Impregnation method can effectively improve physical and mechanical properties of wood.In this study,plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentr...Impregnation method can effectively improve physical and mechanical properties of wood.In this study,plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30%under vacuum-pressure process,and then dried and machined according to the related standards.The results show that the physical and mechanical properties of poplar can be improved by the treatment,except for toughness.The average density of poplar increases from 0.397 to 0.710 g/cm3,the modulus of elasticity in static bending,the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%,112.97%and 87.69%,respectively,compared to the untreated.And the hardness values on radial and tangential sections,and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%,82.78%,71.43%and 22.06%,respectively;while toughness decreases by 48.80%.展开更多
Plantation poplar is one of the most important resources for wood industry,its utilization field is vast.The wettability of Populus tomentosa with different drying methods was judged by measurement of contact angle us...Plantation poplar is one of the most important resources for wood industry,its utilization field is vast.The wettability of Populus tomentosa with different drying methods was judged by measurement of contact angle using distilled water in this paper.The results showed that the specimens from conventional drying have the biggest contact angle,and the air dried have the smallest contact angle,air dried lumbers have a better wettability than the kiln dried.The changes of contact angle in a period of time showed wettability sequence of lumber with different drying methods:air drying>high temperature drying>conventional drying.The basic property for high value-added plantation poplar lumber products was provided to the wood industry.展开更多
This paper studies the characteristics of larch bark pyrolysis and analyzes factors that affect the pyrolysis and the liquid pyrolytic component. The results are as follows: TG curve shows that the pyrolysis can be di...This paper studies the characteristics of larch bark pyrolysis and analyzes factors that affect the pyrolysis and the liquid pyrolytic component. The results are as follows: TG curve shows that the pyrolysis can be divided into three parts: drying process, pyrolytic process, and carbonate and calcinated process. Both the size of grain and the temperature rising rate affect the shape of TG and DTG. Vinegar and sedimentary tar are main components of pyrolyzate products. GC-MS is applied to analyze vinegar. It is shown that the vinegar is a highly complex compound which is composed of phenol and its derivatives (45.620%), organic acid (13.851%), keto derivatives (9.754%), aldehydic derivatives (8.573%), alcoholic derivatives (1.794%), ester and its derivatives (0.205%).展开更多
In this study,plantation poplar wood was first impregnated by low molecular weightphenol-formaldehyde(PF)resin solution by vacuum-pressure process.And then the wettability ofsanded and non-sanded radial and tangential...In this study,plantation poplar wood was first impregnated by low molecular weightphenol-formaldehyde(PF)resin solution by vacuum-pressure process.And then the wettability ofsanded and non-sanded radial and tangential sections from un-impregnated and impregnated poplarwood was tested respectively by the measurement of contact angles using different liquids.Finally,thesurface free energy of different samples was estimated by the plot extrapolation method.The resultsshowed that the wettability of wood declined after impregnation with PF resin,but it could be improvedby sanding;and the contact angle decreased with increasing surface free energy.Both wood texture andtesting liquid affected the wettability.The sequence of the three chemical reagents is:diiodomethane(good)>formamide(medium)>distilled water(bad).展开更多
文摘Impregnation method can effectively improve physical and mechanical properties of wood.In this study,plantation poplar lumbers are impregnated by a low molecular weight phenol-formaldehyde resin solution with concentration of 30%under vacuum-pressure process,and then dried and machined according to the related standards.The results show that the physical and mechanical properties of poplar can be improved by the treatment,except for toughness.The average density of poplar increases from 0.397 to 0.710 g/cm3,the modulus of elasticity in static bending,the bending strength and the compressive strength parallel to grain of treated specimens increase by 56.71%,112.97%and 87.69%,respectively,compared to the untreated.And the hardness values on radial and tangential sections,and nail holding power as well as abrasion resistance of treated specimens improve by 283.87%,82.78%,71.43%and 22.06%,respectively;while toughness decreases by 48.80%.
基金supported by special research fund"research on drying characteristics of impregnated plantation poplar lumber"(CAFINT2007C08)
文摘Plantation poplar is one of the most important resources for wood industry,its utilization field is vast.The wettability of Populus tomentosa with different drying methods was judged by measurement of contact angle using distilled water in this paper.The results showed that the specimens from conventional drying have the biggest contact angle,and the air dried have the smallest contact angle,air dried lumbers have a better wettability than the kiln dried.The changes of contact angle in a period of time showed wettability sequence of lumber with different drying methods:air drying>high temperature drying>conventional drying.The basic property for high value-added plantation poplar lumber products was provided to the wood industry.
文摘This paper studies the characteristics of larch bark pyrolysis and analyzes factors that affect the pyrolysis and the liquid pyrolytic component. The results are as follows: TG curve shows that the pyrolysis can be divided into three parts: drying process, pyrolytic process, and carbonate and calcinated process. Both the size of grain and the temperature rising rate affect the shape of TG and DTG. Vinegar and sedimentary tar are main components of pyrolyzate products. GC-MS is applied to analyze vinegar. It is shown that the vinegar is a highly complex compound which is composed of phenol and its derivatives (45.620%), organic acid (13.851%), keto derivatives (9.754%), aldehydic derivatives (8.573%), alcoholic derivatives (1.794%), ester and its derivatives (0.205%).
基金supported by"Research on Value-added Wood Products Production in the Dongting Lake Drainage Area",a part of The National Forestry Technology Sustentation Project"The Research&Demonstration of Key Technology in Forest Ecosystem Construction"(2006BAD03A1503)
文摘In this study,plantation poplar wood was first impregnated by low molecular weightphenol-formaldehyde(PF)resin solution by vacuum-pressure process.And then the wettability ofsanded and non-sanded radial and tangential sections from un-impregnated and impregnated poplarwood was tested respectively by the measurement of contact angles using different liquids.Finally,thesurface free energy of different samples was estimated by the plot extrapolation method.The resultsshowed that the wettability of wood declined after impregnation with PF resin,but it could be improvedby sanding;and the contact angle decreased with increasing surface free energy.Both wood texture andtesting liquid affected the wettability.The sequence of the three chemical reagents is:diiodomethane(good)>formamide(medium)>distilled water(bad).
