Effects of flexible and rigid parts of ε-caprolactone and tricyclodecanediol derived polyurethane on the polymer properties of epoxy resin

We report the synthesis of a novel polyurethane (PU) obtained from caprolactone (CL) and tricyclodecane diol (TCD-diol) and its reinforcing effect in the epoxy resin. Polycaprolactone (PCL)-TCD-polyol was synthesized by reacting TCD-diol with CL using tin(II)-2-ethylhexanoate. By changing the ratio of CL, PCL-TCD-polyol was synthesized with different molecular weights and chain lengths. Using PCL-TCD-polyol and polytetrahydrofuran (polyTHF) in a ratio of 1:1 with hexamethylene diisocyanate, polyurethane (PCL-TCD-PU) was prepared and used as a reinforcing agent with epoxy resin to improve the polymer properties. The mechanical and thermal properties of the epoxy cured specimens with and without the PCL-TCD-PU reinforcing agent were comparatively analyzed. The addition of PCL-TCD-PU with epoxy resin improved the tensile, impact, and flexural strengths, and it also had excellent physical properties that changed depending on the molecular weight and PU content of the TCD-polyol used in the PU. Furthermore, the fracture surface of the epoxy resin after the impact test had a specific pattern that was thoroughly analyzed by FE-SEM. Furthermore, thermomechanical analysis (TMA) showed that while increasing the PU content in the epoxy resin, the thermal expansion system is close to one, which clearly indicates that PCL-TCD-PU is expected to show excellent adhesive strength. [Display omitted] •Polyurethane was synthesized from CL and TCD-diol with different chain lengths and molecular weights.•Introduction of rigid and mobile components of polyurethane enhanced the polymer properties of the epoxy resin.•The strong interaction between the epoxy polymer resin and the synthesized PCL-TCD-PU was confirmed by FE-SEM.•Addition of PCL-TCD-PU with epoxy resin improved the coefficient of thermal expansion of epoxy polymer.