JEC COMPOSITES MAGAZINE - Issue #110 - January/February 2017 - 33

A new generation of aesthetic composites based on styrenic copolymers

Tab.1: Portfolio of SL grades optimized for back-injection moulding of StyLight composites

Validated
for StyLight Aesthetic

Validated
for StyLight Structural

Materials
for back injection

Unit

Terblend N
NG-02EF SL

Terblend N
NG-04EF SL

Novodur
BX6437*

Terblend
N NG-06EF SL

Base resin

-

ABS/PA GF

ABS/PA GF

ABS GF

ABS/PA GF

Fiber content

%

8

20

16

30

Melt Volume Rate
240°C/10kg

cm3/
10min

40

30

18*

8
* In development stage
Fig. 2: Moisture uptake of StyLight* vs. PA6

under a flexural load of 250 MPa after more
than 2 million cycles (tests performed by IVW,
Kaiserslautern).
Surface aesthetics
Although the new material shows a higher
stiffness and a good stability versus other currently available thermoplastic composites,
these advantages alone would not justify the
investment to develop and launch a new type
of composite thermoplastic on the market.
But the StyLight* composite adds another significant advantage: its surface properties. The
outstanding surface quality inherent to styrenic matrices makes it possible to extend the
application scope of composite thermoplastics
to visible aesthetic parts at a competitive price
level.
The lower shrinkage during the consolidation
step of the amorphous styrenic copolymer
matrix based on modified SAN reduces the
surface roughness ("waviness") significantly,
offering a superior surface quality compared to
most existing standard thermoplastic composites (Figure 3). INEOS Styrolution does not
claim to achieve a high-end Class A surface in a
single compression/injection shot at this point
(see the Demonstrator paragraph). Still, the
surface quality achieved with StyLight* - combined with the high polarity of its surface allowing an easy surface decoration process such
as coating, painting or foil decoration- makes it
an interesting material for semi-structural aesthetic applications.
Beside the surface "flatness" advantage, the
low shrinkage of the styrenic copolymer matrix enhances the dimensional stability of the
finished parts and reduces the risk of warpage.
Combined with the material's low water ab-

Fig.3 : Comparative surface waviness
(LMS method measured at NMF in Fürth)

Fig. 4: StyLight* part made of 3K, 2/2 twill carbon
fibre with a clear coating

sorption, the dimensions of StyLight* parts
remain stable after manufacturing, making
it suitable for applications in vehicle interior
parts or high-tech applications requiring a
good fit and finish. In combination with its
good chemical resistance (environmental
stress crack resistance, ESCR), StyLight* is a
robust and versatile composite solution suitable for aesthetic semi-structural high-performance applications.

No110 January - February 2017

/ jec composites magazine

Feature Automotive

StyLight* (trademark application pending)
is the brand name of this new generation
of thermoplastic composites from INEOS
Styrolution.
Moreover, the low water absorption
(Figure 2) of the amorphous styrenic copolymer, combined with its high glass transition
temperature of 110°C, provides high mechanical stability over a broad temperature
range. The good stability of styrenic copolymers in a wide range of environmental conditions makes this new class of products ideal
for the design of technical parts requiring stable properties and dimensions.
However, in three-dimensional parts typically
used for automotive or sport applications, the
composite sheet only represents the surface
layer. Consequently, the mechanical properties of a composite part should combine the
surface composite skin with the back-injected moulded material to better determine the
finished part performance. For this purpose,
different materials with different property
profiles were developed to optimize the adhesion of the injection-moulded materials on
the StyLight* sheet. Adhesion was measured
to find the optimum material combination,
resulting in a portfolio of short glass fibre-reinforced ABS/PA blends (Terblend® N) and
ABS (Novodur®), which are identified with
the SL suffix (Table 1).
Finally, above and beyond the static mechanical performance of StyLight*, INEOS
Styrolution performed fatigue tests to evaluate the long-term resistance of this new
type of styrenic composite in comparison to
alternative thermoplastics-based composites, as well as epoxy-based composites. The
results show the material's good performance

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Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #110 - January/February 2017
