Novel conjugated polymers based on squaric acid having 2,5-Bis[（E）-N-alkylpyrrol-2-ylvinyl]-3-alkylthiophene （PVTVP） unit in the main chain were successfully synthesized in good yields through polycondensation rea...Novel conjugated polymers based on squaric acid having 2,5-Bis[（E）-N-alkylpyrrol-2-ylvinyl]-3-alkylthiophene （PVTVP） unit in the main chain were successfully synthesized in good yields through polycondensation reaction. Their molecular structures were characterized by PT-IR and IH NMR. They have good solubility in common organic solvents, good thermal stability by thermal gravimetric analysis and high molecular weights. Their optical properties were investigated by UV-vis absorption spectra in CH2C12 solution, the results indicated all these compounds showed broad and strong spectral responses from 200 nm to 900 nm, suggesting their potential for application as organic plastic solar cells.展开更多
The abundance of synthetic polymers has increased due to their uncontrolled utilization and disposal in the environment.The recalcitrant nature of plastics leads to accumulation and saturation in the environment,which...The abundance of synthetic polymers has increased due to their uncontrolled utilization and disposal in the environment.The recalcitrant nature of plastics leads to accumulation and saturation in the environment,which is a matter of great concern.An exponential rise has been reported in plastic pollution during the corona pandemic because of PPE kits,gloves,and face masks made up of single-use plastics.The physicochemical methods have been employed to degrade synthetic polymers,but these methods have limited efficiency and cause the release of hazardous metabolites or by-products in the environment.Microbial species,isolated from landfills and dumpsites,have utilized plastics as the sole source of carbon,energy,and biomass production.The involvement of microbial strains in plastic degradation is evident as a substantial amount of mineralization has been observed.However,the complete removal of plastic could not be achieved,but it is still effective compared to the preexisting traditional methods.Therefore,microbial species and the enzymes involved in plastic waste degradation could be utilized as eco-friendly alternatives.Thus,microbial biodegradation approaches have a profound scope to cope with the plastic waste problem in a cost-effective and environmental-friendly manner.Further,microbial degradation can be optimized and combined with physicochemical methods to achieve substantial results.This review summarizes the different microbial species,their genes,biochemical pathways,and enzymes involved in plastic biodegradation.展开更多
Wood plastic biocomposites of biodegradable poly（butylene succinate） （PBS） and Padauk sawdust was successfully pre- pared by using a twin screw extruder and an injection molding machine. The effects of water absor...Wood plastic biocomposites of biodegradable poly（butylene succinate） （PBS） and Padauk sawdust was successfully pre- pared by using a twin screw extruder and an injection molding machine. The effects of water absorption and sunlight exposure on some properties of the composites were investigated. Water absorption of PBS composites was found to follow the Fick＇s law of diffusion, while the diffusion coefficient increased with increasing wood content. Maximum water absorption of around 4.5% was observed at 30 wt.% sawdust. Optical micrograph indicated the swelling of wood particles by around 1% - 3% after 30 days of water immersion. The tensile and flexural strengths reduced slightly both under the water immersion and sunlight exposure. After 90 days of exposure, the composites clearly looked paler than the non-weathered ones. Thermal scan indicated the re- duction of crystalline region due to the plasticization effect derived from water molecules.展开更多
The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to pr...The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.展开更多
Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed...Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed specimens were characterized using scanning electron microscopy and standard tensile testing. It was observed that recycled polypropylene filaments with 14 wt% short carbon fibre reinforcement contained pores that were dispersed throughout the microstructure of the filament. A two-stage filament extrusion process was observed to improve the spatial distribution of carbon fibre reinforcement but did not reduce the pores. Recycled polypropylene filaments without reinforcement extruded at high screw speeds above 20 rpm contained a centreline cavity but no spatially distributed pores. However, this cavity is eliminated when extrusion is carried out at screw speeds below 20 rpm. For 3D printed specimens, interlayer cavities were observed larger for specimens printed from 14 wt% carbon fibre reinforced recycled polypropylene than those printed from unreinforced filaments. The values of tensile strength for the filaments were 21.82</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 24.22</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, which reduced to 19.72</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 22.70</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, respectively, for 3D printed samples using the filaments. Likewise, the young’s modulus of the filaments was 1208.6</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 1412.7</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, which reduced to 961.5</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 1352.3</span><spa展开更多
Plastic wastes are a major environmental concern that needs to be dealt with to minimize the amount of municipal solid waste and depletion of natural resources thus enhancing the sustainability concept for future gene...Plastic wastes are a major environmental concern that needs to be dealt with to minimize the amount of municipal solid waste and depletion of natural resources thus enhancing the sustainability concept for future generations. The objective of this study is to enhance the properties of plastic products using plastic wastes reinforced with treated natural fibers such as rice straw as well as carbonized rice straw, using a simple and efficient technology.展开更多
文摘Novel conjugated polymers based on squaric acid having 2,5-Bis[（E）-N-alkylpyrrol-2-ylvinyl]-3-alkylthiophene （PVTVP） unit in the main chain were successfully synthesized in good yields through polycondensation reaction. Their molecular structures were characterized by PT-IR and IH NMR. They have good solubility in common organic solvents, good thermal stability by thermal gravimetric analysis and high molecular weights. Their optical properties were investigated by UV-vis absorption spectra in CH2C12 solution, the results indicated all these compounds showed broad and strong spectral responses from 200 nm to 900 nm, suggesting their potential for application as organic plastic solar cells.
基金the research fellowship provided by the Ministry of Education(MoE),Govt.of India to the first author.
文摘The abundance of synthetic polymers has increased due to their uncontrolled utilization and disposal in the environment.The recalcitrant nature of plastics leads to accumulation and saturation in the environment,which is a matter of great concern.An exponential rise has been reported in plastic pollution during the corona pandemic because of PPE kits,gloves,and face masks made up of single-use plastics.The physicochemical methods have been employed to degrade synthetic polymers,but these methods have limited efficiency and cause the release of hazardous metabolites or by-products in the environment.Microbial species,isolated from landfills and dumpsites,have utilized plastics as the sole source of carbon,energy,and biomass production.The involvement of microbial strains in plastic degradation is evident as a substantial amount of mineralization has been observed.However,the complete removal of plastic could not be achieved,but it is still effective compared to the preexisting traditional methods.Therefore,microbial species and the enzymes involved in plastic waste degradation could be utilized as eco-friendly alternatives.Thus,microbial biodegradation approaches have a profound scope to cope with the plastic waste problem in a cost-effective and environmental-friendly manner.Further,microbial degradation can be optimized and combined with physicochemical methods to achieve substantial results.This review summarizes the different microbial species,their genes,biochemical pathways,and enzymes involved in plastic biodegradation.
文摘Wood plastic biocomposites of biodegradable poly（butylene succinate） （PBS） and Padauk sawdust was successfully pre- pared by using a twin screw extruder and an injection molding machine. The effects of water absorption and sunlight exposure on some properties of the composites were investigated. Water absorption of PBS composites was found to follow the Fick＇s law of diffusion, while the diffusion coefficient increased with increasing wood content. Maximum water absorption of around 4.5% was observed at 30 wt.% sawdust. Optical micrograph indicated the swelling of wood particles by around 1% - 3% after 30 days of water immersion. The tensile and flexural strengths reduced slightly both under the water immersion and sunlight exposure. After 90 days of exposure, the composites clearly looked paler than the non-weathered ones. Thermal scan indicated the re- duction of crystalline region due to the plasticization effect derived from water molecules.
文摘The potential usage of virgin Low density polyethelyne (LDPE) reinforced with different concentrations (2%, 5% and 6% by weight) of treated rice straw with different lengths (2 mm, 4 mm and 6 mm) is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.
文摘Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed specimens were characterized using scanning electron microscopy and standard tensile testing. It was observed that recycled polypropylene filaments with 14 wt% short carbon fibre reinforcement contained pores that were dispersed throughout the microstructure of the filament. A two-stage filament extrusion process was observed to improve the spatial distribution of carbon fibre reinforcement but did not reduce the pores. Recycled polypropylene filaments without reinforcement extruded at high screw speeds above 20 rpm contained a centreline cavity but no spatially distributed pores. However, this cavity is eliminated when extrusion is carried out at screw speeds below 20 rpm. For 3D printed specimens, interlayer cavities were observed larger for specimens printed from 14 wt% carbon fibre reinforced recycled polypropylene than those printed from unreinforced filaments. The values of tensile strength for the filaments were 21.82</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 24.22</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, which reduced to 19.72</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 22.70</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, respectively, for 3D printed samples using the filaments. Likewise, the young’s modulus of the filaments was 1208.6</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 1412.7</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa, which reduced to 961.5</span><span style="font-size:10pt;font-family:""> </span><span style="font-family:Verdana;">MPa and 1352.3</span><spa
文摘Plastic wastes are a major environmental concern that needs to be dealt with to minimize the amount of municipal solid waste and depletion of natural resources thus enhancing the sustainability concept for future generations. The objective of this study is to enhance the properties of plastic products using plastic wastes reinforced with treated natural fibers such as rice straw as well as carbonized rice straw, using a simple and efficient technology.
