[Objective] This study was conducted to determine the toxicity of 26 fungicides against Oidium heveae and the synergistic effects of their binary mixtures.[Method] The sensitivity of O.heveae to 26 fungicides was dete...[Objective] This study was conducted to determine the toxicity of 26 fungicides against Oidium heveae and the synergistic effects of their binary mixtures.[Method] The sensitivity of O.heveae to 26 fungicides was determined in vitro and in vivo by calculating EC50 values.Horsfall＇s toxicity rate was preliminarily employed to predict the type of joint action of 180 two-way mixtures,based on which the interaction level of the potentially synergistic mixtures was validated by Sun and Johnson＇s co-toxicity coefficient.[Result] Triflumizole,pyraoxystrobin,flufenoxystrobin,epoxiconazole,pyrametostrobin,flusilazole,pyraclostrobin and tetraconazole were the most potent inhibitors of both spore germination and mycelial growth.An ‘in vitro-in vivo＇ integrated strategy is proposed for screening the inhibitors of O.heveae,according to the fact that data obtained in germination experiment are able to reflect to some extent the effectiveness of fungicide confirmed by pot experiment.Results achieved by Horsfall＇s were in line with that validated by Sun and Johnson＇s,the Horsfall＇s seems to be a convenient means to assess rapidly the potential interaction type and level of fungicides in a binary mixture.Nineteen mixtures interact synergistically：epoxiconazole ＋ pyraclostrobin at the mixing ratio of 6：4,8：2;tetraconazole ＋ flufenoxystrobin at 1：9,2：8,3：7 and 4：6;triadimefon ＋ flufenoxystrobin at 9：1;triflumizole ＋ flufenoxystrobin at 8：2;flusilazole ＋pyrametostrobin at 7：3,8：2 and 9：1;tetraconazole ＋ pyrametostrobin at 6：4;triadimefon ＋ pyrametostrobin at 5：5,8：2;triflumizole ＋ pyrametostrobin at 7：3,8：2;tetraconazole ＋ pyraoxystrobin at 9：1;triflumizole ＋ pyraoxystrobin at 8：2,9：1.[Conclusion] The single fungicides and their binary mixtures are expected to serve as the alternatives to triadimefon and the alternate use of them could delay the buildup of resistant O.heveae isolate.展开更多
In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （...In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （ATR-FTIR） spectrum and X-ray photoelectron spectroscopy （XPS） were used to observe the variation of the functional groups of the modified SIR. Static contact angle （SCA） was employed to estimate the change of hydrophobicity of the modified SIR. The surface energy of SIR is reduced largely from 27.37 mJ/m^2 of original SIR sample to 2.94 mJ/m^2 of SIR sample treated by CF4 CCP modification at RF power of 200 W for a treatment time of 5 rnin. According to the XPS, ATR-FTIR and surface energy analysis, it is suggested that the improvement of hydrophobicity on the modified SIR surface is mainly ascribed to the decrease of surface energy, which is caused by the cooperation of the fluosilicic structure of Si--F or Si--F2 and the fluoric groups of C--CFn induced by the methyl replacement reaction and residual methyl groups of SIR surface.展开更多
Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. ...Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. Ethylene stimulation acts by increasing latex flow to the cells of inner bark from the latex cells, increasing yield and may affect the physical properties of rubberwood. The aim of this work was to assess the permeability properties of ethylene treated rubberwood （TRW） relative to untreated rubberwood （URW）, because in wood industrial technology, permeability relates to bondability and wood preservative treatments. The Hevea samples were of PRIM 600 strain, from 20-25 years old rubber trees. The TRW rubber trees had been stimulated by ethylene gas for six years. The rubberwood specimens were collected at a single plot of plantation to minimize variations in soil fertility, environmental exposures and silvicultural treatments at Tumbon Chaibury, Amphor Chaibury, Suratthani Province, Thailand. The moisture contents （MC） of fresh rubberwood were significantly different （P 〈 0.05） at 75% for TRW and 64% for URW. The permeability experiment followed Darcy＇s law, and the hydrostatic pressure was controlled. The average 0.005 Darcy water permeability of TRW was significantly higher than the 0.001 Darcy for URW. Water absorptions during 4 h water immersion of rubberwood blocks differed significantly, and TRW had higher absorption than URW also across 6 d of immersion. Scanning electron microscope （SEM） imaging showed anatomical effects that contribute to the fivefold permeability increase.展开更多
The research considered urgent ecological reasons linked to environment such as worn tires, the waste tire rubber＇s powder was collected from the tire cars repair shops （passed from the sieve No 18 μm）, and used t...The research considered urgent ecological reasons linked to environment such as worn tires, the waste tire rubber＇s powder was collected from the tire cars repair shops （passed from the sieve No 18 μm）, and used to improve the asphalt concrete properties. Raw materials used were prepared and tested. Varies of asphalt concrete mixtures were prepared with different ratios of bitumen （5, 5.5, 6, 6.5, 7% % of concrete weight）. The Marshall mix design method was used to determine optimum conditions for bitumen in asphalt concrete with specific weight, stability and flow Test, the optimum amount of bitumen was 6.1% of whole asphalt concrete. The different percentages of waste tire rubber powder （0.0, 0.05, 0.10, 0.15% of bitumen weight） were added in optimum bitumen of asphalt concretes, then specific weight and Marshall test were evaluated. These asphalt-rubber mixtures were found to act quite differently from traditional, unmodified asphalt mixtures. However, these results indicate that improved pavement performance can be achieved with asphalt-rubber binder.展开更多
The preparation of natural rubber based isotropic thick magnetorheological elastomers(MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the...The preparation of natural rubber based isotropic thick magnetorheological elastomers(MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the dynamic properties. Effect of magnetic field on the damping ratio was studied on the amplification region of the transmissibility curve. The viscoelastic dynamic damping nature of the elastomer was also studied by analyzing the force-displacement hysteresis graphs. The results show that MR effect increases with the increase in magnetic field as well as carbonyl iron powder particle concentration. It is observed that softer matrix material produces more MR effect. A maximum of 125% improvement in the loss factor is observed for the MRE with 25% carbonyl iron volume concentration. FEMM simulation shows that as carbonyl iron particle distribution becomes denser, MR effect is improved. FEMM analysis also reveals that if the distance between the adjacent iron particles are reduced from 20 μm to 10 μm, a 40% increase in stored energy is observed.展开更多
Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over c...Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.展开更多
Using the industrial technologies of rubber latex irradiation,preparation of nanoscale silica(SiO2) slurry,mixing irradiated rubber latex with SiO2 slurry,and the spray drying,we have prepared the ultrafine fully-vulc...Using the industrial technologies of rubber latex irradiation,preparation of nanoscale silica(SiO2) slurry,mixing irradiated rubber latex with SiO2 slurry,and the spray drying,we have prepared the ultrafine fully-vulcanized powder carboxyl styrene-butadiene rubber(UFPCSBR)/SiO2 nanocompound powder,in which the SiO2 particles and UFPCSBR particles are isolated and stuck each other.When the UFPCSBR/SiO2 nanocompound powder is mixed with crude rubber,the UFPCSBR particles are dispersed well in rubber matrix because of their good compatibility,then the SiO2 particles are also dispersed well in rubber matrix because of the carrier nature of the UFPCSBR particles during the mixing procedure,and the novel rubber/UFPCSBR/SiO2 nanocomposites are fabricated.Compared with the rubber composites prepared by mixing the crude rubber with the UFPCSBR powder and SiO2 powder one after the other,the novel UFPCSBR/SiO2 nanocompound modified rubber/UFPCSBR/SiO2 nanocomposites have better abrasion resistance,higher tensile strength and tear strength,and lower heat build-up data.Noteworthily,the tanδ-temperature curve of the novel rubber/UFPCSBR/SiO2 nanocomposites has the second tanδ peak due to the newly generated boundary layer surrounding the SiO2 particles,increasing the tanδ values in the temperature range of 0-20℃,which is very important to the research of green tyre tread.展开更多
In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original...In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original values. According to the classical theory, the Tg of plastic component shall remain unchanged or move toward the lower Tg of rubber component in a rubber/plastic blend. However, ultra-fine full-vulcanized powdered rubber (UFPR) with a diameter of ca. 100 nm can simultaneously increase the toughness and the Tg of plastics, which is abnormal and is difficult to explain by classical theory. In this feature article, the abnormal behavior and its mechanism are discussed in detail.展开更多
基金financed by the ministry of science and technology of P.R.China
文摘[Objective] This study was conducted to determine the toxicity of 26 fungicides against Oidium heveae and the synergistic effects of their binary mixtures.[Method] The sensitivity of O.heveae to 26 fungicides was determined in vitro and in vivo by calculating EC50 values.Horsfall＇s toxicity rate was preliminarily employed to predict the type of joint action of 180 two-way mixtures,based on which the interaction level of the potentially synergistic mixtures was validated by Sun and Johnson＇s co-toxicity coefficient.[Result] Triflumizole,pyraoxystrobin,flufenoxystrobin,epoxiconazole,pyrametostrobin,flusilazole,pyraclostrobin and tetraconazole were the most potent inhibitors of both spore germination and mycelial growth.An ‘in vitro-in vivo＇ integrated strategy is proposed for screening the inhibitors of O.heveae,according to the fact that data obtained in germination experiment are able to reflect to some extent the effectiveness of fungicide confirmed by pot experiment.Results achieved by Horsfall＇s were in line with that validated by Sun and Johnson＇s,the Horsfall＇s seems to be a convenient means to assess rapidly the potential interaction type and level of fungicides in a binary mixture.Nineteen mixtures interact synergistically：epoxiconazole ＋ pyraclostrobin at the mixing ratio of 6：4,8：2;tetraconazole ＋ flufenoxystrobin at 1：9,2：8,3：7 and 4：6;triadimefon ＋ flufenoxystrobin at 9：1;triflumizole ＋ flufenoxystrobin at 8：2;flusilazole ＋pyrametostrobin at 7：3,8：2 and 9：1;tetraconazole ＋ pyrametostrobin at 6：4;triadimefon ＋ pyrametostrobin at 5：5,8：2;triflumizole ＋ pyrametostrobin at 7：3,8：2;tetraconazole ＋ pyraoxystrobin at 9：1;triflumizole ＋ pyraoxystrobin at 8：2,9：1.[Conclusion] The single fungicides and their binary mixtures are expected to serve as the alternatives to triadimefon and the alternate use of them could delay the buildup of resistant O.heveae isolate.
基金Project(05JT1034) supported by the Plan of Science and Technology Bureau of Hunan Province,China
文摘In order to improve the surface hydrophobicity, silicone rubber （SIR） samples were exposed to CF4 radio frequency （RF） capacitively coupled plasma （CCP）. Attenuated total reflection Fourier transform infrared （ATR-FTIR） spectrum and X-ray photoelectron spectroscopy （XPS） were used to observe the variation of the functional groups of the modified SIR. Static contact angle （SCA） was employed to estimate the change of hydrophobicity of the modified SIR. The surface energy of SIR is reduced largely from 27.37 mJ/m^2 of original SIR sample to 2.94 mJ/m^2 of SIR sample treated by CF4 CCP modification at RF power of 200 W for a treatment time of 5 rnin. According to the XPS, ATR-FTIR and surface energy analysis, it is suggested that the improvement of hydrophobicity on the modified SIR surface is mainly ascribed to the decrease of surface energy, which is caused by the cooperation of the fluosilicic structure of Si--F or Si--F2 and the fluoric groups of C--CFn induced by the methyl replacement reaction and residual methyl groups of SIR surface.
文摘Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. Ethylene stimulation acts by increasing latex flow to the cells of inner bark from the latex cells, increasing yield and may affect the physical properties of rubberwood. The aim of this work was to assess the permeability properties of ethylene treated rubberwood （TRW） relative to untreated rubberwood （URW）, because in wood industrial technology, permeability relates to bondability and wood preservative treatments. The Hevea samples were of PRIM 600 strain, from 20-25 years old rubber trees. The TRW rubber trees had been stimulated by ethylene gas for six years. The rubberwood specimens were collected at a single plot of plantation to minimize variations in soil fertility, environmental exposures and silvicultural treatments at Tumbon Chaibury, Amphor Chaibury, Suratthani Province, Thailand. The moisture contents （MC） of fresh rubberwood were significantly different （P 〈 0.05） at 75% for TRW and 64% for URW. The permeability experiment followed Darcy＇s law, and the hydrostatic pressure was controlled. The average 0.005 Darcy water permeability of TRW was significantly higher than the 0.001 Darcy for URW. Water absorptions during 4 h water immersion of rubberwood blocks differed significantly, and TRW had higher absorption than URW also across 6 d of immersion. Scanning electron microscope （SEM） imaging showed anatomical effects that contribute to the fivefold permeability increase.
文摘The research considered urgent ecological reasons linked to environment such as worn tires, the waste tire rubber＇s powder was collected from the tire cars repair shops （passed from the sieve No 18 μm）, and used to improve the asphalt concrete properties. Raw materials used were prepared and tested. Varies of asphalt concrete mixtures were prepared with different ratios of bitumen （5, 5.5, 6, 6.5, 7% % of concrete weight）. The Marshall mix design method was used to determine optimum conditions for bitumen in asphalt concrete with specific weight, stability and flow Test, the optimum amount of bitumen was 6.1% of whole asphalt concrete. The different percentages of waste tire rubber powder （0.0, 0.05, 0.10, 0.15% of bitumen weight） were added in optimum bitumen of asphalt concretes, then specific weight and Marshall test were evaluated. These asphalt-rubber mixtures were found to act quite differently from traditional, unmodified asphalt mixtures. However, these results indicate that improved pavement performance can be achieved with asphalt-rubber binder.
文摘The preparation of natural rubber based isotropic thick magnetorheological elastomers(MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the dynamic properties. Effect of magnetic field on the damping ratio was studied on the amplification region of the transmissibility curve. The viscoelastic dynamic damping nature of the elastomer was also studied by analyzing the force-displacement hysteresis graphs. The results show that MR effect increases with the increase in magnetic field as well as carbonyl iron powder particle concentration. It is observed that softer matrix material produces more MR effect. A maximum of 125% improvement in the loss factor is observed for the MRE with 25% carbonyl iron volume concentration. FEMM simulation shows that as carbonyl iron particle distribution becomes denser, MR effect is improved. FEMM analysis also reveals that if the distance between the adjacent iron particles are reduced from 20 μm to 10 μm, a 40% increase in stored energy is observed.
文摘Since the introduction of＂green tyres＂ in the early 90＇s, the use of silica as a reinforcing filler, along with a silane coupling agent, has spread and grown worldwide. The greatest advantage of using silica over carbon black as reinforcing filler in a tyre tread compound is that a lower rolling resistance is achieved, while maintaining good wet traction. However, a previous study has shown that the wear resistance of a silica filled ENR （epoxidised natural rubber） compound was not as high as those of conventional OESBR （oil extended styrene butadiene rubber） and NR/BR compounds used in passenger car and truck tyre treads. In this work, with the aim of improving abrasion resistance, the effect of blending BR （butadiene rubber） into a silica filled ENR compound was studied. Blends with 0 to 30 phr BR were prepared in a Polylab Haake internal mixer. The rheological properties of the compounds were measured using a Mooney viscometer and oscillating-disc rheometer. The hardness, tensile strength and DIN abrasion resistance were also measured. The results showed that the ENR/silica compound properties such as tensile strength and hardness were as good as those of the conventional compounds. However, the most important finding was that abrasion resistance increased significantly with BR content, exceeding that of the conventional compound at BR： ENR ratios of greater than 20：80.
基金supported by the National Natural Science Foundation of China (Grant No. 50873049)National High Technology Research and Development Program of China ("863" Program) (Grant No. 2009AA-03Z338)+1 种基金Shandong Young Scientists Encouragement Foundation (Grant No. 2007BS04038)the Scientific Research Foundation of Shandong Education Department (Grant No. J07YA12)
文摘Using the industrial technologies of rubber latex irradiation,preparation of nanoscale silica(SiO2) slurry,mixing irradiated rubber latex with SiO2 slurry,and the spray drying,we have prepared the ultrafine fully-vulcanized powder carboxyl styrene-butadiene rubber(UFPCSBR)/SiO2 nanocompound powder,in which the SiO2 particles and UFPCSBR particles are isolated and stuck each other.When the UFPCSBR/SiO2 nanocompound powder is mixed with crude rubber,the UFPCSBR particles are dispersed well in rubber matrix because of their good compatibility,then the SiO2 particles are also dispersed well in rubber matrix because of the carrier nature of the UFPCSBR particles during the mixing procedure,and the novel rubber/UFPCSBR/SiO2 nanocomposites are fabricated.Compared with the rubber composites prepared by mixing the crude rubber with the UFPCSBR powder and SiO2 powder one after the other,the novel UFPCSBR/SiO2 nanocompound modified rubber/UFPCSBR/SiO2 nanocomposites have better abrasion resistance,higher tensile strength and tear strength,and lower heat build-up data.Noteworthily,the tanδ-temperature curve of the novel rubber/UFPCSBR/SiO2 nanocomposites has the second tanδ peak due to the newly generated boundary layer surrounding the SiO2 particles,increasing the tanδ values in the temperature range of 0-20℃,which is very important to the research of green tyre tread.
文摘In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original values. According to the classical theory, the Tg of plastic component shall remain unchanged or move toward the lower Tg of rubber component in a rubber/plastic blend. However, ultra-fine full-vulcanized powdered rubber (UFPR) with a diameter of ca. 100 nm can simultaneously increase the toughness and the Tg of plastics, which is abnormal and is difficult to explain by classical theory. In this feature article, the abnormal behavior and its mechanism are discussed in detail.
