Research Articles

This report discusses the biometry and microscopic features of Crataegus azarolus wood fibers. A Crataegus azarolus tree was selected and cut from the gardens of Neka city (Mazandaran province). At a breast height, 2.5 m and 3.5 m height, three 5 cm thick disks were prepared and in the transverse direction, the test samples were cut and evaluated sequentially 2 x 2 cm long by 3 cm long from the pith to the bark. The anatomical properties of C. azarolus wood were studied using a light microscope. Wood anatomical features of C. azarolus are as follows: diffuse-porous with multiple vessel grouping in the radial direction (in most cases), homogenous rays, simple perforation plates, alternate intervessel pits, and the average length of vessel elements shorter than 350 microns. There was a significant difference in the fiber length, fiber diameter, fiber lumen diameter, and fiber wall thickness, both in the transverse direction and in the longitudinal direction of the Crataegus azarolus tree stem. The biometric properties of the fibers increased from the pith to the bark. The average fiber length, fiber diameter, fiber lumen diameter, and cell wall thickness of the fibers were 0.78 mm, 22.53 µm, 18.6 µm, and 4.5 µm, respectively.

A wood-based sandwich panel with a corrugated core was developed as a building material. A matched-die mold manufactured from commercial plywood was used to fabricate the corrugated panels through a cold-forming process. A cold-setting resin was applied on southern yellow pine (Pinus spp.) veneers with an average thickness of 4 mm, and four plies of them were formed into a corrugated geometry using a wooden mold. When the resin was cured, the corrugated panel of veneers retained the corrugated shape after load removal. Facesheets of the sandwich structures were fabricated using three plies of the same veneers. To evaluate the effect of this corrugated geometry on the structural performance, the same veneers — regarding number, thickness, and orientation — used for the sandwich panel were adopted to fabricate laminated flat panels. Both sandwich and laminated flat panels were submitted to a four-point bending test. The results confirmed the sandwich effect, i.e. a 1741% increase in the bending stiffness of sandwich panels compared to that of laminated flat panels. Sandwich panels developed in this study were compared to Structural Insulated Panels (SIPs), wood-framed structures known as stud walls, and sandwich panels produced using a hot-pressing technique. The cold-formed sandwich panels had higher structural performance than commercial building materials.

Effects of protective measures were evaluated relative to the compression strength in the direction parallel to the grain of laminated veneer wood (LVL). For this purpose, laminated panels were prepared from Scots pine, Oriental beech, Castanea sativa, and sessile oak wood veneer by gluing them with Desmodur vinyl trie ketonol acetate (D-VTKA), polyvinyl-acetate (PVAc) dispersion D4 adhesive, resorcinol formaldehyde (RF), and melamine formaldehyde (MF). The samples were impregnated with a mixture of wax, linseed oil, and coated with a synthetic-based translucent varnish. The control samples (without the treatment described above), impregnated samples, and varnished samples were kept in the external environment for 1 y and in an ultraviolet (UV) environment for 240 h. The samples were tested to determine the air-dried density, retention amount, and compression strength. The results indicated that, in terms of outdoor conditions, the varnished proceeding provided better protection compared to the impregnated proceeding. The best result for compression strength was obtained on the Oriental beech samples with RF and MF glues. The ratio of the UV environment to represent the external environment was 89%.

Cellulose acetate is an important product derived from cellulose. Cellulose acetate can be used in a variety of applications including coatings, textile fibers, consumer goods, filtration membranes, composites, laminates, pharmaceutical, and medical items. Rice husk is a lignocellulosic material that contains cellulose and hemicellulose. The aims of this study were to determine the effect of process variables on the cellulose acetate product formation by ultrasound-assisted acetylation using iodine as a catalyst and to characterize the cellulose acetate product. The research was conducted through the delignification, bleaching, acetylation, and characterization processes. The results showed that the optimum yield of cellulose acetate was obtained at the temperature of 60 °C, the reaction time of 50 min, the weight of the catalyst of 10% of cellulose weight, and the ratio of cellulose and acetic anhydride of 1:5 (w/v). The acetylation process using iodine as a catalyst with an ultrasound-assisted method was more effective than the conventional acetylation (acetic acid glacial and sulfuric acid as a catalyst).

Among various industries, the construction sector has one of the greatest impacts on the environment. Minimizing the resource use and the waste outputs in this sector could be fulfilled by applying circular economy (CE) strategies. Although research on CE in the construction sector has increased in recent years, there have not been remarkable adjustments by applying these strategies to the construction industry. The purpose of this study was to examine the impacts of using CE strategies in the construction sector. A framework was adapted to guide the application of different CE strategies at the end-of-life of buildings. The framework was assessed by a case study of a residential building in mass timber. This study evaluated the application of CE strategies from the environmental aspect with the life cycle assessment (LCA) method. The results confirmed that circular strategies can deliver lower environmental impacts.

In ancient wooden structures of the Qing dynasty in China, stacked purlins are important longitudinal elements. In this study, a refined finite element model of a four-column timber frame containing stacked purlins was built. The effects of the fangs, spacer boards, and purlins with dovetail ends on the lateral resistance of the timber frame and the mid-span vertical deflection of the purlins were studied. The longitudinal hysteresis curve of the timber frame made up of stacked purlins was found to be S-shaped, centrally symmetrical, with a pinching effect and full at both ends. The Fangs made the greatest improvement on the lateral stiffness, displacement ductility, and total hysteresis energy consumption of the timber frame by reducing the mid-span vertical deflection of the purlins. The spacer boards contributed less to the lateral resistance of the timber frame than Fangs, but they contributed most to the reduction of the mid-span vertical deflection of the purlins. The dovetail connection at the ends of the purlins had a limited effect on reducing the lateral stiffness and ductility of the timber frame and increasing the mid-span vertical deflection of the purlins, but they significantly increased the total energy consumption of the timber frame and its energy consumption capacity.

Carbon fiber fabric reinforced laminated veneer lumber (RLVL) pieces were prepared by using heat-treated beech (Fagus orientalis Lipsky) veneers with polyurethane (PU) adhesive as the binder. Carbon fiber fabric was tested in three different locations with solid material and non-reinforced samples (on the bottom adhesive line, upper adhesive line, and upper and bottom adhesive lines-symmetrical). Prior to the manufacture of LVL and RLVL, heat treatment was conducted in a laboratory oven at three temperatures. These temperatures were 150, 170, and 190 °C. Tests were performed on LVL and RLVL to determine their air-dried density, modulus of rupture (MOR), and modulus of elasticity in bending (MOE). Experimental test results showed that reinforcement with carbon fiber increased the air-dried density, MOR, and MOE. In addition, carbon fiber fabric placed symmetrically close to bottom and upper surfaces gave the highest MOR and MOE values. However, locating the carbon fiber fabric closer to the bottom surface tended to give higher mechanical properties for the reinforced LVL.

Pretreatment processes are essential for the preparation of biofuels from lignocellulosic feedstocks. Based on alkaline H₂O₂ pretreatment, photocatalytic alkaline H₂O₂ pretreatment (U-AHP) was investigated to examine the effects of reaction time, alkali concentration, and H₂O₂ concentration on the enzymatic digestion of corn stover. The optimum process conditions were determined by orthogonal tests: 1% NaOH, 2% H₂O₂, and reaction time of 8 h. Under these conditions, the lignin removal efficiency of U-AHP was 90.2% and the saccharification yield was 94.7%. Furthermore, FT-IR, XRD, and SEM analyses showed that U-AHP pretreatment caused structural damage to the maize straw and increased the crystallinity of the cellulose, and it was speculated that the U-AHP pretreatment reaction was a complex mechanism, which might be a multiple synergistic reaction. This study shows that U-AHP pretreatment is a simple, green and effective method to promote lignin removal.

The aim of this study was to analyze the growth rings and evaluate the effect of the urban environment on the growth of Terminalia catappa L. under intense industrial activity. At least two wood samples were obtained from each tree with an increment borer. The regions of Volta Redonda (Northwest and Southeast regions) and Resende (used as control) were established for the collection. The dendrochronological potential of T. catappa indicated sensitivity to precipitation and temperature in a more exposed urban and industrial steel pollution area because there were differences in growth when compared to an area less exposed to the same pollution. Thus, it was possible to conclude that this species has the potential to be used as a bioindicator of anthropogenic activities. In addition, the delimitation of the growth rings of the studied species contributes to the realization of future dendrochronological studies, expanding the understanding of the behavior of this species present in urban environments at different regional scales. This study reinforces the importance of rainfall and temperature in regulating radial growth in tropical forests.

To increase the loading amount of modifier in wood, a simple and universal approach was developed to improve its permeability. The generated pores in wood can be backfilled with modifiers, thereby improving the function of wood. This study aimed to improve the permeability of Eucalyptus urophylla wood using a urea solution. The wood was treated under different conditions, including urea concentration, treatment duration, and temperature, and the wood permeability before and after treatment was measured using water absorption as an indicator. The treatment temperature and solution concentration had considerable effects on the water absorption capacity of the treated wood. The treatment of eucalyptus wood with a 5% urea solution for 12 h, under normal pressure, resulted in the optimal effect; water absorption reached 40%, which was 78.9% higher than that of the untreated eucalyptus. Fourier-transform infrared spectroscopy, component analysis, and BET analysis were performed to examine the mechanism underlying the effect of urea treatment on eucalyptus, which is as follows: a weak alkaline solution can dissolve the internal components of wood, namely, hemicellulose, lignin, and alcohol-benzene, which leads to the destruction of the microstructure of the wood and increases the number of micropores and mesopores in the wood.