Authors: H. Mahfuz, F. Powell, R. Granata, M. Hosur
Affilation: Florida Atlantic University, United States
Pages: 115 - 118
Keywords: POSS, nanocomposites, carbon fiber, vinyl ester, surface treatment
The fiber/matrix (F/M) interface of carbon/vinyl ester composites has been modified by treating the carbon fiber with polyhedral oligomeric silsesquioxane (POSS). The objective was to improve the durability of the F/M interface in various environments. POSS has hydrophobicity characteristics that decrease the water uptake, swelling and corrosion degradation of composites, which is ideal for marine applications. Two POSS systems with different functionalities, namely octaisobutyl and trisilanolphenyl, have been investigated. Surface treatment involved de-agglomerating the POSS into a solvent by sonication, soaking the fibers for three hours, and then removing the solvent in an oven. Treated and untreated carbon fibers were then used to make composites using Derakane 8084 vinyl ester resin. Composites samples were immersed in three different environments: seawater at room temperature (SWRT), seawater at 40°C (SW40), and in 85% relative humidity at 50°C (HM50). Over a period of six weeks, POSS modified samples absorbed less water reducing absorption by 20-32% compared to control specimens. Short beam shear tests of samples after exposure to environmental conditions have shown that there is no degradation in interlaminar shear strength. Instead there was improvement of about 7-32%. This observation suggests that while under environmental exposure the resin was still curing, especially at elevated temperature.