g-1 substrate of polyoxyethylene(20) sorbitan monooleate (PSM) or high-mass PEG increased the sugar yield by 22% and 12%, respectively, when enzyme loading was at 10FPU g-1 for 24h. PSM behaved better than PEG when different substrate concentrations, temperatures, and enzyme loadings were investigated. PSM provides an opportunity to reduce enzyme dosage while still keeping the same extent of hydrolysis. We also investigated the effect of PSM on the simultaneous saccharification and fermentation of pretreated RS to lactic acid. Results showed that addition of 0.7g L-1 PSM improved the lactic acid production by 24% compared to the reference without PSM addition at 72h.