Enhancement in Compressive Strength and UV Ageing-resistance of Poly( p-phenylene benzobisoxazole) Nanocomposite Fiber Containing Modified Polyhedral Oligomeric Silsesquioxane

Abstract

Modified polyhedral oligomeric silsesquioxane (m-POSS) from trisilanol isobutyl POSS and 4-formylbenzoic acid was synthesized and used for polymerization of poly(p-phenylene benzobisoxazole) (PBO) nanocomposite. PBO and its nanocomposite fibers could be obtained by dry-jet wet spinning the as-polymerized solutions at a liquid crystalline state. No decrease in tensile strength of PBO/m-POSS nanocomposite fibers was observed with the m-POSS content. The tensile modulus of PBO nanocomposite fibers showed the increase 38 % at 2 % loading of POSS and 16 % at 2 % loading of m-POSS compared to PBO fiber. Incorporation of m-POSS into PBO brought to the increase of 19-54 % in compressive strength compared to PBO fiber. The retention of tensile strength was improved from 48 % for PBO to 59 % for PBO/POSS-2.0 mol% fiber and to 62 % for PBO/m-POSS-2.0 mol% fiber after 16 h UV irradiation.