Dependence of viscoelastic properties on segregation degree of components in interpenetrating polymer networks

Abstract

SynopsisThe temperature dependences of elastic moduli, loss moduli, and mechanical loss angle tangent were investigated for the interpenetrating polymer networks: polyurethane-polyurethane acrylate by the method of dynamic mechanical spectroscopy (DMS). The segregation degree of components due to phase separation have been calculated from the parameters of relaxation maxima. An essential change was found in the segregation degree of components with the curing sequence of individual networks being changed. It was shown that, with the conditions and sequence of IPN formation changed, the phase separation degree can be fixed at a particular stage, i.e., the structures with a different segregation degree of components are obtainable. For the IPNs under investigation the variation of elastic moduli of the composites proved possible by fixing the separation degree of components.

Reaction compatibilization in interpenetrating polymer networks II. Polyurethane–polystyrene–oligourethane dimethacrylate system

“…The measurements were done at the frequency of the forced sinusoidal vibration 100 Hz in the temperature interval 220 -470 K. From the temperature dependencies of the tangent of mechanical losses the glass transition temperatures were found. The segregation degree ða segr Þ of components was determined from the parameters of the maxima of mechanical losses using following procedure [13] …”

Heterogeneity of segmental dynamics aroundtg and nanoscale compositional inhomogeneity in polyurethane/methacrylate interpenetrating networks as estimated by creep rate spectroscopy

“…40 Contrarily, when a single T g and broad ⌬T g range are observed, it indicates certainly a miscibility between two constituent networks but is not yet a proof of perfect homogeneous mixing of unlike segments. Compositional heterogeneity could be retained then at least on a nanoscale level making its characterization difficult to study.…”

Phase-Separated Interpenetrating Polymer Networks

“…The dependence of the viscoelastic properties of IPNs based on PU and PUA on the segregation degree was shown in [88,256,257]. Taking into account the interconnection between the chemical kinetics and the kinetics of phase separation, various methods of IPN synthesis have been used, i.e., simultaneous and sequential methods.…”