Reference

Possibility of directed change of the properties of aqueous poly(acrylic acid) solutions

Possibility of directed change of the properties of aqueous poly(acrylic acid) solutions. Zabotin, K. P.; Golovina, A. P. (USSR). Tr. Khim. Khim. Tekhnol., (3), 50-2 (Russian) 1975. CODEN: TKKTAE. DOCUMENT TYPE: Journal CA Section: 35 (Synthetic High Polymers) The viscosity of aq. poly(acrylic acid) (I) [9003-01-4] could be regulated by conducting the soln. polymn. in the presence of ammonium peroxydisulfate [7727-54-0]-potassium pyrosulfate [7790-62-7] oxidn.-redn. system of various ratios, or by adding oxidizing or reducing agents to I solns. after polymn. The changes occurring in I solns. in the presence of peroxides are caused by the oxidn. of I to hydroperoxides, which decompose to free radicals. In aq. solns. these polymeric radicals undergo mainly recombination to form branched, then crosslinked structures. The presence of reducing agents in I solns. inhibits free radical processes and maintains the viscosity of the solns. at a const. value during storage.

Complex formation in pyrosulfate melts

Complex formation in pyrosulfate melts. 3. Density and conductometric measurements of the system vanadium pentoxide-potassium pyrosulfate in the temperature range 350-490°C. Hatem, Gerard; Fehrmann, Rasmus; Gaune-Escard, Marcelle; Bjerrum, Niels J. (Chem. Dep. A, Tech. Univ. Denmark, Lyngby DK-2800, Den.). J. Phys. Chem., 91(1), 195-203 (English) 1987. CODEN: JPCHAX. ISSN: 0022-3654. DOCUMENT TYPE: Journal CA Section: 68 (Phase Equilibriums, Chemical Equilibriums, and Solutions) The densities of the molten V2O5-K2S2O7 system were measured at 11 different compns. in the mol fraction range XV2O5 = 0-0.399 and in the temp. range 360-490°. For each compn. the measurements were fitted to an equation of the form r = A(X) + B(X)(t - 450). All measured data were fitted to a general polynomial r = ?0n AnXn + ?1m Bm(t - 450)m. Excess molar vols. were calcd. for this compn. range. The max. deviation from ideality was found at XV2O5 ~0.3-0.4, indicating complex formation in the melt. The sp. conductivities of the solid and molten V2O5-K2S2O7 system were measured at 15 different compns. in the compn. range XV2O5 = 0-0.5266 and in the temp. range 350-480°. For each compn. in the examd. temp.Several substances with their cas registry numbers 7790-62-7 and 1314-62-1 may be metioned in this study. range, the sp. cond. was expressed by equations of the form k = A(X) + B(X)(t - 450) + C(X)(t - 450)2 + D(X)(t - 450)3. All cond. measurements were fitted to a general polynomial of the type k = ?0n AnXn + ?1m Bm(t - 450)m. The activation energy of the equiv. cond. of the K+ ions in the melt was also calcd. for the given compns. and a large increase was found at increasing mol fractions of XV2O5. This effect is probably due to polymn. in the melt. The exptl. molar cond. of the melt was found at all compns. and compared with theor. values. The large neg. deviations between theor. values and exptl. values are most probably due to complex formation in the melt. The combined results of the 2 methods are in agreement with the concept of complex formation at the compns. K2S2O7:V2O5 2:1 and 1:1. These 2 compns. correspond to max. concns. of the likely species, dimeric (VO2)2(SO4)2S2O74- and polymeric (VO2SO4)nn-, resp. .