Issue 06/2021

Recycling
By:
Fig. 2: small scarf containing 50 % Recycled PAN
S. Schonauer & T. Gries
Institute of Textile Technology,
RWTH Aachen University
Aachen, Germany
Upcycling
process for
PAN from
textile waste
Most synthetic fibres are made from fossil material
sources. Since these are only available in finite
quantities and their use is not always compatible
with today’s environmental goals, it is necessary to develop
an innovative recycling process and close material cycles.
Currently, polyacrylonitrile (PAN)-containing waste from
production and end-of-use waste is sent for thermal
waste treatment, used as a filler, or processed into lowvalue
blended yarns. Although energy recovery is possible,
incineration also releases harmful emissions, and the
material can no longer be fed into a cycle. [1] At ITA of RWTH
Aachen University, approaches to the chemical recycling
of PAN fibres are being pursued under the project name
industrial RePAN, as a step towards closed-loop economy.
The technical feasibility along the entire process chain from
polymer recovery and fibre production up until the finished
product (blankets) is being mapped.
Assuming that newly acquired products replace old
textiles, around 24,500 tonnes of end-of-use waste is
annually generated in the house and home textiles sector
in Germany. Even if only half of this waste could be recycled,
it would offer 12,250 tonnes of new resources. During the
production of PAN staple fibres, about 1 % by weight, and
additionally during processing up to 10 % by weight, of fibre
materials are generated as production waste [2, 3]. This
type of waste served as a secondary raw material source
for these research trials.
The individual stages of the process are presented in
Figure 1, starting with the collection of textile waste from
the blanket production. The waste is dissolved in DMSO
(dimethyl sulphoxide) and chemically precipitated to
produce RePAN-pellets.
During the preparation of the spinning solution, RePANpellets
are mixed with new PAN-powder to equal parts,
resulting in a 50 %- RePAN solution. These fibres with 50 %
recycled material could be spun into yarns that could meet
the same requirements as virgin material.
These characteristics of the produced RePAN fibres
therefore, lead to the assumption that an industrial
feasibility of recycled fibres is possible. The scientists are
now proofing the processability of the yarns and upscale
to semi-industrial scale. Figure 2 shows a product using
RePAN fibres.
[1] Gries, T.: Fibre-tables based on P.-A. Koch, Polyacrylic fibres, 6. Issue,
2002
[2] Herbert, C. (Research and development at Dralon GmbH): Interview,
25.05.2016
[3] Rensmann, R. (managing director of Hermann Biederlack GmbH + Co
KG): Interview, 25.05.2016
www.ita.rwth-aachen.de
Fig. 1: Recycling
process from
waste to new
yarn
Textile waste
RePAN-pellets
Spinning solution
Staple fibres
32 bioplastics MAGAZINE [06/21] Vol. 16