Читать книгу Metal Oxide Nanocomposites - Группа авторов - Страница 53

The HM are made from silica and generally prepared at controlled specific gravity. They are larger than solid glass spheres and available in a wider range of particle sizes. Generally, the microspheres are less sensitive to moisture which reduces the attraction between particles. Hollow spheres were mostly used for thermosetting resin systems, however, strong spheres have been designed which are >5 times and >4 times respectively stronger than HM in static crush strength and times long lasting in shear [23]. The specific gravity of HM is lower than pure resin which makes them to use in lightning resin dominant compounds. Due to their weight reducing features, they are widely utilized in aerospace and automotive industries applications. But they are seldom used in systems requiring high-pressure molding and high shear mixing due to their poor crush resistance than solid spheres. Both, solid or hollow microspheres demonstrated the properties which are directly related to their spherical shape and let them behave like minute ball bearing, resulting in improved flow properties. The microspheres are free of orientation and sharp edges and therefore produce smoother surfaces, whereby distributing the stress homogeneously throughout resin matrices.