Physical and mechanic al properties of pol yurethane/polyhedral oligomeric silsesquioxane ( PU/POSS) nanocom posite

Polyu rethane clear coats are widely used in autom otive indus tries. Incorporation of nano particles have sh own to im prove the properties of these resins leading to appropriate mecha nical properties and high transpa rency provided that th e dispersion process is well accom plished. However, nan o particles h ave usually high aggregation tend ency which make them difficult to disperse. In recent yea rs, Polyhedral Oligomeric Silsesquioxanes (POSS) have emerged as a new type of silica structure wit h structural size of ۱-۳ nm, which have functional site and are capabl e of being dissolved in solvent or vehicle. POSS does not po ssess conventional difficulty of nano particles. Moreover, these mat erials are a ble to act as fire retardant, surfac e energy reducer, cor rosion inhibitor. The main advantage of these nanostructures is their ability to enhance the cross-linking density. In this study hybrid coatings based on polyurethane/polyhedral oligomeric silsesqui oxane were synthesized. The reacti on with POSS has been done by the use of DBTL as catalyst. Furthermore p artial chemical reaction of POSS active sites with NCO part of polyurethane was proved. The effects induc ed by POSS content on chemical, ph ysical and mechanical properties in surface and bulk of bl ank polyurethane coat ing versus polyuretha ne containing ۱, ۳, ۵ percent were investigated.

کلیدواژه ها:

Poly hedral Oligomeric Silses quioxane ، POSS ، Polyurethane ، Na no composite ،