JEC COMPOSITES MAGAZINE - Issue #95 - Special JEC Europe - March 2015 - 99

1 caption).At higher temperatures, the
resin has a thermoplastic behaviour that
makes it possible to "debond" the assembly
and even to further "rebond" it. A simple
test was performed on an electrogalvanized
steel assembly. Right after bonding, the
assembly showed a lap shear strength of
12MPa. It could be debonded by simply
heating the assembly at 120°C and pulling
the coupons apart at the same temperature. The same assembly could be bonded
again using heat, and exhibited the same
lap shear strength as the initial test (i.e.
12MPa).

Composite applications
In order to evaluate the potential of this resin for composite applications, the L-F610
film was used to manufacture five plies of
glass fabric composites by compression
moulding. The glass fabric used was a 600g
/cm2 bi-axial taffeta with a multifunctional
finish. The samples were produced by
Hardwire LCC [1]. The resulting plates had
a thickness of 1.9mm and a fibre volume
content of 60%. The shear stress was
determined employing the ±45° tension
test method according to the ISO14129
standard. This test was chosen in order to
evaluate the in-plane shear/stress response
from the composite, and in particular, the
interlaminar shear cohesive behaviour. The
plates' characteristics, as well as the test
results, are shown in Table 1. The modulus and the shear stress are in the range of
values expected for an epoxy system, but
the interesting feature highlighted by these
mechanical properties results is the high
elongation value (60.8%). This last value is
most likely due to the high affinity between
the resin and the fibres, and also the inherent high ductility from the resin. It could
lead to interesting applications when the
parts can be subjected to fatigue or impact
constraints.
An interesting characteristic of L-F610 is
the ability to assemble composite parts
together using the inherent matrix phase
as the adhesive. In this manner, composite
parts can be bonded together without the
need of an additional structural adhesive.
Composite parts made with L-F610 can
also be bonded to an epoxy thermoset part,
again without the need of an additional

Table 1: Characteristics of composite plates produced from L-F610 resin film/glass fibre taffeta

Process

Compression moulding of resin films on dry
glass fibre laminates

Reinforcement

600g/m² glass fibre taffeta

Resin

L-F610 film (L-TE01 resin based)

Part thickness (mm)

1.92

Fibre volume fraction (%)

61.5

Shear stress (MPa)

57.7

Maximum strain (%)

60.8

Modulus (MPa)

4,948

adhesive. In order to illustrate this feature,
L-F610 composite parts were bonded
together by applying heat (160°C) and
pressure (1.5 bar). The assembly strength
was tested by completing a lap shear test
and demonstrated a resistance superior to
20MPa. The same experiment was made
by bonding an L-F610 composite to a thermoset epoxy composite (Araldite LY564/
Aradur 22962 from Huntsman). Simply by
applying heat and pressure, the assembly
lap shear strength was found higher than
12MPa without any surface treatments.
The formability of L-F610 composite
parts was also evaluated. In this section, we
considered the formation of a part using
reinforced sheets from the aforementioned
five-ply glass fabric laminate. In order to
obtain the final shape, the continuous
fibres must be rearranged to cover the
geometrical variations characterizing the
finished part. For this, the matrix has to
soften during the heating phase to a point
that allows relative fibre movement. The
thermoplastic nature of the resin should be
perfectly suited for such an application. A

thermoforming test was implemented to
demonstrate this property. The principle of
this test consists in placing a flat composite
plate in a metal mould and heating it up in
an oven. The weight of the punch generates a pressure on the surface of the sample
which forms the part. The resulting part
from this simple test (see Figure 2) shows
that it is possible with this resin system to
obtain 3D shaped parts from a composite
L-F610 plate.

Application example
Hardwire, LLC uses the L-F610 film in a
variety of applications. The material has a
great blend of properties, perfect thickness
control, and adhesion to a wide variety
of substrates that makes it possible to do
one-step processing for preforms or final
formed parts up to 1.5 m by 3 m in size.
Hardwire is a composites manufacturing
company that specializes in armour and
thermoplastic composite laminates mainly
for the military, defence, and homeland
security applications. Utilizing its high
pressure (205 bar) vacuum laminating
presses, the company manufactures armour

Fig. 2: Thermoforming test set-up (left) and resulting part (right)

No95 March 2015 /

jec composites magazine 99

JEC COMPOSITES MAGAZINE - Issue #95 - Special JEC Europe - March 2015

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