JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020 - 45

From bottle to blade

Thermoplastic foam extrusion process

A greener core material produced from recycled PET! Gurit vertical integration of the recycling technology

However, it takes approximately four years
for a balsa tree to grow to the point where the
wood can be cut and material production can
start. The lag induced by its natural growth
cycle as well as its exposure to different climate
conditions and other circumstances that
could further prolong the production time is
a challenge, particularly for the dynamic wind
energy industry.
Recycled PET as a
synthetic core material
Given the importance of the core in blade construction, several synthetic cores have been

considered over the years. A modern answer
for a scalable synthetic core technology came
with the adoption of thermoplastic extruded
foam. In this respect, PET is the polymer that
offers the greatest benefits in terms of the
balance of thermal resistance (to withstand
the blade production process), mechanical
performance (delivering the necessary stiffness and strength) and cost.
Moreover, PET offers a well-developed and
resilient supply chain for recycled material,
further improving the environmental credentials of a material and a production technology
that already ensures great efficiency, allowing

A sustainable offering
Both balsa and recycled PET are strong
contributors to the wind energy sector's
target to reduce its environmental footprint
even further and minimize waste without
compromising on mechanical properties or
resin uptake performance - at a competitive
cost. However, despite these innovations and
advancements, challenges remain, for example the recyclability of advanced composite
materials at the end of their life cycle.
The scope of this challenge is such that only a
broader industrial collaboration is likely to be
successful in solving it.

N°136 September - October 2020

More information:
www.gurit.com

/ jec composites magazine

Feature Sustainability

Gurit's sustainable core materials offering for the Wind industry

for any production waste to be recycled into
fresh foam core material.
Recycled PET is a viable raw material for
thermoplastic foam extrusion but, in order
to obtain stable foam, the material's viscosity
needs to be significantly modified and a reactive extrusion process used. Therefore, the
extruder is more than a process aid to introduce a physical blowing agent. It also becomes
a chemical reactor where the molten PET
reacts with a modifier to change the polymer's
behaviour and significantly improve its ability
to maintain a fine low-density foam status
when cooling down.
Since post-consumer PET is widely recycled,
there is an opportunity to utilize an already
well-organized supply chain. Gurit recently
invested in the vertical integration of the
recycling technology, from the recycle stream
(bottle and industrial) to the PET foam,
with the aim of leveraging this supply chain
and giving a second life to PET waste. The
recycled PET is then processed into foam in
a very energy efficient process with minimal
waste. In the subsequent kitting process, PET
structural foam is cut to fit the size and requirements of wind turbine blades. This cutting
process generates waste, which would have
to be disposed of. However, by co-locating
extruders next to the kitting operations, this
waste material can now be directly recycled
in the adjacent extruder. This reduces overall
costs while minimizing waste and transportation emissions. Gurit has started to implement
such a co-location strategy to the benefit of its
customers.

http://www.gurit.com

JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #136 - September/October 2020