A thermogravimetric analysis (TG) was conducted to study the thermal decomposition behavior and kinetics of composites from coal and high density polyethylene (HDPE), linear low density polyethylene (LLDPE) or low den...A thermogravimetric analysis (TG) was conducted to study the thermal decomposition behavior and kinetics of composites from coal and high density polyethylene (HDPE), linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). The results show that coal facilitates melting of the polyethylene before temperatures reach 700 K in nitrogen due to the exothermic effect of coal. Above 700 K, adding coal into the polyethylene will result in smaller maximum rates of mass loss and higher initial mass loss temperatures of the composites. Hence, some chemical interactions, occurring between liquid compounds released in the pyrolysis of the coal and polymer, depend on several factors, such as coal rank and the molecular structure of polymers. Synergetic effects in coal and polymers were also found. Both chemical interactions and synergetic effects control the entire thermal decomposition behavior of compos- ites. The larger the amount of coal in the composites, the greater the decomposition temperature spans and the higher the maximum decomposition temperature, the smaller the devolatilization rates. The effect of coal on the thermal stability of composites lies in the hydrogen acceptor effect of the coals. Thermal decomposition of the coals, the polymers and related composites can be modelled via first order parallel reactions between 563 K and 763 K.展开更多
This paper measured permeability of three-dimension braided preform by radial technology. The results show that principal permeability tensor coincided with their braiding axial direction. The software of one dimensio...This paper measured permeability of three-dimension braided preform by radial technology. The results show that principal permeability tensor coincided with their braiding axial direction. The software of one dimensional flow filling mold was designed using Visual C++ language. Filling time is predicted and validated. The result showed that the filling time of the mold centerline agrees with the prediction value. The filling time of the mould edge is shorter than that of the prediction. An actual plate of 3D braided preform/ modified polyarylacetylene composite is produced according to prediction value and validation analysis.展开更多
WPC （wood plastic composites） are a young generation of composites with rapidly growing usage within the plastics industry. The advantages are the availability and low price of the wood particles, the possibility of...WPC （wood plastic composites） are a young generation of composites with rapidly growing usage within the plastics industry. The advantages are the availability and low price of the wood particles, the possibility of partially substituting the polymer in the mixture and sustainable use of the earth＇s resources. The current WPC products on the market are to a large extent limited to extruded products. Nowadays, there is a great interest in the market for consumer products in more use of WPC as an alternative to pure thermoplastics in injection molding processes. This work presents the results of numerical simulation and experimental visualization of the mold filling process in injection molding of WPC. The 3D injection molding simulations were done with the commercial software package Autodesk~ Moldflow Insight 2016 （AMI）. The mold filling experiments were conducted with a box-shaped test part. In contrast to unfilled polymers, the WPC has reduced melt elasticity so that the fountain flow often does not develop. This results in irregular flow front shapes in the molded part, especially at high filler content.展开更多
The long-term stability of large-span soft rock tunnel is influenced greatly by the creep effect of surrounding rock.The development of a new type of foam concrete which has the property of high compressibility and lo...The long-term stability of large-span soft rock tunnel is influenced greatly by the creep effect of surrounding rock.The development of a new type of foam concrete which has the property of high compressibility and low ductility was introduced.And it was made as filling material of reserved deformation layer between the first lining and the second lining used in large-span soft rock tunnel.The effect of the new type of foam concrete was simulated as filling material of reserved deformation layer using numerical simulation.Through the comparison with the common large-span soft rock tunnel,the vault settlement and surrounding convergence are reduced by about 61% and 45%,respectively,after creep of 100 a.And in the second lining,the plastic zone reduces apparently and the maximum equivalent plastic strain decreases relatively.So,it can be found that the application of the new type of foam concrete as the filling material of reserved deformation layer can relieve the excessive force in second lining induced by rock creep,reduce its deformation and improve the stability of tunnel.展开更多
In Mexico, garbage represents a high pollution index according to national and international organizations; eighty percent of waste products stay in sanitary landfills, out of doors, where no tailings management exist...In Mexico, garbage represents a high pollution index according to national and international organizations; eighty percent of waste products stay in sanitary landfills, out of doors, where no tailings management exists. Plastic products represent 16% of this pollution （one and one-half kilos daily per person in a country with a population of 107 million people）. These sanitary landfills are methane deposits, and consequently emit gases and toxins that cause serious health problems. The object of this is to analyze governmental programs, strategies, policies and procedures which regulate both industrial sectors and society. Society and government share a responsibility since they must implement norms which include the separation, reduction, recycling and reuse of garbage. Results demonstrate that government strategies used to treat railings are complex and are directed more towards sanctions than to motivation. Furthermore these strategies discourage a cultural transformation toward industrial sustainability. Instead of reducing the garbage accumulation problem, they increase the difficulty.展开更多
The demand for fossil fuel is at an all time high worldwide. Annually-30 billion barrels of petroleum is being consumed worldwide. In this busy society, transportation is vital and, for transportation, petroleum is a ...The demand for fossil fuel is at an all time high worldwide. Annually-30 billion barrels of petroleum is being consumed worldwide. In this busy society, transportation is vital and, for transportation, petroleum is a requirement. All the major forms of business, agricultural, exports and imports depend on transportation. There are three forms of major transportation： by ground, air and sea. These transportations require petroleum to function. Vehicles in the road require gasoline/diesel, airway transportation requires aviation fuel and sea transportation requires fuel oil and other forms of fuels. For not only transportation but, petroleum is required to make all kind of daily use plastics. If the consumption of petroleum continues this way, it will be finished in the near future. Emissions released from evaporation and combustion of these fuel contribute to many environmental and health problems, including emitting greenhouse gases that contribute immensely to global warming. Annually-7 billion tons of carbon is released to the environment due to burning of petroleum. Moreover, when the plastics are discarded into the landfill, it becomes waste plastic and since plastic is non-biodegradable, it can remain in the landfill for a long time. Waste plastics presence in the landfill causes environmental problems for example, it can cause soil to decay, pollute underground water resource and cause land to be infertile. Alternative source of energy created from solar, wind, hydrogen fuel, biomass fuel, bio-diesel, green diesel, bio-ethanol, and geo-thermal has been proposed as a solution to these problems and in future with further research, these alternative sources will play an important role in the field of alternative energy.展开更多
基金Project 06JK244 supported by the Special Foundation of Education Department of Shaanxi Province
文摘A thermogravimetric analysis (TG) was conducted to study the thermal decomposition behavior and kinetics of composites from coal and high density polyethylene (HDPE), linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). The results show that coal facilitates melting of the polyethylene before temperatures reach 700 K in nitrogen due to the exothermic effect of coal. Above 700 K, adding coal into the polyethylene will result in smaller maximum rates of mass loss and higher initial mass loss temperatures of the composites. Hence, some chemical interactions, occurring between liquid compounds released in the pyrolysis of the coal and polymer, depend on several factors, such as coal rank and the molecular structure of polymers. Synergetic effects in coal and polymers were also found. Both chemical interactions and synergetic effects control the entire thermal decomposition behavior of compos- ites. The larger the amount of coal in the composites, the greater the decomposition temperature spans and the higher the maximum decomposition temperature, the smaller the devolatilization rates. The effect of coal on the thermal stability of composites lies in the hydrogen acceptor effect of the coals. Thermal decomposition of the coals, the polymers and related composites can be modelled via first order parallel reactions between 563 K and 763 K.
文摘This paper measured permeability of three-dimension braided preform by radial technology. The results show that principal permeability tensor coincided with their braiding axial direction. The software of one dimensional flow filling mold was designed using Visual C++ language. Filling time is predicted and validated. The result showed that the filling time of the mold centerline agrees with the prediction value. The filling time of the mould edge is shorter than that of the prediction. An actual plate of 3D braided preform/ modified polyarylacetylene composite is produced according to prediction value and validation analysis.
文摘WPC （wood plastic composites） are a young generation of composites with rapidly growing usage within the plastics industry. The advantages are the availability and low price of the wood particles, the possibility of partially substituting the polymer in the mixture and sustainable use of the earth＇s resources. The current WPC products on the market are to a large extent limited to extruded products. Nowadays, there is a great interest in the market for consumer products in more use of WPC as an alternative to pure thermoplastics in injection molding processes. This work presents the results of numerical simulation and experimental visualization of the mold filling process in injection molding of WPC. The 3D injection molding simulations were done with the commercial software package Autodesk~ Moldflow Insight 2016 （AMI）. The mold filling experiments were conducted with a box-shaped test part. In contrast to unfilled polymers, the WPC has reduced melt elasticity so that the fountain flow often does not develop. This results in irregular flow front shapes in the molded part, especially at high filler content.
基金Projects(41072238,51009133)supported by the National Natural Science Foundation of China
文摘The long-term stability of large-span soft rock tunnel is influenced greatly by the creep effect of surrounding rock.The development of a new type of foam concrete which has the property of high compressibility and low ductility was introduced.And it was made as filling material of reserved deformation layer between the first lining and the second lining used in large-span soft rock tunnel.The effect of the new type of foam concrete was simulated as filling material of reserved deformation layer using numerical simulation.Through the comparison with the common large-span soft rock tunnel,the vault settlement and surrounding convergence are reduced by about 61% and 45%,respectively,after creep of 100 a.And in the second lining,the plastic zone reduces apparently and the maximum equivalent plastic strain decreases relatively.So,it can be found that the application of the new type of foam concrete as the filling material of reserved deformation layer can relieve the excessive force in second lining induced by rock creep,reduce its deformation and improve the stability of tunnel.
文摘In Mexico, garbage represents a high pollution index according to national and international organizations; eighty percent of waste products stay in sanitary landfills, out of doors, where no tailings management exists. Plastic products represent 16% of this pollution （one and one-half kilos daily per person in a country with a population of 107 million people）. These sanitary landfills are methane deposits, and consequently emit gases and toxins that cause serious health problems. The object of this is to analyze governmental programs, strategies, policies and procedures which regulate both industrial sectors and society. Society and government share a responsibility since they must implement norms which include the separation, reduction, recycling and reuse of garbage. Results demonstrate that government strategies used to treat railings are complex and are directed more towards sanctions than to motivation. Furthermore these strategies discourage a cultural transformation toward industrial sustainability. Instead of reducing the garbage accumulation problem, they increase the difficulty.
文摘The demand for fossil fuel is at an all time high worldwide. Annually-30 billion barrels of petroleum is being consumed worldwide. In this busy society, transportation is vital and, for transportation, petroleum is a requirement. All the major forms of business, agricultural, exports and imports depend on transportation. There are three forms of major transportation： by ground, air and sea. These transportations require petroleum to function. Vehicles in the road require gasoline/diesel, airway transportation requires aviation fuel and sea transportation requires fuel oil and other forms of fuels. For not only transportation but, petroleum is required to make all kind of daily use plastics. If the consumption of petroleum continues this way, it will be finished in the near future. Emissions released from evaporation and combustion of these fuel contribute to many environmental and health problems, including emitting greenhouse gases that contribute immensely to global warming. Annually-7 billion tons of carbon is released to the environment due to burning of petroleum. Moreover, when the plastics are discarded into the landfill, it becomes waste plastic and since plastic is non-biodegradable, it can remain in the landfill for a long time. Waste plastics presence in the landfill causes environmental problems for example, it can cause soil to decay, pollute underground water resource and cause land to be infertile. Alternative source of energy created from solar, wind, hydrogen fuel, biomass fuel, bio-diesel, green diesel, bio-ethanol, and geo-thermal has been proposed as a solution to these problems and in future with further research, these alternative sources will play an important role in the field of alternative energy.
