Studies on Recycled Polyester
31
prevalent melt spinning, Abbasi et al. [19] investigated the influence of take-up
speeds on the physical performance of virgin PET and PET bottles flakes, where
an automatic spinning machine was used. However, the authors failed to note the
extrusion speed, rendering the results incomparable and unreliable. Different PET
blends with the recycled PET and virgin PET grades were studied by Gurudatt et al.
[1]. Unfortunately, in this work, many variables were introduced because individual
processing temperatures were used for the different recycled/virgin PET ratios during
melt spinning. In the study reported by Elamri et al. [25], the thermal and rheological
behaviour of recycled/virgin PET blends were characterized; nevertheless, only one
measured specimen was given to discuss the mechanical properties, and no diameter
value of the investigated fibres was provided. With respect to the virgin/recycled PET
blends, Lee et al. [18] also researched the influence of the different percentage of
virgin PET on the physical properties, but only one draw ratio was applied.
In the aforementioned literature survey on melt spinning, it should be realized
that a systematic paper attempting to explore the physical properties, as well as
the spinnability and fibre surface of virgin and recycled PET with various processing
parameters was missing. Considering this, a research-based and general investigation
was first reported by Qin et al. [12] to assess the potential of producing melt-spun
fibres using recycled and virgin PET materials.
In this chapter, a more comprehensive and complementary research work on the
basis of the previous study [12] is presented. In Sect. 2, the investigated materials, preparation processes and analysis methods used in this study are listed. The
Characterizations of PET Raw Materials are discussed in Sect. 3, where the thermal, molar mass and rheological behaviour of raw materials are examined to deeply
explore properties relevant to melt spinning. In Sect. 4, the thermal and molar mass
behaviour of melt-spun fibres are investigated as well to make a comparison with
those of raw materials. In addition, the surface morphology, diameter distribution,
thermal stability, mechanical properties of melt-spun fibres produced from different PET materials are discussed and compared. Performance-reliability Plot for the
two most desirable PET materials are shown in Sect. 5 and the Comparison with
Reviewed Literature are addressed in Sect. 6.
2 Experimental Part
2.1 Materials Preparation
Two kinds of recycled PET flakes from post-consumer PET bottles in Fig. 1a (copolymers, named rPET-A and rPET-B) were supplied by TEXPLAST GmbH, Germany. rPET-A contains different coloured flakes (white flakes ca. 36%, brown 22%,
green 21%, blue 18%, and others 3%), and rPET-B consists of clear flakes and a very
small portion of blue flakes (less than 5%). Compared to the information provided
by the supplier, the PET recycling process was consistent with physical recycling
31
prevalent melt spinning, Abbasi et al. [19] investigated the influence of take-up
speeds on the physical performance of virgin PET and PET bottles flakes, where
an automatic spinning machine was used. However, the authors failed to note the
extrusion speed, rendering the results incomparable and unreliable. Different PET
blends with the recycled PET and virgin PET grades were studied by Gurudatt et al.
[1]. Unfortunately, in this work, many variables were introduced because individual
processing temperatures were used for the different recycled/virgin PET ratios during
melt spinning. In the study reported by Elamri et al. [25], the thermal and rheological
behaviour of recycled/virgin PET blends were characterized; nevertheless, only one
measured specimen was given to discuss the mechanical properties, and no diameter
value of the investigated fibres was provided. With respect to the virgin/recycled PET
blends, Lee et al. [18] also researched the influence of the different percentage of
virgin PET on the physical properties, but only one draw ratio was applied.
In the aforementioned literature survey on melt spinning, it should be realized
that a systematic paper attempting to explore the physical properties, as well as
the spinnability and fibre surface of virgin and recycled PET with various processing
parameters was missing. Considering this, a research-based and general investigation
was first reported by Qin et al. [12] to assess the potential of producing melt-spun
fibres using recycled and virgin PET materials.
In this chapter, a more comprehensive and complementary research work on the
basis of the previous study [12] is presented. In Sect. 2, the investigated materials, preparation processes and analysis methods used in this study are listed. The
Characterizations of PET Raw Materials are discussed in Sect. 3, where the thermal, molar mass and rheological behaviour of raw materials are examined to deeply
explore properties relevant to melt spinning. In Sect. 4, the thermal and molar mass
behaviour of melt-spun fibres are investigated as well to make a comparison with
those of raw materials. In addition, the surface morphology, diameter distribution,
thermal stability, mechanical properties of melt-spun fibres produced from different PET materials are discussed and compared. Performance-reliability Plot for the
two most desirable PET materials are shown in Sect. 5 and the Comparison with
Reviewed Literature are addressed in Sect. 6.
2 Experimental Part
2.1 Materials Preparation
Two kinds of recycled PET flakes from post-consumer PET bottles in Fig. 1a (copolymers, named rPET-A and rPET-B) were supplied by TEXPLAST GmbH, Germany. rPET-A contains different coloured flakes (white flakes ca. 36%, brown 22%,
green 21%, blue 18%, and others 3%), and rPET-B consists of clear flakes and a very
small portion of blue flakes (less than 5%). Compared to the information provided
by the supplier, the PET recycling process was consistent with physical recycling