The dimeric property of bis(2 - ethylhexyl) phosphoric acid(HDEHP) in different diluents has been studied. The experimental results show that the dimeric degree of HDEHP increases with the decrease of the polarity of ...The dimeric property of bis(2 - ethylhexyl) phosphoric acid(HDEHP) in different diluents has been studied. The experimental results show that the dimeric degree of HDEHP increases with the decrease of the polarity of diluents.This kind of effect has been discussed from the point of view of intermolecular interactions between the extractant molecules and the diluent ones. The dimeric constantswere related to the physical constants and experiencial parameters of the diluents.The following expression hasbeen obtained lg K2 =6 .4 5 9- 4 .4 6 4 (ε- 1) /(2 ε+ 1) - 1.96 5 (n D2 - 1) /(n D2 +1) - 3.199α- 5 .6 6β.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
文摘The dimeric property of bis(2 - ethylhexyl) phosphoric acid(HDEHP) in different diluents has been studied. The experimental results show that the dimeric degree of HDEHP increases with the decrease of the polarity of diluents.This kind of effect has been discussed from the point of view of intermolecular interactions between the extractant molecules and the diluent ones. The dimeric constantswere related to the physical constants and experiencial parameters of the diluents.The following expression hasbeen obtained lg K2 =6 .4 5 9- 4 .4 6 4 (ε- 1) /(2 ε+ 1) - 1.96 5 (n D2 - 1) /(n D2 +1) - 3.199α- 5 .6 6β.
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%.
