Pakistan is at 12th number in the rank of rice production countries. Along with the production of 4,500 thousand metric tons of rice enormous quantity of rice husk is left as waste. Light weight thermal insulating mat...Pakistan is at 12th number in the rank of rice production countries. Along with the production of 4,500 thousand metric tons of rice enormous quantity of rice husk is left as waste. Light weight thermal insulating material was prepared from rice husk. Epoxy resin was used as a binder and was mixed with rice husk to give it strength, the sample was compressed at 7000 psi to produce cylindrical shape block. The thermal conductivity of the sample A, B, C and D of thickness 1, 2, 3 and 4 cm respectively was measured 0.0241, 0.0240, 0.239 and 0.0219 watts/m-k, which was lower than the common mortar by 51.74%, therefore it could be used in buildings and roof as an insulating material. This would be a suitable alternative which would not only save energy but also solve the environmental disposal problems as well. The results are very promising and we hope insulation material prepared would be useable in hot climate regions like Pakistan in buildings to prevent heat transfer.展开更多
Excellent thermal insulating materials are highly demanded in various applications including buildings, aerospace and sport equipment. However, in practical applications,the performance of thermal insulating materials...Excellent thermal insulating materials are highly demanded in various applications including buildings, aerospace and sport equipment. However, in practical applications,the performance of thermal insulating materials usually deteriorates under diverse temperature and humidity conditions.Therefore, it is highly essential to construct a bulk material that exhibits outstanding thermal insulation performance under extremely humid and hot environment. In this work, we have conceived a green and effective strategy to fabricate a superhydrophobic and compressible polyvinylidene fluoride/polyimide(PVDF/PI) nanofiber composite aerogel via electrospinning and freeze-drying technique. Interestingly, the PVDF nanofibers and PI nanofibers function as the hydrophobic fibrous framework and mechanical support skeleton,respectively, forming a robust three-dimensional framework with good mechanical flexibility. The PVDF/PI aerogel possesses outstanding superhydrophobic feature(water contact angle of 152°) and low thermal conductivity(31.0 m W m^(-1)K^(-1))at room temperature. Significantly, even at 100% relative humidity(80℃), the PVDF/PI aerogel still exhibits a low thermal conductivity of only 48.6 m W m^(-1)K^(-1), which outperforms the majority of commercial thermal insulating materials. Therefore, the novel PVDF/PI aerogel is promising as an excellent thermal insulating material for the applications in high-temperature and humid environment.展开更多
文摘Pakistan is at 12th number in the rank of rice production countries. Along with the production of 4,500 thousand metric tons of rice enormous quantity of rice husk is left as waste. Light weight thermal insulating material was prepared from rice husk. Epoxy resin was used as a binder and was mixed with rice husk to give it strength, the sample was compressed at 7000 psi to produce cylindrical shape block. The thermal conductivity of the sample A, B, C and D of thickness 1, 2, 3 and 4 cm respectively was measured 0.0241, 0.0240, 0.239 and 0.0219 watts/m-k, which was lower than the common mortar by 51.74%, therefore it could be used in buildings and roof as an insulating material. This would be a suitable alternative which would not only save energy but also solve the environmental disposal problems as well. The results are very promising and we hope insulation material prepared would be useable in hot climate regions like Pakistan in buildings to prevent heat transfer.
基金the financial support from the National Natural Science Foundation of China (21674019 and 21704014)the Fundamental Research Funds for the Central Universities(2232019A3-03)+3 种基金the Graduate Student Innovation Fund of Donghua University (CUSF-DH-D-2019006)Shanghai Sailing Program(17YF1400200)Shanghai Municipal Education Commission (17CG33)the Ministry of Education of the People’s Republic of China(6141A0202202)。
文摘Excellent thermal insulating materials are highly demanded in various applications including buildings, aerospace and sport equipment. However, in practical applications,the performance of thermal insulating materials usually deteriorates under diverse temperature and humidity conditions.Therefore, it is highly essential to construct a bulk material that exhibits outstanding thermal insulation performance under extremely humid and hot environment. In this work, we have conceived a green and effective strategy to fabricate a superhydrophobic and compressible polyvinylidene fluoride/polyimide(PVDF/PI) nanofiber composite aerogel via electrospinning and freeze-drying technique. Interestingly, the PVDF nanofibers and PI nanofibers function as the hydrophobic fibrous framework and mechanical support skeleton,respectively, forming a robust three-dimensional framework with good mechanical flexibility. The PVDF/PI aerogel possesses outstanding superhydrophobic feature(water contact angle of 152°) and low thermal conductivity(31.0 m W m^(-1)K^(-1))at room temperature. Significantly, even at 100% relative humidity(80℃), the PVDF/PI aerogel still exhibits a low thermal conductivity of only 48.6 m W m^(-1)K^(-1), which outperforms the majority of commercial thermal insulating materials. Therefore, the novel PVDF/PI aerogel is promising as an excellent thermal insulating material for the applications in high-temperature and humid environment.
