High Pressure Laminates(HPL)panels consist of stacks of self-gluing paper sheets soaked with phenol-formaldehyde(PF)resins.An important requirement for such PFs is that they must rapidly penetrate and saturate the pa...High Pressure Laminates(HPL)panels consist of stacks of self-gluing paper sheets soaked with phenol-formaldehyde(PF)resins.An important requirement for such PFs is that they must rapidly penetrate and saturate the paper pores.Partially substituting phenol with bio-based phenolic chemicals like lignin changes the physico-chemical properties of the resin and affects its ability to penetrate the paper.In this study,PF formulations containing different proportions of lignosulfonate and kraft lignin were used to prepare paper-based laminates.The penetration of a Kraft paper sheet was characterized by a recently introduced,new device measuring the conductivity between both sides of the paper sheet after a drop of resin was placed on the surface and allowed to penetrate the sheet.The main target value measured was the time required for a specific resin to completely penetrate the defined paper sample(“penetration time”).This penetration time generally depends on the molecular weight distribution,the flow behavior and the polarity of the resin which in turn are dependent on the manufacturing conditions of the resin.In the present study,the influences of the three process factors:(1)type of lignin material used for substitution,(2)lignin modification by phenolation and(3)degree of phenol substitution on the penetration times of various lignin-phenolic hybrid impregnation resins were studied using a complete twolevel three-factorial experimental design.Thin laminates made with the resins diluted in methanol were mechanically tested in terms of tensile and flexural strains,and their cross-sections were studied by light microscopy.展开更多
Objective:To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of limes of consecutive use,in the assessment of insecticide vector susceptibility tests in...Objective:To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of limes of consecutive use,in the assessment of insecticide vector susceptibility tests in laboratory and field conditions.Methods:Larvae and pupae of Anopheles gambiae s.l.mosquitoes were collected from the breeding sites in Seme-Kpodji and Cotonou districts in Southern Benin in April 2013 during the first rainy season.Anopheles gambiae s.l.mosquitoes were also collected from the breeding sites in Parakou district in Northern Benin in May 2013 at the beginning of the rainy season.Susceptibility tests were done using impregnated paper with bendiocarb(0.1%)following WHO protocol and stock solutions of permethrin(21.5 ug per bottle)and deltamethrin(12.5 ug per bottle)following CDC protocol on unfed female mosquitoes aged 2-5 days old.These bioassays were repeated a certain number of times.The temperature and relative humidity were monitored and recorded during the susceptibility tests.Results:This study showed that a WHO impregnated paper with bendiocarb could be used four times during four consecutive days in field conditions.Regarding a Wheaton coated bottle with permethrin or deltamethrin,they could be used at least three limes during four consecutive days in laboratory conditions.Conclusions:The day storage and the number of times that a WHO impregnated paper and a CDC coated bottle maintained their efficacy are useful in the assessment of insecticide vectors susceptibility tests.展开更多
Charge transport in oil impregnated paper impacts the insulation performance of a transformer.This paper proposes a simulation method for the charge transport in oil impregnated paper insulation.The transient upstream...Charge transport in oil impregnated paper impacts the insulation performance of a transformer.This paper proposes a simulation method for the charge transport in oil impregnated paper insulation.The transient upstream finite element method(FEM)is applied to the transport equations of bipolar charges for establishing a numerical simulation model of charge transport in oil impregnated paper insulation.The method is validated by experimental results.The charge transport and electric field distribution in single-layer oil impregnated paper insulation under different temperature gradients is simulated.The trends of the simulation results are seen to agree with the corresponding experimental results.This paper conducts exploratory research into the simulation of charge transportation phenomenon in oil impregnated paper,and is of importance to the design of oil impregnated paper insulation.展开更多
基金This work was carried out within the COMET program funded by the Austrian FFG,project number 844608.
文摘High Pressure Laminates(HPL)panels consist of stacks of self-gluing paper sheets soaked with phenol-formaldehyde(PF)resins.An important requirement for such PFs is that they must rapidly penetrate and saturate the paper pores.Partially substituting phenol with bio-based phenolic chemicals like lignin changes the physico-chemical properties of the resin and affects its ability to penetrate the paper.In this study,PF formulations containing different proportions of lignosulfonate and kraft lignin were used to prepare paper-based laminates.The penetration of a Kraft paper sheet was characterized by a recently introduced,new device measuring the conductivity between both sides of the paper sheet after a drop of resin was placed on the surface and allowed to penetrate the sheet.The main target value measured was the time required for a specific resin to completely penetrate the defined paper sample(“penetration time”).This penetration time generally depends on the molecular weight distribution,the flow behavior and the polarity of the resin which in turn are dependent on the manufacturing conditions of the resin.In the present study,the influences of the three process factors:(1)type of lignin material used for substitution,(2)lignin modification by phenolation and(3)degree of phenol substitution on the penetration times of various lignin-phenolic hybrid impregnation resins were studied using a complete twolevel three-factorial experimental design.Thin laminates made with the resins diluted in methanol were mechanically tested in terms of tensile and flexural strains,and their cross-sections were studied by light microscopy.
基金Funded by the Ministere de I'Enseignement Superieur et de la Recherche Scientifique(MESRS),Benin and the President's Malaria Initiative of the U.S. Government through USAID
文摘Objective:To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of limes of consecutive use,in the assessment of insecticide vector susceptibility tests in laboratory and field conditions.Methods:Larvae and pupae of Anopheles gambiae s.l.mosquitoes were collected from the breeding sites in Seme-Kpodji and Cotonou districts in Southern Benin in April 2013 during the first rainy season.Anopheles gambiae s.l.mosquitoes were also collected from the breeding sites in Parakou district in Northern Benin in May 2013 at the beginning of the rainy season.Susceptibility tests were done using impregnated paper with bendiocarb(0.1%)following WHO protocol and stock solutions of permethrin(21.5 ug per bottle)and deltamethrin(12.5 ug per bottle)following CDC protocol on unfed female mosquitoes aged 2-5 days old.These bioassays were repeated a certain number of times.The temperature and relative humidity were monitored and recorded during the susceptibility tests.Results:This study showed that a WHO impregnated paper with bendiocarb could be used four times during four consecutive days in field conditions.Regarding a Wheaton coated bottle with permethrin or deltamethrin,they could be used at least three limes during four consecutive days in laboratory conditions.Conclusions:The day storage and the number of times that a WHO impregnated paper and a CDC coated bottle maintained their efficacy are useful in the assessment of insecticide vectors susceptibility tests.
基金supported by National High-tech Research and Development Program of China（863 Program）（2009AA04Z416） National Science Foundation of China（51021005） Scientific Innovation of Colleges and Universities（Project v-200704）
基金supported by the National Basic Research Program(973 Program)(2011CB209404)National Natural Science Foundation of China(51477120).
文摘Charge transport in oil impregnated paper impacts the insulation performance of a transformer.This paper proposes a simulation method for the charge transport in oil impregnated paper insulation.The transient upstream finite element method(FEM)is applied to the transport equations of bipolar charges for establishing a numerical simulation model of charge transport in oil impregnated paper insulation.The method is validated by experimental results.The charge transport and electric field distribution in single-layer oil impregnated paper insulation under different temperature gradients is simulated.The trends of the simulation results are seen to agree with the corresponding experimental results.This paper conducts exploratory research into the simulation of charge transportation phenomenon in oil impregnated paper,and is of importance to the design of oil impregnated paper insulation.
