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. 2023 Aug 29;8(36):32656-32666.
doi: 10.1021/acsomega.3c03419. eCollection 2023 Sep 12.

Investigating the Effects of PA66 Electrospun Nanofibers Layered within an Adhesive Composite Joint Fabricated under Autoclave Curing

Gözde Esenoğlu  1   2 , Metin Tanoğlu  1 , Murat Barisik  1   3 , Hande İplikçi  1 , Melisa Yeke  1 , Kaan Nuhoğlu  1 , Ceren Türkdoğan  1 , Seçkin Martin  1 , Engin Aktaş  4 , Serkan Dehneliler  2 , Ahmet Ayberk Gürbüz  2 , Mehmet Erdem İriş  2
Affiliations

Investigating the Effects of PA66 Electrospun Nanofibers Layered within an Adhesive Composite Joint Fabricated under Autoclave Curing

Gözde Esenoğlu et al. ACS Omega. .

Abstract

Enhancing the performance of adhesively joined composite components is crucial for various industrial applications. In this study, polyamide 66 (PA66) nanofibers produced by electrospinning were coated on unidirectional carbon/epoxy prepregs to increase the bond strength of the composites. Carbon/epoxy prepregs with/without PA66 nanofiber coating on the bonding region were fabricated using the autoclave, which is often used in the aerospace industry. The single lap shear Charpy impact energy and Mode-I fracture toughness tests were employed to examine the effects of PA66 nanofibers on the mechanical properties of the joint region. Scanning electron microscopy (SEM) was used to investigate the nanofiber morphology and fracture modes. The thermal characteristics of Polyamide 66 nanofibers were explored by using differential scanning calorimetry (DSC). We observed that the electrospun PA66 nanofiber coating on the prepreg surfaces substantially improves the joint strength. Results revealed that the single lap shear and Charpy impact strength values of the composite joint are increased by about 79 and 24%, respectively, by coating PA66 nanofibers onto the joining region. The results also showed that by coating PA66 nanofibers, the Mode-I fracture toughness value was improved by about 107% while the glass transition temperature remained constant.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
(a) Nanofiber-coated prepregs in the collector. (b) Continuous substrate winding the electro-spinning collector system with 0.01 to 5 gr/m2 production capacity.
Figure 2
Figure 2
Composite laminates of 12 layers of UD prepregs at [45/0/45/90/–45/0]s (a) without and (b) with electrospun PA66 nanofiber coatings. (c) Operated autoclave setup.
Figure 3
Figure 3
Manufacturing procedure for the autoclave curing of (a) composite laminates based on UD/UD prepregs (CFRP) and (b) composite joints using film adhesives (FM300 K).
Figure 4
Figure 4
Adhesive joining of UD CFRP prepreg fabrics with the electrospun PA66 nanofibers incorporates at the joint interfaces.
Figure 5
Figure 5
Schematic representation of (a) single lap shear, (b) Charpy, and (c) DCB test specimens.
Figure 6
Figure 6
Images of the test specimens under (a) Lap shear and (b) DCB and (c) Charpy loading.
Figure 7
Figure 7
SEM images of 10% by weight PA66 nanofibers at magnification of (a) 50,000×, (b) 100,000×, and (c) 100,000×.
Figure 8
Figure 8
DSC curve of PA66 veils.
Figure 9
Figure 9
Droplet images and wetting angle variations of 10 wt %-PA66 coated surface and uncoated prepreg surface (reference) by time.
Figure 10
Figure 10
Load vs displacement curves of single lap shear tests of five different samples of (a) uncoated reference and (b) 10 wt %-PA66-3 coated surfaces joined using 3 FM300 K plies.
Figure 11
Figure 11
Average values for lap shear strength of test specimens.
Figure 12
Figure 12
Fracture surface of (a) reference samples and (b) 10 wt % PA66 specimens after a single lap shear test.
Figure 13
Figure 13
Charpy impact energy of composite samples with/without PA66 nanofiber.
Figure 14
Figure 14
Image of (a) bare and (b) PA66 added specimens after the Charpy test and the joint region SEM images.
Figure 15
Figure 15
Photographs of PA66 composite specimens under Mode-I loading.
Figure 16
Figure 16
GIC and delamination length curve of (a) PA66 nonadded and (b) PA66 added composite samples.
Figure 17
Figure 17
Photograph of the DCB surfaces of fractured (a) reference and (b) PA66 added composite.
See this image and copyright information in PMC

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