Effect of hydrogen bonding and ionic aggregation on the melt rheology of an ethylene–methacrylic acid copolymer and its sodium salt

Abstract

A study has been made of the dynamic and steady shear melt rheology of an ethylene-methacrylic acid copolymer, its methyl ester, and 70% neutralized sodium salt. Measurements were made with a Rheometrics mechanical spectrometer using the eccentric rotating disks and cone-and-plate geometries over a temperature range of 120-180°C and a frequency range of 10-3 to 102 rad/sec. Correspondence was found between steady shear viscosity and the complex dynamic viscosity for the ester and acid materials. Over the temperature and frequency range studied the time-temperature superposition principle was applicable to G' data for each of the derivatives and a supermaster curve could be constructed from the three individual master curves. Time-temperature superposition was found not applicable to an data for the sodium salt. Differences in rheological response between the ester and acid copolymers are explained by differences in Tg. It is suggested that differences in temperature shifts i!!i.T required to produce G' superposition between the three derivatives reflect differences in M for interchain interactions. A mechanism for flow of clustered ionomers is suggested consisting of an initiation and a propagation step.

Intravenous itraconazole for prophylaxis of systemic fungal infections in patients with acute myelogenous leukemia and high‐risk myelodysplastic syndrome undergoing induction chemotherapy

“…The diminution of MI values of copolymers of S and MA and their salts containing primarily sodium and potassium ions was observed earlier15–17, but there were no measurements of MI of S and AA copolymers and of the ionomers obtained.…”

“…The documented rheological studies of ionomers based on ethylene,16 propylene,17 and styrene18, 19 also indicated an enhancement of melt viscosity and activation energy of viscous flow of these ionomers with an increase in the content of salt. These observations are a consequence of intermolecular interactions between salt groups for the metal salt derivatives.…”

Nonlinear Rheology of Lightly Sulfonated Polystyrene Ionomers

“…A small number of studies have reported steady shear behavior of ionomers, including studies with polymer backbones based on polyethylene, 14,18,19 polypropylene, 20 poly(styrene-co-ran-butyl methacrylate), 21 polyester, 22,23 and polystyrene. 24−29 Nonlinear extensional flows have also been used to characterize the rheological behavior of ionomers, but that literature is very limited.…”

Ethylene Propylene Rubber Polyampholytes and their Blends with Polypropylene as an Alternative to Chemically Cross‐Linked Thermoplastic Elastomers and Thermoplastic Vulcanizates

“…Similarly to peroxide cured polymers, which experience an increase in viscosity and modulus owing to the formation of chemical cross‐links, the addition of ionic functionality to non‐polar polymers alters their melt rheology because of the network effects of ion‐pair aggregation . This enables us to monitor the kinetics of the reaction through simple time sweep experiments, which record the evolution of the LVE functions of the polymer as a function of time.…”