Amir Zamani; Ahmad Jahan Latibari; Aghang Tajdini; Abolfazl Kargarfard
Abstract
In this investigation, the surface chemical properties of the beech wood layers were characterized and the impact of drying condition on the strength of the bond was examined. Defect free beech logs were harvested and then the layers were prepared. The moisture content of the specimens were adjusted ...
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In this investigation, the surface chemical properties of the beech wood layers were characterized and the impact of drying condition on the strength of the bond was examined. Defect free beech logs were harvested and then the layers were prepared. The moisture content of the specimens were adjusted at 30, 40 and 50% (dry basis) and then the specimens were air dried under the environment of 30% relative humidity and 21ºC to reach the equilibrium moisture content of about 10% (dry basis). The pH and buffering capacity of the surface layer and the layer 0.5 mm underneath the surface were measured. The dried specimens were bonded using urea-formaldehyde resin and the tensile strength and wood failure were measured using relevant ASTM method. The results showed that as the moisture content prior to air drying was increased, the tensile strength was reduced, but the effect of this variable on tensile strength was not statistically significant. However, the effect of moisture content on wood failure was statistically significant at 99% significance level. The effect of the pH of the under layer on both tensile strength and wood failure was statistically significant at 95%. As the moisture content of the wood increased, the pH of the surface layer increased and the strength of the bond with urea-formaldehyde resin was deteriorated. At higher initial moisture of the wood, the alkaline buffering capacity of the surface layer was lower and its effect of the strength was not statistically significant, but it was significant on wood failure at 99% level. The alkaline buffering capacity of under layer was also changed and statistically affected the bond strength and wood failure at 95% level. The higher alkaline buffering capacity of the under layer adversely affected the tensile strength of the bond. The lowest acid buffering capacity was measured from specimens with 40% initial moisture content and as the acid buffering capacity was increased, the tensile strength was reduced and the wood failure was higher. The impact of surface layer acid buffering capacity on tensile strength was on statistically significant, but on wood failure was statistically significant at 99% level.
Sina Modirrahmati; Ahmad Jahan-Latibari; Mansor Minaei
Abstract
The influence of nanoclay addition on the strength properties of HDPE/ Wheat straw powder Composite was investigated. Composites compounds were produced using 73%HDPE, 25% wheat straw powder and 2% MAPE and three amounts of nanoclay (1, 2, and 3% of composite compound). First, HDPE and nanoclay was melt- ...
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The influence of nanoclay addition on the strength properties of HDPE/ Wheat straw powder Composite was investigated. Composites compounds were produced using 73%HDPE, 25% wheat straw powder and 2% MAPE and three amounts of nanoclay (1, 2, and 3% of composite compound). First, HDPE and nanoclay was melt- mixed and after cooling, the extrudate was milled to fine granules. This granules were then melt compounded with pre-weighted amount of wheat straw powder and MAPE followed by injection moulding to produce test specimens. The flexural, tensile and impact strength were measured. The results showed that the addition of nanoclay to the composite improved flexural strength and modulus, tensile strength and modulus. However the notched Izod strength was reduced.
amir lashgari; Payam Khodayari; Seid Ali Mohammadi
Abstract
In this research the effect of nail′s length on three different values (32,42,48 mm)the nail number (2 and 3)and the kind of of particleboard and MDF on tensile strength and bending moment has been analyzed ,The member dimension of of 10*15*1.6 cm.have been elected for making of L –type ...
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In this research the effect of nail′s length on three different values (32,42,48 mm)the nail number (2 and 3)and the kind of of particleboard and MDF on tensile strength and bending moment has been analyzed ,The member dimension of of 10*15*1.6 cm.have been elected for making of L –type joint. The junction have not used out of any adhesive as an adjuvant. From combination of this variable factors and examination of any strength some 24 samples have created,that due to the 4 iterations,96 specimens of L shaped joints have been coustructed totally.the bending and tensile strength of produced junction has been measured by mechanical test machine.based on captured results the interaction of constituents of,nail penetration length,nails number and members nature on joint strenght weren′t significant in front of tensile and bending.this research indicated that the junctions with the penetration length of 48 mm,the most amount of nail(three nails)on MDF member elements,have the greatest strength against bending strength,and the link with penetration length of 42mm alone with the most amount of nail(3 nails)on MDF have the greatest strength against tensile,as copared with each other.
Sina Modirahmati; Ahmad Jahan Latibari; Amir Nourbakhsh; Mehran Roohnia; Mansor Minaei
Abstract
The impact of nanoclay addition on the properties of polypropylene/ OCC fibers/ nanoclay Composite was investigated. Composites were prepared using 67% polypropylene, 30% OCC fiber, 3% MAPP and three dosages (2.5, 5, 7.5% based on total weight of PP/OCC/MAPP) of nanoclay. Premix- ...
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The impact of nanoclay addition on the properties of polypropylene/ OCC fibers/ nanoclay Composite was investigated. Composites were prepared using 67% polypropylene, 30% OCC fiber, 3% MAPP and three dosages (2.5, 5, 7.5% based on total weight of PP/OCC/MAPP) of nanoclay. Premix- melting of nanoclay and polypropylene was used to add nanoclay to the composite mixture. Pre-mixed nanoclay/ polypropylene was melt-mixed with OCC fibers and MAPP and then test samples were made using this compound. The results revealed that addition of nanoclay to polypropylene/OCC fiber composite reduced flexural strength , tensile strength and notched Izod impact strength, but the flexural modulus and tensile modulus of final composite were improved significantly. The influence of nanoclay addition on flexural strength and tensile modulus of composite was statistically significant at 99% level whereas its effect on tensile strength was statistically significant at 95%. However, the effect of nanoclay on both flexural modulus of elasticity and impact strength was not statistically significant. The addition of nanoclay to the composite reduces the bonding between polypropylene and OCC fibers. In the case of notched Izod strength, nanoclay particles generated stress concentration point within the composite structure initiating easier failure. Water absorption after 2 and 24 hours immersion was reduced.
Mechanical conversion of wood and wooden fittings
amir lashgari
Abstract
In this study, distribution pattern and tension concentration as well as failure prediction in dowel joint were analyzed. The effect of dowel diameter (6, 8, 10 mm) and wood type (Beech, Alder and white spruce) on tension resistance and bending moment were examined. The dimensions for making T-form joints ...
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In this study, distribution pattern and tension concentration as well as failure prediction in dowel joint were analyzed. The effect of dowel diameter (6, 8, 10 mm) and wood type (Beech, Alder and white spruce) on tension resistance and bending moment were examined. The dimensions for making T-form joints were 5×5×2/5 cm. Wooden dowel used in this research was carpinus betulus which accounts as the common dowel in market. Also, PVA was used in Joints. A total of 36Tshape samples comprising 9 combinations of the above factors in 4 replications were made. Tension resistance and bending moment were measured by mechanical test machine. For exertion strength due to analyzing the resistance loading speed equal to 1.25 mm/min were applied. Also, to analyze distribution pattern and tension concentration in affected joints, finite element method and ANSYS Software were used. According to the results of the simulation modeling, joint which endured the maximum tension complied with the real joints. Distribution of tension in the middle of the bending moment depth was greatest and tension in dowel joints was concentrated in impaired points.
