In November 2011, the European Commission’s Joint Research Centre (JRC) was
entrusted by DG Enterprise to verify the validity and applicability of the testing
methods, proposed by DuPont, for the identification and quantification of their new
fibre polytrimethylene terephthalate (PTT). The fibre is a type of polyester that differs
from the common one polyethylene terephthalate (PET) as it contains one more
methylene group in the aliphatic chain that links the terephthalic moiety.
Experimental results confirmed that PTT can be identified using Fourier Transform
Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). FT-IR
is able to distinguish among the three types of polyester PTT, PET and polybutylene
terephthalate (PBT), whereas DSC can differentiate only between PTT and PET on
the basis of their melting points.
For quantification purposes, the normal pre-treatment described in the EU Regulation
1007/2011, was proved to be applicable to PTT and its correction factor b for mass
loss during pre-treatment was established (0 %). This means that the novel fibre is
completely insoluble when the normal pre-treatment is applied. The agreed allowance
of the new fibre (which represents its humidity regain) was measured (0.34 %). The
European network of national experts on Textile Labelling (ENNETL) established the
value of 1.50 % for PTT agreed allowance, for consistency with the already
established values for polyester and elastomultiester. The solubility properties of PTT
were evaluated with 15 methods described in EU Regulation 1007/2011, all of them
with the exception of one (method 12). The new fibre was insoluble in methods 1-11,
13 and 16. The d correction factors were established on the basis of the experimental
work carried out by the JRC. The resulting values were:
• 1.00 for methods 1, 2, 3, 7 and 11;
• 1.01 for methods 4, 5, 9 and 10;
• 1.02 for method 13;
• 1.03 for methods 6, 8 and 16.
PTT was completely soluble in method 14, whereas it was partially soluble in method
15 that consequently cannot be used in the quantification of blends containing PTT.
2
For the quantification of PTT in binary mixtures, manual separation is an adequate
technique, whenever applicable. The following chemical dissolution methods can also
be used: 1-11, 13, 14 and 16.
The quantification results of binary mixtures PTT/PET obtained by DSC method,
using calibration curves built up with PTT and PET manually extracted from the
sample under evaluation, were in very good agreement with the reference ones
obtained through manual separation. In fact, the differences expressed in terms of bias
were in all cases lower than 1%. In these conditions, the DSC method can be judged
accurate.
A consensus among the members of ENNETL was reached on the need to validate the
new, if possible improved, DSC quantification method to be added to the Textile
Regulation. Consequently, the JRC was entrusted to organise the validation exercise
at European level according to ISO 5725:1994. The discussion concerning the name
and the definition of this fibre would be held in the final ENNETL meeting, which
will be organised in April-May 2013.
PICCININI Paola;
SENALDI Chiara;
ALBERTO LOPES João Filipe;
2013-01-24
Publications Office of the European Union
JRC78840
978-92-79-28309-3,
1831-9424,
EUR 25777 EN,
OP LB-NA-25777-EN-N,
https://publications.jrc.ec.europa.eu/repository/handle/JRC78840,
10.2788/82737,
