The free-radical copolymerization of 40-85 wt % of conjugated low-saturation soybean oil (CLS), and a 9 : 1 ratio of acrylonitrile (AN) and either divinylbenzene (DVB) or dicyclopentadiene (DCP) using AIBN as the initiator affords transparent yellow samples, which range from hard to slightly rubbery. DMA analysis indicates that the samples containing DCP have tan delta values ranging from 0.32 to 0.49, while the damping properties of the DVB samples are slightly lower. Extraction analysis shows that complete chemical incorporation of the CLS into the polymeric network is achieved when the original CLS content ranges from 40 to 65 wt %. Lower incorporation of the CLS into the polymer network occurs when the oil content exceeds 70 wt %. In this case, up to 30% of the CLS remains unreacted. These observations are supported by H-1 NMR and solid-state NMR. Thermogravimetric analysis indicates a just one important stage of degradation, implying that the polymer network is highly homogeneous in composition. The temperatures of 10% weight loss for the DCP system range from 402 to 428 degrees C, and from 370 to 391 degrees C for the DVB system. The temperature of maximum degradation ranges from 458 to 518 degrees C for the DCP polymers, and 406 to 422 degrees C for the DVB system. (C) 2007 Wiley Periodicals, Inc.