Poly networks phase-separation process, morphologies

Table III. Phase-Separation Process, Morphologies, and Properties for Neat or Modified Poly(cyanurate) Networks...

The morphology of poly(vinylacetate)-polypyrrole composite film is very different from that of polymer blend prepared from the solution polymerization. Polypyrrole aggregates are connected with each other in the former case, which results in a polypyrrole network throughout the composite, while polypyrrole aggregates are separated from each other in the latter case. It is expected in the former case that a spinodal decomposition occurs during the phase separation process because of sudden changes in the concentration of pyrrole and ferric chloride as well as the viscosity of poly (vinylacetate). These sudden changes are caused by the evaporation of solvent. 

A polyurethane (PU)/poly(n-butyl methacrylate) (PBMA) system has been selected for an investigation of the process of phase separation in immiscible polymer mixtures. Within this system, studies are made of the XX, lx, xl, and the 11 forms. In recognition of the incompatibility of PBMA with even the oligomeric soft segment precursor of the PU, no attempt was made to equalize the rates of formation of the component linear and network polymers. Rather, a slow PU formation process is conducted at room temperature in the presence of the PBMA precursors. At suitable times, a relatively rapid photopolymerization of the PBMA precursors is carried out in the medium of the slowly polymerizing PU. The expected result is a series of polymer mixtures essentially identical in component composition and differing experimentally only in the time between the onset of PU formation and the photoinitiation of the acrylic. This report focuses on the dynamic mechanical properties cf these materials and the morphologies seen by electron microscopy. 

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