GB/T 39026-2020 PDF in English
GB/T 39026-2020 (GB/T39026-2020, GBT 39026-2020, GBT39026-2020)
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Test method for the identification of recycled polyethylene terephthalate(PET) fiber
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Standards related to (historical): GB/T 39026-2020
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GB/T 39026-2020: PDF in English (GBT 39026-2020) GB/T 39026-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.060.20
W 50
Test Method for the Identification of Recycled
Polyethylene Terephthalate (PET) Fiber
ISSUED ON: JULY 21, 2020
IMPLEMENTED ON: FEBRUARY 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Principle ... 4
5 Instruments, Equipment, Reagents and Materials ... 5
6 Test Procedures ... 6
7 Test Report ... 14
Test Method for the Identification of Recycled
Polyethylene Terephthalate (PET) Fiber
1 Scope
This Standard specifies the test method for the identification of recycled polyethylene
terephthalate (PET) fiber (hereinafter referred to as recycled polyester).
This Standard is applicable to natural and colored recycled polyester. Other functional
recycled polyester may take this as a reference.
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 4146 (all parts) Textiles - Man-made Fibers
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods
3 Terms and Definitions
What is defined in GB/T 4146, and the following terms and definitions are applicable
to this document.
3.1 Recycled Polyethylene Terephthalate (PET) Fiber
Recycled polyethylene terephthalate (PET) fiber refers to polyethylene terephthalate
fiber made from waste polyester (PET) polymer and waste polyester (PET) textile
materials through recycling and processing.
4 Principle
Based on the essential difference between the processing process of recycled
polyester and primary polyester, which causes certain characteristics to be different,
process the specimen in accordance with the specified conditions, then, test it on a
high performance liquid chromatograph. In accordance with the difference in the
relative peak area of the specimen under different retention times, the purpose of
qualitative identification is reached.
5.1.5 Bench vice or other fixing device.
5.1.6 Automatic pipetting device or pipette: 1 mL, 20 mL and 25 mL.
5.1.7 Measuring cylinder: 50 mL and 200 mL.
5.1.8 Volumetric flask: 2 L.
5.1.9 2 mL threaded sample bottle that can be used for automatic sample injection of
the high performance liquid chromatograph, with PTFE liner.
5.1.10 Syringe-driven filter, filter membrane 0.45 μm; made of PTFE.
5.1.11 Reagent reservoir, with a stopper; made of glass.
5.1.12 Centrifuge.
5.1.13 Refrigerator with a refrigerating chamber.
5.2 Reagents and Materials
5.2.1 Methanol, analytically pure.
5.2.2 Methanol, chromatographically pure.
5.2.3 Catalyst: zinc acetate, analytically pure.
5.2.4 Transesterification solution: weigh-take 60 mg of zinc acetate; use methanol to
dissolve it and dilute to 2 L.
5.2.5 Sulfolane, analytically pure.
5.2.6 Acetonitrile, analytically pure.
5.2.7 Comply with Grade-2 water of GB/T 6682.
6 Test Procedures
6.1 Methanolysis
6.1.1 Weigh-take 0.8 g (accurate to 0.1 mg) of the specimen to be tested.
6.1.2 Place the specimen into the reaction tube; accurately add 25 mL of the
transesterification solution. Use the bench vice to tighten the cap of the reaction tube
(to ensure air tightness); vertically put it into the heating device. At (220 ± 5) °C, react
for 2 h, then, take it out. Use tap water to cool it down to room temperature. Open the
reaction tube; filter the supernatant through the syringe-driven filter to a 2 mL sample
bottle. Place it in the refrigerating chamber of the refrigerator at 4 °C ~ 6 °C; maintain
for above 8 h. Then, filter it through the syringe-driven filter to another 2 mL sample
bottle; let it stand, till it reaches the room temperature. This can be used for high
performance liquid chromatography detection.
6.2 Swelling-extraction
6.2.1 Weigh-take about 5 g of the same specimen to be tested; place it in a drying oven
that is previously heated to 105 °C to dry for 30 min. Then, take it out and put it in a
desiccator to cool it down; reserve it for later use.
6.2.2 Use a measuring cylinder to respectively weigh-take 160 mL of sulfolane and 40
mL of acetonitrile. Put them into the reagent reservoir, put on the cap; shake it well and
reserve it for later use.
6.2.3 Accurately weigh-take about 1.4 g (accurate to 0.1 mg) of the specimen treated
in 6.2.1; put the specimen into the reaction tube. Use the pipetting device to add 35
mL of the solution described in 6.2.2; tighten the cap of the reaction tube (to ensure air
tightness); place it into the heating device. At (180 ± 5) °C, react for 90 min, then, take
it out. Use tap water to cool it down to room temperature.
6.2.4 Pour the sample into a centrifuge tube, then, at a centrifugal speed of 4,000 r/min,
centrifuge for 8 min. Take the supernatant; filter it through the syringe-driven filter to a
2 mL sample bottle. Then, place it in the refrigerating chamber of the refrigerator at
4 °C ~ 6 °C; maintain for above 8 h. Then, filter it through the syringe-driven filter to
another 2 mL sample bottle; let it stand, till it reaches the room temperature. This can
be used for high performance liquid chromatography detection.
6.3 High Performance Liquid Chromatography Detection
Respectively conduct high performance liquid chromatography detection on the
treatment liquids treated in accordance with 6.1 and 6.2. After the chromatographic
detection is completed, derive the original signal data of high performance liquid
chromatography.
The test result depends on the instrument being used, and it is impossible to provide
the common parameters of chromatographic analysis. The following operating
conditions have been proven to be suitable for testing:
a) Chromatographic column: XDB C18 (5 μm), 250 mm 4.6 mm, or equivalent;
b) Flow rate: 1.0 mL/min;
c) Column temperature: 30 °C;
d) Injection volume: 10.0 μL;
e) Detector: diode array detector (DAD);
n2---the number of other samples in the sample library;
μi1k---the relative content of a specific fingerprint peak of each recycled polyester in the
sample library;
n1---the number of recycled polyester samples in the sample library.
In accordance with Formula (10), standardize Xi value to Zi1, then, query the standard
normal distribution probability table to obtain the probability F (Zi1) corresponding to Zi1.
In accordance with Formula (11), standardize Xi value to Zi2, then, query the standard
normal distribution probability table to obtain the probability F (Zi2) corresponding to Zi2.
When μi1 > μi2, the precision rate Pi shall be calculated in accordance with Formula (12);
when μi1 < μi2, the precision rate Pi shall be calculated in accordance with Formula (13).
Respectively calculate the discriminant function values W3, W4, W6 and W7 and the
precision rates P3, P4, P6 and P7.
P3, P4, P6 and P7 respectively correspond to W3, W4, W6 and W7. From P3, P4, P6 and
P7, choose the maximum value Pmax; find the corresponding discriminant function value
Wi. If Wi is greater than 0, then, it is determined that “this sample contains recycled
polyester component”, and Pmax is used as the precision rate of the conclusion that
“this sample contains recycled polyester component”; if W3, W4, W6 and W7 are all
smaller than 0, then, it is determined that “this sample is primary polyester”.
NOTE: this method is based on a great deal of benchmark sample data.
7 Test Report
The test report shall include the following contents:
a) Serial No. of this Standard;
b) Sample description;
c) Discriminant function values W3, W4, W6 and W7 and precision rates P3, P4, P6
and P7;
d) Conclusion of identification;
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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