Graphene and graphene derivatives toughening polymers: Toward high toughness and strength

The invention of carbon and its allotropes have transformed the electronic and optoelectronic industry due to their encouraging properties in a large spectrum of applications. The interesting characteristic of carbon is its ability to form many allotropes due to its valency. In recent decades, various allotropes and forms of carbon have been invented, including fullerenes, carbon nanotubes (CNTs), and graphene (GR). Since the inception of nanotechnology, carbon allotropes-based nanocomposites have become a leading sector of research and advancement due to their unique bonding properties. Fullerenes and CNTs-based polymer nanocomposites have attracted significant research interest due to their vast applications in every sphere of science and technology. Current research impetus reveals that carbon and its allotropes have revolutionized the industry and academia due to their fascinated properties. Recent advances in various aspects of graphene, CNTs, graphene nanoribbons, fullerenes, carbon encapsul...

Magical Allotropes of Carbon: Prospects and Applications

In this work, thermoplastic composites based on poly(ethylene 2,6-naphthalate) (PEN) have been investigated with the aim to elucidate the effect of temperature on static and impact properties. The matrix was reinforced with four different high performing woven fabrics based on carbon, Twaron, Vectran, basalt fibres. Composites were manufactured by using the film stacking technique, alternating layers of balanced plain weave fabrics (0/90) and films of amorphous PEN, keeping the fibre volume fraction around 40%. The compression moulding process was optimized to obtain optimal fabric impregnation and to keep the void content lower than 1%. The structural response was evaluated at 20 °C, 60 °C and 100 °C by means of static flexural and low velocity impact tests. Dynamic mechanical scans (DMA) were also performed to evaluate the stiffness of the laminates at temperatures ranging from – 80 °C to 230 °C. The flexural modulus and strength of laminates resulted to be very high in proportion with the fibre stiffness. The flexural behaviour was affected by the temperature but a limited reduction of the stiffness (lower than 20%) was exhibited by all but PEN/Vectran up to temperatures of 100 °C. PEN/carbon resulted the best performing system at each testing temperature (flexural modulus equal to 38.8 GPa, flexural strength equal to 714 MPa at 20 °C). Results from DMA tests demonstrated a satisfactory agreement with static tests (differences within ±13%, except that for PEN/Vectran). The impact resistance of the composites was found to depend on the fibre type, temperature and interface strength. PEN/basalt resulted the best performing composite followed by PEN/Twaron (perforation energy at 20 °C: 44.3 J and 38.2 J, respectively). The PEN/carbon laminate exhibited the lowest impact performance but, unlike PEN/basalt and PEN/Vectran, the impact resistance improved with the increasing temperature.

Effect of temperature on static and low velocity impact properties of thermoplastic composites

An atomistic multiscale modelling approach is used to simulate the nonlinear pullout behaviour of interlinked single walled carbon nano tubes (SWCNT) and single layer graphene sheets (SLGS) embedded in an epoxy polymer. The pullout forces have been computed for various configurations of nanocomposites (SWCNT-SWCNT, SLGS-SLGS and hybrid SLGS-SWCNT), also by evaluating the effect provided by three different interlink compounds. The interfacial strength due to fibre pullout predicted by the hybrid atomistic-FE model is compared against experimental and molecular dynamics results available in open literature. The results show the specific deformation characteristics (localised auxetics) that provide an increase of pullout forces and interfacial strength with the use of the links.

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Pullout strength of graphene and carbon nanotube/epoxy composites

Hyperbranched polyether epoxy grafted graphene oxide for benzoxazine composites: Enhancement of mechanical and thermal properties

A small amount of Graphene and Multi walled carbon nanotubes (MWCNT) by direct mixing were employed to disperse these nanoparticles into a mono-component epoxy system and used as matrix for advanced composites with woven Glass and Carbon fiber reinforcements. These nanoparticles were added directly into the hosting system and dispersion was carried out by using mechanical stirring. In this study the hybrid polymer composite with Glass fiber, Carbon fiber and epoxy polymer in the ratio of 9:12.5:78.5, 13.5:18.75:67.75 and 18:25:57 percent of volume with addition of fillers, Graphene (0.2 wt%) and MWCNT (0.2wt%) have been developed. The mechanical characterization results confirm that the composite developed by using graphene nanoparticles represents a fundamental feature in enhancing the tensile elastic modulus and hardness behavior of the composite system, where as MWCNT has significant effect on the bending modulus and impact behavior. The optical microscopic study for the fractured samples reveals a significant increase in the fiber-matrix interface adhesion where as decrease in fiber breakage, fiber pullout and debonding. Copyright © 2013 VBRI press.

Effects of multi walled carbon nanotubes and graphene on the mechanical properties of hybrid polymer composites

Improved fracture toughness in carbon fibre epoxy composite through novel pre-preg coating method using Epoxy Terminated Butadiene Nitrile rubber

Mode-I fracture behavior of glass-carbon fiber reinforced hybrid polymer composite was investigated based on experimental and finite element analysis. The compact tension (CT) specimen was employed to conduct mode-I fracture test using special loading fixtures as per ASTM standards. Fracture toughness was determined experimentally for along and across the fiber orientation of the specimen. Results indicated that the cracked specimens are tougher along the fiber orientations as compared with across the fiber orientations. A similar fracture test was simulated using finite element analysis software ANSYS. Critical stress intensity factor (K) was calculated at fracture/failure using displacement extrapolation method, for both along and across the fiber orientations. The fractured surfaces of the glasscarbon epoxy composite under mode-I loading condition was examined by electron microscope.

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Fracture Toughness of Glass-Carbon (0/90)S Fiber Reinforced Polymer Composite - An Experimental and Numerical Study

Laminates of fibre-reinforced prepreg have excellent in-plane mechanical properties, but have inadequate performance in the through thickness direction. Here, we address this issue by application o...

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Drawdown prepreg coating method using epoxy terminated butadiene nitrile rubber to improve fracture toughness of glass epoxy composites

This paper deals with the study of mechanical properties of Potassium Titanate Whisker (PTW) reinforced epoxy based Polymer Matrix Composites (PMCs). Epoxy composites filled with PTW in various content of 0-20 wt% were prepared using the casting technique. Data on neat epoxy is also included for comparison. All tests were conducted at room temperature and as per ASTM standards. It was observed that inclusion of PTW affected most of the mechanical properties of neat epoxy. Density, hardness and heat deflection temperature of neat epoxy were found to increase with the PTW content. However tensile and flexural properties of the developed composites exhibited a varying trend with respect to PTW content. Epoxy filled with 10 wt% PTW showed good improvement in tensile strength and flexural strength of neat epoxy. It was observed that PTW is not beneficial in improving the impact strength of neat epoxy. Composites with 20 wt% PTW exhibited least impact strength. This paper also highlights the possible reasons for variation in the mechanical properties of developed polymer composites.

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Dayananda Jawali

Papers

Effects of multi walled carbon nanotubes and graphene on the mechanical properties of hybrid polymer composites

Improved fracture toughness in carbon fibre epoxy composite through novel pre-preg coating method using Epoxy Terminated Butadiene Nitrile rubber

Fracture Toughness of Glass-Carbon (0/90)S Fiber Reinforced Polymer Composite - An Experimental and Numerical Study

Drawdown prepreg coating method using epoxy terminated butadiene nitrile rubber to improve fracture toughness of glass epoxy composites

Mechanical Properties of Potassium Titanate Whisker Reinforced Epoxy Resin Composites