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Feng R.-S.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Feng R.-S.,Southwest Petroleum University | Ji W.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Ji W.,Southwest Petroleum University | And 4 more authors.
Acta Polymerica Sinica | Year: 2014

Intrinsic viscosity and strength of hydrophobic association of hydrophobically associated water-soluble polymers (HAWSP) were investigated in different solvents containing formamide and salt, through the capillary tube method and fluorescence probe technique. Weight-average molecular weight of HAWSP was measured by static light scattering method under suitable solvent conditions that could eliminate the hydrophobic association and polyelectrolyte effect. The experimental results showed that NaCl had the capability of eliminating the polyelectrolyte effect, but NaCl can not destroy hydrophobic association. And NaCl promoted hydrophobic interaction because of increasing the polarity of HAWSP solutions. Macromolecular aggregation would be greater at higher levels of hydrophobe, which explains the observed rise in molecular weight. As a result, the weight-average molecular weight of HAWSP measured in NaCl solvent was not the real molecular weight. However, hydrophobic association can be completely destroyed by formamide. Moleculars of HAWSP dispersed in the formamide solvent, and real molecular weight of HAWSP can be measured. The results showed that weight-average molecular weight of HAWSP can be measured accurately in 50% formamide solvent with 0. 2 mol/L NaCl. When hydrophobic association was eliminated completely, the values of weight-average molecular weight were identical with increasing formamide concentration; when the polyelectrolyte effect was removed, altering the salt concentration would not change the results of weight-average molecular weight.


Feng R.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Feng R.,Southwest Petroleum University | Sun J.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Sun J.,Southwest Petroleum University | And 4 more authors.
Speciality Petrochemicals | Year: 2014

The photopolymeruation process and the controllahle factors were discussed by the initiation mechanism of photoinitiator, and a novel rotary type photopolymerization reactor was designed to get control of these factors. Polyacrylamide was synthesized using 2-hydroxy-2-methyl-l-[4 (2-hydroxyc-thoxy) phenyl]-l-propanone as photoinitiator in aqueous solution under photopolymerization. The methods of orthogonal design and uniform design were employed to study on the controllable factors, such as light intensity, the inner diameter of reaction vessel, rotation speed and reaction time, and the regression equation was created by the mathematical analysis software. The optimum polymerization conditions were described with the maxima value of regression equation as follows: light intensity was 0. 15 mW/cm2 , the inner diameter of reaction vessel was 36 mm, rotation speed was 10 r/min and reaction time was 135 min. Under the optimal conditions, it was obtained that the relative molecular weight of polyacrylamide was about 2. 1 X 107 and the monomer conversion was more than 98%.


Feng K.-S.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Feng K.-S.,Southwest Petroleum University | Guo Y.-J.,State Key Laboratory of Oil and Gas Reservoirs Geology and Exploration | Guo Y.-J.,Sichuan Guangya Polymer Chemical Company | And 6 more authors.
Acta Polymerica Sinica | Year: 2016

The hydrophobic association and polyelectrolyte effect of hydrophobically associated water-soluble polymers (HAWSP) were eliminated in solvents containing 50% (volume percent concentration) 1, 3-propylene glycol, 0. 2 mol/L NaCl and water that could make molecules of HAWSP disperse in dilute solutions. Then the polymers of different molecular weights were split through the microporous membrane equipment with different aperture microporous membranes according to the principle of membrane aperture separation. The cumulative percentage of each fraction was calculated through the quantity of each fraction polymer solution which was measured by the curve of percolate quantity-filtration time fitted with a quadratic equation, and the concentration of each fraction polymer solution was measured by spectrophotometry. The Mark-Houwink equation [η] = 0. 182M0.586 of HAWSP which was used to accurately determine the molecular weight of each HAWSP fraction, was calibrated through the static light scattering and capillary tube viscosity methods. The molecular weight distribution curve was determined according to the molecular weight (M) and cumulative percentage (W) of each fraction by using the 4-parameter equation curve. The method of microporous membrane grading to determine the molecular weight distribution of HAWSP was compared with the method of dynamic light scattering for measurement of particle size, the results of the two methods were consistent with each other.

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