When choosing mineral powder for plastics, look at these 11 indicators

Common mineral powder materials used in the plastics industry include calcium carbonate (heavy calcium, light calcium, nano calcium), talc, kaolin, wollastonite, brucite powder, mica powder, barite powder, barium sulfate and many other varieties. For the main purpose of filling increment, it can generally be used to tens to hundreds of phr. For the purpose of improving performance and reducing costs, it can generally be used to dozens of parts.

The properties of inorganic mineral fillers have many effects on plastic products, including physical and chemical composition and properties, particle size and distribution, particle shape and surface properties, as well as density, hardness, whiteness, etc., which have an impact on the performance and process parameter requirements of plastics.

1. Geometric shape characteristics
The influence of filler particles of different geometric shapes on the strength of their plastic products is generally fibrous> flake> columnar> cubic> spherical. Flake fillers help to improve the mechanical strength of products, but are not conducive to molding processing.

2. Particle size and surface characteristics
Generally speaking, the smaller the particle size of inorganic non-metallic mineral fillers, the better the mechanical properties of plastics when they are evenly dispersed. However, while reducing the particle size of filler particles, the processing technology becomes more complicated and the cost increases accordingly.

3. Specific surface area
The larger the specific surface area, the better the affinity between filler and resin, but the more difficult it is to activate the surface of the filler and the higher the cost. However, for filler particles of the same volume, the rougher the surface, the larger the specific surface area.

4. Density
Particles of different shapes have different particle sizes and distributions. When the mass is the same, the apparent density of particles with the same true density may not be the same due to different stacking volumes.

5. Hardness
High hardness can improve the wear resistance of products, but it will wear processing equipment. People do not want the benefits of using fillers to be offset by the wear of processing equipment. For fillers of a certain hardness, the wear intensity of the metal surface of the processing equipment increases with the increase of the filler particle size, and its wear intensity tends to be stable after a certain particle size.

6. Color
In order to avoid obvious changes in the color of the filled material matrix or adverse effects on the coloring of the matrix, most production requirements require the whiteness to be as high as possible.

7. Oil absorption value
The oil absorption value of the filler affects the amount of plasticizer used in the filling system and the processability of the material. Fillers with low oil absorption values ​​have good processability of the filling system and are easy to mix with resins, which can reduce the amount of plasticizer used.

8. Optical properties
Some products can use the light absorption of fillers to increase the temperature, such as agricultural plastic greenhouses.

9. Electrical properties
Except for graphite, most inorganic mineral fillers are electrical insulators.

10. Chemical composition
The chemical activity, surface properties (effects), thermal properties, optical properties, electrical properties, magnetic properties, etc. of inorganic mineral fillers depend to a large extent on the chemical composition.

11. Thermochemical effect
Polymers are easy to burn, but most inorganic mineral fillers, due to their own non-combustibility, reduce the combustible substances after being added to the polymer matrix and delay the combustion of the matrix. Environmentally friendly flame retardant filler.

In short, the role of inorganic non-metallic mineral fillers in polymer composites can be summarized as increasing, enhancing and giving new functions. However, because inorganic non-metallic mineral fillers and organic polymers have poor compatibility, inorganic non-metallic mineral fillers are modified to improve their compatibility with organic polymers and avoid uneven stress dispersion caused by direct addition.