Enhancing Thermal Insulation of EPDM Ablators via Constructing Alternating Planar Architectures

Area of Science:

• Materials Science
• Polymer Engineering
• Aerospace Engineering

Background:

• Ethylene-propylene-diene monomer (EPDM) composites with ablative additives are used for solid rocket motor (SRM) casings.
• High thermal conductivity of conventional ablative fillers leads to poor thermal insulation, risking rocket motor failure.

Purpose of the Study:

• To develop novel EPDM composites with enhanced thermal insulation and mechanical properties for SRM applications.
• To investigate the effectiveness of a multilayered structure combining ablative and heat-insulating EPDM layers.

Main Methods:

• Preparation of multilayer EPDM composites using layer-multiplying extrusion.
• Alternating layers of ablative EPDM (AM) and heat-insulated EPDM (HM) were co-extruded.
• Evaluation of thermal insulation, mechanical properties, and ablation resistance using oxyacetylene testing.

Main Results:

• Multilayer composites exhibited superior thermal insulation and mechanical properties compared to conventional EPDM.
• A 40-layer AM/HM composite showed a significant reduction in maximum back-face temperature (from 96.2 °C to 75.6 °C) during oxyacetylene testing.
• Ablative properties were maintained in the AM layers, while thermal insulation was enhanced by the HM layers and composite structure.

Conclusions:

• The alternating multilayer EPDM composites effectively combine ablative resistance and thermal insulation.
• Improved performance is attributed to additive orientation and interrupted conductive pathways in the through-plane direction.
• These anisotropic EPDM composites demonstrate significant potential for aerospace applications due to their robustness and protective qualities.