A preliminary study on liquid crystalline epoxy curatives from natural abietic acid

摘要

Abietic acid was used for preparing two thermotropic liquid crystalline curing agents with different mesogens (LCC1 and LCC2). The chemical structure of the synthesized LCCs was investigated by FTIR and1HNMR spectroscopic techniques. Their LC phase transition temperatures and texture were identified by differential scanning calorimeter (DSC) and polarized optical microscope (POM), respectively. Both LCCs show nematic droplet texture -as revealed by POM micrographs- but different isotropization temperatures. Eventually, they were used for producing epoxy coatings using a multifunctional abietic acid based epoxy resin; prepared in our previous study. Cured coats were evaluated by standard coating testing and compared with a commercial curing agent. Dynamic mechanical (DMA) and thermogravimetric (TGA) analyses show that the fully bio-based cured epoxies by either LCCs possess high glass transition temperature (Tg), high modulus (G′) and improved thermal stability.