Objective The influence mechanism of different bamboo fiber particle sizes and raw material ratios on the physical and mechanical properties of bamboo fiber/polypropylene/calcium carbonate composites was expounded, which could provide reference for the industrial production and application of BFs/PP/CaCO₃ composites.

Method Taking calcium carbonate, bamboo fiber and polypropylene as the raw materials, BFs/PP/CaCO₃ composites were prepared by controlling the particle size of bamboo fiber (40, 80 and 120 mesh) and the ratio of raw materials, and their physical and mechanical properties were investigated. The microstructure, thermal stability, and fluidity of the composites were characterized by scanning electron microscope, thermogravimetric analyzer, and melt index instrument, respectively. Finally, considering the production cost and related performance requirements, some suggestions were put forward for the production and application of BFs/PP/CaCO₃ composites.

Result With the increase of calcium carbonate content, the tensile strength, flexural strength, and elastic modulus of the composites decreased gradually, while the density increased. The particle size of bamboo fiber had a significant effect on the physical and mechanical properties of composites. When the particle size of bamboo fiber was 80 mesh, and the addition of calcium carbonate and bamboo fiber was 5% and 45%, respectively, the tensile strength, bending strength, and elastic modulus of the composites were the best, which were 36.09 MPa, 62.6 MPa and 4.30 GPa, respectively. The addition of calcium carbonate had little effect on the impact strength of composites. In addition, with the increase of calcium carbonate content, the thermal stability and melt fluidity of the composites also improved. When the proportion of calcium carbonate mass was 20%, the melt flow rate of the composites was 16.50 g/10 min, which was 8.98% higher than that of the group without calcium carbonate, thus the processability was improved.

Conclusion The composite material with 80 mesh bamboo fiber exhibites excellent physical and mechanical properties. After adding calcium carbonate, the raw material cost of the composite material can be reduced by 1.63%−6.54%, and its related indexes were still far higher than the requirements of industry standards.