Three, summary of the invention
The purpose of this invention is to provide a kind of quick, easy Fourier transform infrared spectrometer of utilizing and measure the method for methyl content in ethene and different monomers (propylene, butylene, the hexene) multipolymer, thereby obtain the molal quantity of monomer in the polymkeric substance.
Technical solution of the present invention is: quick determination method for methyl content in a kind of ethene and different monomers (propylene, butylene, the hexene) multipolymer, it is to measure ethene and different monomers (propylene, butylene, hexene) polyethylene copolymer sample methyl characteristic peak 1378-1379cm with Fourier transform infrared spectrometer
-1Peak area (is chosen the baseline scope of methyl absorption peak: 1400-1330cm
-1) absorbance and polyethylene copolymer characteristic peak 2100-1980cm
-1The ratio X of the absorbance of peak area is then to calculate the content Y% of methyl through regression formula Y=KX+b.Y% is the methyl molal quantity in 100 ethene segments.
For same instrument, the same test condition, K and b are constant among the regression formula Y=KX+b, and they can be tried to achieve by the infrared spectrum of standard model, and standard model can be used
13The C-NMR method is measured and is obtained.Assay method of the present invention, methyl content in ethene and different monomers (propylene, butylene, the hexene) multipolymer, K and b value are values inequality among its regression formula Y=KX+b.The inventor measures the range section of polyethylene and ethylene copolymers according to conditions such as employed instruments: ethylene-propylene copolymer methyl content section, 0.1≤Y%≤13%; Second fourth multipolymer methyl content section, 0.1≤Y%≤4.7%; The own multipolymer methyl content of second section, 0.1≤Y%≤4.5%. wherein Y% is the mole percentage of methyl content.
The effect of invention
(1) this method is to measure a kind of universal method of methyl content in ethene and different monomers (propylene, butylene, the hexene) multipolymer with Fourier transform infrared spectrometer, the fast measuring of methyl content in large-scale production plant suitability for industrialized production ethene such as particularly suitable such as vapor phase method, slurry process and different monomers (propylene, butylene, the hexene) multipolymer.
(2) this method is the mensuration at methyl content in ethene and different monomers (propylene, butylene, hexene) multipolymer (bipolymer)----thermoplastics.
(3) this method is all applicable to polyethylene and ethylene copolymers pellet or powder.
(4) this method is simple and direct, quick, accurate
Five, embodiment
Further specify the present invention by the following examples:
Embodiment 1
Determining of polyethylene and ethylene copolymers standard specimen methyl content
With
13Each ethene of C-NMR nmr for the determination and different monomers (propylene, butylene, hexene) multipolymer methyl content value (being set at actual value),
13The C-NMR nmr for the determination is finished by the approved qualified Chinese University of Science and Technology structured testing center (national open laboratory) of State Metrological Bureau.
This method is looked the difference of comonomer in the polyethylene and ethylene copolymers, is divided in methyl content in the ethylene-propylene copolymer, the second fourth multipolymer methyl content three parts in methyl content, the own multipolymer of second.For simplicity, decide R=10X.
1.1 methyl content regretional analysis in the ethylene-propylene copolymer, standard working curve are formulated:
The measurement range of formula: 0.1≤Y%≤13%
Standard specimen | 1# | 2# | 3# | 4# | 5# | 6# |
Y%
13C-NMR
| 0.10 | 1.15 | 2.16 | 6.35 | 9.90 | 12.55 |
R ratio | 0.4655 | 1.1303 | 1.4286 | 3.2353 | 5.2622 | 6.6375 |
Regression equation | Y=2.0425R-0.8135 |
1.2 methyl content regretional analysis in the second fourth multipolymer, standard working curve are formulated:
The measurement range of formula: 0.1≤Y%≤4.7%
Standard specimen | 7# | 8# | 9# | 10# | 11# | 12# |
Y%
13C-NMR
| 0.1 | 0.41 | 1.1 | 2.1 | 3.72 | 4.70 |
R ratio | 0.1554 | 0.4154 | 0.9943 | 1.8899 | 3.3386 | 4.2057 |
Regression equation | Y=1.1319R-0.0533 |
1.3 methyl content regretional analysis in the own multipolymer of second, standard working curve are formulated:
The measurement range of formula: 0.1≤Y%≤4.5%
Standard specimen | 13# | 14# | 15# | 16# | 17# |
Y%
13C-NMR
| 0.1 | 0.67 | 1.91 | 2.78 | 4.42 |
R ratio | 0.1852 | 0.3854 | 0.8254 | 1.1340 | 1.7159 |
Regression equation | Y=2.8211R-0.4196 |
Embodiment 2
2.1 testing tool
This method is suitable for various model FT-IR Fourier transform infrared spectrometer.The used instrument of the present invention is:
(1) the German Brooker IFS 66/S of company type infrared spectrometric analyzer
Energy of light source:>26000
Resolution: 4.0cm
-1
Scanning times: 32 times
(2) U.S. PE company: SPECAC molding press
Pressure: 0-15t
Temperature: 0-300 ℃
2.2 test condition
Test environment temperature: 25 ± 5 ℃
Test environment humidity: R≤55%
2.3 specimen is made
(1) sample pellet (or powder) is placed the metal die of SPECAC molding press of lining aluminium foil (being convenient to peeling off of diaphragm), selecting the mould frame by the Beer law is " C " frame
(2) the molding press temperature is controlled at 172 ℃ ± 2 ℃.Metal die is placed on heating and melting on the SPECAC molding press.When treating that temperature is raised to 172 ℃ ± 2 ℃, be forced into (gauge pressure) behind the 4t, unload immediately and be depressed into " O ", and take out the cooling box that metal die places chilled water, be cooled to room temperature
(3) diaphragm of sample in the taking-up metal die measures diaphragm thickness with slide calliper rule.Diaphragm thickness control 52-53 μ m, parallel plate thickness difference<0.2 μ m.Otherwise compacting is after made sample diaphragm is qualified, to be measured again.
2.4 testing procedure
(1) whether the temperature of checkout environment, humidity meet the requirements, and operate under the constant temperature of stipulating, constant humidity condition
(2) after the FT-IR infrared spectrometer was started shooting 30 minutes, the energy of inspection apparatus, whether resolution, signal to noise ratio (S/N ratio) reach the given index of instrument, carry out the scanning of 0%, 100% transmitance and background noise.After normal, enter next step operation
(3) polyethylene specimen is made, and the strict accuracy of controlling heating-up temperature and measuring with the assurance methyl content pressing time
(4) set FT-IR infrared spectrometer wave-number range at 4500~350cm
-1, and carry out background scans.After normal, carry out sample test
(5) testing sample that will suppress, that meet the requirements inserts on the FT-IR infrared spectrograph sample test bracket, measures the transmitted infrared light spectrogram, and deposits computing machine in, and is pending
2.5 test result, calculating
(1) gained polyethylene and ethylene copolymers transmitted infrared light spectrogram is converted to the absorbance infrared spectrogram.
(2) on FT-IR absorbance infrared spectrogram, utilize computing machine to calculate 2100-1980cm respectively
-1Peak area absorbance and 1378-1379cm
-1Peak area (is chosen the baseline scope of methyl absorption peak: 1400-1330cm
-1) absorbance.(referring to Fig. 1)
(3) calculate A (1378-1379)/A (2100-1980) peak area absorbance ratio and enlarge 10 times the R value.
(4) find corresponding methyl content according to R value size from working curve, or will calculate the methyl content of this sample in the R value substitution regression equation.(do above-mentioned test with a plurality of standard models, then can calculate K and b value in the regression formula)
2.5.1 ethylene-propylene copolymer regression equation
Methyl content express-analysis in the sample 3# ethylene-propylene copolymer
13The C-NMR method is measured (actual value): 3#=2.16 (mol%)
(1) different print FT-IR measured
values
| 3#-1 | 3#-2 | 3#-3 | 3#-4 | 3#-5 |
R ratio | 1.4286 | 1.3821 | 1.3768 | 1.4706 | 1.4615 |
Y% | 2.07 | 1.98 | 1.97 | 2.16 | 2.14 |
Absolute error | -0.09 | -0.18 | -0.19 | 0 | -0.02 |
Mean value Y=2.06mol%
Mean absolute error: 2.06-2.16=-0.1
Relative error: 0.1/2.16*100%=4.6%
(2) same print difference FT-IR measured
value
| 3#-2-1 | 3#-2-2 | 3#-2-3 | 3#-2-4 | 3#-2-5 |
R ratio | 1.325 | 1.3243 | 1.3050 | 1.3126 | 1.3058 |
Y% | 1.86 | 1.86 | 1.82 | 1.84 | 1.82 |
Absolute error | -0.3 | -0.3 | -0.34 | -0.32 | -0.34 |
Mean value Y=1.84mol%
Mean absolute error: 1.84-2.16=-0.32
Relative error: 0.32/2.16*100%=1.5%
2.5.2 second fourth multipolymer regression equation
Methyl content express-analysis in the sample 10# second fourth multipolymer
13The C-NMR method is measured (actual value): 10#=2.1 (mol%)
(1) different print FT-IR measured values
Print | 10#-1 | 10#-2 | 10#-3 | 10#-4 | 10#-5 |
R ratio | 2.1263 | 2.1439 | 2.0378 | 1.9758 | 1.8520 |
Y% | 2.35 | 2.37 | 2.25 | 2.18 | 2.04 |
Absolute error | 0.25 | 0.27 | 0.15 | 0.08 | -0.06 |
Mean value Y=2.24mol%
Mean absolute error: 2.24-2.1=0.14
Relative error: 0.14/2.1*100%=6.7%
(2) same print difference FT-IR measured value
Print | 10#-2-1 | 10#-2-2 | 10#-2-3 | 10#-2-4 | 10#-2-5 |
R ratio | 1.9758 | 1.8623 | 2.1066 | 1.8998 | 2.0986 |
Y% | 2.18 | 2.05 | 2.34 | 2.09 | 2.32 |
Absolute error | 0.08 | -0.05 | 0.24 | -0.01 | 0.22 |
Mean value Y=2.20mol%
Mean absolute error: 2.20-2.1=0.10
Relative error: 0.1/2.1*100%=4.8%
2.5.3 the own multipolymer regression equation of second
Methyl content express-analysis in the own multipolymer of sample 16# second
13The C-NMR method is measured (actual value): 16#=2.78 (mol%)
(1) different print FT-IR measured values
Print | 16#-1 | 16#-2 | 16#-3 | 16#-4 | 16#-5 |
R ratio | 1.1462 | 1.0792 | 1.0613 | 1.1370 | 1.1267 |
Y% | 2.81 | 2.63 | 2.57 | 2.79 | 2.76 |
Absolute error | 0.03 | -0.15 | -0.21 | 0.01 | -0.02 |
Mean value Y=2.71mol%
Mean absolute error: 2.71-2.78=-0.07
Relative error: 0.07/2.78*100%=2.5%
(2) same print difference FT-IR measured value
Print | 16#-3-1 | 16#-3-2 | 16#-3-3 | 16#-3-4 | 16#-3-5 |
R ratio | 1.0613 | 1.0988 | 1.1103 | 1.0879 | 1.1093 |
Y% | 2.57 | 2.68 | 2.71 | 2.65 | 2.71 |
Absolute error | -0.21 | -0.10 | -0.07 | -0.13 | -0.07 |
Mean value Y=2.66mol%
Mean absolute error: 2.66-2.78=-0.12
Relative error: 0.12/2.78*100%=4.3%