Effect of Blending on the Structure of Thermoplastic Interpenetrating Polymer Networks

Abstract

The infrared absorption spectra of thermoplastic interpenetrating polymer networks based on semicrystalline polyurethane (CPU) and a styrene/acrylic acid blockcopolymer (S-b-AA(K þ ), salt form) have been measured over the spectral range between 4000 and 600 cm 21 in an attempt to study their structure. The analysis of the spectra of the individual polymers and CPU/S-b-AA(K þ ) blends has shown the mutual influence of components on the formation of a network of intra and intermolecular physical bonds between functional groups of the components. In close agreement with these observations, the composition behaviors of experimental results of density, tensile strength, differential scanning calorimetry, and dynamic mechanical spectroscopy reveal deviations from a simple additive law which have been associated to a weak affinity of the individual components. It has been suggested that the existence of specific weak interactions (H-bonds) between the functional groups of the two components ensure the formation of a mixed microphase.