Mechanical conversion of wood and wooden fittings
Vahid Sokhandan; Hamidreza Mansouri; Mohammad Dahmardeh Ghaleno; Mohammad Shamsian
Abstract
Background and Objectives: Historical wooden constructions clearly depict the identity, architecture, culture and lifestyle of the people of a period of history and are available to future generations as precious treasures. Therefore, the disconnection of the joints of historical wooden constructions ...
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Background and Objectives: Historical wooden constructions clearly depict the identity, architecture, culture and lifestyle of the people of a period of history and are available to future generations as precious treasures. Therefore, the disconnection of the joints of historical wooden constructions is a big problem to preserve these valuable works in the long term. This research was carried out with the aim of improving and strengthening polyvinyl acetate (PVAc) adhesive using using nanocellulose fibers (NFC) and glass nanofibers (GNF) to improve the joints of the tongue and groove in the traditional beech wood constructions.Materials and methods: In this research, in order to study the effects of reinforcements on the properties of PVAc adhesive, NFC and GNF were investigated at three different levels including 0, 3, and 6% based on the dry weight of the adhesive (9 treatments; each treatment with 3 repetitions). The connection of the palate and the tongue using polyvinyl acetate glue without NFC and GNF were considered as control samples. After preparing the samples, quantitative and qualitative tests including tensile strength, bending strength (modulus of rupture and modulus of elasticity), accelerated aging test, FTIR spectroscopy and evaluation of the samples using electron microscope scanning (SEM) was done.Results: According to the results, there was a significant difference between the studied treatments in terms of tensile strength and modulus of rupture and modulus of elasticity (P<0.05). Among the examined treatments, the highest amount of tensile strength (13.9 MPa), modulus of rupture (130.5 MPa) and modulus of elasticity (11785.36 MPa) were observed in PVAc treatment modified with 3% CNF and 3% GNF. In addition, the results showed a significant difference between the treatments in terms of accelerated aging rate (P<0.05). The lowest rate of accelerated aging (4.0) was observed in PVAc treatment modified with 3% NFC and 3% GNF. FTIR spectroscopy showed that when CNFs are inserted into the PVAc polymer matrix, hydrogen bonds are formed between the hydroxyl groups (OH) of polymer chains and the hydroxyl groups of nanocellulose, which causes the formation of coherent three-dimensional networks. Also, according to the observations from scanning electron microscope (SEM), it was found that CNFs and GNFs were relatively well dispersed in the PVAc polymer matrix.Conclusion: This study showed that by adding 3% NFC and 3% GNF to PVAc adhesive, the mechanical properties of joints in beech wood structures increase. Considering this issue, it is recommended to use a combination of cellulose nanofibers (NFC) and glass nanofibers (GNF) in order to improve the resistance properties of joints in traditional wooden structures.
Composite wood products
Haniye Shurvazi; Mohammad Shamsian; Ali Bayatkashkoli; Mohammad Dahmardeh Ghaleno
Abstract
Background and purpose: This study was conducted with the aim of investigating parallel strand lumber (PSL) made from reed waste and laminated veneer lumber (LVL) obtained from poplar wood that reinforced with glass fiber reinforced polymer (FRP) and epoxy resin.Materials and methods: The independent ...
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Background and purpose: This study was conducted with the aim of investigating parallel strand lumber (PSL) made from reed waste and laminated veneer lumber (LVL) obtained from poplar wood that reinforced with glass fiber reinforced polymer (FRP) and epoxy resin.Materials and methods: The independent variable was LVL and PSL with FRP and their comparison control sample 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 in the form of completely randomized design by SPSS software.Results: Results showed that of all of the studied mechanical properties, the use of FRP strengthened 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 during reinforcement 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 their shear strength by 31%, while this value is only 2.5% for LVL. in the internal bonding test, strengthening 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 with FRP.Conclusion: According to the obtained results, it can be stated that the use of glass fibers and epoxy resin has a significant positive effect on the mechanical resistance of PSL made of reed and LVL and it is possible to use low quality raw materials such as reed and waste poplar wood layers.
Composite wood products
Mohammad Hamed; Babak Nosrati; Ali Shalbafan; Mohammad Dahmardeh Ghaleno; Saeid Reza Farrokhpayam
Abstract
In recent years, the most important challenge for wood-based compact producers has been an increasing demand for a variety of wood materials, raw material prices, and rising transportation costs. On the other hand, the use of lightweight elements in the manufacture of decoration and furniture has received ...
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In recent years, the most important challenge for wood-based compact producers has been an increasing demand for a variety of wood materials, raw material prices, and rising transportation costs. On the other hand, the use of lightweight elements in the manufacture of decoration and furniture has received much attention. The present study aimed at evaluating the effect of different levels of two variables on the size and amount of expanded polyurethane chips in the production of lightweight composite particle boards. To this end, the size of polyurethane particles at three levels (10, 5, and 15 mm) and their amount at four levels (10, 5, 0, and 15%) were chosen as research variables, and the amount of adhesive consumption, press pressure, board thickness, and final density were considered as fixed factors. The results showed that flexural strength, the flexural modulus of elasticity, internal adhesion, and thickness elongation increased significantly with increasing the size of polyurethane particles in the middle layer of the board, but the effect of size was not significant on the water absorption of the samples. Also, increasing the percentage of polyurethane in the middle layer increased the mechanical properties and improved the physical properties compared to the control sample, and it had the largest effect on the internal adhesion of the samples.
