Effect of Polyhedral Oligo Silsesquioxanes (Poss) Particles on Cavitation Resistance of Hybrid Composite Films

Abstract

The objective of this study is to investigate the influence of the polyhedral oligo silsesquioxanes (POSS) structure on cavitation erosion of hybrid acrylate composite films. Cavitation is used as a method for estimation of adhesion quality of a composite film on a metal substrate. The hybrid composite films consist of UV cured Bisphenol A glycidyl methacrylate/triethylene glycol dimethacrylate (BisGMA/TEGDMA) as matrix and reactive POSS structures as adhesion enhancers. POSS structure is established in dependence of content of hydroxyl groups and cross-linkable functionalities that affect the system compatibility. Composites are made with 1, 3, and 5 wt. % of three different types of POSS reagents containing: i) hydroxyl groups (POSS-M), ii) both hydroxyl and allyl groups (POSS-M-A), and iii) methacrylate groups (POSS-M-Cl). Morphology of composite films is examined by scanning electron microscope (SEM) and atomic force microscopy (AFM). The roughness after cavitation erosion of hybrid films with POSS-M-A determined by AFM was decreased for ~86% when compared to the polymer matrix. The loss of mass after cavitation erosion is significantly reduced by the addition of 5 wt. % of POSS particles. The best resistance to cavitation evaluated as the mass loss has a composite film with POSS-M-A particles and it exhibits ~94% lower mass loss when compared to the neat polymer matrix. Likewise, hybrid composite films with POSS-M-Cl and POSS-M particles decreased mass loss after cavitation test by ~91% and ~89%, respectively. The results indicate that improved mechanical properties and enhanced adhesion to the metal substrate contributed to improved resistance to cavitation erosion. Methods used in this study for estimation of adhesion quality and wear resistance clearly indicate that the best compatibility with BisGMA/TEGDMA matrix is achieved with POSS reagent containing both hydroxyl and allyl functional group.