Highly Bio‐Based Unsaturated Polyester Resins with Improved Performance by Incorporating Isosorbide into the Polyester Prepolymer

Abstract

Herein, the successful design of a highly bio‐based family of unsaturated polyester resins (UPRs) is presented, comprising of an isosorbide (ISO) incorporated unsaturated polyester prepolymer (UP) and a reactive diluent of 4‐vinylguaiacol acetyl ester (ACVG). A series of UPs are prepared by copolymerizing ISO with other green monomers, i.e., itaconic acid, ethylene glycol and oxalic acid, in a variation of ISO fraction. The UP/ACVG mixtures exhibit very low viscosity ranging from 2.8 to 3.7 Pa s. After curing at 135 °C to form a network, the resulting thermosets exhibit remarkable improvements in terms of glass transition (Tg, about 131 °C), storage modulus (2564–3342 MPa), and tensile strength (around 76.6 MPa), which are significantly better than the UP thermosets reported in previous works, The incorporation of ISO units into the UPs reveals a favorable effect on thermal stability of the thermosets as well. The best Td5% is measured to be 320.4 °C, and the volatile molecular information collected using a TGA‐GC/MS set suggests that the decomposition mechanism of the cross‐linked resins becomes heat‐resistant due to the ISO incorporation. Moreover, after being reinforced by cotton fabrics, an outstanding compatibility between the ISO containing UPRs and cotton fibers is found to be suitable for composite fabrication.

Evaluation of 2,5‐Furandicarboxylic Acid as Building Block for Unsaturated Polyester Resins

“…Supporting Information for this article can be found under DOI: https://doi.org/10.1002/cite.202300148. This document includes all experimental procedures, measurements as well as additional references to primary literature relevant for this research [76–99].…”

The Evolution and Future Trends of Unsaturated Polyester Biocomposites: A Bibliometric Analysis

“…In some cases, green monomers are used during UPR polymerization. A recent example is the addition of itaconic acid, ethylene glycol, and oxalic acid, which improves the mechanical and thermal properties, such as the glass transition temperature of the neat matrix [66]. On other occasions, this strategy used monomers obtained from recycled polyethylene terephthalate (PET) instead, which promotes the reuse of polymer waste [67].…”

“…When considering composite design, the reinforcement configuration is a key aspect that affects the mechanical behavior. In the analyzed articles, 13 reinforcement configurations were identified, including woven fabrics [66,[70][71][72][73], non-woven fabrics [74][75][76], short fibers [49,77], powders [78,79], nanofibers [63,80], and nanocrystals [30], or nanostructuration with self-assembled block polymers [81].…”

Enhanced performance of a bio‐based diluent with both vinyl and epoxide groups for unsaturated polyester resin applications

“…This viscosity is lower than several bio-based UPRs reported recently, and acceptable for a wide range of applications. 39,44 According to the Hansen's theory, 45 solubility of a compound is strongly influenced by its molecular S2, the PMSD and DE4VG have very similar solubility parameters, suggesting they are highly miscible. The high solubility of the mixture may be the main contributor for the lower viscosity.…”

“…10 Further works demonstrated that the acetylation of the phenolic hydroxyl group produces 4-vinylguaiacol acetyl ester (AC4VG) can eliminate the inhibition defect of 4VG. 10,43,44 Unfortunately, the acetylation of 4VG required a mass of toxic triethylamine (TEA) as catalyst, and failed to realize a high conversion to AC4VG. Besides, AC4VG only provides a limited number of cross-linkages to improve thermo-mechanical properties of the cured UPR because only the double bond involving to the network formation.…”