Mihailo S. Jaćović

Synthesis and rheological study of some maleic acid and fumaric acid stereoregular polyesters

SummaryFirst unsaturated polyester fibers were prepared starting from stereoregular, macromolecular poly(octamethylene fumarate). Fibers obtained from octamethylene copolyesters of fumaric and terephthalic acids manifested improved mechanical properties and higher melting points. All unsaturated polyester fibers prepared in the study, based on the homopolymer and on copolymers of fumaric acid, even those containing as low as 10% of fumaric acid residues, are able to be covalently bonded to an unsaturated polyester matrix.

Synthesis of some fumaric acid polyamides from active diester monomers

SummaryThe solution polycondensation of two active diesters, bis(2,4-dinitrophenyl) fumarate and 1,1′-(fumaroyldioxy)bis(benzotriazole), with a series of alphatic and aromatic diamines in N-methyl pyrolidone at room temperature, was investigated. The polycondensation reactions yielded a series of fumaric acids polyamides. The polymers obtained from aliphatic diamines were soluble in trifluroacetic acid and exhibited well-defined melting points. The polymers obtained from aromatic diamines are infusible at temperatures below 300°C but were thermally stable and soluble in dimethylacetamide containing 4% LiC1.

Viscoelastic properties of poly(dibutyl itaconate) melts

Complex dynamic viscosities η* of poly(dibutyl itaconate) melts were determined for nonuniform polymers with viscosity-average molecular weights varying from 8000 to 327000 in the temperature range from 323 to 463 K and the frequency range from 0,1 to 100 rad/s. By applying the time and temperature superposition principle, master curves for the selected reference temperature T0 = 383 K were obtained, permitting the estimation of the Newtonian viscosity in terms of molecular weights. The temperature dependence of viscous flow was analysed by verification of the linearity of the aT shift factor, interpreted via the Williams-Landel-Ferry equation. Deviations from linearity were observed only for very low molecular weights M and at the highest temperatures. The activation energy of viscous flow was calculated by applying the concept of absolute reaction rates and the concept of free volume. Good agreement was observed. The linearized η* vs. M dependence changes slope at a critical molar mass Mc = 69000 with exponents of M α = 1,05 below and β = 2,92 above the Mc value in the function η* = f(M). The rheological properties of poly(dibutyl itaconate) are discussed in terms of substituent size and compared to those of other related vinyl polymers.