JEC COMPOSITES MAGAZINE - Issue #101 - November/December 2015 - 26

graphene
Tab.1: Dispersion cycle

Dispersion cycle definition

Fig. 2: Assembled modular multi-layer envelope
based on biocomposites integrating the developed
biocomposite profile

profiles can also be used to finish existing
masonry partition walls, mechanical and
extraction shaft cladding, and column
cladding. The profiles were designed to
be processed from a bio-based epoxy
resin, graphene and using flax fibres as
reinforcement. They were integrated
in the modular multi-layer envelope as
described in Figure 2.

Modifying graphene
for better interaction with
the bio-based epoxy resin
The incorporation of nanomaterials
into polymers is currently being studied
in order to improve their mechanical
and flame-resistance properties, as well
as the adhesion between the polymer
matrix and the fibre. Adding graphene to
polymers offers significant potential for
the development of advanced materials
in a vast number of applications due to
its large specific surface area which has
a dramatic impact on mechanical and
fire resistance properties [6]. Although
adding graphene can greatly improve
properties such as modulus, toughness
and fatigue properties, strong interfacial
adhesion between the graphene plate-

Fig. 4: Three-roll mill used in the dispersion of
graphene at pilot plant level

let and the composite matrix is crucial
to achieving these gains [7]. Interfacial
adhesion can be greatly improved by
chemically functionalizing the graphene
surface, which can also aid platelet dispersion in the matrix.
Different strategies can be used to modify the chemistry of graphene and create
a high number of interactions with thermosetting resins. In the particular case
of the OSIRYS project, various reactants
and reactions were tested in order to
functionalize graphene and create good
interactions with the neat bio-based
epoxy resin. As a result, modification in
a friendly medium (simple alcohol) was
selected as the most appropriate pathway
to functionalize graphene. Figure 3 illustrates the different phases involved in
the modification of graphene.

Dispersion of modified graphene
into the bio-based epoxy resin
One of the main problems for the incorporation of nanomaterials into polymeric matrices is their tendency to form
agglomerates. From a technical point of
view, several factors need to be considered to obtain a good dispersion of nanomaterials: the elimination of agglomerates, the dispersion of aggregates and the

Fig. 3: Phases involved in the chemical modification of graphene

26 jec composites magazine / No101 November - December 2015

Cycle 1

gap 130/45

Cycle 2

gap 90/30

Cycle 3

gap 60/20

Cycle 4

gap 30/10

Cycle 5

gap 15/5

stabilization of the medium. The equipment used for nanomaterial dispersion
depends on the required particle size.
In the OSIRYS project, a three-roll mill
pilot plant was used for the dispersion of
the modified graphene into the bio-based
epoxy resin, as shown in Figure 4. This
was done considering technical aspects
such as the high viscosity of the resin and
the high shear stresses involved in the
mixing process, among others. The dispersion cycle of graphene into the biobased epoxy resin was studied and finally
optimized, as described in Table 1. The
composites prepared with the different
modifications were characterized using a
dynamomechanical analyzer (DMA) to
determine the effect of graphene on the
viscoelastic modulus, and subsequently
on the mechanical properties and on the
glass transition temperature (Tg). This
modulus provides information about the
degree of dispersion and thus the effect
of material quality on the thermal stability and the mechanical properties. The
DMA results are shown in Table 2.
Tg onset E´: Occurs at the lowest
temperature and relates to mechanical
failure [8].
Tg peak E'': Occurs at the middle tem-

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #101 - November/December 2015