Semi‐interpenetrating Networks in Blends of Epoxidized Natural Rubbers

Abstract

Blends of immiscible ENRs are crosslinked by dicarboxylic acids at 180 ° C in the presence of 1,2-dimethylimidazole. Due to the different epoxidation levels, the cure of ENR50 is complete well before that of ENR10. Depending on the ratio ENR10/ENR50, the blend morphology of the resulting materials, switches from diacid-enriched nodules of ENR50 dispersed in a soft matrix of ENR10 to a continuous texture, giving rise to elastomeric properties. Even in minority, ENR50 is able to create a network by semi-interpenetrating the non-crosslinked ENR10. This behavior is associated with the migration of the dicarboxylic acid into the more reactive ENR50. Since ENR10 remains still available for further crosslinking, the system opens the door to elastomeric materials based on interpenetrated networks.

Reinforcing styrene butadiene rubber with lignin-novolac epoxy resin networks

“…Epoxy resins also have been synthesized by an insitu vulcanization to reinforce SBR [19]. Meanwhile, various interpenetrating polymer networks in the rubber compounds have been prepared [20][21][22][23]. However, to the best of our knowledge, there is no report about lignin-novolac epoxy resin networks reinforced SBR.…”

About the Art and Science of Visualizing Polymer Morphology using Transmission Electron Microscopy

“…This difference in reactivity was exploited to quench the macrophase separation of the two immiscible ENR by competitive crosslinking. [55] By increasing the fraction of ENR50 in a mixture ENR10/ENR50, the resulting material switches from a soft rubber to a strong elastomer (Figure 7a). TEM explains this behavior: For 15% ENR50, nodules of ENR50 are dispersed in a soft matrix of non-crosslinked ENR10 (Figure 7b), but above 37.5% ENR50, a cocontinuous structure is obtained, in which ENR50 is crosslinked while ENR10 is not (Figure 7c).…”

“…ENR50 is fully crosslinked in 12 min, much quicker than ENR10. This difference in reactivity was exploited to quench the macrophase separation of the two immiscible ENR by competitive crosslinking . By increasing the fraction of ENR50 in a mixture ENR10/ENR50, the resulting material switches from a soft rubber to a strong elastomer ( Figure a).…”

“…d) 85/15 sample, higher magnification showing crystalline features inside nodules of ENR50. Adapted with permission . Copyright 2013, Wiley‐VCH.…”

Dual Cross-linking of Epoxidized Linseed Oil with Combined Aliphatic/Aromatic Diacids Containing Dynamic S−S Bonds Generating Recyclable Thermosets

“…Moreover, the strategy of double aliphatic/aromatic cross-linking, with different reactivities of the monomer toward the two hardeners, can open the door to novel materials with unique mechanical properties, as applied, for example, to produce super-tough hydrogels with strong interfacial adhesion. 31,32 The addition of BA as an aromatic diacid in the ELO matrix will not only introduce its rigid structure into the network, increasing the mechanical properties, but also will incorporate aromatic disulfide bonds with low BDE, allowing to accelerate the disulfide metathesis reactions, therefore enhancing the reprocessing ability of final materials. The mechanism responsible for the self-healing process in disulfide-based materials has been discussed in recent literature, 25,33−37 both theoretically and experimentally.…”