Aromatic Hyperbranched Polyester/RTM6 Epoxy Resin for EXTREME Dynamic Loading Aeronautical Applications.

Area of Science:

• Materials Science
• Polymer Chemistry
• Mechanical Engineering

Background:

• Thermosetting resins like epoxy are widely used but can lack sufficient fracture toughness.
• Hyperbranched polymers offer unique properties for composite material enhancement.
• Aromatic hyperbranched polyester (AHBP) was synthesized for potential use as a filler.

Purpose of the Study:

• To investigate the impact of AHBP on the thermal, mechanical, and fracture toughness properties of epoxy resins.
• To evaluate the performance of AHBP as a filler in thermosetting systems.
• To understand the strain rate sensitivity of AHBP/epoxy composites.

Main Methods:

• Synthesis of AHBP via bulk poly-condensation reaction.
• Fabrication of AHBP/epoxy composites at 0.1, 1, and 5 wt% AHBP loading.
• Characterization using Differential Scanning Calorimetry (DSC) and Dynamical Mechanical Analysis (DMA).
• Evaluation of fracture toughness and static/dynamic compression tests at various strain rates.

Main Results:

• AHBP addition resulted in a slight decrease in glass transition temperature (Tg) by ~4 °C at 5 wt%.
• Fracture toughness improved significantly, with a +18% increase in critical stress intensity factor and +83% in critical strain energy release rate at 5 wt% AHBP.
• AHBP/epoxy systems exhibited pronounced strain rate sensitivity.
• Compressive strength increased with AHBP content, with the best improvement at 0.1 wt% AHBP.

Conclusions:

• AHBP effectively enhances the fracture toughness and compressive strength of epoxy resins.
• The addition of AHBP leads to improved mechanical performance, particularly under dynamic loading conditions.
• AHBP shows promise as a reinforcing filler for thermosetting composites, especially at low concentrations for compressive strength.