Radical Oxidation of Itaconic Acid-Derived Unsaturated Polyesters under Thermal Curing Conditions

Abstract

Itaconic acid has attracted a lot of interest as a green and low-cost building block toward the synthesis of biobased polyesters and polyurethanes with a wide range of applications in the UV-curing field. However, the thermal curing of itaconic acid-derived polyesters has been not extensively investigated. To gain deeper insight into the thermally induced crosslinking process, the curing of poly­(hexylene itaconate) was investigated by advanced isoconversional analysis performed under isothermal and non-isothermal conditions. Rheology and thermal analysis pointed out a three-step mechanism (initiation, propagation, and termination) typical of free-radical polymerization associated with the double bond conversion. Moreover, due to the comprehensive information obtained by different analytical techniques such as isothermal DSC, ATR-FTIR, and DMTA, we speculate that thermo-oxidative mechanisms occur under thermal curing conditions of poly­(hexylene itaconate). Thus, β-scissions of poly­(hexylene itaconate) chains might lead to the formation of anhydride and oligomeric radicals, which can recombine to a highly branched and crosslinked poly­(hexylene itaconate) resin.

Exploring and Understanding the Recycling of a Bio-Based Epoxy Thermoset via Saponification

“…The results of these calculations provide E α as a function of the extent of conversion α, without necessitating assumptions about the underlying reaction mechanism. These E α dependencies have been demonstrated to enable meaningful mechanistic analyses and enhance our comprehension of multi-step processes. ,,− …”

UV-Curing Additive Manufacturing of Bio-Based Thermosets: Effect of Diluent Concentration on Printing and Material Properties of Itaconic Acid-Based Materials

“…More specifically, over 80 ktons/a is produced via sugar fermentation by the fungus Aspergillus terreus and the price is less than 2 €/kg. − In addition, itaconic acid has the advantage to be very versatilely applicable. First, it is considered as an alternative to maleic acid in bio-based unsaturated polyester resins for thermosetting applications. − In this respect, recent studies have shown that the utilization of itaconic acid in these applications results in the reduction of greenhouse gas emissions and of the total energy consumption . Second, the external double bond exhibits a higher reactivity toward radical reactions compared to the internal double bond of the maleic acid.…”

“…First, it is considered as an alternative to maleic acid in bio-based unsaturated polyester resins for thermosetting applications. 8 − 13 In this respect, recent studies have shown that the utilization of itaconic acid in these applications results in the reduction of greenhouse gas emissions and of the total energy consumption. 14 Second, the external double bond exhibits a higher reactivity toward radical reactions compared to the internal double bond of the maleic acid.…”

Robust Itaconic Acid-Based Polymer Adhesive Nanocomposites Containing Bioinspired Multiple Hydrogen Bonds at the Polymer–Nanofiller Interface

“…By contrast, biomass-sourced molecules derived from various raw materials possess well-defined functionality and accurate molecular structures . Itaconic acid as one of the top 12 biomass-derived molecules provides a renewable feedstock alternative for fabricating polymer materials. – …”