Polybenzoxazine are a thermosetting polymer that have superior properties to traditional phenolic resins, including near zero volume shrinkage during cure, high glass transition temperature (Tg) and elevated char yields. These enhanced properties make polybenzoxazine exciting candidates as the polymer precursor for carbon-carbon composites (CCC). The main challenge in fabricating carbon-carbon composites is the cost to manufacture them on a large scale. Increasing the amount of carbon deposited (char yield) and understanding any volume change the matrix experiences during pyrolysis is of critical importance in addressing these processing challenges. Benzoxazine monomers using different phenolic derivatives and either furfurylamine or aniline as the primary amine were synthesized and pyrolyzed to form carbon. The furfurylamine-based benzoxazines had increased Tg and char yield compared to the aniline-based benzoxazines. In regard to the carbon, higher final char yields resulted in carbons that experienced volume shrinkage (negative volume change) as opposed to volume expansion (positive volume change). This study shows that furfurylamine-based benzoxazines outperform aniline-based benzoxazine when looking at important properties for the polymer precursor of carbon matrix. Furthermore, principles that can predict matrix volume change solely from the carbonization reaction of the polymer precursor were presented. These principles may lead to the design of more efficient polymer precursors as the carbon matrix for carbon/carbon composites.

Investigation between carbon ofrmation and polymer precursor for aniline-based and furfurylamine-based polybenzoxazines

ACS Spring 2022

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