SUGAR-DERIVED POLYURETHANE ACRYLATES: SYNTHESES, PROCESSABILITY, AND COMPOSITE PROPERTIES

This research studied the structure-property-processing relationships of bioderived polyurethane-acrylate (PUA) thermosets and composites that utilize sugar-alcohols in the polymer’s backbone. Three PUAs were synthesized and modified with initiator and inhibitor concentrations ranging from 1000-7000 ppm to understand workability and develop basic composite processing parameters. Thermal gravimetric analysis (TGA) was used to understand degradation characteristics of the cured formulations and verify cure conditions. Rheological measurements were taken to observe isothermal viscosity changes and working times, while differential scanning calorimetry (DSC) was utilized to study the formulations’ impacts on cure onset, peak temperature, and cure enthalpy. The 7000 ppm PUA formulations were down-selected for use in carbon fiber composites to study the impact of the sugar-alcohol component on composite thermal and mechanical properties. Dynamic mechanical analysis (DMA) was utilized to study the glass transition temperatures (Tg) of the formulations, while flexural and tensile testing were used to obtain elastic modulus, peak stress and failure strain of the composites. The Tg’s of the bio-derived composites were on average, 5-10 °C higher than the petroleum-derived composites. Similarly, the mechanical properties of bio-derived PUA composites were also generally higher than the petroleum-derived composite, suggesting the sugar-alcohols’ molecularly “rigid-yet-interactive” chemical structures provide enhanced performance.