The technique for preparing phenol formaldehyde resin from phenolated wood (PWF) and its characters were studied and analyzed. Poplar (Populus spp.) wood meal was liquefied by phenol in the presence of sulfuric acid a...The technique for preparing phenol formaldehyde resin from phenolated wood (PWF) and its characters were studied and analyzed. Poplar (Populus spp.) wood meal was liquefied by phenol in the presence of sulfuric acid as a catalyst. After the liquefied products were cooled, alkaline catalyst and formaldehyde were added. The mixture was kept at (60?) C for 1h and then was heated to (85?) C for 1h. The influence of molar ratio of formaldehyde to phenol (F/P) was investigated. The results showed when the molar ratio of formaldehyde to phenol was over 1.8, the PWF adhesives had high bond quality, bond durability and extremely low aldehydes emissions.展开更多
The last years,Central European forests have suffered from drought as a direct consequence of climate change.All these forests have a long management history and it lies in the landowner’s responsibility to replant d...The last years,Central European forests have suffered from drought as a direct consequence of climate change.All these forests have a long management history and it lies in the landowner’s responsibility to replant damaged forests.Hence,landowners and the government are searching currently for species suitable to replant in areas affected by tree die-offs.It is a matter of fact that good knowledge of drought resistance of species is a critical measure for the current replanting efforts.We determined a widely recognized trait for leaf drought tolerance(leaf water potential at turgor loss point at full hydration,πtlp)in 41 woody species native or introduced in Central Europe.The osmometric rapid assessment method was used to measure the leaf osmotic potential at full hydration(πosm)of sun-exposed leaves and converted toπtlp.Meanπtlp of the native species was−2.33±0.33 MPa.The less negativeπtlp was found in the introduced species Aesculus hypocastania and was at−1.70±0.11 MPa.The most negativeπtlp,and thus the potentially highest drought tolerance,were found in the introduced species Pseudotsuga menzesii and was at−3.02±0.14 MPa.High or less negativeπtlp is associated with lower drought tolerance,whereas low or more negativeπtlp stands for higher resistance to drought stress.For example,the two native species Illex aquifolium and Alnus glustinosa are species naturally associated with moist habitats and are characterized by the least negativeπtlp of−1.75±0.02 and−1.76±0.03 MPa,respectively.展开更多
文摘The technique for preparing phenol formaldehyde resin from phenolated wood (PWF) and its characters were studied and analyzed. Poplar (Populus spp.) wood meal was liquefied by phenol in the presence of sulfuric acid as a catalyst. After the liquefied products were cooled, alkaline catalyst and formaldehyde were added. The mixture was kept at (60?) C for 1h and then was heated to (85?) C for 1h. The influence of molar ratio of formaldehyde to phenol (F/P) was investigated. The results showed when the molar ratio of formaldehyde to phenol was over 1.8, the PWF adhesives had high bond quality, bond durability and extremely low aldehydes emissions.
文摘The last years,Central European forests have suffered from drought as a direct consequence of climate change.All these forests have a long management history and it lies in the landowner’s responsibility to replant damaged forests.Hence,landowners and the government are searching currently for species suitable to replant in areas affected by tree die-offs.It is a matter of fact that good knowledge of drought resistance of species is a critical measure for the current replanting efforts.We determined a widely recognized trait for leaf drought tolerance(leaf water potential at turgor loss point at full hydration,πtlp)in 41 woody species native or introduced in Central Europe.The osmometric rapid assessment method was used to measure the leaf osmotic potential at full hydration(πosm)of sun-exposed leaves and converted toπtlp.Meanπtlp of the native species was−2.33±0.33 MPa.The less negativeπtlp was found in the introduced species Aesculus hypocastania and was at−1.70±0.11 MPa.The most negativeπtlp,and thus the potentially highest drought tolerance,were found in the introduced species Pseudotsuga menzesii and was at−3.02±0.14 MPa.High or less negativeπtlp is associated with lower drought tolerance,whereas low or more negativeπtlp stands for higher resistance to drought stress.For example,the two native species Illex aquifolium and Alnus glustinosa are species naturally associated with moist habitats and are characterized by the least negativeπtlp of−1.75±0.02 and−1.76±0.03 MPa,respectively.
