Studies on Recycled Polyester
Yijing Qin, Muchao Qu, Joachim Kaschta, Vincent Allen
and Dirk W. Schubert
Abstract In this chapter, poly(ethylene terephthalate) (PET) melt-spun fibres from
five different PET materials were fabricated by a capillary rheometer, which was
equipped with an air aspirator for aerodynamic stretching. Two recycled PET of
coloured rPET-A and clear rPET-B from waste PET bottle flakes were used, and
three virgin PET with different grades of the bottle-grade vPET-2, fibre-grade vPET1 and fibre-grade vPET-3 were chosen as reference benchmark. During the extrusion
process, two processing temperatures of 270 and 280 °C in the capillary rheometer
were applied, combined with six different take-up pressures from 0.5 to 3.0 bar for
fibre stretching during the spinning process. An empirical equation was given, to
predict the water content of PET materials under the specific drying temperature and
drying time. Afterwards, the characteristics of the raw materials and drawn PET fibres
were discussed comprehensively from the perspective of thermal behaviour, molar
mass characteristic, rheological properties, surface morphology, diameter, tenacity
and elongation at break. rPET-B and vPET-1 materials yielded optimal spinnability
and demonstrated to be the most suitable materials to fabricate fibres with a desirable tenacity, an outstanding elongation at break and an excellent fibre fineness.
Crystallinity and orientation of fibres from these two materials were explored to give
a potential explanation for the higher tenacity. Furthermore, performance-reliability
plots were applied, and a semi-empirical equation was suggested for the first time
relating the tenacity and elongation at break of fibres. This study proves the possibility
to produce PET fibres from bottle-grade recycled co-polymer PET material, which
have similar properties as fibres produced from fibre-grade virgin homo-polymer
PET. All the specific information of the five investigated PET materials, especially
rPET-B and vPET-1, can provide guidance for melt spinning process in the future.
Y. Qin · M. Qu · J. Kaschta · V. Allen · D. W. Schubert (B)
Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg,
Martensstr. 7, 91058 Erlangen, Germany
e-mail: dirk.schubert@fau.de
Y. Qin
e-mail: yijingqin1991@gmail.com
Y. Qin · M. Qu · D. W. Schubert
KeyLab Advanced Fiber Technology, Bavarian Polymer Institute, Dr. Mack-Strasse 77,
90762 Fürth, Germany
© Springer Nature Singapore Pte Ltd. 2020
S. S. Muthu (ed.), Recycled Polyester, Textile Science and Clothing Technology,
https://doi.org/10.1007/978-981-32-9559-9_3
29
Yijing Qin, Muchao Qu, Joachim Kaschta, Vincent Allen
and Dirk W. Schubert
Abstract In this chapter, poly(ethylene terephthalate) (PET) melt-spun fibres from
five different PET materials were fabricated by a capillary rheometer, which was
equipped with an air aspirator for aerodynamic stretching. Two recycled PET of
coloured rPET-A and clear rPET-B from waste PET bottle flakes were used, and
three virgin PET with different grades of the bottle-grade vPET-2, fibre-grade vPET1 and fibre-grade vPET-3 were chosen as reference benchmark. During the extrusion
process, two processing temperatures of 270 and 280 °C in the capillary rheometer
were applied, combined with six different take-up pressures from 0.5 to 3.0 bar for
fibre stretching during the spinning process. An empirical equation was given, to
predict the water content of PET materials under the specific drying temperature and
drying time. Afterwards, the characteristics of the raw materials and drawn PET fibres
were discussed comprehensively from the perspective of thermal behaviour, molar
mass characteristic, rheological properties, surface morphology, diameter, tenacity
and elongation at break. rPET-B and vPET-1 materials yielded optimal spinnability
and demonstrated to be the most suitable materials to fabricate fibres with a desirable tenacity, an outstanding elongation at break and an excellent fibre fineness.
Crystallinity and orientation of fibres from these two materials were explored to give
a potential explanation for the higher tenacity. Furthermore, performance-reliability
plots were applied, and a semi-empirical equation was suggested for the first time
relating the tenacity and elongation at break of fibres. This study proves the possibility
to produce PET fibres from bottle-grade recycled co-polymer PET material, which
have similar properties as fibres produced from fibre-grade virgin homo-polymer
PET. All the specific information of the five investigated PET materials, especially
rPET-B and vPET-1, can provide guidance for melt spinning process in the future.
Y. Qin · M. Qu · J. Kaschta · V. Allen · D. W. Schubert (B)
Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg,
Martensstr. 7, 91058 Erlangen, Germany
e-mail: dirk.schubert@fau.de
Y. Qin
e-mail: yijingqin1991@gmail.com
Y. Qin · M. Qu · D. W. Schubert
KeyLab Advanced Fiber Technology, Bavarian Polymer Institute, Dr. Mack-Strasse 77,
90762 Fürth, Germany
© Springer Nature Singapore Pte Ltd. 2020
S. S. Muthu (ed.), Recycled Polyester, Textile Science and Clothing Technology,
https://doi.org/10.1007/978-981-32-9559-9_3
29