Determination of Mechanical and Surface Properties of Semicrystalline Polyhedral Oligomeric Silsequioxane (POSS) Nanocomposites

摘要

Polyhedral Oligomeric Silsesquioxanes are three dimensionally precise silicon/oxygen nanoparticles. These nanoparticles can be tailored to maximize the interactions between the POSS compounds and the polymer by the modification of the organic groups surrounding the inorganic cage. This study examines the ability of POSS to improve the mechanical and surface properties of three semicrystalline polymers, fluorinated ethylene-propylene (FEP), poly(vinylidene fluoride) (PVDF) and isotactic polypropylene (PP). The POSS materials used included methyl(sub-8)T(sub-8) and two FluoroPOSS compounds, fluorodecyl(sub-8)T(sub-8) and fluorooctyl(sub-8)T(sub-8). The FluoroPOSS compounds have been shown to exhibit remarkable surface characteristics, which have been observed in water contact angle measurements. In a comparative study, five and ten weight percent of methyl(sub-8)T(sub-8) was melt blended into PVDF, FEP and PP and the same weight percent loadings of fluorodecyl(sub-8)T(sub-8) and fluorooctyl(sub-8)T(sub-8) were investigated in PVDF and FEP. The addition of methyl(sub-8)T(sub-8) was found to increase the modulus of FEP and PP, while the incorporation of all three POSS compounds decreased the modulus of PVDF. In addition, the methyl(sub-8)T(sub-8) in PP increased the tensile strength, Izod impact strength, and heat deflection temperature. The injection molded FEP blend samples showed indirect evidence of surface migration, as demonstrated in the core/shell morphology observed in pulled tensile bars and disks for surface analysis. The incorporation of FluoroPOSS into FEP and PVDF drastically increased the hydrophobicity and oleophobicity of those materials.