New soybean oil-styrene-divinylbenzene thermosetting copolymers. VI. Time-temperature-transformation cure diagram and the effect of curing conditions on the thermoset properties

A new class of thermosetting resins has been developed that is based on the cationic copolymerization of regular soybean oil (SOY), low saturation soybean oil (LSS), or conjugated LSS (CLS) with various alkene comonomers initiated by boron trifluoride diethyl etherate (BFE) or related modified initiators. The activation energy for the gelation process for these thermosets ranges from 95 to 122kj/mol. A time-temperature-transformation (TTT) isothermal cure diagram has been established for the model system LSS45-ST32-DVB15-(NFO5-BFE3) ie 45 wt% low saturation soybean oil, 32 wt% styrene, 15 wt% divinylbenzene, and 5 wt% Norway fish oil ethyl ester plus 3 wt% boron trifluoride diethyl etherate. The effect of curing conditions on the thermophysical and mechanical properties, including the mechanical damping and shape memory properties, has been subsequently investigated using this model thermoset. These findings allow the efficient optimization of desired properties for specific applications. (C) 2003 Society of Chemical Industry.