Green composites made from bamboo fibers and biodegradable resins were fabricated with press molding.On the basis of the Weibull distribution and the weakest-link theory,the statistical strength and distribution of ba...Green composites made from bamboo fibers and biodegradable resins were fabricated with press molding.On the basis of the Weibull distribution and the weakest-link theory,the statistical strength and distribution of bamboo fiber were analyzed,and the tensile strength of green composites was also investigated.The result confirms that the tensile statistical strength of fiber fits well with two-parameter Weibull distribution.In addition,the tensile strength of bamboo fiber reinforced composites is about 330 MPa with the fiber volume fraction of 70%.This value is close to or higher than that of other natural fiber reinforced green composites.展开更多
The permeability,alkali silica reaction,workability and strength of GHPC(green high performance concrete) were studied in this paper.The results show that GHPC has an excellent durability and the effects of mass rat...The permeability,alkali silica reaction,workability and strength of GHPC(green high performance concrete) were studied in this paper.The results show that GHPC has an excellent durability and the effects of mass ratio of flyash to high calcium slag,water binder ratio,content of water reducer,and crushed coarse aggregate type on the workability and strength of GHPC were considerably evident.A new path for the concretes continuous development was put forward.展开更多
In the current work,we have synthesized vegetable oil-based polyurethane-OMMT clay nanocomposite(PUNC)adhesive with the incorporation of different wt%of organically modified nanoclay(1 to 5 wt%)into the biobased polyu...In the current work,we have synthesized vegetable oil-based polyurethane-OMMT clay nanocomposite(PUNC)adhesive with the incorporation of different wt%of organically modified nanoclay(1 to 5 wt%)into the biobased polyurethane(PU)matrix through in-situ polymerization process via ultrasonication method.At the initial stage,PU adhesive was prepared using polyol and partially biobased aliphatic isocyanate,wherein polyol was derived from the transesterified castor oil using ethylene glycol.The formation of PU and PUNC adhesive was confirmed using Fourier transform infrared(FTIR)spectroscopy analysis.The tensile strength of PU with different wt%of nanoclay was determined and the analysis showed that the loading of 3 wt%of nanoclay within the PU matrix showed better performance as compared to the others.Furthermore,shear strength of PU and PUNC(3 wt%nanoclay)adhesives were determined using lap shear test,in which PUNC adhesive showed higher adhesive strength at 70°C.Subsequently,the dispersibility of OMMT nanoclay within the PU matrix along with exfoliation and amorphous structure was confirmed through wide angle X-ray diffractometer(WAXD)and transmission electron microscopy(TEM)analysis.The phase separation structure was analyzed using dynamic mechanical analysis(DMA).The analysis revealed that with the addition of organically modified nanoclay in the PU matrix,the glass transition temperature(Tg)of the damping curve was shifted towards higher temperature.展开更多
XN901 is a K-type three-line hybrid wheat with a high yield potential, and its leaves and stem remaining green during grain maturation, suggesting much assimilate stay in leaves and stem. The grain water content, grai...XN901 is a K-type three-line hybrid wheat with a high yield potential, and its leaves and stem remaining green during grain maturation, suggesting much assimilate stay in leaves and stem. The grain water content, grain volume, carbohydrate content, and enzyme activity of sucose metabolism in the grain, as well as source-sink relationship were studied in order to investigate the physiological reason of the assimilate remaining in leaves and stem at the late stage. The results showed that the hybrid grains had more water and soluble sugar, higher activities of acid invertase and sucrose synthase at the early stage that led to a faster expansion growth, greater grain volume and faster starch synthesis at the early to mid stage of grain development. Also it had a longer period for actively filling. As a result, the grain weight and yield of the hybrid were increased by 14 and 15% respectively compared to that of Shaan 229. Additionally, the biomass of XN901 was 41.7% more than that of control, but its harvest index was 9% lower than Shaan 229. However, its lower activity of sucrose synthase indicated a lower sink activity at the late stage, resulting in a slow rate of filling and starch synthesis. Also, the hybrid wheat XN901 had a large source-sink ratio. It is the main reason for much assimilate remaining in the straw at the late stage and lower harvest index. Strengthening the sink activity and raising the harvest index should be the key means of improving the yield of hybrid wheat.展开更多
基金Project(2007BAQ0104901) supported by the 11th Five-Year-Plan National Scientific & Technological ProgramProject(200704020) supported by the National Special Program on the Public Welfare Forests supported by Ministry of Science and Technology of China
文摘Green composites made from bamboo fibers and biodegradable resins were fabricated with press molding.On the basis of the Weibull distribution and the weakest-link theory,the statistical strength and distribution of bamboo fiber were analyzed,and the tensile strength of green composites was also investigated.The result confirms that the tensile statistical strength of fiber fits well with two-parameter Weibull distribution.In addition,the tensile strength of bamboo fiber reinforced composites is about 330 MPa with the fiber volume fraction of 70%.This value is close to or higher than that of other natural fiber reinforced green composites.
文摘The permeability,alkali silica reaction,workability and strength of GHPC(green high performance concrete) were studied in this paper.The results show that GHPC has an excellent durability and the effects of mass ratio of flyash to high calcium slag,water binder ratio,content of water reducer,and crushed coarse aggregate type on the workability and strength of GHPC were considerably evident.A new path for the concretes continuous development was put forward.
文摘In the current work,we have synthesized vegetable oil-based polyurethane-OMMT clay nanocomposite(PUNC)adhesive with the incorporation of different wt%of organically modified nanoclay(1 to 5 wt%)into the biobased polyurethane(PU)matrix through in-situ polymerization process via ultrasonication method.At the initial stage,PU adhesive was prepared using polyol and partially biobased aliphatic isocyanate,wherein polyol was derived from the transesterified castor oil using ethylene glycol.The formation of PU and PUNC adhesive was confirmed using Fourier transform infrared(FTIR)spectroscopy analysis.The tensile strength of PU with different wt%of nanoclay was determined and the analysis showed that the loading of 3 wt%of nanoclay within the PU matrix showed better performance as compared to the others.Furthermore,shear strength of PU and PUNC(3 wt%nanoclay)adhesives were determined using lap shear test,in which PUNC adhesive showed higher adhesive strength at 70°C.Subsequently,the dispersibility of OMMT nanoclay within the PU matrix along with exfoliation and amorphous structure was confirmed through wide angle X-ray diffractometer(WAXD)and transmission electron microscopy(TEM)analysis.The phase separation structure was analyzed using dynamic mechanical analysis(DMA).The analysis revealed that with the addition of organically modified nanoclay in the PU matrix,the glass transition temperature(Tg)of the damping curve was shifted towards higher temperature.
基金support from the National Natural Science Foundation of China(39670436)Young Scientists’ Fund of National Natu-ral Science Foundation of China (30600075)Young Scientific Cadremen’s Fund of Northwest A&F University, China
文摘XN901 is a K-type three-line hybrid wheat with a high yield potential, and its leaves and stem remaining green during grain maturation, suggesting much assimilate stay in leaves and stem. The grain water content, grain volume, carbohydrate content, and enzyme activity of sucose metabolism in the grain, as well as source-sink relationship were studied in order to investigate the physiological reason of the assimilate remaining in leaves and stem at the late stage. The results showed that the hybrid grains had more water and soluble sugar, higher activities of acid invertase and sucrose synthase at the early stage that led to a faster expansion growth, greater grain volume and faster starch synthesis at the early to mid stage of grain development. Also it had a longer period for actively filling. As a result, the grain weight and yield of the hybrid were increased by 14 and 15% respectively compared to that of Shaan 229. Additionally, the biomass of XN901 was 41.7% more than that of control, but its harvest index was 9% lower than Shaan 229. However, its lower activity of sucrose synthase indicated a lower sink activity at the late stage, resulting in a slow rate of filling and starch synthesis. Also, the hybrid wheat XN901 had a large source-sink ratio. It is the main reason for much assimilate remaining in the straw at the late stage and lower harvest index. Strengthening the sink activity and raising the harvest index should be the key means of improving the yield of hybrid wheat.
