Epoxy/Nanosilica Organic-inorganic Hybrid Materials -Effect of Functional Group of POSS

Epoxy (EP) was mixed and cured with either 1.0, 3.0, 5.0 or 8.0 parts of one polyhedral oligomeric silsesquioxanes (POSS) per hundred parts of epoxy resin, using ethylene diamine as cure agent. Each system was precured at 80 °C for 1 h and last cured at 170 °C for 1 h, and an appropriate temperature programing was set to ensure that the temperature rise was not too fast to avoid possible poor diffusions. Four POSSs used are glycidyl POSS (G-POSS), aminopropyl isobutyl POSS (A-POSS), PEG POSS (P-POSS), and trisilanol isobutyl POSS (T-POSS). Bearing hard aggregate particles in hybrid composites was found for (EP/T-POSS) and (EP/A-POSS) (both reflected by the pencil hardness), and the tensile strength values were ranked as the first and third, respectively. The (EP/P-POSS) system was ranked the second in tensile strength, where both (EP/P-POSS) and (EP/G-POSS) have uniform distribution of POSS with little aggregation in epoxy matrix. Note that G-POSS was expected to form extensive networks with epoxy, since it has abundant glycidyl groups. The extensive network formation was found to increase Tg with increasing the G-POSS content. The TGA results were nicely compiled with the use of integral procedural decomposition temperature.