Branko Dunjic

Rheological study of the copolymerization reaction of acrylate‐terminated unsaturated copolyesters with styrene

The free radical copolymerization reaction of three series of acrylate-terminated unsaturated polyesters with styrene, using benzoyl peroxide/N,N -dimethylaniline as the redox initiator system, was followed by dynamic mechanical analysis. The presence of double bonds at both chain ends allows the formation of a regular network during the crosslinking copolymerization with styrene. The evolution of the rheological parameters, such as storage modulus G ′ and loss modulus G″, was recorded. The polymerization reaction, leading to the formation of a crosslinked structure, is described by a second order phenomenological equation, which takes into account a self-acceleration effect, as a consequence of not only the chemical reaction of crosslinking after the gel point but also phase segregation. This rheokinetic model of curing acrylate-terminated polyesters permits the determination of the numerical values of the kinetic equation constants and the degree of rheological conversion as a function of cure time. The influence of the terminal double bonds as well as of the cis-trans configuration on the curing kinetics of the unsaturated copolyesters was evaluated.

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.