Polyhedral oligomeric silsesquioxane (POSS)-modified phenolic resin: Synthesis and anti-oxidation properties

In this work, octamercapto polyhedral oligomeric silsesquioxane (POSS-8SH) and octaphenol polyhedral oligomeric silsesquioxane (POSS-8Phenol) were successfully synthetized. POSS-8Phenol was added into the synthesis process of liquid thermoset phenolic resin (PR) to obtain POSS-modified phenolic resin (POSS-PR). Chemical structures of POSS-8SH, POSS-8Phenol, and POSS-PR were confirmed by FTIR and H-1-NMR. TG and DTG analysis under different atmosphere showed that char yield of POSS-PR at 1,000 degrees C increased from 58.6% to 65.2% in N-2, which in air increased from 2.3% to 26.9% at 700 degrees C. The maximum pyrolysis temperature in air increased from 543 degrees C to 680 degrees C, which meant better anti-oxidation properties. XRD results confirmed both POSS-8Phenol and POSS-PR-generated crystalline SiO2 in air, which could explain the improvement of anti-oxidation properties. SEM showed that the POSS-PR had phase separation during curing process. Finally, carbon fiber fabric-reinforced POSS-PR (C-POSS-PR) was prepared to verify the anti-oxidation properties of POSS-PR.

Automated summary

POSS-8SH and POSS-8Phenol were successfully synthesized and incorporated into POSS-PR, leading to improved oxidation resistance as confirmed by TG and DTG analysis. XRD results and SEM observation provided further evidence for the enhanced anti-oxidation properties of POSS-PR.