Synthesis of a Degradable High-Performance Epoxy-Ended Hyperbranched Polyester

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Thermosetting epoxy resins, like diglycidyl ether of bisphenol-A (DGEBA), present significant challenges in degradation and recycling.
• Developing sustainable alternatives and additives is crucial for the circular economy in the polymer industry.

Purpose of the Study:

• To synthesize a novel degradable epoxy-ended hyperbranched polyester (DEHP).
• To investigate the effect of DEHP on the mechanical properties and degradability of DGEBA-based composites.
• To assess the potential for enhanced recycling of thermosetting epoxy resins.

Main Methods:

• Synthesis of carboxyl-ended hyperbranched polyester (DCHP) via esterification of citric acid and maleic anhydride.
• Synthesis of DEHP by reacting DCHP with epichlorohydrin.
• Characterization of DCHP and DEHP using Fourier transform infrared and 1H NMR spectroscopy.
• Formulation and mechanical testing (tensile, flexural, impact) of DEHP/DGEBA composites.
• Evaluation of the degradation behavior of the composites under thermal conditions.

Main Results:

• DEHP was successfully synthesized and characterized.
• Incorporation of DEHP improved the reinforcing and toughening effects on DGEBA.
• Optimal DEHP content and molecular weight led to significant increases in tensile (34.2-43.4%), flexural (35.6-48.1%), and impact (117.9-137.8%) strengths.
• DEHP promoted composite degradation, with 12 wt% DEHP enabling complete degradation in 2 hours at 90°C.

Conclusions:

• The synthesized DEHP effectively enhances the mechanical performance of DGEBA composites.
• DEHP significantly improves the degradability of epoxy resins, paving the way for easier recycling.
• This approach offers a promising solution for the sustainable management of thermosetting epoxy resins.