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Polymer–solvent interactions of bisphenol a polycarbonate in different solvents

1965; Inderscience Publishers; Volume: 3; Issue: 8 Linguagem: Inglês

10.1002/pol.1965.100030803

1542-6246

G. Sitaramaiah,

Polymer Nanocomposites and Properties

Abstract Bisphenol A polycarbonate (Lexan, General Electric) was fractionated from methylene chloride by progressive precipitation with methanol and the fractions were characterized by osmometry, light scattering, and viscometry. Intrinsic viscosities of eight fractions in the molecular weight range 10,000–70,000 were obtained in five solvents at different temperatures to study the molecular expansion of polycarbonate. Light‐scattering molecular weights, measured for the three high viscosity fractions, agreed within ±5% with the M v values. The M v / M n ratio of the fractions was between 1.1 and 1.3, as compared to 2.7 for the unfractionated polymer. This indicates a relatively narrow distribution of the fractions. The exponent, a , in the Mark‐Houwink equation showed no appreciable change with temperature. Values of d [η]/ dT were generally negative. The unperturbed dimensions of polycarbonate, evaluated by the relation [η] = KM ½ ‐α 2.43 , suggest a stiff molecule. Values of K and d log α 3 / dT indicate increased chain flexibility at higher temperatures. Experimental data demonstrate that the Kurata‐Stockmayer‐Roig expression, based on the equivalent ellipsoidal model of a linear polymer molecule, is well suited to interpret the molecular expansion of polycarbonate. The Flory relation, α 5 − α 3 versus M ½ , is found to be of limited applicability.