Can calcium carbonate filler be added to plastic - polypropylene flame - retardant panels?

Calcium carbonate is a white solid, odorless and tasteless. It exists in two forms: amorphous and crystalline. 

Among the crystalline forms, it can be further divided into the orthorhombic system and the hexagonal system, presenting a columnar or rhombic shape. 

It has a relative density of 2.71. It decomposes at a temperature range of 825 to 896.6 °C, and decomposes into calcium oxide and carbon dioxide at approximately 825 °C. Its melting point is 1339 °C, and under a pressure of 10.7 MPa, the melting point is 1289 °C. 

It is hardly soluble in water and alcohol. It reacts with dilute acids, simultaneously releasing carbon dioxide and showing an exothermic reaction. It is also soluble in ammonium chloride solution. It is almost insoluble in water. 

From this, it can be seen that calcium carbonate cannot be added to polypropylene flame-retardant sheets!