Ablation performance and characterization of thermoplastic polyurethane elastomer nanocomposites

We investigated the potential of thermoplastic polyurethane elastomer nanocomposites (TPUNs) as alternative elastomeric heat shielding materials (EHSMs) in ablative applications. Three different nanofillers were tested – montmorillonite clay (MMT clay), multi-walled carbon nanotubes (MWNTs), and carbon nanofibers (CNFs) – and formulations were made for each material with a range of weight loadings. Small scale ablation testing was performed using an oxyacetylene test bed and Kevlar-filled EPDM as the baseline EHSM. Mass loss, recession, and char thickness values were measured in addition to in situ internal temperatures. The TPUN formulations with 5 and 7.5 wt% MMT clay showed the best results, outperforming the baseline in recession and peak temperature values. SEM images of the char from MMT clay containing TPUNs showed ablative re-assembly, which likely served to enhance the material performance. Overall, results showed that the TPUN ablatives performed well relative to the baseline EHSM.