Molecular relaxation behavior of fatty acid-based vinyl ester resins

The experimental characterization of the time-dependent properties of fatty acid-based vinyl ester resins with reduced styrene content and emissions was conducted and compared with that of various commercial vinyl ester (VE) resins. Constant heating rate and isothermal, multifrequency sweep experiments were conducted over a wide temperature range using dynamic mechanical analysis. Storage and loss modulus master-curves were formed using time-temperature superposition (TTSP) and analyzed to quantify the molecular relaxation behavior using accepted techniques and theories. Special attention was focused on determining the effect of reducing styrene weight percent on the derived viscoelastic properties. The fatty acid-based VE resins were found to have similar or slightly inferior thermomechanical properties and a more pronounced viscoelastic response compared with the commercial resins. However, the research definitively demonstrates that the evaluated fatty acid VE resins are a viable replacement to commercial resins in certain applications with concomitant attractive environmental benefits. (c) 2008 Wiley Periodicals, Inc.