CaCO3 is an important element in a plastic compound. It decreases surface energy and imparts opacity and gloss to the products.
CaCO3 As A Filler-
- It improves the material’s finishing impact strength.
- High percentage filter loading in PVC pipes.
- It can improve the material’s luster, tensile force, elongation, and other properties.
- These grades of powder are used for the production of flexible and rigid PVC pipes.
Calcium carbonate improves the basic characteristics of polyvinyl chloride or PVC. It increases stiffness and impact resistance by shrinking the particle sizes. Calcium carbonate can also be used to improve compounding performance for PVC pipes. It helps disperse different ingredients into PVC powder blends and makes polymer flow more homogeneous.
- PVC pipes are produced by extrusion from raw material PVC. They generally follow the same steps that typical pipe extrusion operations.
- PVC twin screw extruder feeds raw material and powder.
- Melting and heating of multiple extruder zones
- Making a pipe by using a die.
CaCO3 increases both the impact strength and flexural flexibility of the material if it is well controlled.
The compositions of PVC pipe materials often contain different types and amounts of calcium carbonate. Calcite is a plastic filler that helps to harden the plastic. Calcium carbonate is used to create PVC flexible compounds. This includes tubing, wire, as well as other compounds like conduits, extruded pipe, conduits, and so on.
Many thermoplastic resins may be combined with calcium carbonate. Many polypropylene materials are filled with calcium carbonate to increase their strength, which is crucial for high-temperature operations. These piping applications have a wide variety of performance requirements. The particular application and the main property requirements of that application will dictate the product selection. To maximize formulation pliability and property growth, surface-treated carbonates will provide high-quality dispersion as well as excellent incorporation within the polymer matrix. PVC pipes can be repaired easily and are resistant to corrosion. A PVC compound’s impact strength can be dramatically affected by calcium carbonate as a powder filler.
Precipitated Vs. Ground Calcium Carbonates
It is not enough to have high impact strength by simply considering the median or average size of particles. PVC, or any other polymer, has a limit on its impact strength because of the size of the largest particles. The impact strength of two fillers will differ if they have different distributions of particle sizes.
Precipitated calcium carbonates are more effective than ground calcium carbonates (GCCs) because they have a smaller particle size distribution. The plot below compares the particle sizes of a PCC to a GCC with the same median size particle.
Precipitated calcium carbonate has smaller particles than the ground. Additionally, the GCC’s largest particles are smaller than the PCC’s. This can be seen in scanning electron microscopic images. You can see a PCC as well as a GCC. Each has a median particle size between 0.7 and 0.8 microns.
Specialty Minerals Inc. (SMI) submicron-sized PCC fillers such Calofort S and Ultra Pflex S are particularly effective in increasing the impact strength of rigid PVC. Their steep particle distribution curves make them especially useful. The large particles in the PCCs are not as common as those in the GCCs. This helps to reduce stress concentrator points within the polymer matrix.
A high-aspect-ratio, small particle size filler can give you the best of both worlds. The impact strength of the particle is dependent on its size while stiffness depends on how large it is. Unfortunately, it is not possible to make a filler of both dimensions. Additionally, the critical size of the filler particle is the largest dimension. Small particles, to have high aspect ratios, must also be very thin.