Biobased epoxy resin from canola oil

Abstract

Epoxidized canola oil (ECO)-based thermoset epoxy resins were formulated with phthalic anhydride (PA) as the curing agent for different ratios of ECO to PA (1:1, 1:1.5, and 1:2 mol/mol) at curing temperatures of 155, 170, 185, and 200 C. The gelation process of the epoxy resins and the viscoelastic properties of the systems during curing were studied by rheometry, whereas the dynamic mechanical and thermal properties of the cured resins were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry. We found that the thermomechanical properties of the resins were not strongly dependent on the curing temperature of the resin, although elevated temperatures significantly accelerated the curing process. However, an increase in the curing agent (PA) amount significantly altered both the reaction rate and the thermomechanical properties of the final resin. Thus, in the ECO/PA system, the selection of the combination of the curing temperature and the molar ratios of the curing agent could be used to design thermoset resins with unique thermomechanical properties.

Recent advances in bio‐based epoxy resins and bio‐based epoxy curing agents

“…For example, in a 2014 study aiming to find renewable, bio‐based sources for lubricant applications, Somidi et al ., found sulfated SnO 2 to be the most selective and stable catalyst for epoxidation of canola oil . Some work has also been done using canola oil to create bio‐based polymers with improved physical properties …”

“…Omonov and Curtis created ECO‐based thermosets with phthalic anhydride (PA) as the curing agent at various temperatures, 155 °C, 170 °C, 185 °C, and 200 °C, and with various molar ratios of ECO to PA, 1:1, 1:1.5, and 1:2 . The T g s (based on peak of tan δ) of the cured resins do not vary much with curing temperature, 37.8 °C to 39.1 °C for 1:2 ECO:PA cured at 155 °C and 200 °C, respectively, but, do increase with increasing amount of PA, −3.6 °C to 37.8 °C when the molar ratio of PA is doubled at a cure temperature of 155 °C . For all the polymers, the storage moduli below the T g s were inversely proportional to the amount of PA used while the storage moduli above the T g s increased with increasing amount of PA .…”

The Development of Epoxidized Hemp Oil Prepolymers for the Preparation of Thermoset Networks

“…The curing reactions for TMA are different due to the presence of the reactive cyclic anhydride, which does not react directly with the epoxy group (Fisch et al, ; Steinmann, ). Instead, to initiate uncatalyzed curing with TMA, the anhydride ring is first opened by a hydroxyl group to form carboxylic acids, which then react with epoxy groups (Kolar and Svitilova, ; Omonov and Curtis, ; Steinmann, ). Scheme , Path II shows possible anhydride ring opening via hydrolysis of TMA to form TMLA due to residual water present (Barabanova et al, ) in EHO or acetone.…”

“…At the same time, each molecule of EHO has 5.4 epoxide groups on average. Hence, the expected stoichiometric ratio of the reactive moieties of these components was closen to 1:1 at a molar ratio of EHO to CA of 1.0:1.8 (Omonov and Curtis, ).…”

“…The dynamic mechanical thermal properties of the thermosets were measured with a TA Instrument DMA Q800 (New Castle, DE, USA) equipped with a liquid nitrogen cooling system. The DMA experiments were carried out according to ASTM E 1640‐09 in the dual cantilever bending mode at a fixed frequency of 1 Hz, strain 0.04%, and a constant heating rate of 2 °C min −1 from −50 to 175 °C, as described elsewhere (Omonov and Curtis, ). At least two similar sized specimens with approximate dimensions of 60 mm ×12 mm×4 mm were prepared by the cutting of the bulk thermosets and the results of the measured glass transition temperatures were averaged.…”