Decreasing the acetic acid consumption in purified terephthalic acid （PTA） solvent system has become a hot issue with common concern. In accordance with the technical features, the electrical conductivity is in dire...Decreasing the acetic acid consumption in purified terephthalic acid （PTA） solvent system has become a hot issue with common concern. In accordance with the technical features, the electrical conductivity is in direct proportion to the acetic acid content. General regression neural network （GRNN） is used to establish the model of electrical conductivity on the basis of mechanism analysis, and then particle swarm optimization （PSO） algorithm with the improvement of inertia weight and population diversity is proposed to regulate the operating conditions. Thus, the method of decreasing the acid loss is derived and applied to PTA solvent system in a chemical plant. Cases studies show that the precision of modeling and optimization are higher. The results also provide the optimal operating conditions, which decrease the cost and improve the profit.展开更多
The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature a...The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.展开更多
基金Supported by the National Natural Science Foundation of China （60774079）, the National High Technology Research and Development Program of China （2006AA04Z184）, and Sinopec Science ＆ Technology Development Project of China （205073）.
文摘Decreasing the acetic acid consumption in purified terephthalic acid （PTA） solvent system has become a hot issue with common concern. In accordance with the technical features, the electrical conductivity is in direct proportion to the acetic acid content. General regression neural network （GRNN） is used to establish the model of electrical conductivity on the basis of mechanism analysis, and then particle swarm optimization （PSO） algorithm with the improvement of inertia weight and population diversity is proposed to regulate the operating conditions. Thus, the method of decreasing the acid loss is derived and applied to PTA solvent system in a chemical plant. Cases studies show that the precision of modeling and optimization are higher. The results also provide the optimal operating conditions, which decrease the cost and improve the profit.
文摘The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.
