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

Abstract 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. Highlights The role of nano‐CaCO₃ in plant fiber composite materials was explored. The relationship between the content of nano‐CaCO₃ and the various properties of tri‐phasic plant fiber composite materials was demonstrated. The mechanisms by which nano‐CaCO₃ enhances plant fiber composite materials were analyzed at both macroscopic and microscopic levels.