Oil additives demonstrate dual effects on thermal and mechanical properties of cross-linked hydroxy-DCPD thermosets

The influences of oil additives on thermomechanical properties of polymers made by ROMP of DCPD-OH are explored. A noticeable correlation between the gradual increase of T g values and the rise of cross-linking densities vs . oil content in the polymeric films was observed. A fine interplay between cross-linking and plasticizing effects determines the film's mechanical properties. • DCPD-OH, oil additives and G-II catalyst afforded tunable ROMP cross-linked polymers. • All polymeric blends display higher T g ’s than that of the parent poly-DCPD-OH. • Polymeric blends gained strength, as well as reduced plastic strain compared to poly-DCPD-OH. • Cross-linking and plasticizing effects determined the film's mechanical properties. • Several oils can improve the thermal and mechanical properties of DCPD-based polymers. Ring opening metathesis polymerization (ROMP) derived poly-dicyclopentadiene (poly-DCPD) materials enjoy high impact strength, and high chemical resistance. They offer control over the thermomechanical properties of the resulting cross-linked polymers, depending on initiator type and loading, the curing method and the monomer's chemical structure. Herein, we report on an additional method to tune properties of novel thermoset polymers obtained by ROMP by using blended mixtures containing 1-hydroxy-dicyclopentadiene ( DCPD-OH ) and four different oil additives, silicone oil ( SO ), mineral oil ( MO ), jojoba oil ( JO ) and linseed oil ( LO ). Various parameters such as curing behavior, glass transition temperatures ( T g ), cross-link densities and mechanical properties were studied. Accordingly, all the polymeric blends are amorphous, display higher T g than that of the parent poly-DCPD-OH and retained their thermal stability. T g values increased with a rise in the oil content until phase segregation in the polymeric films was dominant. This trend was also manifested by a gradual increase in the calculated cross-linking density values. Tensile analysis of polymeric blends with the highest cross-linking density values revealed that, although the films gained strength, they also showed reduced plastic strain compared to the parent poly-DCPD-OH. This behavior is explained by the divergent interplay between the plasticizing effects and the cross-linking density in thermoset composites.