graphene core 1 graphene-based disruptive technologies ... · graphene core 1 d14.1 18 september...

Project funded by the European Commission under Grant Agreement n°696656

Graphene Core 1 Graphene-Based Disruptive Technologies

Horizon 2020 RIA

WP14 Polymer Composites Deliverable 14.1 “Benchmarking of Commercial GRM

Materials for Composites Application” Version 2

Main Author(s): Emanuele Treossi, CNR; Julio Gómez Cordón, AVA; Robert Young UNIMAN; Costas

Galiotis, FORTH; Vincenzo Palermo, CNR.

Due date of deliverable: 13 March 2017

Actual submission date: 20 March 2017

Re-submission date: 19 September 2017

Dissemination level: PU

Graphene Core 1 D14.1 18 September 2017 2 / 25

TABLE OF CONTENTS

List of Contributors .................................................................................................. 3

Summary ................................................................................................................... 4

1 Benchmarking of Commercial GRM Materials for Applications in Composites ............................................................................................................... 5

2 Criteria for the Selection of GRM Samples for Benchmarking ....................... 6

3 Sample Characterisation Techniques ............................................................... 7

3.1 Laser Granulometry ................................................................................................7 3.2 Surface Area Measurement.....................................................................................8 3.3 Scanning Electron Microscope (SEM)....................................................................8

4 List of GRM Samples Analysed ......................................................................... 8

5 Conclusions of GRM Benchmarking: ............................................................. 15

Annexes ................................................................................................................... 17

1 Companies Considered but not Included in the Benchmarking ................... 17

2 Case Studies: Assessment of GRM-Based Commercial Products .............. 17

3 Example of Cost/Performance Analysis Procedure of GRM vs. Other Commercial Carbon Additives .............................................................................. 20

4 Motivation for the Selection of Nanotubes Type for the Benchmarking ...... 22

References .............................................................................................................. 25


List of Contributors

Partner Acronym Partner Name Name of the contact

02 CNR Consiglio Nazionale delle

Ricerche

Vincenzo Palermo, Emanuele

Treossi, Alessandro Kovtun,

Nicola Mirotta, Alessandra

Scidà, Meganne Christian,

Vittorio Morandi, Maria del

Rosso

31 AVA Avanzare Innovacion

Tecnologica SL Julio Gómez Cordón

06 UNIMAN The University of

Manchester Ian Kinloch, Robert Young

30 FORTH Foundation for Research

and Technology Hellas

Costas Galiotis, George

Anagnostopoulos


Summary Bulk composites are currently the most common, commercially available applications of GRM.

The number of products containing these composites is increasing continuously, from tennis

rackets to bicycles to skis. However, the lack of a clear metrology and of quality control for

graphene is creating confusion among industrial end-users, with some companies advertising

materials as “graphene” what instead is graphite powders, platelets or other carbon materials.

Whilst nomenclature1 and a classification framework2 has been proposed for 2D graphene-

based materials by Flagship partners (WP4 Health and Environment), a clear agreement on

international standards is still missing.

The high number of graphene producers worldwide provide GRM with a very broad range of

morphology and quality; it is thus difficult to evaluate correctly if the new materials developed

within the flagship are truly competitive with commercially available ones, either in performance

or in production cost.

To develop innovative and industrially relevant applications of GRM it is fundamental to have

a realistic evaluation of the state-of-the-art of existing commercialised products. To this aim,

here we describe a procedure to benchmark GRM materials produced within the flagship

versus commercial products from industrial producers worldwide.

It should be underlined that this benchmarking activity is not comprehensive but rather a proof-

of-principle exercise. We used a small part of WP14 resources to analyse 32 out of the >1600

products that are claimed to be commercially available worldwide. An extensive benchmarking

analysis would have required allocation of significantly large amount of additional resources

for this task. The objective of this report is thus not to give a complete analysis of commercial products, but to be the first step towards establishing commonly accepted procedures and guidelines for the benchmarking. These procedures should be based on selected techniques, able to provide information on GRM products with good statistics within a reasonable timeframe. The results of this report will then be transferred to WP19, which will

perform a more extended analysis of commercial GRM in Core 2 phase.

This report does not contain benchmarking data about other important types of GRM materials

such as inks and chemical vapour deposition (CVD) graphene, most useful for electronics

applications. While some work is ongoing also on these materials, the amount of available data

is still not sufficient for a systematic comparison. We hope that the measurements reported

here could be useful for academic and industrial partners of the Flagship to assess the quality

of the materials commercially available, allowing to have more objective data for evaluating

the possible applications claimed for this unique material.

This report is divided as follows:


1) In the main part of the document we describe the characterisation of different kinds of GRM

flakes for industrial applications, available within and outside the flagship, typically on the

kilogram scale. The materials were analysed with a combination of different techniques, as

detailed later in the text, to compare their exfoliation grade, average thickness, and the

statistical distribution of their lateral size.

2) In the annex, we report some exploratory work on the analysis of complete GRM based

devices which are already commercialised, with the aim of establishing if, and how, they truly

contain graphene inside.

3) Finally, we show a representative example of cost/performance analysis, comparing

selected materials from the flagship with alternative additives for composites (carbon black,

carbon nanotubes, graphite).

1 Benchmarking of Commercial GRM Materials for Applications in Composites

The size and exfoliation grade of 2D materials are fundamental parameters to be evaluated

because they have an impact on final materials performance, influencing the mechanical and

electrical properties in polymer composites,3,4 charge transport,5 gas permeation in thin films6

and even biological activity in cells.7

Most of published articles and technical datasheets available report just the average lateral

size of GRM, quantified by using two common statistical parameters: arithmetic mean and

standard deviation, assuming implicitly that the nanosheets’ length follows a Gaussian

distribution. However, all published experimental data show that, for any given 2D material8,9

the size distribution is non-Gaussian and is highly asymmetric. CNR and FBK recently

analysed in detail the size distribution of monoatomic GO nanosheets during sonication, using

scanning probe microscopy (SPM) and image processing to measure the sheet size and shape

of thousands of individual sheets, then explaining their size distribution and the fragmentation

mechanism with standard mathematical models.10 However, this approach is not suitable to

analyse commercial GRM, where usually a significant fraction of the material feature a high

thickness, which is problematic for SPM analysis. Thus, we decided to study the morphology

of these materials by Laser Granulometry, Surface Area (SA) and Scanning Electron

Microscope (SEM), as detailed below in “Sample characterisation techniques” section. The

content of oxygen or other types of defects of GRM materials is not reported in this report and

will be part of a future work.


2 Criteria for the Selection of GRM Samples for Benchmarking

The industrial sector of graphene production is in rapid evolution, with the number of graphene

producers increasing continuously. It would have been impossible to provide a complete analysis of all GRM available; as example, the web portal Alibaba.com lists >1600

commercially available graphene powders (update august 2017). Thus, we had to select a

small group of GRM products to analyse as part of our proof-of-principle approach.

The criteria used for the selection are as follows:

A) Industrial Interest Within the Flagship

We prioritised GRM from producers which, being Flagship partners, are more likely to be used

by our industrial end-users to develop industrial applications. The good exchange of

information and low confidentiality barriers are one of the major added values of the flagship,

facilitating both our analysis and the collaboration between industries producing GRM and the

industries using them.

For completeness, we have now included in the analysis also GANF nanofibers produced by

ANTOLIN within WP15; we underline that these materials cannot be compared directly with

the typical commercial GRM, because they have very different shape, size and use from the

typical graphene nanoplatelets. They are composed of helical ribbon carbon nanofibres, which

need to have very small size (<1 μm) to penetrate between the carbon fibers of the final

composite, and partially exfoliate only during their milling into the polymer matrix.

B) Production Scale

Many producers sell graphene mostly for R&D use, on few grams scale, at prices which are

acceptable for research work, but not for industrial use and applications. In this survey, we

focused thus on the companies able to deliver GRM on the kilogram scale, which are the most

interesting for industrial applications. Thus, we requested to all companies involved to provide

a significant quantity of GRM, typically 1 Kg for the analysis.

C) Capability to Deliver in Europe

We prioritised companies which shall, in case of large-scale applications, commercialise their product to our end-users, fostering one of the major goals of the flagship, i.e. to foster the

development of graphene technology in EU countries. Currently some companies are not

offering products in the EU due to SDS regulations requiring explicit disclosure of formulations

(a typical example is GRM American producer Vorbeck).

A table in the Annex 1 shows a list of companies that were considered by us for this activity

but, for the reasons mentioned in the criteria above, were not included in the final analysis.

To avoid any possible conflict of interest, all the analysis of GRM were performed by CNR

partner, who was also the coordinator of WP14 activities. The GRM producers benchmarked,

regardless whether they were flagship partners or not, were not involved in this work.


A single, particular activity described in the annex (the cost/performance analysis) was though

performed with the help of AVA partner which apart from being a GRM producer is also a well-

established provider of other specialty additives for different materials, mainly plastics and

rubber, across different industries.

3 Sample Characterisation Techniques

3.1 Laser Granulometry

Laser granulometry allows to evaluate the lateral size of a powder in liquid suspensions. In the

granulometer, a liquid suspension is fluxed in a hydraulic circuit crossing the path of a laser,

while a CCD camera measures the intensity of the scattered light. The analysis in this report

was done with a Saturn II instrument (Micromeritics, USA). The output signal is the scattered

intensity vs the scattering angle; by using numerical models following Fraunhofer or Mie

diffraction theory it is possible to calculate the size distribution of the particles composing the

suspension. Small particles scatter low amount of light in all the directions, whereas large

particles scatter a significant amount of light mainly in forward direction (small angle

scattering). The accessible range of lateral sizes is between few µm and fractions of mm. This

type of characterization is extensively used as routine standard characterisation in many

industrial sectors (e.g. Food and Pharmaceutical). Should anyhow be noted that in the models

used by all granulometry instruments the particles are assumed as spherical, and this can be

a problematic approximation for the characterisation of highly anisotropic, flat platelets.

Figure 1 shows an example of the measured size distribution of a graphene-based powder

(XGNP-M25). The abscissa axis reports the lateral size, while the ordinate gives the

incremental percentage of volume occupied by the particles.

Figure 1: Incremental Volume Percent distribution. Sample XGNP-M25 measured using Saturn II.

For practical reasons, different characteristic parameters of the distribution are always

reported; the most useful and intuitive is the D50.


In a poly-dispersed sample, 50% of the particles will have a diameter smaller than D50, 50%

larger; D50 is thus also known as the "mass median diameter". Similarly, D10 and D90 are

given, i.e. the diameters respectively smaller than the 10% and 90% of total particles.

The liquid suspension was obtained by dispersing few mg of powder in a 20mL vial of

Isopropanol and 2-minutes sonication. The dispersion procedure should be carefully tuned to

avoid aggregation of particles on one side, but also to avoid further exfoliation or fragmentation

of the particles, as example by prolonged sonication. Two samples were prepared and

measured for each powder, using the arithmetic mean of the values measured as main value,

and the semi-dispersion as the error.

3.2 Surface Area Measurement

The specific surface area (m2/g) SA is a key parameter to understand the morphology of a

powder. The numerical quantification of the area of high surface powders is performed by

measuring the amount of physi-sorbed gas in controlled temperature and pressure conditions.

The fundamental theory used in most commercial and scientific instruments is the BET model

(Brunauer–Emmett–Teller), and for carbon based powders the normative ASTM D6556-1011-

13 is used. By this technique it is possible to measure specific surface areas from thousands of

m2/g down to <1 m2/g. This value shall be used to give rapidly an estimate of how much GRM

are exfoliated, if they are more similar to “ideal”, perfectly exfoliated graphene (which would

have a surface area >2600 m2/g) or to powder graphite (≈0.1 m2/g).

We thus performed the measurements following the ASTM D6556-10 standard method. All the

samples were degassed at 300 °C for 3 h. The instrument used was the ASAP 2020

(Micromeritics, USA). Two samples were prepared and measured for each powder, using the

arithmetic mean of the values measured as main value, and the semi-dispersion as the error.

3.3 Scanning Electron Microscope (SEM)

The Scanning Electron Microscope (SEM) is a powerful tool to probe matter from the mm scale

down to a few nm. It is possible to obtain SEM images with a spatial resolution up to less than

5 nm. The samples were prepared by depositing a small amount of powder on a conductive

scotch tape and the Scanning Electron Microscopy (SEM) images were obtained with a ZEISS

1530 instrument in High-Vacuum conditions (10-6 mBar).

4 List of GRM Samples Analysed

In the tables here below, “given” values are the values reported by the producers on technical

datasheets or web pages. Measured values are the ones measured experimentally by us. The

way the “Given” particle size is measured is often not detailed; this value should be considered

an arithmetic average, thus shall be compared to the D50 value measured experimentally. All


comparative analyses of the materials from different producers have been performed by CNR,

evaluating in the same way materials produced inside or outside the Flagship.

Avanzare Innovacion Tecnologica (based in Spain) is a company

specialised in the development, production and commercialisation of

specialty additives for different materials, mainly plastics and rubber. Avanzare has >10 years

of expertise in 2D materials research and is specialised in the production of graphene/graphite

nanoplatelets with different particle size, thickness, and oxygen content. It is a partner of the

Graphene Flagship14.

Figure 2. a) Measured and given properties of Avanzare products. SEM images of b) AVA 18, c, d) AVA 23.

Graphenea, a Spanish technology company set up in 2010, is one of

the main producers of CVD graphene. It also produces graphene oxide

(GO) and reduced graphene oxide (RGO) for universities, research centres and industries. It

is a partner of the Graphene Flagship.15


Figure 3. a) Measured and given properties of Graphenea RGO product. b, c) SEM images of RGO.

Nanesa is an Italian-based innovative start-up company that produces

graphene-based nanometric products, developing new applications with end-users for

composites materials, conductive inks, coatings. The company currently produces graphene

nanoplatelets, graphene oxide and graphene-based multifunctional sheets with high graphene

content (over 60%) with different thickness and polymeric binders. Nanesa has developed an

industrial process with low environmental impact (solvent-free) and has acquired a strong

expertise in dispersion and homogenization techniques. It is a partner of the Graphene

Flagship.16

Figure 4. a) Measured and given properties of Nanesa product. b) SEM images of G2NAN. .

The University of Freiburg (FMF) is an academic partner of the flagship, and its

products have been included in the benchmarking activity because it has recently

set up a pilot-plant for large scale production of graphene oxide. The research of

FMF is focused on the development and production of functionalised graphene e.g. highly

thermally exfoliated and reduced graphene oxide (TRGO) and the corresponding polymer

nanocomposites.17,18


Figure 5. a) Measured and given properties of University of Freiburg TRGO. b) SEM images of TRGO.

Graphene Laboratories (owned by Graphene 3D Lab) is an

American company that develops and markets a broad range

of graphene nanomaterials and 2D materials. Graphene Labs operates an online store called Graphene Supermarket, which offers online graphene-related products and other advanced

materials.19

Figure 6. a) Measured and given properties of Graphene Labs product. b) SEM image of GC1.

Xiamen Knano Graphene Technology Co. Ltd is a company involved in

mass production and graphene nanoplatelets applications in China. It also

developed tailored graphene nanoplatelets masterbatches for polymer

modifications.20

Figure 7. a) Measured and given properties of Knano products. b) SEM images of KNG-G5, c) Optical image of Kng-C162 pellets.

NanoXplore is an advanced materials company in

Canada providing customers with graphene-enhanced

polymers, including masterbatches in pellet form, few

layer graphene powders, and custom graphene solutions. 21


Figure 8. a) Measured and given properties of Nanoxplore product. b) SEM image of Hexo-G V.

NanoInnova Technologies is based in Madrid and is a spinoff company from the

Universidad Autónoma de Madrid. NanoInnova designs, develops and

commercialises instrumentation and nanostructured surfaces for research

groups. The company offers graphene-oxide, reduced graphene-oxide and other graphene

and related materials.22

Figure 9. a) Measured and given properties of Nanoinnova products. b) SEM images of Graphenit-OX.

The Sixth Element Materials Technology Co. Ltd, is a public Chinese

manufacturer of GRM producing graphene oxide, graphene powder products and

suspensions, plus CVD based graphene film products for various applications

such as flexible screens. Claimed production scale is 260 tons/y of graphene oxide and 130

tons/y of graphene.23

Figure 10. a) Measured and given properties of The Sixth Element products. b) SEM images of SE1231.

Thomas Swan & Co. Ltd. is an independent UK chemical

manufacturing company; today it produces over 100 products, in

kilogramme to multi-tonne quantities. Thomas Swan, in collaboration with Trinity College

Dublin, has developed an industrially scalable route to non-oxidised graphene nanoplatelets


for highly conductive materials. In 2014, it realized a pilot line for the manufacture of Elicarb®

Graphene products, capable of producing 1kg/day of GNPs.24

Figure 11. a) Measured and given properties of Thomas Swan product. b) SEM image of Elicarb.

United Nanotech Innovations (UNI), owned by Darwish Bin

Ahmed Group, is an India-based nanotechnology company that

produces graphene materials and multi-walled carbon nanotubes

(MWCNTs). Graphene products sold by United Nanotech Innovations are graphene powders

at the ton scale, graphene oxide, graphene inks and masterbatches and hybrid products with

graphene and carbon nanotubes.25

Figure 12. a) Measured and given properties of United Nanotech products. b) SEM images of Industrial-Gr.

XG Sciences is an American graphene manufacturer. They

manufacture and sell graphene nanoplatelets and develop advanced

engineered materials based on them. They work with end-users (including Samsung, POSCO,

and Cabot Corporation26), compounders, universities and research groups to customize

materials for specific applications.


Figure 13. a) Measured and given properties of XG Sciences products. SEM images of b) XGnP M25, d) XGnP C750.

Grupo Antolin is a leading global supplier of components for the automotive

industry. It is a partner of the Graphene Flagship. ANTOLIN produces GANF nanofibres, used within the flagship for a specific application, i.e., infiltration of a thermoset

resin into a composite preform made of dry carbon fibres.

In this preform the fibre volume can be close to 60% and the distance between each fibre is

just a few microns. Thus, it is challenging to disperse the graphene into the resin and inject it

amongst the fibres.

GANF is composed of helical ribbon carbon nanofibres, which need to have very small size

(<1 μm) in order to penetrate between the carbon fibres of the final composite, and partially

exfoliate only during their milling into the polymer matrix.

Thus, their initial exfoliation grade is not representative of the final exfoliation grade27.

Figure 14. a) Measured and given properties of Antolin GANF product. b, c) SEM images of GANF.


5 Conclusions of GRM Benchmarking:

We characterised different kinds of GRM for industrial applications, available within and

outside the flagship. The powders analysed had a lateral size in the range from a few to tens

of microns. Noteworthy, the apparent size of the GRM, as seen by SEM, is not always

indicative of the real exfoliation grade; in some case (see as example RGO Graphenea in

Figure 2 or AVA23 in Figure 1), the product is formed by agglomerates of GRM flakes, which

are held together by weak forces, but which anyhow give large surface areas, which shall

separate in smaller flakes upon sonication in solvents or extrusion in polymers.

Most of samples feature a restricted range of surface area (<250 m2/g) and lateral sizes (<50

µm). Exceptions include materials such as TRGO which, due to the oxidation-reduction step,

can reach SA >1100 m2/g. Figure 15 and 16 plots the D50 and SA of all measured samples.

Larger D50 are obtained also for some materials, but are due to the presence of aggregates,

more than to the size of single flakes as described previously.

The SA and D50 values for all of the materials in this report have been obtained using the same

parameters, and thus can be compared directly; they are often different from the values

provided by the companies, indicating that the different producers most probably obtain them

using different measurements parameters. This implies that the lack of standards and widely

accepted methods to measure the morphology of GRM materials is still a critical issue in this

industrial sector.

Figure 15: Correlation between D50 and Surface area of all the GRM flakes analyzed.


Figure 16: Zoom in of the red area of Figure 15


Annexes

1 Companies Considered but not Included in the Benchmarking

COMPANY EXPLANATION

Vorbeck (www.vorbeck.com) Not currently offering products in the EU due to

SDS regulations requiring explicit disclosure of

formulations

Directaplus (www.directa-plus.com/) Requires specific commercial agreements to

provide product

Standard Graphene (www.standardgraphene.com/) Graphitene (www.graphitene.com) Nanointegris (www.nanointegris.com/) GrapheneShop (www.grapheneshop.pl/) The Graphene Box (www.thegraphenebox.com/)

Price of graphene derivatives analyzed and

considered currently unsuitable for large scale

industrial applications

2 Case Studies: Assessment of GRM-Based Commercial Products

Commercial online retails such as Amazon and Alibaba sell hundreds of end-user products

claiming to use graphene. Whilst benchmarking of GRM powders can be performed in a

systematic way, it is more difficult to evaluate the role of GRM in commercial products based

on composites, and how much the presence of GRM improves the materials performance. Typical commercial products containing GRM (i.e., tyres, rackets etc.) have different shapes,

properties and overall composition vs. non-GRM ones, thus hindering any objective

comparison. Notwithstanding this, it is possible to analyse commercial products to understand

at least if they truly contain GRM, and which type of GRM they contain. To this aim, some

exploratory work has been undertaken recently by the WP partners. The text here below

describes three examples of such analysis. Example 1: The Microstructure of a Graphene-Reinforced Tennis Racket The microstructure of a graphene-reinforced tennis racquet (Figure S1) was analysed using a

combination of optical microscopy and Raman spectroscopy by UNIMAN partner.28 It was

shown that the main structural components in the racquet frame are high-strength carbon fibres

in an epoxy resin matrix. Polished sections of different areas of the racquet handle and shaft

were also obtained in which there was a complex arrangement of fibres. At least two extra


Raman bands were observed in this area; a well-defined band at around 2680 cm-1 and another

close to the main aromatic resin band at 1605 cm-1. The presence of these two extra bands is

an indication of the presence of a second phase in the epoxy resin matrix in this region. Close

inspection of the matrix microstructure shows that there is a speckled pattern of white particles

with sub-micron dimensions in the epoxy matrix. It was found that GRM are used to reinforce

resin-rich regions in the shaft of the racquet at the discontinuity in the fibre tows, where the

handle is joined to the racquet head. From a detailed analysis of the relative positions and

intensities of the Raman G and 2D bands, it was demonstrated that the GRM employed in the

racquet are most probably graphite nanoplatelets which have been added to improve the

mechanical properties of the resin-rich regions.

Figure S1. The HEAD graphene tennis racquet (model Youtek Graphene Instinct Junior) showing the two regions investigated a) the tip and b) the shaft. Example 2: The Structure of a Vittoria G+ Cycle Tyre The structure of a Vittoria cycle tyre (Figure S2) was analysed using a combination of optical

microscopy and Raman spectroscopy. The tread was found to be composed of GRM-modified

natural rubber along with a Kevlar-reinforced cotton sidewall. The rubber, Kevlar and GRM

were all identified from their different Raman spectra. The Raman spectrum from the GRM is shown in Figure S2b; it can be seen that there are two strong characteristic bands, one at

1580 cm-1 and the other at 2680 cm-1, indicative of the presence of graphite nanoplatelets.

Carbon black, which is normally used in tyres has a very different Raman spectrum consisting

of two broad bands at around 1350 cm-1 and 1600 cm-1. It was found that high loadings of

these graphite nanoplatelets were present in both the surface and interior of the tyre tread.


Figure S2. The Vittoria G+ cycle tyre a) Photograph of the tyre (b) Raman spectrum from the GRM in the tread.

Example 3: Analysis of CVD Graphene in a Heating Element (Commercial Waist Protector) The thermal performance of a commercial graphene-based waist protector (Figure S3a, b and c) product was fully assessed (publication in preparation). The encapsulated graphene

(produced by CVD) was under initial biaxial compression of about -0,10% in the pristine device,

as estimated by Raman spectroscopy. For 3 h of continuous operation, no significant change in the temperature distribution was observed by IR imaging (Figure S3c) indicating that the

device was properly functioning. However, after 12 h of continuous operation certain

fluctuations in the temperature distribution were recorded and for an uninterrupted operation

of 5 days, two distinct areas which had ceased to generate heat were noted. These fluctuations were also ‘sensed’ by Raman microscopy (by the 2D band’s position and width).

Finally, the measured resistance of the device increased exponentially with the applied time

interval of the accelerating thermal fatigue testing, which is also related to the temperature

decrease and the malfunctioning of certain areas of the graphene heating device.

Overall, these measurements confirmed that graphene can work well as a heating element in

commercial devices and can retain its functionality under many hours of continuous operation.

This work has also indicated the areas for which further work is needed for the improvement

of the current commercial product.

Figure S3 a) “The Graphene Intelligent Physical Therapy Waist Protector” product (Shenzhen Grahope New Materials Technologies Inc. b) A schematic representation of the graphene therapy waist protector components. c) Thermal image of working device. Conclusions The analysis of commercial devices claiming to contain GRM is a very important field of study

as it allows us to understand which kind of material they contain (few-layers graphene, graphite platelets, CVD graphene etc.) and how they function vis-à-vis existing commercial devices.

This work is currently in its infancy and will be intensified as new products and applications

enter the market claiming advantages over competitive products.


3 Example of Cost/Performance Analysis Procedure of GRM vs. Other Commercial Carbon Additives

A wide range of published works demonstrates that graphene can be an ideal additive to

improve the mechanical, electrical and thermal properties of composites. However, similar

improvements can often be obtained using cheaper, widely diffused materials such as carbon

black or graphite. Any serious attempt to evaluate if GRM could be effective for a given

application should thus be based on an objective benchmarking of the GRM versus other

materials, comparing the performance not only at similar loading (measured in %weight), but

also at the cost required to achieve a given performance. The cost/performance of different

materials produced in the flagship for electrical or thermal conductivity applications was thus

compared with a representative number of commercial products used by the composites

industry:

• Conductive Carbon Black: Ketjenblack EC300J (KB 300), cost 16 €/Kg, producer

AzkoNobel

• Conductive Carbon Black: Ketjenblack EC600JD (KB600), cost 40 €/Kg, producer

AzkoNobel

• Conductive expanded graphite (EG): C-THERM2 (CT2), cost 14 €/Kg, producer Imerys

• Multi wall carbon nanotubes (MWCNTs): NC7000, 90 €/Kg, producer Nanocyl

• GRM: AVA221, SA 512 m2/g, D50 42 μm, cost 125 €/Kg (estimated selling price at 250

kg/day scale), producer Avanzare.

• GRM: AVA240, SA 37 m2/g, D50 50 μm, cost 35 €/Kg (estimated selling price at 250

kg/day scale), producer Avanzare.

A major problem of nano-additives is that they modify the properties of the molten polymer

and, in this way, hinder conventional processing by extrusion or moulding.29,30 We have thus

studied how different materials influence the viscosity of the dispersion in order to evaluate the

processability. An increase in viscosity produces lower flocculation of the particles and usually

better electrical conductivity, however it decreases the processability of the polymer, especially

when the processing of GRM should be implemented into an already optimized industrial

process.

We have compared the properties of polymers reinforced with GRMs with that of polymers

reinforced with other industrial additives, such as graphite, carbon black and carbon nanotubes

and we report below some examples of the results achieved.

We studied the enhancement of the thermal conductivity of the polymer PA6 using three different types of materials: Graphene Nanoplatelets AVA240, expanded graphite CT2 and

carbon nanotubes NC7000, as reported in Figure S4. Results show that AVA240 is extremely


effective to increase the thermal conductivity in this thermoplastic composite, due mainly to the

large lateral size of the graphene nanoplatelets, and the low number of defects.

We have also studied the electrical conductivity in vinylester resins of GRM (AVA 240) and other carbon-based materials (Carbon Black and Expanded Graphite) (Figure S5). AVA 240

shows higher electrical conductivity at lower loading compared to other carbon materials.

Using AVA 240 it is possible to obtain very high electrical conductivity (1 S/m with less than

0,5 % w). Moreover, we observed that carbon black and expanded graphite increase the

viscosity of the vinylester resin more than AVA 240 (not shown). The increase in the viscosity

limits considerably the industrialisation and final use of these materials.

Moreover, we have carried out a cost analysis of the performance of different materials

(graphite, carbon black, carbon nanotubes and GRM) in epoxy resin, in particular measuring

the smallest increase of cost needed to obtain a) electrical percolation, i.e. the smallest current

measurable in the composite, or b) a conductivity of 0,1 S/m, which is high enough for practical applications (Figure S6).

No significant differences between AVA240, AVA221 and NANOCYL NC7000 can be noticed

for the percolation threshold (blue rectangles), all materials achieving percolation for cost ≈0,1

€/Kg. Significant differences are instead observed for the cost needed to achieve an electrical

conductivity of 0.1 S/m, a key target for many industrial applications. For this goal AVA221

presents the best price/performance values followed by AVA240 and NC7000.

Noteworthy, we found that it is possible to achieve 10 S/m using AVA221 at an extremely

competitive price of ≈1.3 €/Kg and without a significant increase in viscosity (star symbol in Figure S6), which could allow innovative applications in composites, as example for antistatic

or EMI shielding.

In summary, we compared the performance of GRM available in the WP14 with other industrial

additives, such as graphite, carbon black and carbon nanotubes for improving the electrical

and thermal properties of target polymer composites. The GRM selected perform better than other standard additives, also offering some advantage in term of processability, i.e. lower

reduction of viscosity of composites. We compared not only the absolute performance at fixed

loading, but also the performance achievable at a given cost, thus taking into account also the

large differences in the current commercial price between these different classes of materials.


4 Motivation for the Selection of Nanotubes Type for the Benchmarking

Similarly to graphene, also carbon nanotubes (CNTs) are available in different forms. We had

to choose a specific CNT product for the comparison described above. We chose CNT from

Nanocyl even if other options, as example CNT from Mitsubishi, were possible. The selection

of Nanocyl CNT was based on the following factors:

• The global carbon nanotube market is fragmented due to the presence of a large

number of medium and small industry participants. Key industry players include

Arkema SA, CNano Technology Limited, Hanwha Nanotech Corporation, Korea

Kumho Petrochemical Company Ltd., and Nanocyl SA. Other prominent participants

include Carbon Solutions, Inc., Showa Denko K.K., Future Carbon GmbH, CNT Co.,

Ltd., Continental Carbon Nanotechnologies, Inc., Raymor Industries Inc., Klean

Commodities, Hyperion Catalysis International Inc., and Nanothinx S.A.

• It would have been impossible to test all these suppliers in our benchmarking, so we

selected a supplier based upon the market focus of our European supply train:

o Nanocyl is identified as one of the leaders in the production of MWCNTs based

in many market reports: ARKEMA, NANOCYL, CNano, Hyperion, Mitsubishi Rayon, Toray, etc.

o The annual production of Nanocyl is about 400 TM, similar to Arkema and

Showa Denko. Mitsubishi Corporation production is only 10 – 30 TM/year (data

from 2015).

o European users are primarily using Arkema or Nanocyl CNTs. In fact,

according to the European Chemicals Agency (ECHA) Nanocyl, Arkema and

Baytubes are the only CNT manufacturers registered in Europe for production

or import (Baytubes was discontinued from 2013). This indicates that, for other

CNT such as Mitsubishi, the imports in Europe must be <1 TM/year.

o CNTs of Showa Denko are relatively thick (approx. 150 nm) for the ranges

examined here.


Figure S4: Through plane thermal conductivity enhancement of PA6 reinforced respectively with

MWCN (NC7000), EG (CTHERM2), and GRM (AVA240). Error bars represent experimental error.

Figure S5: Volumetric electrical conductivity of composites in a vinylester resin matrix using as fillers GRM (AVA0240), EG (CT2) and carbon black (KBEJ300C). Error bars represent experimental error.


Figure S6: Cost increase in €/Kg needed in electrical conductive epoxy composites for large scale

production with different carbon fillers in order to achieve the percolation threshold (blue) or a

conductivity of 0.1 S/m (red).


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