Calcium carbonate has many advantages such as easily available raw materials, low price, good stability, and non-toxicity. When used for filling HDPE, it can not only reduce material costs, but also increase toughness and reinforcement, improve material impact strength, and improve material elastic modulus. Tensile performance has become one of the most important filling materials for HDPE.

1. Coupling agent activated calcium carbonate modified HDPE: the interaction between micron calcium carbonate treated with coupling agent and polymer segments can slow down or limit the movement between segments, so that the silver streak of the composite material can reduce the impact toughness improve. Adding 2% silane coupling agent to activate nano-CaCO3 in recycled HDPE can significantly improve the tensile, bending, and impact properties of the modified resin, approaching or even reaching the level of engineering plastics.

2. Organic matter activated calcium carbonate modified HDPE: Common organic matter used to modify calcium carbonate powder includes fatty acids (salts), stearic acid, etc. Using fatty acid to treat CaCO3 for filling modified regenerated HDPE, the melting point, tensile stress and impact strength of composite materials are significantly improved compared with HDPE. Treating CaCO3 with stearic acid to modify HDPE found that the composite material can maintain higher impact toughness and elongation at break at lower temperatures. This is mainly due to the nucleation effect of CaCO3 that reduces the spherulites of the material. The formation of the size improves the Young's modulus and yield strength of the material.

3. Polymer activated calcium carbonate modified regenerated HDPE: Polymer surface treatment can be divided into reactive cellulose surface treatment and graft polymer surface treatment. Through interface modification, a ternary composite material (regenerated HDPE/POE/CaCO3) with CaCO3 as the core and maleic anhydride grafted ethylene-octene copolymer elastomer (POE) as the shell is prepared, due to the "core-shell" structure The formation of the elastomer and CaCO3 show a synergistic toughening effect. Compared with the untreated CaCO3 composite material, at the same CaCO3 content, the surface treated CaCO3 forms a stronger interfacial adhesion with the elastomer. As a result, the "brittle-to-tough" transition of the ternary composite material occurs at a lower elastomer content. The nano-calcium carbonate activated by surfactants improves the performance of the composite material due to the improvement of dispersibility and the strengthening of the entanglement with the HDPE matrix. The unactivated nano-calcium carbonate is prone to agglomeration. As a stress point in HDPE, it will reduce the performance of the composite material.