Synthesis, Characterization, Properties Of Temperature-resistance And Salt-resistance Polyacrylamides

Polyacrylamide (PAM) is commonly used as thickening agent in the third process of oil recovery, and to improve its temperature-resistance, salt-resistance and shear-resistance are the key aspects. The ultrahigh molecular weight partially hydrolyzed polyacrylamide (HPAM) and hydrophobically-modified polyacrylamides are the two main products of temperature-resistance and salt-resistance polyacrylamides which are used as thickening agents. In this thesis, the measurement of hydrolysis degree and molecular weight of ultrahigh molecular weight partially hydrolyzed polyacrylamide was studied, and the synthesis and rheological properties of cation hydrophobically-modified polyacrylamides were also investigated. In this paper, different molecular weight of PAM and HPAM with various hydrolysis degree from the same PAM were synthesized. The applicability of pH potentiometer titration and conductance titration which were used to measure the hydrolysis degree of HPAM was comparatively studied. The Molecular weight (Mw) of PAM was measured by static light scattering and the intrinsic viscosity [η] of PAM and HPAM was measured in 1M NaCl-citric acid- K2HPO4 aqueous solution with the temperature 30℃. The range of molecular weight of PAM was 3.75*106-20.4*106 and the MHS equation of PAM was established as: [η]=5.987*10?3Mw0.7833The revised MHS equation of HPAM with the molecular weight of PAM: 3.75*106-16.1*106 and hydrolysis degree: 0-40mol% was also established as: [η]= 3.54×10?3 M w 0.8196+5.175×10?4(1?h1/2)h?Mw1.027 It showed that the first equation was accord with GB 12005.1-89, and the error was within 10%; the second equation was consistent with theory of expansion for polyelectrolyte and it was accurate and covered quite extensive molecular weight range. The error was commonly within 15%, but it would be within 10% if the hydrolysis degree of HPAM was in the range of 4-35%.Thereinto, The intrinsic viscosity [η] of PAM and HPAM with middle or low molecular weight could be extrapolated by the point of intersection of Huggins and Kraemer equations, while KH from Huggins equation and Kk from Kraemer equation were hardly affected by shear rate; the intrinsic viscosity [η] of PAM and HPAM of ultrahigh molecular weight could be extrapolated by either Schulz-Blaschke or Huggins equation, while Kk>>KH≈Ks≈0was resulted from high shear rate.