Mohammad Hosain Beheshty

This study comparatively evaluates wet filament winding and towpreg winding techniques, focusing on multi‐walled carbon nanotubes (MWCNTs)' influence on filament‐wound tube composites' mechanical performance. Building on optimized towpreg parameters, it investigates MWCNTs' role in enhancing structural properties. Four composite systems were fabricated using carbon fibers and epoxy resins: a commercial resin, an optimized blend, and two MWCNTs‐reinforced variants (0.1 and 0.5 phr). Mechanical characterization covered transverse tensile strength, interlaminar shear strength (ILSS), pipe stiffness, and energy absorption. Towpreg winding significantly improved transverse tensile strength (45.3%), strain (109.0%), and ILSS (47.3%) versus wet winding. Adding 0.1 phr MWCNTs further enhanced performance, increasing transverse tensile strength (+60.5%), strain (+113.6%), and ILSS (+51%) versus wet‐wound baseline. While 0.1 phr MWCNTs provided optimal enhancement, higher CNT loading (0.5 phr) led to increased brittleness and reduced energy absorption, clarifying this optimization trend. Helical‐wound tubes with 0.1 phr MWCNTs also showed a 53.2% increase in pipe stiffness. SEM revealed improved fiber–matrix adhesion and reduced void content in CNT‐reinforced towpreg specimens. Crushing tests confirmed towpreg‐wound composites had higher total and specific energy absorption than wet‐wound counterparts. Overall, CNT‐reinforced towpreg winding offers a scalable, effective route for producing lightweight composites with superior strength, stiffness, and reliability for demanding applications (e.g., aerospace, automotive, pressure vessels).

This study was conducted to evaluate the effects of the silanization of multiwall carbon nanotube (CNT) and graphene oxide (GO) nanoplates and their hybrid on the mechanical properties of epoxy/dicyandiamide (DICY)/carbon fiber (CF) composites. The silanized CNT (S-CNT) and GO (S-GO) were synthesized by refluxing (3-glycidyloxypropyl) trimethoxysilane in 97% ethanol. The silane grafting on CNT and GO was characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The nanocomposites' transverse tensile, flexural, and interlaminar shear strength (ILSS) were characterized. The transverse tensile and flexural strengths of the S-CNT0.5/epoxy/DICY/CF composite were 18% and 27% greater than those of the neat composite. Moreover, enhancements of approximately 34% and 39% were observed in the flexural moduli of the 0.5 wt.% S-CNT and S-GO filled samples, respectively. The tensile and flexural moduli of CF nanocomposite containing the hybrid of S-CNT-GO0.5 was enhanced by 31% and 45%, respectively. The evaluation of the tensile fracture surface of the samples revealed that the incorporation of GO and S-GO improved the CF‒epoxy interfacial bonding. The transverse interlaminar shear strength of the 0.5wt% S-CNT, S-GO, and S-CNT-GO hybrid-filled composites were enhanced by 18%, 10%, and 25%, respectively.

This study investigates the impact of replacing traditional wet filament winding with tacky towpreg winding. A novel aspect of this work is the precise exploration of the relationship between the precuring percentage of towpregs (10%, 15%, and 20%) and their physical state (wet, tacky, or dry), as well as the winding process and the resulting composite quality. Additionally, a suitable commercial resin system for filament winding, alongside a one‐component blend, was used to compare with the wet winding process. Comprehensive evaluations, including viscometry, impregnation, winding, and mechanical property assessments, were conducted to optimize the resin formulation and impregnation temperature. Results demonstrate significant improvements in mechanical properties for towpreg composites, with tensile strength in the fiber direction, transverse tensile strength, and interlaminar shear strength increased by 12%, 45%, and 47%, respectively, compared to wet‐wound samples. Additionally, cross‐sectional imaging revealed a substantial reduction in void content, from 6% in wet winding to just 2% in towpreg winding. This study highlights the innovative potential of tacky towpregs with a certain degree of precure in filament winding, offering enhanced mechanical performance and reduced void content while providing critical insights into the role of precuring in optimizing composite quality.

Unidirectional carbon fiber-reinforced epoxy (UCFRE) is suffering from weak transverse mechanical properties and through-thickness properties. The effect of different amount (0.1, 0.3 and 0.5 phr which is proportional to 0.09, 0.27 and 0.46 wt%, respectively) of multiwall carbon nanotube (MWCNT), on transverse tensile properties, flexural strength, fracture toughness in transverse and longitudinal fiber directions, interlaminar shear strength and lap shear strength of UCFRE has been investigated. Dicyandiamide was used as a thermal curing agent of epoxy resin. MWCNT was dispersed in the epoxy resin by ultrasonic instrument and their dispersion state was investigated by scanning electron microscopy (SEM). The curing behavior of epoxy resin and its nanocomposites was assessed by differential scanning calorimetry. Results show that transverse tensile strength, modulus and strain-at-break were increased by 28.5%, 25% and 14%, respectively by adding 0.1 phr of MWCNT. Longitudinal flexural properties of UCFRE was not changed by adding different amount of MWCNT. Although longitudinal flexural strength was increased by 5% by adding 0.1 phr of MWCNT. Fracture toughness in transverse and longitudinal fiber directions was increased by 39% and 9%, respectively at 0.3 phr of MWCNT. Results also show that interlaminar shear strength and lap shear strength were increased at 0.3 phr of MWCNT by 8% and 5%, respectively. These increases in mechanical properties were due to the good adhesion of fibers to the matrix, interlocking and toughening action of MWCNT as revealed by SEM.