Effect of Hollow Silica Microspheres on Compressive and Dynamic Mechanical Properties of Hydroxyl-Terminated Polybutadiene-Based Polyurethane Composites.

Porous polyurethane composites containing hollow silica microspheres were prepared by one-step bulk polymerization to study cyclic compressive and dynamic mechanical properties of the composites. Cyclic compression testing was conducted to record the stress versus strain curves during the loading and unloading cycles and in order to study the compressive behavior and time-dependent recovery of the composites. Effect of frequency on the dynamic mechanical properties of the composites was also evaluated using dynamic mechanical analysis. Master curves were constructed based on time-temperature superposition principle in order to show long-term dynamic mechanical behavior of the composites.

Porous Silicone Polymeric Composites Filled with Hollow Silica Particles: Thermal Conductivity, Thermal Stability and Mechanical Properties.

Porous silicone composites containing different types and volume fractions of hollow silica particles (HSPs) were prepared and characterized in terms of thermal insulation performance, thermal stability, and tensile and dynamic mechanical properties. The comparative study on measured and theoretical thermal conductivity of porous silicone/HSP composites was performed. Dependence of shell thickness, defined as the ratio (η) of internal (ri) to outer (r0) radius, and volume fraction (Φ) of HSPs on the thermal insulation performance of composites was predicted theoretically by Felske model. Tensile properties and dynamic mechanical measurements showed the incorporation of HSPs led to mechanical reinforcement in the silicone composites. Theh Guth and Gold equation showed mechanical reinforcement of porous silicone/HSP composites was primarily due to the hydrodynamic effect of HSPs in the silicone matrix at low HSP contents (Φ < 0.5).