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Background and purpose: This study was conducted with the aim of investigating parallel strand lumber (PSL) made from reed residue and laminated veneer lumber (LVL) obtained from poplar wood reinforced with glass fiber reinforced polymer (FRP) using epoxy resin. Materials and methods: The independent variable was FRP reinforcement for either LVL or PSL and control sample either LVL or LSL without FRP. The mechanical properties of the manufactured boards including bending strength (MOR) and modulus of elasticity (MOE) in the width and edge of the test sample, shear strength, compression strength parallel to the grain, internal bonding and screw withdrawal strengths were investigated as dependent variables. The obtained results were analyzed using completely randomized design and SPSS software. Results: Results showed that for all studied mechanical properties, the use of FRP increased the strength the PSL and LVL panels. For LVL, the effect of strengthening the samples with FRP was significant at the level of 1% and also for the modulus of rupture of the width and edge samples showed an increase of 93% and 59%, respectively. The value of MOE for samples reinforced with FRP showed an increase of 89.6 and 132% for the width and length of the PSL samples, respectively. For LVL, the MOE value of the width and edge of the samples increased by 54 and 95.5% with reinforcement. Reinforced PSL samples have improved shear strength by 31%, while this value was only 2.5% for LVL. In case of internal bonding, reinforcement with FRP improved the internal bonding strength of the samples by 92%. Screw withdrawal strengths improved by 27% due to the strengthening of the test samples by FRP. Conclusion: According to the results, it can be stated that the use of glass fibers and epoxy resin has a significant positive effect on the mechanical strength of PSL made of reed and LVL and it is possible to use low quality raw materials such as reed and low quality poplar wood layers. [ABSTRACT FROM AUTHOR]

This work evaluates the effect of plasma treatment on the wettability, dynamic mechanical and thermal properties of compression-molded composite panels produced from wood fiber (WF) and polypropylene (PP). Initially, WF was treated with different plasma durations (60, 120, and 180 s radiation). Afterward, the contact angle, moisture uptake, storage modulus, loss modulus, damping loss, and weight loss of the specimens prepared from untreated and plasma-treated were evaluated. Results revealed that the plasma treatment facilitates the interactions between WF and PP, and increases the adhesion properties. Compared with the lowest contact angle of 74.8° for the untreated specimens, the highest contact angle was found in the treated specimens around 79.06°, 81.29°, and 82.7°, using 60 and 15 using 180 s plasma radiations. Furthermore, the water absorption of the specimens reduced as a result of plasma treatment. The plasma-treated specimens demonstrated better molecular restriction and larger dynamic modulus than the unmodified ones. The tan δ peak signifying the glass transition temperature of composites shifted to a higher temperature, in the presence of plasma treatment. It was noted that the thermal stability of the composite panels produced from plasma-treated wood was remarkably improved. [ABSTRACT FROM AUTHOR]

This research was conducted to examine the effect of SiO2 and TiO2 nanoparticles on the mechanical and morphological properties of wood flour-polypropylene nanocomposites. For this purpose, 60 (wt.%) wood flour was mixed with polypropylene. 4% maleic anhydride polypropylene was also used in all the compounds as a coupling agent. In addition, SiO2 and TiO2 nanoparticles were used as mineral fillers at 0, 1, 3 and 5%. The mixing process was performed inside an extruder and the test specimens were prepared by injection molding method. Bending and tensile tests were then performed on the specimens according to the ASTM standard. Scanning electron microscopy (SEM) was also used to show the distribution of nanoparticles over the composite substrate. The results showed that the composites containing nano-SiO2 had more favorable mechanical properties compared to those containing nano-TiO2. On the other hand, increasing the nanoparticles from 0 to 3% led to an increase in mechanical strength, however, the addition of more nano-fillers resulted in a significant decrease in mechanical strength. The results of SEM also showed a proper dispersion of nanoparticles at 1 and 3% levels, but using 5% nanoparticles caused the particles to aggregate on the composite substrate. [ABSTRACT FROM AUTHOR]

Small-diameter poplars (Populus euramericana, or Populus deltoids, or Populus nigra) are an important raw material resource for the wood and paper industry. Both manufacturers and governments are increasingly interested in obtaining this raw material from poplar plantations. A small-diameter poplar is between fifteen and thirty five centimetres in diameter at breast height. In this study small-diameter poplars were graded visually for use in peeling. Traditional rules currently in use were applied when grading small-diameter poplars, and standard layer-sorting rules were used on the outputs from the peeling process. The field study has shown that standard sorting by layer doesn't correspond well when small-diameter poplars are sorted. For instance, the best small-diameter poplar is rarely classified as class A or B by standard layer sorting. In this research, small-diameter poplars are classified accurately using specific, alternative rules, and the grading scale ranges are presented. Some defects, such as knot and splits, have a strong influence on the quality of the final product, but often, existing standard-sorting methods do not reflect the degree to which the defects have affected the final product. A new method for classifying small-diameter poplars is presented, which groups the wood by its value in the final product. [ABSTRACT FROM AUTHOR]

Concrete-wooden composite beams are structural systems in which an upper concrete flange is connected to a lower timber web. In this study, the concrete-wooden composite beams are produced by using tangential boards of Pinus sp. (dimensions of 100 cm × 5 cm × 2.5 cm). The concrete is reinforced by nail and wire. Concrete-wooden composite beams are made from two types of design. The two arrangement types include one side of the timber and opposite side concrete and, also, it includes the two side timbers and concrete center. Nails (No. 4 and 5) with 3 cm and 5 cm spacing were used for preparing wooden-concrete composite. The nails were hammered about 1.5 cm deep into the boards. After the wooden-concrete composite beams were constructed, their mechanical properties (three-point bending) were measured. The results showed that composite beams with nailing spaces of 3 cm, the concrete height of 5 cm, and the arrangement of two side timbers have been the best mechanical properties. Whereas composite beams with one-sided timber, nailing spaces of 5 cm, and the concrete height of 10 cm have shown the least mechanical strength. The beams of concrete-wooden composite have shown a nonlinear break behavior. [ABSTRACT FROM AUTHOR]

Wood-based panels are used at inside and outside of various building, and termites feed mostly from these lignocelluloses materials. The aim of present study identifies biological resistance of four wooden products that include medium density fiberboard, 3-plywood and particleboard against Microcerotermes diversus termite via field method. Degradation grading the termite attack was performed in accordance with the ASTM D 1758-06 specifications. This research was conducted in Sistan region and Jiroft for 15 months. On the base of this result, all testing samples have been degraded. Both weight loss and grading values indicated that the 3-plywood and medium density fiberboard had the lowest and highest degradation, respectively. The weight loss and grading values of wood based panel specimens against the Microcerotermes diversus attack is the same. Field observations showed that the degradation of composite specimens located at Sistan are similar to Jiroft, except of particleboard specimen degradation. [ABSTRACT FROM AUTHOR]