Mode-II toughness of nanostitched carbon/epoxy multiwall carbon nanotubes prepreg composites: Experimental investigation by using end notched flexure

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4249-4271 ◽  
Author(s):  
Kadir Bilisik ◽  
Gulhan Erdogan ◽  
Erdal Sapanci ◽  
Sila Gungor
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Multiwall Carbon Nanotubes ◽  
Fold Increase ◽  
Woven Fabric ◽  
Woven Composites ◽  
Mode Ii ◽  
Stick Slip ◽  
Pull Out ◽  
Multiwall Carbon

The mode-II interlaminar fracture toughness properties following the end notched flexure method of nanostitched carbon/epoxy nanoprepreg composites were studied. The fracture toughness (GIIC) of the nanostitched and stitched composites showed 3.4 fold and 2.7 fold increase compared to the control, respectively. Thus, the nanostitching improved the mode-II toughness of all the carbon/epoxy composites with regard to the nano, and base composites. It was assumed that the type of stitch fiber as well as fabric pattern, in particular prepreg carbon stitching fiber and satin prepreg woven fabric, was effective. The basic mechanism for the enhancement of the GIIC toughness in the nanostitched composite was the interlaminar resin layer failure especially as a form of shear hackle marks where nanostitching arrested the delamination in the stitching zone during crack propagations. Multiwall carbon nanotubes in the matrix and filament also mitigated the stress concentration probably as an outline of debonding/pull-out/stick-slip/friction. Therefore, nanostitched as well as stitched carbon/epoxy woven composites exhibited improved damage tolerance performance with regard to the base composites.

Seawater effects on interlaminar fracture toughness of glass fiber/epoxy laminates modified with multiwall carbon nanotubes

2020 ◽  
pp. 002199832095078
Author(s):  
Julio A Rodríguez-González ◽  
Carlos Rubio-González
Keyword(s):  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Glass Fiber ◽  
Composite Laminates ◽  
Multiwall Carbon Nanotubes ◽  
Mode I ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Multiscale Composite ◽  
Multiwall Carbon

In this work, the effect of seawater ageing on mode I and mode II interlaminar fracture toughness ([Formula: see text] and [Formula: see text]) of prepreg-based woven glass fiber/epoxy laminates with and without multiwall carbon nanotubes (MWCNTs) has been investigated. The first part of the investigation reports the moisture absorption behavior of multiscale composite laminates exposed to seawater ageing for ∼3912 h at 70 °C. Then, the results of mode I and mode II fracture tests are presented and a comparison of [Formula: see text] and [Formula: see text] for each type of material group and condition is made. Experimental results showed the significant effect of seawater ageing on [Formula: see text] of multiscale composite laminates due to matrix plasticization and fiber bridging. The improvement in [Formula: see text] of the wet glass fiber/epoxy laminate was about 50% higher than that of the neat laminate (without MWCNTs) under dry condition. It was also found that the presence of MWCNTs into composite laminates promotes a moderate increase (8%) in their [Formula: see text] as a result of the additional toughening mechanisms induced by CNTs during the delamination process. Scanning electron microscopy analysis conducted on fracture surface of specimens reveals the transition from brittle (smooth surface) to ductile (rough surface) in the morphology of composite laminates due to the influence of seawater ageing on the polymeric matrix and fiber/matrix interface.

Plain para-aramid/phenolic multiwall carbon nanotubes prepreg/multistiched preform composites: Experimental characterization of mode-I toughness

2018 ◽  
Vol 53 (13) ◽  
pp. 1847-1864 ◽  
Author(s):  
K Bilisik ◽  
E Sapanci
Keyword(s):  
Fracture Toughness ◽  
Multiwall Carbon Nanotubes ◽  
Beam Theory ◽  
Mode I ◽  
Multiwall Carbon Nanotube ◽  
Axial Filament ◽  
Pull Out ◽  
Fiber Bridging ◽  
Nanotube Composites ◽  
Multiwall Carbon

The fracture toughness (mode-I) properties of nanostitched para-aramid/phenolic multiwall carbon nanotube prepreg composites were investigated. The fracture toughness (GIC) of the stitching and nanostitched composites showed 42-fold and 41-fold (beam theory), 18-fold and 21-fold (modified beam theory) increase compared to the control, respectively. The prepreg para-aramid stitching yarn and nanostitched yarn were dominant parameters. The toughness resistance to arrest crack growth in the nanostitched composite was primarily due to nanostitching fiber bridging and pull-out, and was secondarily due to nanotubes and biaxial fiber bridging and pull-out. The failed surfaces of the nanostitched and stitching composites had tensile filament failures in the aramid stitching fibers where filament/matrix/nanotube debonding and axial filament fibrillar splitting were found. The results indicated that stitching yarn and the nanotubes arrested the crack propagation. Therefore, the nanostitched and stitched para-aramid/phenolic composites displayed a better damage resistance performance compared to those of the control or nanotube composites.

Mode-II fracture of nanostitched para-aramid/phenolic nanoprepreg composites by end-notched flexure

2020 ◽  
Vol 54 (24) ◽  
pp. 3537-3557
Author(s):  
Kadir Bilisik ◽  
Gulhan Erdogan ◽  
Erdal Sapanci ◽  
Sila Gungor
Keyword(s):  
Fracture Toughness ◽  
Composite Structures ◽  
Phenolic Resin ◽  
Mode Ii ◽  
Stick Slip ◽  
Blunt Crack ◽  
Pristine Sample ◽  
Pull Out ◽  
Filament Bundles ◽  
Phenolic Composite

The mode-II interlaminar fracture toughness considering the end-notched flexure method of nanostitched para-aramid/phenolic composite structures was investigated. The fracture toughness (GIIC) of the nanostitched and stitched composites exhibited a slight increase as compared to the pristine sample. Hence, the nanostitching enhanced the fracture toughness of the para-aramid/phenolic composite structures. Although the type of stitch fiber was not effective, the fabric interlacement frequency, notably prepreg Twaron nanostitched yarn and basket nanoprepreg biaxial interlaced fabric was of critical importance. The principle mechanism for raising the GIIC in the nanostitched composite structure was the interlayer resin fracture particularly as a form of slight shear hackle marks. Cracks grew around the inter- and intrayarn boundaries where the resin was fractured half way around each yarn cross-section. This is called a “zigzag crack path,” and microcracks moved to the through-the-thickness of the composite where nanostitching arrested the crack growth and suppressed delamination in the stitching zone. At the blunt crack tip, carbon nanotubes in the phenolic resin and multiple filament bundles probably diminished the stress clustering via friction/debonding/pull-out/sliding or stick-slip. Thus, nanostitched para-aramid/phenolic composite structures demonstrated better damage tolerance behavior considering the neat structure.

Microwave Absorbing Nanocomposites Composed with and without Polyaniline by Use as Radar Absorbing Structure

2012 ◽  
Vol 730-732 ◽  
pp. 920-924 ◽  
Author(s):  
Luiza de Castro Folgueras ◽  
Mirabel Cerqueira Rezende
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Properties ◽  
Woven Fabric ◽  
Electromagnetic Properties ◽  
Naval Research ◽  
Radar Absorbing Structure ◽  
Physical And Chemical ◽  
Multiwall Carbon ◽  
And Chemical Properties

In the past decade, new materials have been developed based on the physical and chemical properties of carbon nanotubes. The combination of polyaniline with multiwall carbon nanotubes results in a new functional material with advantageous electromagnetic properties. The objective of this study was to produce a radar absorbing structure consisting of glass fiber woven fabric impregnated with a formulation containing carbon nanotubes, polyurethane resin, with or without polyaniline. A different formulation was used for each woven sheet (multilayer structure). The electromagnetic properties of these nanocomposite materials were characterized by reflectivity measurements using Naval Research Laboratory arch method (frequency range, 8 to 12 GHz). The attenuation of both sides of each nanocomposite material was also measured and compared. The attenuation of electromagnetic energy was as high as 70 %, approximately, indicating that these materials can be used as microwave absorbers.

scholarly journals Enhancing The Mechanical Properties of Chopped Basalt Composites by Incorporating of Multiwall Carbon Nanotubes

2019 ◽  
Vol 9 (1) ◽  
pp. 5646-5650
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Fracture Toughness ◽  
Mechanical Performance ◽  
Testing Machine ◽  
Basalt Fiber ◽  
Multiwall Carbon Nanotubes ◽  
Tensile Modulus ◽  
Basalt Fibre ◽  
Multiwall Carbon

This study aims to develop and determine mechanical properties chopped basalt fibre reinforced composites (CBFRP) modified with multiwall carbon nanotubes (CNT). Chopped basalt composite modified with CNT was fabricated using a combination of mechanical stirring and hand layup process. Three different weight percentages of CNT i.e. 0.5, 1, 1.5wt. % were filled into epoxy resin before mixing with chopped basalt fiber. The mechanical performance namely tensile properties and fracture toughness behaviour of the fabricated chopped basalt composites was assessed using Universal Testing Machine in accordance to ASTM standard D368 and D695, respectively. The results showed that the incorporation of CNT enhanced tensile and fracture toughness properties of the CBFRP composites. However, a higher amount of CNT (1.5wt%) incorporated into the CBFRP caused reduction in tensile strength, tensile modulus and Gic by 4.40%, 2.46% and 30.36 %, respectively, as compared to those of 1.0CNT-CBFRP

Three-dimensional nanoprepreg and nanostitched aramid/phenolic multiwall carbon nanotubes composites: Experimental determination of in-plane shear

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4077-4096 ◽  
Author(s):  
Kadir Bilisik ◽  
Gulhan Erdogan ◽  
Erdal Sapanci ◽  
Sila Gungor
Keyword(s):  
Carbon Nanotubes ◽  
Three Dimensional ◽  
Multiwall Carbon Nanotubes ◽  
Nano Composites ◽  
Plane Shear ◽  
Pull Out ◽  
Out Of Plane ◽  
The Matrix ◽  
Multiwall Carbon

In-plane shear of nanostitched three-dimensional para-aramid/phenolic composites were experimentally investigated. Adding the nanostitched fiber into nanoprepreg para-aramid fabric preform composites slightly improved their shear strengths. The carbon-stitched composite exhibited comparatively better performance compared to the para-aramid stitched composite probably due to well bonding between carbon fiber and phenolic resin. The stitched nano composites had mainly matrix breakages and micro shear hackles in the matrix; matrix debonding and filament pull-out in the composite interface; fibrillar peeling and stripping on the filaments due to angular deformation. This mechanism probably prohibited extensive interlaminar opening in the nanostitched composites. The result exhibited that the introducing of the nano stitched fiber where multiwall carbon nanotubes were transferred to the out-of-plane of the base structure enhanced its transverse fracture as a form of confined delamination area. Therefore, the damaged tolerance properties of the stitched nano composites were enhanced compared to the base.

Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

2018 ◽  
Author(s):  
Gen Hayase
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Aqueous Solutions ◽  
High Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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