Dynamic Mechanical and Thermal Analysis for the Determination of RFL Morphology

Abstract

Abstract From dynamic mechanical and DSC studies, we have concluded that resorcinolformaldehyde-latex (RFL) adhesive systems are two-phase materials. This is consistent with the limited electron microscopy work published on these polymers. However, while finer details of RFL morphology have never been resolved by electron microscopy, a comparison of the dynamic mechanical results with theoretical models provides evidence that the RFL has an interpenetrating network (IPN) morphology. The resorcinol-formaldehyde thermoset provides a continuous glassy network, while the butadienestyrene-vinyl pyridine terpolymer latex forms a continuous rubbery phase at ordinary use temperatures. The mechanical properties of the IPN are dominated by the volume fraction, chemistry, and thermal history of the RF thermoset. The dynamic mechanical properties of films made from ammonia-containing RFL adhesives are particularly sensitive to thermal history. This is consistent with the long-accepted belief that ammonia forms therma...