Research Articles

In this study, effects of panel density and adhesive ratio on some physical and mechanical properties of peanut (Arachis hypogaea L.) hull particleboards for general purposes were investigated. Panels were manufactured with various densities (0.5, 0.6, 0.7, and 0.8 g/cm3) and adhesive ratios (core layer 8-9% and face layer 10-11%) using urea-formaldehyde (UF) as an adhesive. All panels were tested for some mechanical (internal bond, modulus of elasticity, and modulus of rupture) and physical (water absorption and thickness swelling) properties. Results indicated that increase in the panel density and adhesive ratio, resulted in an improvement in mechanical and physical properties. Only the panels with 0.8g/cm3 density almost met the requirements for the TS-EN 312 Standard for general purposes. Also, the boards having the lower mechanical properties tested in this study can be used as insulating material in buildings because such materials would not be subjected to any mechanical stress.

Stone groundwood (SGW) is a fibrous matter commonly prepared in a high yield process, and mainly used for papermaking applications. In this work, the use of SGW fibers is explored as reinforcing element of polypropylene (PP) composites. Due to its chemical and superficial features, the use of coupling agents is needed for a good adhesion and stress transfer across the fiber-matrix interface. The intrinsic strength of the reinforcement is a key parameter to predict the mechanical properties of the composite and to perform an interface analysis. The main objective of the present work was the determination of the intrinsic tensile strength of stone groundwood fibers. Coupled and non-coupled PP composites from stone groundwood fibers were prepared. The influence of the surface morphology and the quality at interface on the final properties of the composite was analyzed and compared to that of fiberglass PP composites. The intrinsic tensile properties of stone groundwood fibers, as well as the fiber orientation factor and the interfacial shear strength of the current composites were determined.

Several timbers and crop by-products were subjected to an enzymatic treatment to obtain a xylo-oligosaccharides-enriched preparation. The process was performed by means of the commercial endo-β-1,4-xylanase Buzyme 2511®. The enzymatic cocktail was applied onto the raw ground materials with yield up to 5.3 ± 1.0 g/L xylo-oligosaccharides for apple pomace. In order to make the materials more accessible to enzymatic hydrolysis, they were subjected to thermal-alkaline treatment. The biocatalysis process over the thermo-alkaline treated materials yielded xylo-oligosaccharide solutions with the following concentrations (g/l): 1.3 white poplar (Populus alba), 2.9 giant cane (Arundo donax), 3.7 apple pomace (Malus domestica), and 6.5 stalk of grapes (Vitis vinifera). The preparation resulting from biotransformation of grape stalk contained mostly xylo-oligosaccharides (96% w/v) with a small amount of xylose (3% w/v). The same ratio was obtained when pure xylan from birchwood was used as feedstock.

Due to scarcity of cellulosic wood fibers five bamboo species, namely B. tulda, D. hamiltonii, B. balcooa, M. baccifera, and B. arundinacea, and two eucalyptus species, namely E. tereticornis and E. grandis, were grown under North Indian climatic conditions in order to sustain fiber supply through social forestry. After four years of cultivation, these cellulosic raw materials were evaluated for anatomical structures, fibre dimensions, chemical characterization, and pulp and paper making characteristics. B. balcooa and M. baccifera contained higher holocellulose and α-cellulose contents compared to other bamboo species and lower ash contents, indicating that they are likely to pose less problem during chemical recovery. E. grandis contained higher holocellulose, α-cellulose, and lower lignin contents than that of E. tereticornis. Morphologically, bamboo species did not show much difference in fiber dimensions and their derived values. E. grandis showed problems of kink and curl due to longer fiber length than E. tereticornis. Based on pulp yield, brightness, and pulp viscosity B. balcooa, M. baccifera and E. grandis are better options for social forestry among other species.

Soda pulping was performed using kenaf stalk, core, and bast as raw materials. It was observed that all these components could yield good paper characteristics when the resulting pulps were beaten to a freeness of 200 to 300 mL. Soda pulp made from the stalk was comparable to the frond from oil palm in sheet properties, but the latter would require higher beating energy to reach similar freeness as compared to the former.

Chemotaxonomy, also known as chemosystematics, can be regarded as a hybrid science which can classify plants based on their unique extractives (secondary metabolites). In this work, we investigated the chemotaxonomic marks of Paulownia species by studying the extractives of Paulownia tomentosa (Thunb.) Steud. var. tomentosa, a hardwood species widely used in Chinese medicine and pulping industries. Nine phenolic extractives, including two flavonoids (naringenin (1), and quercetin (2)), two phenolic acids (cinnamic acid (3), and gallic acid (4)), and five phenylpropanoid glycosides (cistanoside F (5), acteoside (6), isoacteoside (7), campneoside II (8), and isocampneoside II (9)), were isolated from the n-BuOH soluble fraction of P. tomentosa var. tomentosa bark, by repeated sephadex LH-20 open column chromatography coupled by Thin Layer Chromatography detection. The structures of the phenolic extractives were elucidated and characterized on the basis of their spectroscopical data and physiochemical properties. This was the first time to report the nine extractives from P. tomentosa var. tomentosa bark. Our chemotaxonomic analysis demonstrated that phenylpropanoid glycosides in P. tomentosa var. tomentosa were interesting and phenylpropanoid glycosides may possibly be considered as a useful chemotaxonomic marker within the species of Paulownia.

With increased interest in using high-yield pulps (HYP) in uncoated and coated wood-free paper, Such tests were carried out by means of a Dynamic Sheet Former (DSF) sheet with white water recirculation, considering the high fines content of HYP and the usually high filler content in fine papers. In this study, we evaluated the use of a DSF that is equipped with a white water recirculation tank for making oriented sheets under various conditions. The effects of different factors such as operational variables, use of retention aids, and recirculation of white water were examined and clarified in terms of retention of fines and fillers as well as their impact on paper properties. The effect of HYP content on filler retention was also examined.

Graft copolymerization of acrylamide (Am) onto rubberwood fibre (RWF) was carried out by free radical initiation. Ceric ammonium nitrate was used as an initiator system. The effects of temperature, dose of initiator, ratio of monomer to fibre, and nitric acid concentration, on the grafting percentage were investigated. The optimum reaction temperature was found to be about 50°C for 4h and with an appropriate ratio of monomer to fibre of 3:1 wt/wt. The optimum concentration of initiator and nitric acid were 0.007 M and 0.2 M, respectively. The polyacrylamide (PAm) homopolymer was removed from the graft copolymer by Soxhlet extraction using distilled water. The pre-treatment RWF before the grafting procedure showed that grafting of acid-treated had a higher efficiency than alkali- treated and untreated RWF. Fourier transform infrared spectroscopy was used to confirm and characterize the PAm-graft-RWF.

Crude tall oil (CTO) soap, purified and neutralised CTO, and neutralised distilled tall oil (DTO) were pyrolysed (at 750ºC for 20 s) by pyrolysis gas chromatography with mass-selective and flame ionisation detection (Py-GC/MSD and FID) to clarify their thermochemical behaviour. In each case, the pyrolysates were characteristically dependent on the feedstock, and a wide range of volatile aliphatic and aromatic compounds with some chemically bound oxygen formed. The CTO soap pyrolysate was typically composed of initial extractives-type compounds together with a significant amount of unsaturated aliphatic hydrocarbons and aromatics, whereas the DTO pyrolysate contained mostly just unsaturated aliphatic hydrocarbons and aromatics. These data are of importance when considering the suitability of various extractives-derived resources for producing bioliquids and chemicals.

Mixed US southern hardwood chips were impregnated and cooked under various conditions in the laboratory. Kappa numbers between 15 and 55 were obtained. The reject content, kappa number, and yield were studied as a function of time, temperature, and alkali charge in the cooking. The results indicate that by using modern cooking technology, i.e. CompactCookingTM, an optimal point with respect to the studied pulp parameters can be found. Selected pulps were bleached to high brightness with several different bleaching sequences. These pulps were beaten in a PFI mill and their physical properties were compared at a constant bulk. High kappa, well impregnated fully bleached pulps exhibited improved yield with equivalent or better physical properties as compared to conventional kraft pulps. The high kappa, well impregnated pulps were also found to have improved bleachability as compared to conventionally cooked, bleachable grade kappa number pulps.