Browsing by Author "PIEROLA, IF"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    COMPLEXATION OF POLY(MONOBENZYL ITACONATE) AND POLY(N-VINYL-2-PYRROLIDONE) IN DILUTE-SOLUTION
    (1989) PEREZDORADO, A; PIEROLA, IF; BASELGA, J; GARGALLO, L; RADIC, D
  • No Thumbnail Available
    Item
    COMPLEXATION OF POLY(MONOBENZYL ITACONATE) AND POLY(N-VINYL-2-PYRROLIDONE) IN DILUTE-SOLUTION .2. INFLUENCE OF VARIABLES INVOLVED IN SAMPLE PREPARATION
    (1990) PEREZDORADO, A; PIEROLA, IF; BASELGA, J; GARGALLO, L; RADIC, D
    Upon mixing dilute solutions of poly(monobenzyl itaconate)c) (PMBI) and poly(N-vinyl-2-pyrrolidone) (PVP) in methanol, a soluble interpolymer complex is formed whose properties depend on the method employed to prepared the sample. It was found that the local concentration of the polyacid is the controlling factor. Depending on that concentration, a metastable polymer complex is formed which turns to equilibrium upon sonication. Cooling or heating and aging time have a minor effect. The turbidity of the polymer complex depends on the polyacid concentration to the power-nu (at constant polybase/polyacid ratio). For the metastable complex, nu-almost-equal-to 2, typical of weak polymer complexes. Changes in turbidity are accompanied by a decrease in nu. In the equilibrium state, nu almost-equal-to 1,5 a value being more typical of strong complexes.
  • No Thumbnail Available
    Item
    EXCIMER FORMATION IN CHAIN SELF-CONTACT POINTS
    (1991) RENAMAYOR, CS; GOMEZANTON, MR; CALAFATE, B; MANO, EB; RADIC, D; GARGALLO, L; FREIRE, JJ; PIEROLA, IF
    Fluorescence spectra of poly(indene) (PIN) and poly(acenaphthylene) (PAN) samples of molecular weight ranging from 1.8 x 10(3) to 2.9 x 10(5) were measured in dilute solution at different temperatures (2, 10, 25, and 40-degrees-C). The fluorescence ratio (I(E)/I(M)) of PIN decreases upon increasing the chain molecular weight and becomes zero for chains of about 500 monomeric units. By contrast, the fluorescence ratio of PAN increases with molecular weight. The temperature dependence is also different for both polymers: in the range of temperatures studied here, PIN is in the high-temperature limit and PAN is in the low-temperature limit. These results are interpreted in terms of the number of chain self-contact points in the equilibrium conformation and also taking into account segmental diffusion. Monte Carlo simulation results of the number of self-contact points in Gaussian chains of different length are also presented.
  • No Thumbnail Available
    Item