Basic property requirements of fillers

The basic characteristics of fillers refer to the characteristics that have the greatest impact on the performance of the filled material and the composite formed by the filler in the application, and play a dominant role.
A The shape characteristics and size of particles: particles are the basic units of fillers, and the shape and size of particles are the basic parameters of particles. The shapes of particles include spheres, cubes, blocks, flakes, fibers, etc., and the size of the particle size is defined by the equivalent spherical diameter;
B Particle size distribution: the filler itself is an aggregate of particles, and it is impossible to be an aggregate of particles of uniform size. It is graded by screening and some fractions are removed. Particle size distribution is an important property of fillers, generally represented by a particle distribution curve, which directly affects its rheological properties, wear resistance, particle stacking and other properties;
C Specific surface area and surface free energy of particles: Specific surface area is the surface area per unit mass of fillers, expressed in m/g. Its large value indicates that the contact surface provided by the filler is large, which involves the adsorption capacity and chemical reaction capacity of the filler, indicating that there are more opportunities for contact; surface free energy refers to the dispersion of solid filler particles in liquid materials. Or when the liquid infiltrates the filler particles, it must overcome the energy barrier on the contact surface because the cohesive force between the molecules is greater than the attraction between the two different components. Its value is related to the specific surface area and composition of the filler, and directly affects the dispersion of the filler in the polymer material;
D Particle packing density: refers to the volume occupied by a certain mass of filler, which directly affects the quality and efficiency of the filled material;
E Chemical composition of filler: represents the chemical structure of the filler. Two fillers with the same components show different performance after filling, which shows that the chemical composition of the filler cannot fully represent its performance. Other properties such as particle size and particle distribution also have an important impact on the filling effect.