11 knowledge points to tell you the impact of inorganic fillers on plastic modification

The influence of the nature of inorganic mineral fillers on plastic products is multifaceted, including physical and chemical composition and properties, particle size and distribution, particle shape and surface properties, as well as density, hardness, whiteness, etc. They have an impact on the performance of plastics and process parameters required.
 

1. Geometric shape characteristics

Different geometric shapes of the filler grains on the strength of its plastic products is generally fibrous > flake > column > cube > spherical. Flake filler helps to improve the mechanical strength of the product, but is not conducive to molding process. On the contrary, the spherical filler can improve the molding and processing performance of the products, but it may make the mechanical strength decrease.
 

2. Particle size and surface characteristics

Generally speaking, the smaller the particle size of inorganic non-metallic mineral filler, the better the mechanical properties of the plastic in the case of uniform dispersion, but the reduction of the particle size of the filler also makes the processing process complicated and the cost is increased.

In addition, the surface roughness of the filler particles and the different free energy also have an impact on the plastic manufacturing process, in actual production requires the reduction of the filler particles surface free energy to avoid cohesion between the particles, so as to avoid uneven distribution of product stress.
 

3. Specific surface area

The larger the specific surface area, the better the affinity between the filler and resin, but the more difficult and costly the activation process of the filler surface. However, for the same volume of filler particles, the rougher the surface, the larger the specific surface area.
 

4. Density

The particle size and distribution of different shapes are different, and when the quality is the same, the apparent density is not necessarily the same for particles with the same true density because of the different volume of stacking.
 

5. Hardness

High hardness can improve the wear resistance of the products, but it will wear the processing equipment, and people do not want the benefits brought by the use of fillers to be offset by the wear and tear of the processing equipment. For a certain hardness of the filler, the wear strength of the metal surface of the processing equipment increases with the increase in the particle size of the filler, and the wear strength tends to stabilize after a certain particle size.
 

6. Color

In order not to bring obvious changes to the color of the filled material matrix or not to bring adverse effects on the coloring of the matrix, most of the production requirements the higher the whiteness the better.

7. Oil absorption value

The size of the filler oil absorption value affects the amount of filling system plasticizing additives and the processability of the material. Low oil absorption value of the filler, the filler system of good processability, easy to mix with resin, can reduce the amount of plasticizing aids. For the same fineness of the same inorganic mineral filler, surface organic modification can reduce the oil absorption value of inorganic mineral filler.

8. optical properties

Some products can use the light-absorbing properties of the filler to increase the temperature, such as agricultural plastic sheds.

9. Electrical properties

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

10. Chemical composition

The chemical activity, surface properties (effects) and thermal properties, optical properties, electrical properties, magnetic properties of inorganic mineral fillers depend largely on the chemical composition. Drawing on the different effects of different types of fillers on the products in the table below, different fillers are selected according to the required product characteristics.
 

11. Thermochemical effects

Polymers are easy to burn, but most inorganic mineral fillers, due to their own non-combustibility, reduce the combustible material after adding to the polymer matrix, delaying the combustion of the matrix. Such as magnesium hydroxide and aluminum hydroxide decomposition temperature is low, and the decomposition generates water vapor and metal oxides, which has excellent flame retardant properties and does not produce toxic smoke, so it is an environmentally friendly flame retardant filler for polymer matrix composites.

In conclusion, the role of inorganic non-metallic mineral fillers in polymer composites is summarized as increment, enhancement and giving new functions. However, because of the poor compatibility between inorganic nonmetallic mineral fillers and organic polymers, inorganic nonmetallic mineral fillers are modified to improve their compatibility with organic polymers and avoid uneven stress dispersion caused by direct addition.