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Tung Oil-Based Unsaturated Co-ester Macromonomer for Thermosetting Polymers: Synergetic Synthesis and Copolymerization with Styrene
- Liu Chengguo, Shang Qianqian, Jia Puyou, Dai Yan, Zhou Yonghong, Liu Zengshe
- ACS sustainable chemistry 2016 v.4 no.6 pp. 3437-3449
- Fourier transform infrared spectroscopy, acrylates, biocompatible materials, bioplastics, chemical elements, chemical structure, copolymerization, equations, gel chromatography, glass transition temperature, maleates, nuclear magnetic resonance spectroscopy, storage modulus, styrene, tensile strength, thermal stability, tung oil
- A novel unsaturated co-ester (co-UE) macromonomer containing both maleates and acrylates was synthesized from tung oil (TO) and its chemical structure was characterized by FT-IR, ¹H NMR, ¹³C NMR, and gel permeation chromatography (GPC). The monomer was synthesized via a new synergetic modification of TO, by introducing maleic groups first and acrylic groups subsequently onto TO molecules. The influence of experimental factors on thermomechanical properties of the cured bioresins was evaluated to better understand structure–property relationships of the biomaterials and optimize experimental conditions. The obtained TO-based co-UE monomer possessed a highly polymerizable CC functionality, consequently resulting in rigid bioplastics with high cross-link densities (νₑ) and excellent mechanical properties. For instance, the bioplastic prepared under the optimal synthesis conditions demonstrated a νₑ of 4.03 × 10³ mol/m³, storage modulus at 25 °C of 2.40 GPa, and glass transition temperature (Tg) of 127 °C, as well as tensile strength and modulus at 36.3 MPa and 1.70 GPa, respectively. A new theory for determining optimal comonomer concentration was further developed according to the copolymerization equation. The proposed theory accurately predicted the best styrene dosage for the co-UE monomer. At last, the hydroxyethyl acrylate (HEA)-modified TO-based resin was compared with the unmodified one in thermomechanical properties, thermal stability, microstructural morphologies, and curing behaviors. The new co-UE bioresin showed higher CC functionality and cross-link density, superior properties including Tg and thermal stability, and similar curing behaviors. The developed eco-friendly rigid biomaterials provide potential application in structural plastics such as sheet molding compounds.