Flow of mixtures of poly(ethylene oxide) and hydrolyzed polyacrylamide solutions through opposed jets

The flow of solutions of poly(ethylene oxide) (PEO), hydrolyzed polyacrylam ide (HPAA), and their blends through opposed jets is investigated. Measurem ents of pressure drop across the jets as a function of strain rate were use d to characterize the elongational flow behavior. In deionized water, solut ions of PEO/HPAA mixtures exhibit a synergistic increase in flow resistance with respect to the parent polymer solutions. The addition of amounts of H PAA as low as 2 ppm to a 500 ppm PEO solution cause sizeable increases in p ressure drops. Such increases have been interpreted as arising from the for mation of interpolymer transient entanglement networks that become mechanic ally active at time scales equivalent to the lowest strain rates available. In the case of excess salt environment, the flow resistance of the mixture s seems to be dominated by the PEO in the concentration range explored. (C) 2000 John Wiley & Sons, Inc.