In recent years, the bio-refining industry has developed a number of cyclic molecules with unique attributes derived from renewable carbohydrate feedstocks. Isosorbide is one such compound that has a distinctive fused bicyclic ring system that provides a scaffold for the development of novel bio-based resin systems. We synthesized isosorbide-methacrylate (IM) by the direct esterification of isosorbide using highly reactive species such as methacryloyl chloride or methacrylic anhydride and a base catalyst. IM is a low viscosity (157 cP) cross-linking resin that free radically reacts to form a thermoset polymer with extent of cure at 85%. The resulting polymer has a T_g greater than 240 °C and main degradation temperature of ∼400 °C. Mechanical test results showed that IM had a modulus of ∼4 GPa and strength of 85 MPa. These thermal and mechanical properties show that IM has a significantly higher temperature operating window than any known vinyl ester resin and has similar performance to expensive high temperature epoxy resins. As such, this material has good potential for use in composite applications where a moderate to high temperature free radical cured polymer matrix is needed.

Cardanol is a renewable resource based on cashew nut shell liquid (CNSL), which consists of a phenol ring with a C15 long aliphatic side chain in the meta position with varying degrees of unsaturation. Cardanol glycidyl ether was chemically modified to form side-chain epoxidized cardanol glycidyl ether (SCECGE) with an average epoxy functionality of 2.45 per molecule and was cured with petroleum-based epoxy hardeners, 4-4′-methylenebis(cyclohexanamine) and diethylenetriamine, and a cardanol-based amine hardener. For comparison, cardanol-based diphenol diepoxy resin, NC514 (Cardolite), and a petroleum-based epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) were also evaluated. Chemical and thermomechanical analyses showed that for SCECGE resins, incomplete cure of the secondary epoxides led to reduced cross-link density, reduced thermal stability, and reduced elongation at break when compared with difunctional resins containing only primary epoxides. However, because of functionality greater than two, amine-cured SCECGE produced a T_g very similar to that of NC514 and thus could be useful in formulating epoxy with renewable cardanol content.

Additive manufacturing (AM) is one of the fastest-growing manufacturing technologies in modern times. One of the major challenges in the application of 3D-printed polymeric objects is expanding the applications to structural components, as they are often limited by their mechanical and thermal properties. To enhance the mechanical properties of 3D-printed thermoset polymer objects, reinforcing the polymer with continuous carbon fiber (CF) tow is an expanding direction of research and development. A 3D printer was constructed capable of printing with a continuous CF-reinforced dual curable thermoset resin system. Mechanical performance of the 3D-printed composites varied with the utilization of different resin chemistries. Three different commercially available violet light curable resins were mixed with a thermal initiator to improve curing by overcoming the shadowing effect of violet light by the CF. The resulting specimens’ compositions were analyzed, and then the specimens were mechanically characterized for comparison in tensile and flexural performance. The 3D-printed composites’ compositions were correlated to the printing parameters and resin characteristics. Slight enhancements in tensile and flexural properties from some commercially available resins over others appeared to be the result of better wet-out and adhesion.