Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion.Although,...Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion.Although,several debatable issues including feedstock availability and price,fuel and food competition,changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel.However,non-crop feedstocks could be a promising alternative.In this article,waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation.The important factors such as the quantity of waste cooking oil produced,crude oil and vegetable oil import expenses,high-speed diesel imports,waste management issues and environmental hazards are considered.Moreover,process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted.The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66 USD·L-1.We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.展开更多
Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or ...Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate （10 nrn/s） to a maximum indentation displacernent （1000 nrn）. A 30-second hold segrnent was included at the maximum load to account for any creep eft）ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode （CSM） indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values.展开更多
基金Supported by Higher Education Commission(HEC)of Pakistan(No.21-1084).
文摘Biodiesel utilization has been rapidly growing worldwide as the prime alternative to petrodiesel due to a global rise in diesel fuel demand along with hazardous emissions during its thermochemical conversion.Although,several debatable issues including feedstock availability and price,fuel and food competition,changes in land use and greenhouse gas emission have been raised by using edible as well as inedible feedstocks for the production of biodiesel.However,non-crop feedstocks could be a promising alternative.In this article,waste cooking oils have been recommended as a suitable option for biodiesel production bearing in mind the current national situation.The important factors such as the quantity of waste cooking oil produced,crude oil and vegetable oil import expenses,high-speed diesel imports,waste management issues and environmental hazards are considered.Moreover,process simulation and operating cost evaluation of an acid catalyzed biodiesel production unit are also conducted.The simulation results show that the production cost of waste cooking oil-based biodiesel is about 0.66 USD·L-1.We believe that the present overview would open new pathways and ideas for the development of biofuels from waste to energy approach in Pakistan.
文摘Poly（ether ether ketone） （PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate （10 nrn/s） to a maximum indentation displacernent （1000 nrn）. A 30-second hold segrnent was included at the maximum load to account for any creep eft）ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode （CSM） indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values.
