Characterization of Eumelanin as an Additive in High‐Temperature Phthalonitrile‐Based Resin Blends

Abstract

AbstractBio‐manufactured eumelanin is investigated as a sustainable high‐char carbon additive for use with moldable high temperature resins. Blends of Bisphenol A poly‐ether‐ether‐ketone (PEEK)‐based phthalonitrile (PN) with 0–30 wt% melanin are prepared and characterized for their compositional, thermal, and mechanical properties. Although the char yield increases from 10 to 30 wt% melanin loading, the presence of melanin decreases the thermal stability compared to PN resin alone. Despite this, the melanin‐PN resins still maintain a very high char yield (>64%) up to 1000 °C under nitrogen. Rheology, thermal analysis, and mechanical measurements suggest off‐gassing of the melanin and increased crosslinking between the melanin and PN, leading to a lower flexural strength resin with higher additive loadings. Spectroscopic studies suggest possible interaction between melanin and PN during co‐curing, which ultimately can affect the processing and final properties of melanin‐additive composite materials.