Jialong Zhao

Rice husk is a byproduct of rice production, often discarded or burned, leading to environmental pollution. In this study, rice husk fiber‐reinforced polypropylene (RF/PP) composites were prepared using a physical foaming injection molding technique. The effects of fiber content on the physical, mechanical, and environmental properties of the RF/PP composite were analyzed. The results showed that the incorporation of RF reduced the melt flow rate, enhanced the crystallinity of PP, and increased both the density and moisture sensitivity. The RFs were uniformly dispersed within the PP matrix, improving the stability of the foaming process. The developed foamed RF/PP composite not only significantly reduced the material density (by 10%–14%) but also improved mechanical properties, including a 26.18% increase in flexural strength and a 58.85% increase in impact strength, while reducing carbon emissions by nearly 10%. This provides a sustainable solution for applications in automotive lightweighting, construction materials, and related fields. The research results promote the high‐value utilization of agricultural waste, support the development of a circular economy, and provide technological support for companies to fulfill their environmental responsibilities and enhance market competitiveness.Highlights: Innovative use of rice husk fibers in sustainable RF/PP composites via foaming. RF improves composite molding and foaming quality. Eco‐friendly solution with reduced density for RF/PP composites. Comprehensive analysis reveals RF's potential in green, lightweight composites.

The in‐mold decoration and microcellular foaming injection molding (IMD‐MIM) process was proposed to solve the apparent quality problem of polypropylene in microcellular foaming injection molding. Based on physical experiments and finite element simulation, stainless steel (ST) and polyethylene glycol terephthalate (PET) decorative films were selected for analysis, and the influence of the type and thickness of the decorative films on the cell structure, surface morphology, warpage deformation, and mechanical properties was revealed. The results show that the surface quality of the samples coated is significantly improved, and the asymmetric temperature field caused by the films changes the structure and distribution of the cells. The cell density on the coated side is higher than that on the non‐coated side, and the average cell diameter is smaller, and the foam core layer is shifted to the coated side. The warpage caused by ST film is larger, up to 2.836 mm. With the intervention of ST film and PET film, the impact properties of the samples have little change, but the tensile and flexural properties of the foamed samples have been effectively improved. The tensile strength increased by 28.6% and 25.9%, while the flexural strength increased by 28.6% and 28.1%, respectively. This study provides new insights into the comprehensive optimization of the structure and performance of polypropylene microcellular foaming materials and provides support for the development and application of lightweight materials in the future.

To explore the potential application of plant fiber reinforced composites for automotive component applications, this study prepared bamboo fiber (BF)/nano‐talc/polypropylene (PP) composites based on the injection molding process, comprehensively evaluated the effect of reinforcement materials on the forming properties of composites, including thermal performance, mechanical properties, water absorption, etc. Furthermore, taking a certain automotive injection molded interior part as the object, a life‐cycle assessment from production to the gate was conducted based on the real energy and material consumption during the composite preparation process. The results indicate that adding BF and talc powder increased the thermal stability, density, hardness, viscosity, and crystallinity of the composites while reducing the water contact angle on the surface. Surface‐modified BF and PP showed good compatibility. Talc powder exhibited good dispersibility in PP, and the synergistic effect of BF and talc powder effectively enhanced the composite performance. The tensile, flexural, and impact strength of the composites were improved by 40.64%, 51.48%, and 66.51%, respectively, compared with pure PP. The modulus of the composite increased nearly 2 times compared with pure PP. Additionally, the composite demonstrated good friction and wear properties. The environmental impact of the BF composite manufacturing process was significantly higher than that of pure PP. The substantial consumption of electricity, chemicals, and water resources in the extraction and modification processes of BF were the main factors. The findings of this study contribute to achieving green, high‐performance BF composite manufacturing and the expansion of its applications.Highlights: Composites have a higher environmental impact compared to PP. BF and talc can synergistically enhance the performance of composites. BF shows good compatibility with PP. Composites exhibit good friction and wear characteristics.

In this paper, the surface morphology of the parts was improved by the in‐mold decoration and microcellular foaming injection molding (MIM‐IMD), and the mechanical properties of the parts were improved by inorganic particles modification. The effects of different inorganic particles (CaCO₃, MMT, Talc) on the rheological behavior, crystallization properties, cell structure, surface quality, and mechanical properties of the MIM‐IMD composites were analyzed through experimental research and comprehensive macro and micro characterization. It was found that the foamed composite added with MMT had the highest surface quality, the best cell structure, the minimum average cell diameter of 78.4 μm and the maximum cell density of 3.09 × 10⁶ cells/cm³. Talc improved the crystallinity of polypropylene (PP) matrix, and the resulting mechanical properties were the most significant improvement. Tensile, flexural, and impact strength were increased by 20.3%, 11.6%, and 45.2%, respectively.Highlights: The MIM‐IMD process was used to improve the surface quality of the samples. The enhancement of different inorganic particles on the properties were compared. The properties were evaluated by macro‐ and micro‐characterization. Inorganic particles can significantly improve the cell structure. Inorganic particles can greatly improve mechanical properties.

In this study, under the conformity of engineering reality, considering the influence of slip coefficient on the variation range of winding angle, 15 composite lay‐up schemes of hydrogen storage vessels were designed using grid theory, and the hydrogen storage vessels's structural strength was analyzed. The distribution of non‐geodesic fiber windings on the outer surface of the inner layer was solved using differential theory and the winding principle, and ABAQUS established the finite element model. The maximum stress value and stress distribution of the composite layer of the hydrogen storage vessel along the fiber direction were studied, the damage of the composite layer was analyzed, and the pressure and mode of the bursting were predicted. Results show that the structural strength of the hydrogen storage vessel designed by this method can be effectively guaranteed. The hoop winding layer bears the majority of the stress on the hydrogen storage vessel, while the helical winding layer's fiber strength is not entirely utilized. The hydrogen storage vessel gains greater structural strength when the circumferential winding layer is concentrated and situated at the outermost portion of the composite layer. The layup scheme has an impact of approximately 17.21% on burst pressure. Highlights: Effect of slip coefficient on the change of winding angle. Different forms of composite lay‐up schemes were designed. The stress distribution in the composite layer was studied. Analyzed structural strength and damage of the composite layer. Predicted the pressure and mode of bursting.

Considering the nonlinearity of shear in the mechanics of composite materials, the increase of shear strength when the substrate interface is compressed, and the shear of the matrix itself, the Chang–Chang criterion is improved. The improved Chang–Chang criterion was used to establish a progressive damage model of low‐velocity impact of composites. The low‐velocity impact process of T700/EM134 composite laminates in the energy range from 5 to 10 J was compared by physical tests and finite element simulations, and the calculated impact response curves and material damage were in good agreement with the test results, which proved that the model of the improved criterion was suitable for the damage prediction of low‐velocity impact of composite laminates.Highlight: Consider various situations in composite material shearing. Improved based on the Chang–Chang criterion. Establishing a progressive damage model for low‐speed impacts. Comparison through physical experiments and finite element simulation. Prove that the improved criterion model is suitable for damage prediction.

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.

Resource depletion and environmental degradation have become important issues affecting the human development process. Plant fiber‐reinforced composites (PFRCs) are characterized by high natural availability, good mechanical properties, low density, recyclability, and eco‐friendliness. Expanding human applications of plant fibers is an important measure to combat resource and environmental problems. The injection molding process has the characteristics of strong product size adaptability, high molding precision, and high production efficiency. It is suitable for large‐scale production in the industry and is one of the main molding methods of PFRCs. Currently, there are still challenges and opportunities for high‐performance manufacturing of PFRCs based on the injection molding process. This article reviews the complete process of manufacturing‐service life‐remanufacturing of PFRCs based on the injection molding process. Emphasis is placed on the pretreatment technology and selection strategy of multi‐phase blended raw materials, the molding process conditions, functional applications, and simulation analysis, the aging and degradation characteristics during service, and the remanufacturing characteristics of the composites. Finally, the future research focus is summarized and prospected. The research in this paper will help promote the continuous progress of key technologies in the production process of PFRCs and help the industry to truly realize high‐performance green manufacturing in the future.Highlights: Plant fibers exhibit variability in morphology and properties. The link between the structure and performance of PFRCs is unclear. The degradability and durability of PFRCs are contradictory. The functionality and mechanical properties of PFRCs are contradictory. PFRCs have good characteristics for remanufacturing.

In this study, the viscoelastic constitutive equation of continuous glass fiber reinforced polypropylene composites based on the generalized Maxwell model and SCFM model was constructed by combining genetic algorithm. Based on this, a multi-scale numerical model for describing material relaxation and creep is proposed, and the accuracy of different scale models was compared through experiments. The forming state of the workpiece under various stamping speeds and preheating temperatures was also examined using a hot stamping numerical model. The independent design of the hot stamping hemispherical mold was used to confirm the hot stamping model's accuracy. The study's findings demonstrate that the macroscopic model can accurately simulate the relaxation and creep of composite materials. The hot stamping simulation results are match up well with experimental results. Composite molding defects appeared at the waist of the part, and defects were accompanied by resin loss.