The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid...The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.展开更多
Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density...Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.展开更多
This research work developed and evaluated the mechanical properties of coconut fibre reinforced low density polyethylene (LPDE) composite material. The effect of fibre loading on the mechanical properties: tensile, f...This research work developed and evaluated the mechanical properties of coconut fibre reinforced low density polyethylene (LPDE) composite material. The effect of fibre loading on the mechanical properties: tensile, flexural, and impact of the developed composite material have been investigated. Also carried out was the effect of fibre loading on the water absorptivity of the developed material. Sample categories of the developed composite were prepared by varying the fibre contents by weight at 0%, 10%, 20%, and 30%. The aim is to reduce the excessive waste disposal of LDPE materials that are largely found in the form of disposed water package materials (or pure water sachets) that usually affects the environment in the form of pollution. The water retting process was applied in extracting and cleaning fibre (or coir), while the mixed coir-LDPE (or developed composite material) was prepared by Compression Moulding Technique (CMT). The tensile and flexural properties were tested using Hounsfield Monsanto Tensometer (type w) while the impact properties were tested using the Charpy Impact testing machine. The microstructure of the composite was investigated using Scanning Electron Microscopy (SEM). The fractured surface morphology of the composite samples indicated a homogeneous mixture of the coir fibre and LDPE matrix. However, weak interfacial bonding between the coir fibre and LDPE matrix was also observed. The analysis of the water absorptivity showed that the developed composite materials have low water absorptivity at low fibre loading. However, at higher fibre loading, the water absorptivity increases significantly.展开更多
The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites (plastic and carbon mat...The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites (plastic and carbon matrix) have been investigated. The microstructure of unloaded and cracked samples was studied by optical microscopy and scanning electron microscopy (SEM), respectively whereas the mechanical behaviour was examined by 3- point bending experiments. Exclusively one type of experimental resole type phenolic resin was applied. A strong fibre/matrix bonding, which is needed for high strength of carbon fibre reinforced plastic (CFRP) materials leads to severe composite damages during the pyrolysis resulting in low strength, brittle failure and a very low utilisation of the fibres strain to failure in C/C composites. Inherent fabric parameters such as an increasing fabric density or bundle size or a reduced fibre volume fraction introduce inhomogenities to the CFRP's microstructure. Results are lower strength and stiffness whereas the strain to failure increases or remains unchanged. Toughness is almost not affected. In C/C composites inhomogenities due to a reduced bundle size reduce strain to failure, strength, stiffness and toughness. Vice versa a declining fibre volume fraction leads to exactly the opposite behaviour. Increasing the fabric density (weight per unit area) causes similar effects as in CFRPs.展开更多
The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities...The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter- mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in- crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m^3 is 2.8 times higher than that at 1.4 Mg/m^3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interracial mechanical interaction between fibre surface and soil matrix.展开更多
In this research the effect of Coconut (CN) fibre on the fresh and thermo gravimetric properties of self-compacting concrete (SCC) at elevated temperatures was investigated experimentally and statistically. The mixtur...In this research the effect of Coconut (CN) fibre on the fresh and thermo gravimetric properties of self-compacting concrete (SCC) at elevated temperatures was investigated experimentally and statistically. The mixtures containing cement, water, fly ash, fine aggregate, coarse aggregate and super plasticizer with the addition of CN fibres (0%, 0.05%, 0.10 %, and 0.15%) by volume of the mixtures were prepared. The fresh and thermo gravimetric properties of the SCC specimens were determined after mixing at elevated temperatures (200℃, 400℃, and 600℃) testing in a laboratory. Three control specimens with 0% CN fibres were used for every mixture of SCC. Regression models were developed to determine the responses. The optimum of the CN fibres was measured.展开更多
This study investigates the mechanical,thermal and morphological properties of rHDPE(Recycled High Density Polyethylene)and a mixture of rPE HD/LD(High and Low Density Polyethylene),both reinforced with rNP(Reclaimed ...This study investigates the mechanical,thermal and morphological properties of rHDPE(Recycled High Density Polyethylene)and a mixture of rPE HD/LD(High and Low Density Polyethylene),both reinforced with rNP(Reclaimed Newsprint Paper)fibres.To enhance the composite properties,the addition of highly grafted maleic anhydride polyethylene wax,as CA(Coupling Agent),and semi crystalline copolymer of propylene and ethylene,as IM(Impact Modifier),was included into the material formulation by a twin-screw extruder.Mechanical and morphological properties were studied on tensile test specimens,prepared by injection moulding,by tensile testing machine and SEM(Scanning Electron Microscope),respectively.Thermal properties,i.e.melting and crystallization behaviour,were investigated by DSC(Differential Scanning Calorimetry).Mechanical analysis showed that the addition of rNP in both composites increased the young modulus and significantly decreased the elongation at break.The DSC results revealed that the addition of the rNP in the rHDPE matrix led to a substantial decrease of crystallinity,which consequently affects the tensile strength of the composite(17 MPa)in contrast to the neat rHDPE(25 MPa).On the contrary,fibre addition in rPE HD/LD matrix had no specific impact on the crystallinity index,but did contribute to the increased tensile strength(26 MPa)when compared with neat rPE HD/LD(16 MPa).SEM photomicrographs of the impact fracture surfaces demonstrated a solid adhesion bond between the natural fibres and the rPE HD/LD matrix.Reclaimed newsprint fibres can thus be considered as a perspective alternative to the inorganic fillers in the rPE HD/LD composite.展开更多
Collapse-type shrinkage is one of highly refractory drying defects in low-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD), microfibril angle (MFA), double fibre cell wall ...Collapse-type shrinkage is one of highly refractory drying defects in low-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD), microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP), unit cell wall shrinkage, total shrinkage and residual collapse, which are associated with collapse-type shrinkage characteristics, were investigated by using simple regression method for three species of collapse-susceptible Eucalyptus urophyll, E. grandis and E.urophyllaxE.grandis, planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that : unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strong positive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA; total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but not able to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712); residual collapse was negatively correlated with BD and DWT, linearly positively correlated with MFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used as single factor (R^2≥0.9412) to predicate unit cell wall shrinkage and RP is the relatively sound indicator for predicting residual展开更多
We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis × E. urophylla), GR283 and GR330, grown in Tumkur district of Kamataka (India), and felled 5-6 years old three trees of each clone. We r...We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis × E. urophylla), GR283 and GR330, grown in Tumkur district of Kamataka (India), and felled 5-6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 (37 %). Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.展开更多
Wood anatomical structures of various tree species help identify the wood. The characteristics and composition of these structures affect their utilisation. In this work, the microstructure of Blighia sapida a lesser-...Wood anatomical structures of various tree species help identify the wood. The characteristics and composition of these structures affect their utilisation. In this work, the microstructure of Blighia sapida a lesser-known Ghanaian hardwood species using light microscope and scanning electron microscope (SEM) was studied. The relationship between the microstructure and some physical properties such as density, and bending strength were also studied. The anatomical features studied were fibre length, double fibre wall thickness, fibre proportion, vessel diameter and proportion, rays and axial parenchyma proportions. It was observed that the use of SEM in studying the anatomical or ultra-structural aspects of wood gives a clearer understanding of the features and structures found in wood. Anatomical features such as presence of crystals and absence of axial parenchyma in Blighia sapida are reported in the work. The study also established that Blighia sapida had a low water uptake even though it had vessel distribution of 12 vessels/mm<sup>2</sup>. Having not very distinct axial parenchyma may have accounted for the low water uptake. The presence of occluded pits could also account for the low water uptake and the fibre wall thickness may also account for a medium bending strength of 62.8 N/mm<sup>2</sup> at 12% moisture content.展开更多
基金funded by e-Science 02-01-02-SF0403 from the Ministry of Science,Technology and Innovation,Malaysia
文摘The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.
文摘Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.
文摘This research work developed and evaluated the mechanical properties of coconut fibre reinforced low density polyethylene (LPDE) composite material. The effect of fibre loading on the mechanical properties: tensile, flexural, and impact of the developed composite material have been investigated. Also carried out was the effect of fibre loading on the water absorptivity of the developed material. Sample categories of the developed composite were prepared by varying the fibre contents by weight at 0%, 10%, 20%, and 30%. The aim is to reduce the excessive waste disposal of LDPE materials that are largely found in the form of disposed water package materials (or pure water sachets) that usually affects the environment in the form of pollution. The water retting process was applied in extracting and cleaning fibre (or coir), while the mixed coir-LDPE (or developed composite material) was prepared by Compression Moulding Technique (CMT). The tensile and flexural properties were tested using Hounsfield Monsanto Tensometer (type w) while the impact properties were tested using the Charpy Impact testing machine. The microstructure of the composite was investigated using Scanning Electron Microscopy (SEM). The fractured surface morphology of the composite samples indicated a homogeneous mixture of the coir fibre and LDPE matrix. However, weak interfacial bonding between the coir fibre and LDPE matrix was also observed. The analysis of the water absorptivity showed that the developed composite materials have low water absorptivity at low fibre loading. However, at higher fibre loading, the water absorptivity increases significantly.
文摘The effects of fibre/matrix bonding, fabric density, fibre volume fraction and bundle size on microstructure, mechanical properties and failure mechanisms in carbon fibre reinforced composites (plastic and carbon matrix) have been investigated. The microstructure of unloaded and cracked samples was studied by optical microscopy and scanning electron microscopy (SEM), respectively whereas the mechanical behaviour was examined by 3- point bending experiments. Exclusively one type of experimental resole type phenolic resin was applied. A strong fibre/matrix bonding, which is needed for high strength of carbon fibre reinforced plastic (CFRP) materials leads to severe composite damages during the pyrolysis resulting in low strength, brittle failure and a very low utilisation of the fibres strain to failure in C/C composites. Inherent fabric parameters such as an increasing fabric density or bundle size or a reduced fibre volume fraction introduce inhomogenities to the CFRP's microstructure. Results are lower strength and stiffness whereas the strain to failure increases or remains unchanged. Toughness is almost not affected. In C/C composites inhomogenities due to a reduced bundle size reduce strain to failure, strength, stiffness and toughness. Vice versa a declining fibre volume fraction leads to exactly the opposite behaviour. Increasing the fabric density (weight per unit area) causes similar effects as in CFRPs.
基金supported by the National Natural Science Foundation of China(Grant Nos.41072211,41322019)Natural Science Foundation of Jiangsu Province(Grant No.BK2011339)Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(SKLGP2013K010)
文摘The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter- mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in- crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m^3 is 2.8 times higher than that at 1.4 Mg/m^3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interracial mechanical interaction between fibre surface and soil matrix.
文摘In this research the effect of Coconut (CN) fibre on the fresh and thermo gravimetric properties of self-compacting concrete (SCC) at elevated temperatures was investigated experimentally and statistically. The mixtures containing cement, water, fly ash, fine aggregate, coarse aggregate and super plasticizer with the addition of CN fibres (0%, 0.05%, 0.10 %, and 0.15%) by volume of the mixtures were prepared. The fresh and thermo gravimetric properties of the SCC specimens were determined after mixing at elevated temperatures (200℃, 400℃, and 600℃) testing in a laboratory. Three control specimens with 0% CN fibres were used for every mixture of SCC. Regression models were developed to determine the responses. The optimum of the CN fibres was measured.
文摘This study investigates the mechanical,thermal and morphological properties of rHDPE(Recycled High Density Polyethylene)and a mixture of rPE HD/LD(High and Low Density Polyethylene),both reinforced with rNP(Reclaimed Newsprint Paper)fibres.To enhance the composite properties,the addition of highly grafted maleic anhydride polyethylene wax,as CA(Coupling Agent),and semi crystalline copolymer of propylene and ethylene,as IM(Impact Modifier),was included into the material formulation by a twin-screw extruder.Mechanical and morphological properties were studied on tensile test specimens,prepared by injection moulding,by tensile testing machine and SEM(Scanning Electron Microscope),respectively.Thermal properties,i.e.melting and crystallization behaviour,were investigated by DSC(Differential Scanning Calorimetry).Mechanical analysis showed that the addition of rNP in both composites increased the young modulus and significantly decreased the elongation at break.The DSC results revealed that the addition of the rNP in the rHDPE matrix led to a substantial decrease of crystallinity,which consequently affects the tensile strength of the composite(17 MPa)in contrast to the neat rHDPE(25 MPa).On the contrary,fibre addition in rPE HD/LD matrix had no specific impact on the crystallinity index,but did contribute to the increased tensile strength(26 MPa)when compared with neat rPE HD/LD(16 MPa).SEM photomicrographs of the impact fracture surfaces demonstrated a solid adhesion bond between the natural fibres and the rPE HD/LD matrix.Reclaimed newsprint fibres can thus be considered as a perspective alternative to the inorganic fillers in the rPE HD/LD composite.
基金This work was supported by both the project ( No. 30170754)from Chinese National Natural Science Fund and the national significant fundamental research 'Ascending Plan' program (No.95- 07) authorized by Ministry of Science and Technology, China. And was partly presented at the 54th Annual Meeting of the Japan Wood Research Society in Hokkaido, Japan and at the 7th Pacific Rim Bio-based Composites Symposium in Nanjing, P. R. China.
文摘Collapse-type shrinkage is one of highly refractory drying defects in low-medium density plantation-grown eucalypt wood used as solid wood products. Basic density (BD), microfibril angle (MFA), double fibre cell wall thickness (DWT), proportion of ray parenchyma (RP), unit cell wall shrinkage, total shrinkage and residual collapse, which are associated with collapse-type shrinkage characteristics, were investigated by using simple regression method for three species of collapse-susceptible Eucalyptus urophyll, E. grandis and E.urophyllaxE.grandis, planted at Dong-Men Forest Farm in Guangxi autonomous region, China. The results indicated that : unit cell wall shrinkage had a extremely strong positive correlation with BD, moderately strong positive correlation with DWT, and a weakly or moderately negative correlation with RP and MFA; total shrinkage was positively correlated with BD, DWT and RP and negatively related to MFA, but not able to be predicted ideally by any examined factors alone owing to lower R^2 value (R^2≤0.5712); residual collapse was negatively correlated with BD and DWT, linearly positively correlated with MFA, and had strongly positive linear correlation with RP. It is concluded that BD can be used as single factor (R^2≥0.9412) to predicate unit cell wall shrinkage and RP is the relatively sound indicator for predicting residual
文摘We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis × E. urophylla), GR283 and GR330, grown in Tumkur district of Kamataka (India), and felled 5-6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 (37 %). Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.
文摘Wood anatomical structures of various tree species help identify the wood. The characteristics and composition of these structures affect their utilisation. In this work, the microstructure of Blighia sapida a lesser-known Ghanaian hardwood species using light microscope and scanning electron microscope (SEM) was studied. The relationship between the microstructure and some physical properties such as density, and bending strength were also studied. The anatomical features studied were fibre length, double fibre wall thickness, fibre proportion, vessel diameter and proportion, rays and axial parenchyma proportions. It was observed that the use of SEM in studying the anatomical or ultra-structural aspects of wood gives a clearer understanding of the features and structures found in wood. Anatomical features such as presence of crystals and absence of axial parenchyma in Blighia sapida are reported in the work. The study also established that Blighia sapida had a low water uptake even though it had vessel distribution of 12 vessels/mm<sup>2</sup>. Having not very distinct axial parenchyma may have accounted for the low water uptake. The presence of occluded pits could also account for the low water uptake and the fibre wall thickness may also account for a medium bending strength of 62.8 N/mm<sup>2</sup> at 12% moisture content.