In situ preparation of carbon fiber fabric reinforced poly(lactic acid) composites by vacuum‐assisted resin transfer molding

Self Cite

In fiber‐reinforced composites, the interfacial bonding between fibers and the matrix is crucial for determining the material's performance. A vacuum‐assisted resin transfer molding (VARTM) process was utilized in this work to fabricate glass fiber fabric‐reinforced polyamide 6 (GFF/PA6) composites through in‐situ polymerization using caprolactam (CL) as the precursor. To enhance the fiber‐matrix interfacial bonding, polyethylene glycol (PEG) was incorporated into the polymerization system, improving the hydrogen bonding between the matrix and fibers. Morphological observations and interface layer analysis revealed that the introduction of PEG resulted in improved interfacial bonding and increased interface layer thickness. Molecular dynamics simulations indicated that the amino formate groups formed by the reaction with PEG exhibited more hydrogen bonds with the hydroxyl groups on the glass fiber surface, thereby promoting interfacial bonding between the matrix and fibers. When the PEG content was 10 wt%, the tensile strength and the elongation at break of the corresponding composite increased by 160% and 300% compared to GFF/PA6 composites without PEG. This study presents a promising strategy for enhancing the fiber‐matrix interfacial bonding by modifying the matrix, offering a prospective approach for developing high‐strength thermoplastic composites.Highlights GFF/PA6 composites were fabricated via the VARTM method. The addition of PEG for matrix modification improved the interfacial bonding. The modification enhances the hydrogen bonding between the matrix and fibers. Good interfacial bonding can greatly promote the crystallization of the matrix. The composites exhibited a significant increase in strength and toughness.

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Significant enhancement of mechanical properties for glass fiber fabric‐reinforced polyamide 6 composites by improving interfacial bonding

Fang,

Jia,

Chen

et al. 2024

Self Cite

Spray and deposition characteristics of unsaturated polyester resin applied for impregnating long fiber preform composites

Zegeye,

Delele,

Tsegaw

et al. 2023

Spray up is a method intensively applied for short fiber reinforced plastic (FRP) products manufacturing. The current study investigated the application of spray up for impregnation and manufacturing of long fiber FRP products, which can bring major advantages of minimized impregnation time and fewer product defects. Computational fluid dynamics (CFD) modeling was applied to investigate the spray and deposition characteristics of the viscous general‐purpose unsaturated polyester resin on a glass fiber preform. Validation of CFD results was done using phase Doppler anemometer and camera imaging techniques, and errors were calculated. Droplet velocity distributions 30 cm from the nozzle tip showed an average absolute percentage error of 4.3% and root mean square error value of 0.68 m/s, which are minimal. CFD and experimental values of sprayed resin area coverage (main area) after 4 s of spray were 17 and 16.3 cm in diameter, respectively; this is a relatively small error. Resin pool thickness on the target surface was variable, values predicted numerically. Non‐uniformity of pool thickness can be compensated by using appropriate compaction mechanisms. It is also possible to impregnate large size and complex shape products using multiple nozzles of proper arrangement.

Bamboo fiber‐reinforced epoxy composites fabricated by vacuum‐assisted resin transfer molding (VARTM): Effect of molding sequence and fiber content

Shi,

Wu,

Zhang

et al. 2023

Fabricating bamboo fiber‐reinforced epoxy composites (BFREs) using the vacuum‐assisted resin transfer molding (VARTM) process has many advantages, such as low cost, high product quality, controllability, and broad applicability. However, the immature fabrication process seriously affects product performance and hinders the full exploitation of the advantages of the VARTM process. The effects on the physical‐mechanical and thermal properties of BFREs by molding sequence and fiber content were investigated in this study. The molding sequence of fiber compression followed by resin injection was beneficial to ensure hermeticity, thus reducing the voids in the BFREs. The mechanical properties of BFREs gradually increased with increasing fiber content. With 50 wt% fiber content, the bending strength and modulus, shear strength, and impact toughness of BFREs reached 71.27 MPa, 6.78 GPa, 11.68 MPa, and 5.45 kJ/m2, respectively. Although the thermal stability of the BFREs was slightly lower than that of pure epoxy, the bamboo fibers' high rigidity evidentially increased the epoxy's dynamic mechanical properties. The life cycle assessment indicated that the BFREs effectively reduced the environmental impacts and production energy consumption compared to the glass fiber correspondent. The VARTM‐fabricated BFREs have great potential for construction, transportation, household items, packaging, sports equipment, and leisure goods applications.Highlights Fiber compression followed by resin injection could ensure great hermeticity. Micro‐CT accurately measured the void characteristics of the composites. Voids had detrimental effects on the properties of the composites. Dense bamboo fiber preforms enhanced the mechanical properties of epoxy. Bamboo fibers reinforcing epoxy reduced the impact on the environment.