Why is calcium carbonate (CaCO3) added to biodegradable bags?

Although PBAT has excellent performance, it is expensive, and defects such as tensile strength and low modulus also limit its application. Calcium carbonate (CaCO3) is derived from nature and is inexpensive, abundant and diverse. Using calcium carbonate as a plastic additive can effectively reduce production costs while maintaining good mechanical properties of the plastic matrix.

There are many hydroxyl groups on the surface of calcium carbonate, which has poor compatibility with organic polymer materials, and is easy to agglomerate when it reaches a certain fineness, so surface modification is a necessary auxiliary means. At present, titanate and silane are widely used coupling agents, among which titanate is a proton reactant that does not need water condensation, silane is a hydroxyl reactant that needs water condensation, when calcium carbonate is combined with PBAT, siloxane can react with CaCO3 and water molecules remaining on the surface of PBAT, which can slow down the degradation rate of molecular chains, which is very suitable for reinforcement and modification applications.