JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o - 120

TECHNOLOGY pultrusion

Fig. 3: Pultrusion line equipped with pullwinding units
Table 1: Properties of the pultrusion resins developed by Structil

Fig. 4: Speed/temperature monitoring diagram from the development line

Resin Reference

RP 14

RP 43

RP 30

Chemical composition

Epoxy

Polyurethane

Glass Transition
Temperature

Tg (°C)

195

105

Tensile Strength

s (MPa)

2000

2150

2170

Tensile Modulus

E (GPa)

140

170

155

PASSED

NOT PASSED

Fire resistance compliance*

Pullwinding technology
With this initial principle, most of the fibres are oriented along the
length of the profile. Pullwinding (Figure 3) is an additional technology that uses usually contra-rotating satellites to generate layers
at two opposite angles of identical value (+θ and -θ). The satellites
can be used in a serial mode. These layers bring additional performance to the final product in compressive and torsional modes.
Structil uses its strong pullwinding experience to produce parts for
very high performance applications such as transmission shafts or
connecting rods for the aerospace industry. The aesthetical aspect
is also improved by the use of external pullwinding.
Outstanding know-how
Structil, as a long-time formulator of thermoset resins, benefits
from considerable knowledge in this field. Several resins were developed to best meet customer requirements such as gelation time,
viscosity growth, thermomechanical performance, etc. Although
epoxy resins are the main pultrusion matrices used by the company, some products are also based on polyurethane matrices, which
bring interesting properties in terms of output rate, surface finish
or chemical resistance. Specific developments also resulted in resins compatible with fire-resistant applications or high Tg requirements (Table 1).
Different types of fibres can be used, especially carbon fibres (more
than 90% of the company's business), but also glass or basalt fibres,
which offer interesting properties at lower price.
The reinforcements used in pultrusion are mostly in the form of
rovings or spools, but also fabrics, mats, braids or woven fibres,

120

jec composites magazine / N°111 March 2017

helping improve the behaviour of the profiles under multidirectional stresses.
Fully understanding the pultrusion process implies hard and comprehensive work. In fact, many parameters play a significant role
in the final product performance, especially spool tension (creel),
distribution scheme (distribution grid), resin spinning rate (bar
feed zone), die temperature, residence time/pulling speed, and
pulling force. Structil is equipped with a development pultrusion line fully instrumented to monitor the process parameters
(Figure 4).
Pultrusion developments at Structil currently focus on three main
topics: multiaxial reinforcement, fire-retardant profiles and thermoplastic matrices.
Multiaxial reinforcement is a key challenge in pultrusion, a production process initially intended for profiles with 0° fibres. One
of the potential approaches consists in using fabrics in the process.
However, this is a challenge because the friction with the die can
affect the fabric's geometry. Several improvements were made to
facilitate the pultrusion of profiles incorporating fabrics.
The second topic, which is a specific request in aerospace applications, is fire resistance. Pultrusion can rapidly offer interesting
results due to the high fibre content (around 65% to 70% by volume) that helps improve fire resistance. Over the past years, Structil worked hard to develop a new resin for these applications.
The last key challenge is the pultrusion of profiles made of thermoplastic resins. In fact, thermoplastic matrices open the way to
post-forming, welding and many other ways to add functionality.
Moreover, thermoplastics exhibit a higher tenacity than thermoset
resins and inherent fire resistance.
All these recent developments, combined with 30 years of experience in composite manufacturing, make Structil a leader in
pultrusion and resin preparation, recognized within the world of
composite manufacturers.
Meet Safran Structil on JEC World, Booth N28, Hall 6
Contact: jeremy.viale@safrangroup.com
More information: www.structil.com

http://www.structil.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o