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GB/T 14190-2017 PDF in English


GB/T 14190-2017 (GB/T14190-2017, GBT 14190-2017, GBT14190-2017)
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GB/T 14190-2017: PDF in English (GBT 14190-2017)

GB/T 14190-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.060.20
W 50
Replacing GB/T 14190-2008
Testing methods of fiber grade polyester (PET) chip
ISSUED ON. DECEMBER 29, 2017
IMPLEMENTED ON. JULY 01, 2018
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 General rules of test ... 8
4.1 Sampling ... 8
4.2 General specifications ... 8
5 Test methods ... 8
5.1 Test methods for intrinsic viscosity ... 8
5.2 Test methods for diethylene glycol ... 15
5.3 Test methods for melting point ... 22
5.4 Test methods for terminal carboxyl groups ... 25
5.5 Test methods for chromaticity ... 29
5.6 Test method for aggregated particles ... 31
5.7 Test methods for moisture ... 32
5.8 Test methods for powder and irregular chip ... 34
5.9 Test methods for titanium dioxide content ... 37
5.10 Test method for ash content ... 42
5.11 Test method for iron content ... 44
5.12 Test report ... 46
Annex A (informative) Numerical relationship between test methods for the
intrinsic viscosity of solvents of two different ratios ... 48
Annex B (informative) Recommended specification for diethylene glycol test
reaction tube ... 49
Testing methods of fiber grade polyester (PET) chip
Warning - Solvents such as phenol, tetrachloroethane, o-cresol, and
methanol used in the test methods are toxic, it shall avoid contact with
skin and inhalation of steam. Reagents such as sulfuric acid,
hydrochloric acid, and hydrogen peroxide are highly corrosive, it shall
avoid contact with the skin. The operator shall take appropriate safety and
health protection measures. When operating the gas chromatograph, if
the detector does not ignite, it is forbidden to open the hydrogen needle
valve to prevent the hydrogen from leaking into the space and causing an
explosion.
1 Scope
This Standard specifies the test methods for each analysis item of fiber grade
polyester (PET) chips.
This Standard applies to fiber grade polyester (PET) chips produced from
terephthalic acid and ethylene glycol. Other differential and functional
polyesters may also refer to this Standard.
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
GB/T 601 Chemical reagent - Preparations of standard volumetric solutions
GB/T 603 Chemical reagent - Preparations of reagent solutions for use in
test methods
GB/T 4146 (all parts) Textiles - Man-made fibers
GB/T 6283 Chemical products - Determination of water Karl. Fischer method
(general method)
GB/T 6678 General principles for sampling chemical products
2 times that of the normal chip; less than 1/4 of the conventional particle (or
prescribed size); and of irregular shape.
4 General rules of test
4.1 Sampling
The laboratory samples in batch samples are in accordance with GB/T 6678,
and the sample volume is not less than 0.5 kg.
4.2 General specifications
The reagents and water used in this Standard refer to the analytical reagents
and the tertiary water specified in GB/T 6682 when no other requirements are
specified.
The standard titration solutions, preparations and products used in this
Standard are prepared in accordance with GB/T 601 and GB/T 603 when no
other requirements are specified.
5 Test methods
5.1 Test methods for intrinsic viscosity
5.1.1 Method A (capillary viscometer method)
5.1.1.1 Method summary
DETERMINE the elution time of the solvent at 25 °C and the PET solution at a
concentration of 0.005 g/mL, and CALCULATE the intrinsic viscosity according
to the determined elution time and the solution concentration of the sample.
The capillary viscometer uses 1B to meet the requirements that the kinetic
energy correction term of the viscometer is not considered.
5.1.1.2 Instruments and equipment
5.1.1.2.1 Constant temperature bath. temperature control (25.00 ± 0.05) °C.
5.1.1.2.2 Ubbelohde viscometer. a gas-liquid column Ubbelohde viscometer
(see Figure 1) in accordance with ISO 3105, model number 1B. Other types of
viscometers listed in ISO 3105 can also be used, and the measurement results
shall be guaranteed to be equal to the Ubbelohde viscometer specified above.
In case of dispute, an Ubbelohde viscometer shall be used.
5.1.1.2.3 Erlenmeyer flask with stopper. 100 mL.
WEIGH 0.125 g ~ 0.128 g of sample, accurate to 0.1 mg; PUT it into the sample
dissolution bottle, ADD a certain amount of solvent, to PREPARE the sample
with a concentration of (0.5000 ± 0.0070) g/100 mL; DISSOLVE it on the
heating device. After the sample is dissolved, COOL it to room temperature,
and MEASURE the filtrate with a relative viscometer. If the water content in the
sample is higher than 0.5 %, the treatment method is the same as 5.1.1.4.1; if
the sample contains inorganic materials or other additives, and their mass
fraction exceeds 0.5 %, the mass fraction shall be entered as an impurity into
the instrument parameter setting table.
According to the selected solvent and the corresponding mathematical model,
the instrument automatically calculates the intrinsic viscosity of the sample.
5.1.2.5 Expression of results
The calculation result is expressed as the average value of the test values of
the two parallel samples, and is rounded off to the third decimal place according
to GB/T 8170.
5.1.2.6 Precision
5.1.2.6.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the intrinsic viscosity is 0.630 dL/g ~ 0.720 dL/g,
the absolute difference between the two tests does not exceed the repeatability
limit (0.006 dL/g), and the case where it exceeds the repeatability limit (0.006
dL/g) does not exceed 5 %.
5.1.2.6.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the intrinsic viscosity is 0.630 dL/g ~
0.720 dL/g, is not greater than the reproducibility limit (0.010 dL/g), and the
case where it exceeds the reproducibility limit (0.010 dL/g) does not exceed
5 %.
5.2 Test methods for diethylene glycol
5.2.1 Method A (methanol transesterification method)
5.2.1.1 Method summary
The sample is subjected to a transesterification reaction at high temperature
and in the presence of methanol, diethylene glycol is released, and then the
diethylene glycol content in the filtrate is measured by gas chromatography.
5.2.1.10.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the given diethylene glycol is 0.80 % ~
1.60 %, is not greater than the reproducibility limit (0.08 %), and the case where
it exceeds the reproducibility limit (0.08 %) does not exceed 5 %.
5.2.2 Method B (ethanolamine degradation method)
5.2.2.1 Method summary
The sample is degraded at high temperature and in the presence of
ethanolamine, diethylene glycol is released, and then the diethylene glycol
content in the filtrate is measured by gas chromatography.
5.2.2.2 Instruments and equipment
5.2.2.2.1 Gas chromatograph. with a hydrogen flame ionization detector.
5.2.2.2.2 Chromatography column. capillary column or packed column, the
fixing solution is PEG-20M. Other columns with equal separation effects can
also be used.
5.2.2.2.3 Balance. the minimum division value is 0.1 mg.
5.2.2.2.4 Heating device. temperature control (220 ± 20) °C.
5.2.2.2.5 Spherical condenser. 300 mm in length.
5.2.2.2.6 Pipette. 10 mL, 20 mL.
5.2.2.2.7 Graduated pipette. 5 mL.
5.2.2.2.8 Microinjector or automatic sample injector. 1 μL, 10 μL.
5.2.2.2.9 Erlenmeyer flask with stopper. 100 mL.
5.2.2.2.10 Glass funnel. φ50 mm.
5.2.2.2.11 Qualitative filter paper. φ90 mm.
5.2.2.2.12 Volumetric flask. 100 mL, 2000 mL.
5.2.2.3 Reagents
5.2.2.3.1 Ethanol.
5.2.2.3.2 Ethylene glycol (EG).
basis.
5.2.2.6 Calculation of slope of calibration curve
The slope K of the diethylene glycol calibration curve is calculated in the same
manner as in 5.2.1.7.
5.2.2.7 Test procedure
5.2.2.7.1 WEIGH approximately 1 g of sample, to the nearest 0.1 mg, PLACE
in an Erlenmeyer flask. ADD about 3 mL of ethanolamine (immerse the sample).
MOUNT the condensing tube on the Erlenmeyer flask with, HEAT to reflux on
a heating device at 240 °C for 40 min.
5.2.2.7.2 SEPARATE the Erlenmeyer flask mounted with the condensing tube
from the heating device with a heat shield for about 3 min, and slowly ADD 20
mL of the internal standard solution B from the upper part of the condensing
tube.
5.2.2.7.3 After the heat shield is removed and the reflux is continued for about
5 min, TURN OFF the heating device, REMOVE the Erlenmeyer flask and
COOL it with water; ADD 4 g to 5 g of terephthalic acid to neutralize to neutrality.
5.2.2.7.4 PIPETTE 1 μL of the filtrate for test by gas chromatography.
5.2.2.7.5 The diethylene glycol content of the sample is calculated according to
formula (8).
5.2.2.8 Expression of results
The calculation result is expressed as the average value of the two test-values,
and is rounded off to two decimal places according to GB/T 8170.
5.2.2.9 Precision
5.2.2.9.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the given diethylene glycol is 0.80 % ~ 1.60 %,
the absolute difference between the two tests does not exceed the repeatability
limit (0.08 %), and the case where it exceeds the repeatability limit (0.08 %)
does not exceed 5 %.
5.2.2.9.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the given diethylene glycol is 0.80 % ~
1.60 %, is not greater than the reproducibility limit (0.10 %), and the case where
5.3.1.4.4 According to the melting point of the standard and the displayed
temperature, calculate the correction value of the temperature indication.
5.3.1.5 Test procedure
5.3.1.5.1 CUT the sample into 25 μm thick slices with a slicer, and then TAKE
a sample of about 0.5 mm2 with scissors, PLACE it on a glass slide, and
COMPRESS with a cover slip.
5.3.1.5.2 PLACE the slide on the heating table, rapidly RAISE the temperature
to 180 °C, then RAISE the temperature at a rate of 10 °C/min to 240 °C (for
other functional polyesters, it can be adjusted according to the melting point),
and then RAISE the temperature at a heating rate of 2 °C/min. OBSERVE the
initial melting as needed, RECORD the reading.
5.3.1.5.3 After the sample has reached initial melting, rapidly RAISE the
temperature to 280 °C, keep it at this temperature for 3 min, then rapidly
REDUCE to 180 °C, then RAISE the temperature to 240 °C at a heating rate of
10 °C/min, and then RAISE the temperature at a rate of 2 °C/min. OBSERVE
the final melting, and the temperature indicated is the melting point of the
sample.
5.3.1.6 Expression of results
The calculation result is expressed as the average value of the two test-values,
and is rounded off to one decimal place according to GB/T 8170.
5.3.1.7 Precision
5.3.1.7.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the given melting point is 250.0 °C ~ 263.0 °C,
the absolute difference between the two tests does not exceed the repeatability
limit (0.5 °C), and the case where it exceeds the repeatability limit (0.5 °C) does
not exceed 5 %.
5.3.1.7.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the given melting point is 250.0 °C ~
263.0 °C, is not greater than the reproducibility limit (1.0 °C), and the case
where it exceeds the reproducibility limit (1.0 °C) does not exceed 5 %.
5.3.2 Method B (differential scanning calorimetry)
5.3.2.1 Method summary
according to GB/T 8170.
5.3.2.7 Precision
5.3.2.7.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the given melting point is 250.0 °C ~ 263.0 °C,
the absolute difference between the two tests does not exceed the repeatability
limit (0.5 °C), and the case where it exceeds the repeatability limit (0.5 °C) does
not exceed 5 %.
5.3.2.7.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the given melting point is 250.0 °C ~
263.0 °C, is not greater than the reproducibility limit (1.0 °C), and the case
where it exceeds the reproducibility limit (1.0 °C) does not exceed 5 %.
5.4 Test methods for terminal carboxyl groups
5.4.1 Method A (capacity titration method)
5.4.1.1 Method summary
The sample is dissolved in a mixed solvent under reflux. Bromophenol blue is
used as an indicator after cooling. Titration is carried out using a potassium
hydroxide-ethanol standard titration solution. The terminal carboxyl groups
content is calculated according to the volume of the standard titration solution
consumed.
5.4.1.2 Instruments and equipment
5.4.1.2.1 Balance. the minimum division value is 0.1 mg.
5.4.1.2.2 Heating device. with constant temperature adjustment and stirring
device.
5.4.1.2.3 Grinding Erlenmeyer flask. 250 mL.
5.4.1.2.4 Ball type condensing tube. matching with 250 mL grinding port, with
more than six balls.
5.4.1.2.5 Titration device or microburette. the division value is 0.01 mL.
5.4.1.2.6 Pipette or dosing device. 50 mL.
5.4.1.3 Reagents
where.
X2 - the terminal carboxyl groups content of the sample, in moles per ton
(mol/t);
V - the value of the volume of the potassium hydroxide-ethanol standard
titration solution consumed by the sample solution, in milliliters (mL);
V0 - the value of the volume of the potassium hydroxide-ethanol standard
titration solution consumed by the blank solution, in milliliters (mL);
c - the concentration of potassium hydroxide-ethanol standard titration
solution, in moles per liter (mol/L);
m - the mass of the sample, in grams (g).
5.4.1.7 Expression of results
The calculation result is expressed as the average value of the two test-values,
and is rounded off to one decimal place according to GB/T 8170.
5.4.1.8 Precision
5.4.1.8.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the terminal carboxyl group is 15.0 mol/t ~ 35.0
mol/t, the absolute difference between the two tests does not exceed the
repeatability limit (2.0 mol/t), and the case where it exceeds the repeatability
limit (2.0 mol/t) does not exceed 5 %.
5.4.1.8.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the terminal carboxyl group is 15.0 mol/t
~ 35.0 mol/t, is not greater than the reproducibility limit (3.0 mol/t), and the case
where it exceeds the reproducibility limit (3.0 mol/t) does not exceed 5 %.
5.4.2 Method B (photometric titration method)
5.4.2.1 Method summary
The sample is dissolved in a mixed solvent under reflux, and after cooling,
bromophenol blue is used as an indicator. According to the change of the color
of the solution, the light transmittance of the solution also changes, and the
photometer converts the light transmittance into an electrical signal and
transmits it to the titrator, the titrator outputs the titration curve, and
automatically determines the end point of the titration, and records the volume
5.4.2.5.2 TRANSFER the sample solution to the titration cell, ADD 5 drops to 6
drops of bromophenol blue indicator, INSERT the photometric probe into the
solution at 1 cm under the liquid surface; TITRATE the solution with potassium
hydroxide-ethanol standard titration solution (5.4.2.3.3) at a wavelength of 600
nm. The instrument automatically determines the end point of the titration.
RECORD the number of milliliters consumed by the standard titration solution.
5.4.2.5.3 CARRY OUT the blank test under the same conditions.
5.4.2.6 Calculation of results
The calculation method is the same as 5.4.1.6.
5.4.2.7 Expression of results
The calculation result is expressed as the average value of the two test-values,
and is rounded off to one decimal place according to GB/T 8170.
5.4.2.8 Precision
5.4.2.8.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the terminal carboxyl group is 15.0 mol/t ~ 35.0
mol/t, the absolute difference between the two tests does not exceed the
repeatability limit (2.0 mol/t), and the case where it exceeds the repeatability
limit (2.0 mol/t) does not exceed 5 %.
5.4.2.8.2 Reproducibility
The absolute difference between the two independent test results obtained
under reproducibility conditions, when the terminal carboxyl group is 15.0 mol/t
~ 35.0 mol/t, is not greater than the reproducibility limit (3.0 mol/t), and the case
where it exceeds the reproducibility limit (3.0 mol/t) does not exceed 5 %.
5.5 Test methods for chromaticity
5.5.1 Method A (dry pulverization method)
5.5.1.1 Method summary
After the sample is dried and pulverized, the chromaticity of the sample is tested
with an automatic color difference meter, and the results are expressed in
HunterLab color systems L, a, and b.
NOTE. The color value test can only be compared if the materials are the same, the chip dicing,
size and appearance are basically the same, the instrument geometry is the same and the
viewing hole surface is close.
precision refer to 5.5.1, but two cups of sample are to be tested. The average
value of the calculated results of the two cups of sample is taken as the test
result.
5.6 Test method for aggregated particles
5.6.1 Method summary
The aggregated particles in the sample are observed under a microscope, the
size is measured, and the number is counted.
5.6.2 Instruments and equipment
5.6.2.1 Microscope (magnification 200 times to 400 times) and microscope
illumination.
5.6.2.2 Slicer. the division value is 1 μm.
5.6.2.3 Balance. the minimum division value is 0.1 mg.
5.6.2.4 Cover slip. the thickness is 0.17 mm.
5.6.2.5 Medical tweezer and scissor.
5.6.2.6 Micrometer. the division value is 0.01 mm.
5.6.2.7 Slide. the thickness is 1 mm.
5.6.3 Reagents
Oil or wetting agent of which the refractive index is close to nD20 = 1.51.
5.6.4 Test procedure
5.6.4.1 Randomly TAKE five PET chips from the sample, and CUT each chip
into 5 to 8 pieces of slices with a thickness of 20 μm with the slicer, so that the
total mass of the sliced slices reaches 3 mg ~ 5 mg, to the nearest 0.1 mg.
PLACE the slices on a clean glass slide, WET them well with reagents (or other
physical means), PRESS the cover slip tightly against the sample to form a flat
surface.
5.6.4.2 PLACE the slide containing the slices on the microscope stage,
ADJUST the focal length of the microscope, and OBSERVE the aggregated
particles larger than or equal to 10 μm (or the required size) with transmitted
light. Round particles are measured and counted by their diameter, and
particles of other shapes are measured and counted by the longest part.
NOTE. For full dull chips, due to poor light transmission, a slice of 10 μm to 15 μm can be cut
In the halogen heating unit, the moisture of the sample quickly escapes. When
the instrument display value remains stable, the moisture of the sample is
calculated according to the weight loss.
5.7.2.2 Instruments and equipment
5.7.2.2.1 Halogen moisture meter.
5.7.2.2.2 Aluminum sample tray.
5.7.2.3 Test procedure
5.7.2.3.1 When the instrument is stared for the first time, warm up for 30 min.
After the instrument is stable, set the shutdown mode to weight loss less than
1 mg in 140 s and the temperature rise mode to step-by-step temperature rise
mode. The instrument heating temperature is set to 120 °C; the test time is set
to 30 min.
5.7.2.3.2 WEIGH about 20 g of the sample into the halogen moisture meter tray,
and the sample shall be evenly distributed on the sample tray (do not stack).
5.7.2.3.3 START the step-by-step temperature rise mode. When the halogen
moisture meter tray is automatically popped out, the result shown on the display
is the actual moisture of the sample.
5.7.2.4 Expression of results
The test result is rounded off to two decimal places according to GB/T 8170.
5.7.2.5 Precision
For the determined values of the two independent test results obtained under
repeatability conditions, when the given moisture is 0.10 % to 0.40 %, the
absolute difference between the two tests does not exceed the repeatability
limit (0.05 %), and the case where it exceeds the repeatability limit (0.05 %)
does not exceed 5 %.
5.8 Test methods for powder and irregular chip
5.8.1 Method A (dry method)
5.8.1.1 Method summary
The sample is sieved through the sample sieve of a predetermined size, the
powder is sieved out and weighed, and the irregular particles are extracted from
the sieve residue and weighed. This method applies to the minimum detection
limit of powder of 50 mg/kg.
According to GB/T 8170, the calculated value of the powder content is rounded
off to the whole number; the calculated value of the irregular chip is rounded off
to two decimal places.
5.8.1.6 Precision
Since the distribution of the powder and the irregular chip of the sample does
not conform to the normal distribution, the method does not specify repeatability
and reproducibility.
5.8.2 Method B (wet method)
5.8.2.1 Method summary
The chip is placed in a mixed solution of absolute ethanol and water, the powder
floats, and the powder is filtered out and weighed.
5.8.2.2 Instruments and equipment
5.8.2.2.1 Beaker. 500 mL, 200 mL, 2000 mL.
5.8.2.2.2 Oven.
5.8.2.2.3 Balance. the minimum division value is 0.1 mg.
5.8.2.2.4 Suitable filter material.
5.8.2.2.5 Glass rod.
5.8.2.3 Reagents
A mixed solution of absolute ethanol and water in a volume ratio of 1.1.
5.8.2.4 Test procedure
5.8.2.4.1 WEIGH (100 ± 1) g of sample with the balance and denote it as m.
5.8.2.4.2 Carefully POUR the sample into a 500 mL beaker.
5.8.2.4.3 ADD 200 mL of the mixed solution of absolute ethanol and water (1.1
ratio by volume), STIR with a glass rod to make the powder floated, and
carefully POUR the mixed solution with powder in the beaker into a 2000 mL
beaker.
5.8.2.4.4 REPEAT the operation of step 5.8.2.4.3 until no powder is floating.
5.8.2.4.5 FILTER the mixed solution with powder in the 2000 mL beaker using
suitable filter material (a suitable filter material may be a sand core funnel that
NOTE. According to the titanium dioxide content of the sample, other sizes of cuvettes can be
selected.
5.9.1.2.2 Balance. the minimum division value is 0.1 mg.
5.9.1.2.3 Heating device.
5.9.1.2.4 Volumetric flask. 100 mL, 1000 mL.
5.9.1.2.5 Graduated pipette. 2 mL, 5 mL, 10 mL.
5.9.1.2.6 Flask. 50 mL Kjeldahl flask or 250 mL Erlenmeyer flask.
5.9.1.2.7 Beaker. 100 mL, 2000 mL.
5.9.1.2.8 Reagent bottle. 1000 mL.
5.9.1.3 Reagents
5.9.1.3.1 Sulfuric acid.
5.9.1.3.2 Ammonium sulfate.
5.9.1.3.3 Sulfuric acid solution. c(H2SO4) = 5 mol/L.
5.9.1.3.4 Hydrogen peroxide.
5.9.1.3.5 Hydrogen peroxide solution. 3 %.
5.9.1.3.6 Titanium dioxide. purity 99.9 %.
5.9.1.3.7 Titanium standard solution. 1 mg/mL. ADD 166.8 mg of titanium
dioxide (equivalent to 100 mg of titanium), 5 g of ammonium sulfate and 10 mL
of sulfuric acid (5.9.1.3.1) to a 100 mL beaker and HEAT to dissolve. After
natural cooling, TRANSFER the solution to a 100 mL volumetric flask, DILUTE
to the mark with distilled water, SHAKE well.
5.9.1.4 Plotting of working curve
5.9.1.4.1 PIPETTE 0 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, and 1.0 mL of
titanium standard solution (5.9.1.3.7) into 100 mL volumetric flasks respectively.
5.9.1.4.2 ADD 50 mL of distilled water and 20 mL of sulfuric acid solution
(5.9.1.3.3) to each of the above flasks, SHAKE well; ADD 10 mL of 3 %
hydrogen peroxide solution with pipette to each flask, and finally DILUTE with
distilled water to the mark, SHAKE well.
5.9.1.4.3 At the wavelength of 410 nm of the spectrophotometer, determine the
For the determined values of the two independent test results obtained under
repeatability conditions, when the titanium dioxide content is 0.250 % ~ 0.350 %,
the absolute difference between the two tests does not exceed the repeatability
limit (0.020 %), and the case where it exceeds the repeatability limit (0.020 %)
does not exceed 5 %; when the titanium dioxide content is 2.00 % ~ 3.00 %,
the absolute difference between the two tests does not exceed the
reproducibility limit (0.120 %), and the case where it exceeds the reproducibility
limit (0.120 %) does not exceed 5 %.
5.9.1.8.2 Reproducibility
For the absolute difference between the two independent test results obtained
under reproducibility conditions, when the titanium dioxide content is 0.250 %
~ 0.350 %, the absolute difference between the two tests does not exceed the
reproducibility limit (0.040 %), and the case where it exceeds the reproducibility
limit (0.040 %) does not exceed 5 %; when the titanium dioxide content is 2.00 %
~ 3.00 %, the absolute difference between the two tests does not exceed the
reproducibility limit (0.20 %), and the case where it exceeds the reproducibility
limit (0.20 %) does not exceed 5 %.
5.9.2 Method B (X-ray method)
5.9.2.1 Method summary
Titanium can produce fluorescence under the action of X-rays. On the surface
of the sample, the fluorescence intensity is proportional to the titanium content.
The titanium dioxide content is quantified by determining the fluorescence
intensity of the surface of the sample.
5.9.2.2 Instruments and equipment
5.9.2.2.1 X-ray fluorescence spectrophotometer.
5.9.2.2.2 Special chrome type X-ray tube.
5.9.2.2.3 Special lithium fluoride crystals.
5.9.2.2.4 Hot press (able to melt the sample).
5.9.2.2.5 Special mold.
5.9.2.3 Reagents
5.9.2.3.1 P-10 gas. methane (10 %), argon (90 %) of high purity.
5.9.2.3.2 Titanium dioxide standard sample plate.
5.9.2.4 Test conditions
5.9.2.8 Expression of results
The calculation result is rounded off to three decimal places according to GB/T
8170.
5.9.2.9 Precision
5.9.2.9.1 Repeatability
For the determined values of the two independent test results obtained under
repeatability conditions, when the titanium dioxide content is 0.250 % ~ 0.350 %,
the absolute difference between the two tests does not exceed the repeatability
limit (0.020 %), and the case where it exceeds the repeatability limit (0.020 %)
does not exceed 5 %; when the titanium dioxide content is 2.00 % ~ 3.00 %,
the absolute difference between the two tests does not exceed the
reproducibility limit (0.12 %), and the case where it exceeds the reproducibility
limit (0.12 %) does not exceed 5 %.
5.9.2.9.2 Reproducibility
For the absolute difference between the two independent test results obtained
under reproducibility conditions, when the titanium dioxide content is 0.250 %
~ 0.350 %, the absolute difference between the two tests does not exceed the
reproducibility limit (0.040 %), and the case where it exceeds the reproducibility
limit (0.040 %) does not exceed 5 %; when the titanium dioxide content is 2.00 %
~ 3.00 %, the absolute difference between the two tests does not exceed the
reproducibility limit (0.20 %), and the case where it exceeds the reproducibility
limit (0.20 %) does not exceed 5 %.
5.10 Test method for ash content
5.10.1 Method summary
The sample is carbonized and burned at a high temperature, and the ash
content is calculated according to the burning residue and the titanium dioxide
content. The minimum detection limit of this method. 0.005 %.
5.10.2 Instruments and equipment
5.10.2.1 Balance. the minimum division value is 0.1 mg.
5.10.2.2 Porcelain crucible. 50 mL or 100 mL.
5.10.2.3 Electric furnace or ashing furnace.
5.10.2.4 Muffle furnace. ......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.