Research on properties and cellular structure of nano-CaCO3/rice-husk fiber/polypropylene three-phase thermoplastic microcellular foaming composites

Microcellular foamed plant fiber composites have the advantages of low density, low cost, and biodegradability, so it has great development potential in the industry. Nevertheless, the existence of cellular structures diminishes the mechanical performance of plant fiber composites. To overcome this problem, in this study, nano-CaCO3 was used to enhance the microcellular foamed plant fiber composites, and the three-phase thermoplastic composites, comprised of nano-CaCO3, rice-husk fiber, and polypropylene (PP), were fabricated using a chemical foaming injection molding technique. The study analyzed how the nano-CaCO3 concentration affected the melt viscosity, crystallization characteristics, mechanical properties, and cellular structure of the composites. According to the findings, the mechanical characteristics of microcellular foamed three-phase thermoplastic composites were enhanced initially and subsequently diminished as the nano-CaCO3 content was augmented, and obtained optimal value at 2 wt% nano-CaCO3 content. By observing the cells of microcellular foamed three-phase thermoplastic composites in vertical and parallel melt flow directions, it was found that the nano-CaCO3 content of 2 wt% three-phase thermoplastic composite had the best cellular structure.