JEC COMPOSITES MAGAZINE - Issue #101 - November/December 2015 - 27

perature and is more closely related to
the physical property changes attributed to the glass transition in plastics. It
reflects molecular processes and agrees
with the idea of Tg as the temperature
at the onset of segmental motion [6].
Tg tan delta: Occurs at the highest temperature and has been used historically
in literature. It is a good measure of the
"leather like" midpoint between the
glassy and rubbery states of a polymer.
The height and shape of the tan delta
peak change systematically with amorphous content [6].

Production of pultruded
bio-composite profiles

At an early stage in the OSIRYS project, trials were carried out using the
neat bio-based epoxy resin and glass
fibre as reinforcement. The objective
was to evaluate the ability of the resin
system to be processed through the
pultrusion process and to assess the
curing cycle, as illustrated in Figure 6
and Figure 7. Further work was undertaken using the bio-based epoxy resin
and introducing modified graphene, as
described in Figure 8.

Sample

Tg onset E' (°C)

Tg peak E'' (°C)

Tg tan delta (°C)

Neat epoxy resin

76.82

78.16

93.86

0.5% modified graphene

78.48

79.59

95.39

Glass roving was used as reinforcement
for the pultruded profiles. These new
tests were intended to evaluate the processing of materials and to determine
the most suitable operating parameters
and mechanical properties. Prior to
the introduction of the bio-based
epoxy resin in the pultrusion process,
the graphene was dispersed into the
polymer using the three-roll mill and
following the dispersion cycle defined
in Figure 8.

Conclusions
From the results obtained, it can be
concluded that bio-composite profiles
can be obtained using the bio-based
epoxy resin modified with graphene. No
impregnation problems were observed
in the pultruded profiles at the end of
the process. Moreover, the developed
pultruded bars showed good surface
finish. Regarding their mechanical properties, an increase in the Tg values was
observed after the introduction of 0.5%

Fig. 5: General schematic of the pultrusion process

Fig. 6: Different steps involved in the processing of the bio-composite profiles

Fig. 7: Detail of the optimised bio-composite profiles produced by pultrusion

No101 November - December 2015 / jec

Feature Building & Construction

Different techniques can be used for
the production of biocomposites depending on the raw materials and the
required product geometry, properties,
processing time and cost. Pultrusion
is a continuous manufacturing process
for composite profiles. It uses continuous fibres as the major reinforcement.
Different resin systems can be used
to obtain the final desired properties.
Flexibility in design and the variety
of material combinations are the main
advantages of pultrusion technology.
The structural possibilities are almost
unlimited. In the pultrusion process,
the fibres are impregnated with a
thermosetting resin and pulled through
a heated die where curing takes place.
Different laminate lay-ups are possible
with roving, mat and fabric reinforcements. The finished profiles are cut to
length by a saw at the end of the line.
Figure 5 shows a general schematic of
the pultrusion process.

Tab. 2: DMA results (modified and unmodified graphene)

composites magazine 27
Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #101 - November/December 2015
