Effect of polyamide-6,6 (PA 66) nonwoven veils on the mechanical performance of carbon fiber/epoxy composites

Abstract

In this study, carbon fiber/epoxy (CF/EP) composites were interleaved with polyamide-6,6 (PA 66) nonwoven veils at two different areal weight densities (17 and 50 gsm) to improve their delamination resistance against Mode-I loading. Mode-I fracture toughness (DCB), tensile, open hole tensile (OHT), flexural, compression, short beam shear (ILSS) and Charpy-impact tests were performed on the reference and PA 66 interleaved composite specimens. The DCB test results showed that the initiation and propagation Mode-I fracture toughness values of the composites were significantly improved by 84 and 171% using PA 66-17 gsm veils respectively, as compared to reference laminates. The use of denser PA 66-50 gsm veils in the interlaminar region led to higher improvement in fracture toughness values (349% for initiation and 718% for propagation) due to the higher amount of veil fibers involved in fiber bridging toughening mechanism. The incorporation of PA 66-50 gsm nonwoven veils also increased the ILSS and Charpy impact strength of the composites by 25 and 15%, respectively. On the other hand, the PA 66 veils reduced in-plane mechanical properties of CF/EP composites due to lower carbon fiber volume fraction and increased thickness.

Experimental and statistical analysis of carbon fiber/epoxy composites interleaved with nylon 6,6 nonwoven fabric interlayers

“…31 For instance, Beylergil et al. 25 studied the tensile and compressive properties of a carbon/epoxy [0 o ] 4 laminate interleaved with the 17 and 50 gsm nylon 6,6 nonwoven fabrics. They showed that the tensile and compressive strength decreased with improved areal weight density by about 41% and 13%, respectively.…”

“…As previously stated, although the microfiber interleaving improves Mode-I fracture toughness significantly, it deteriorates in-plane mechanical properties of composite laminates due to the reduced fiber volume fraction, thickness increase and formation of voids. 25 In nanofiber interleaving technique, it is possible to improve not only delamination resistance but also in-plane mechanical properties of composite laminates. This win-win situation is the unique characteristic of nanofiber interleaving technique.…”

“…Interleaving heavy microfiber nonwoven fabrics increases the effectiveness of the interleaf material; however, it deteriorates the other in-plane mechanical properties such as tensile, compressive and flexural properties. 31 For instance, Beylergil et al 25 studied (1/(1-median rank) (ln(1/(1-median rank) the tensile and compressive properties of a carbon/epoxy [0 o ] 4 laminate interleaved with the 17 and 50 gsm nylon 6,6 nonwoven fabrics. They showed that the tensile and compressive strength decreased with improved areal weight density by about 41% and 13%, respectively.…”

Investigation of toughening effect of biomass‐derived SiCB on basalt fiber‐reinforced unsaturated polyester composites

“…[18] The above methods are effective on fiber-reinforced polymer composites, but complicated in fabrication, high in cost, and even cause loss of in-plane mechanical properties. [19,20] An approach that is excellent to alleviate the above challenges is matrix modification by adding particles. [21] Matrix modification by adding a proper amount of nano or micro particles can significantly improve the overall properties of the composites.…”

Effect of toughened polyamide/carbon fiber interlace braid fabric on the mechanical performance of CFRP laminates

“…10 A thermoplastic interleaved method which is inserted with a veil, nanofiber, nano-web, or microparticles at the interlaminer region have been adopted to interrupt crack propagation in fiber reinforced composites. [11][12][13][14][15] Liu et al 16 performed compression after impact (CAI) and transverse flexural experiments on Polyamide (PA)/ carbon epoxy and PA/Polyethersulfone (PES)/carbon epoxy composite laminates. The enhanced interlaminar properties were attributed to the toughening interlayer of the PA microparticles and strong interfacial adhesion between the PA microparticles and epoxy matrix.…”