Abstract
New tung oil (TO)-based, unsaturated, co-ester (Co-UE) macromonomers bearing steric hindrance were synthesized by modifying a TO-based maleate (TOPERMA) monomer with an anhydride structure with hydroxyethyl methacrylate (HEMA) and methallyl alcohol (MAA), respectively. The obtained Co-UE monomers (TOPERMA-HEMA and TOPERMA-MAA) were then characterized by 1H NMR and gel permeation chromatography (GPC). For comparison, hydroxyethyl acrylate (HEA)-modified TOPERMA (TOPERMA-HEA) was also synthesized and characterized. Subsequently, the obtained Co-UEs were thermally cured with styrene, and the ultimate properties of the resulting materials were studied. It was found that by introducing the structure of steric hindrance into the TO-based Co-UE monomer, the tensile strength and Young’s modulus of the resulting materials were improved. Furthermore, by reducing the length of the flexible chain in the Co-UE monomer, the tensile strength, Young’s modulus, and glass transition temperature (Tg) of the resultant materials were also improved. The TOPERMA-MAA resin gave the best performance in these TO-based Co-UE resins, which showed a tensile strength of 32.2 MPa, Young’s modulus of 2.38 GPa, and Tg of 130.3 °C. The developed ecofriendly materials show promise in structural plastic applications.
Highlights
Unsaturated polyester resin (UPR) is one of the most frequently used thermosetting polymers because of its low price, ease of handling, and good balance of mechanical, thermal, electrical, and chemical properties
All the chromatographs of tung oil (TO)-based Co-unsaturated ester (UE) moved to a shorter retention time compared with TOPERMA, indicating the growth of the molar masses for all the Co-UE monomers [29]
Compared with the TOPERMA-hydroxyethyl acrylate (HEA) resin, the σ and E values for the TOPERMA-hydroxyethyl methacrylate (HEMA) resin increased by 0.6 MPa and 0.10 GPa, suggesting that the stiffness of the Co-UE resins was improved by the incorporation of steric hindrance
Summary
Unsaturated polyester resin (UPR) is one of the most frequently used thermosetting polymers because of its low price, ease of handling, and good balance of mechanical, thermal, electrical, and chemical properties. MA-modified AESO (MAESO) could reach a C=C functionality up to 5.9, and the resulting materials with 38 wt % of styrene showed a tensile strength of 41−44 MPa, Young’s modulus of 2.2–2.5 GPa, and Tg of 115–130 ◦ C. In an effort to improve the C=C functionality of a tung oil (TO)-based maleate (TOPERMA) monomer bearing an anhydride structure, hydroxyethyl acrylate (HEA) was used to further modify the TOPERMA, and a new TO-based Co-UE macromonomer was obtained [27]. A novel tung oil-based Co-UE monomer (TOPERMA-HEA) was obtained, which had a tensile strength of 36.3 MPa, Young’s modulus of 1.70 GPa, and Tg of 127 ◦ C after curing with 40 wt % of styrene. Synthesis of tung oil-based, unsaturated co-esters (Co-UEs) by modifying tung oil (TO)-based maleate (TOPERMA) with different unsaturated alcohols
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