A method for discriminating chlorinated polyethylene and chlorosulfonated polyethylene

Abstract

A new method for distinguishing chlorinated polyethylene (CPE) from chlorosulfonated polyethylene (CSM) by infrared spectrum is disclosed. Although the structures of CPE and CSM are similar, CPE has a special absorption peak at 1500-1520 cm ‑1 , while CSM contains S=O and SO2 groups, so it has a S=O stretching vibration absorption peak at 1350-1400 cm ‑1 , and a SO2 stretching vibration absorption peak at 1150-1200 cm ‑1 . By analyzing the spectral characteristics of the two polymers in the range of 1000-1400 cm ‑1 , the two polymers can be distinguished accurately.

Description

Technical Field

[0001] This invention belongs to the field of qualitative analysis of polymer materials, and involves infrared spectroscopy analysis, particularly for distinguishing the chemical structures of chlorinated polyethylene and chlorosulfonated polyethylene. Background Technology

[0002] Chlorinated polyethylene (CPE) and chlorosulfonated polyethylene (CSM) are both chlorine-containing polymers. Chlorinated polyethylene (CPE) is a polymer produced by chlorination substitution of high-density polyethylene, possessing good weather resistance, ozone resistance, and aging resistance, and is commonly used in wire and cable insulation and sheathing materials. Chlorosulfonated polyethylene (CSM) is a special chlorine-containing elastomer with a highly saturated chemical structure, exhibiting excellent resistance to chemical media corrosion and oil erosion. It is commonly used in products such as conveyor belts. These two rubbers share similarities in performance and structure; however, using them interchangeably in different applications may lead to substandard product performance. Therefore, accurate identification is crucial. However, when using pyrolysis gas chromatography-mass spectrometry (PCCMS) for identification, the resulting fragmentation peaks are almost identical, making differentiation difficult. Summary of the Invention

[0003] The purpose of this invention is to provide a simple and accurate method for identifying chlorinated polyethylene and chlorosulfonated polyethylene.

[0004] The technical solution adopted in this invention is infrared analysis to identify uncured and vulcanized chlorinated polyethylene and chlorosulfonated polyethylene rubber. The specific steps are as follows:

[0005] (1) Uncured or non-black-cured chlorinated polyethylene and chlorosulfonated polyethylene rubber were directly detected by infrared spectroscopy ATR (total reflectance attenuation).

[0006] (2) Black vulcanized chlorinated polyethylene (CPE) and chlorosulfonated polyethylene (CSM) rubber: First, cut the sample into small particles and extract it with acetone. Then, bake the extracted sample at 70°C for 2 hours. Place the baked sample in a test tube and burn the test tube with an alcohol lamp until the sample produces cracked oil. Apply the cracked oil to an infrared carrier and test it.

[0007] (3) Analysis of the spectrum showed that CPE was between 1500 and 1520 cm⁻¹ -1 It has a unique absorption peak, while CSM does not have this absorption peak, such as Figure 1 As shown, CSM contains S=O and SO2 groups, therefore in

[0008] 1350~1400cm -1 There will be an absorption peak of S=O stretching vibration at 1150–1200 cm⁻¹. -1The stretching vibration absorption peaks generated by SO2 are present, while CPE does not exhibit these two absorption peaks. Figure 2 As shown, these three stretching vibration absorption peaks are used to distinguish between qualitative CPE and CSM. Attached Figure Description

[0009] Figure 1 This is the infrared chromatogram of chlorinated polyethylene;

[0010] Figure 2 This is the infrared chromatogram of chlorosulfonated polyethylene raw rubber;

[0011] Figure 3 This is the infrared chromatogram of a non-black vulcanized product of chlorosulfonated polyethylene;

[0012] Figure 4 This is an infrared chromatogram of a black vulcanized product made of chlorosulfonated polyethylene. Detailed Implementation

[0013] 1. Sample preparation

[0014] (1) Sample 1# is a white powder vulcanized chlorinated polyethylene sample, and Sample 2# is a vulcanized red chlorosulfonated polyethylene rubber sheet. Sample 2# was cut into thin slices of about 1 mm and subjected to ATR infrared spectroscopy.

[0015] (Total reflection attenuation) is used for detection, such as Figure 3 As shown. Sample 1# can be directly detected using infrared spectroscopy ATR (Total Reflectance Attenuation). Figure 1 As shown.

[0016] (2) Sample 3# is black vulcanized chlorosulfonated polyethylene (CSM) rubber. The sample was first cut into small particles of approximately 1g, extracted with acetone, and then dried at 70℃ for 2 hours. The dried sample was placed in a test tube and heated with an alcohol lamp until pyrolysis oil was produced. The pyrolysis oil was coated onto an infrared slide and detected using infrared spectroscopy. Figure 4 As shown.

[0017] 2. Infrared spectroscopy detection and analysis

[0018] In the infrared spectrometer, set the scanning range to 400–4000 cm⁻¹, the resolution to 4 cm⁻¹, and the number of scans to 32. Start the infrared spectrometer to perform the scan. Figure 1 As shown, we found that CPE vulcanizate has a distinct absorption characteristic peak at 1509 cm⁻¹, while chlorosulfonated polyethylene does not. Figure 3 and Figure 4Chlorosulfonated polyethylene exhibits S=O absorption peaks at 1377 cm⁻¹ and 1379 cm⁻¹, as well as absorption peaks at 1173 cm⁻¹ and 1191 cm⁻¹ at the SO₂ group, while chlorinated polyethylene does not. Comparison with the infrared spectrum of standard chlorosulfonated polyethylene shows a good match of characteristic absorption peaks. This confirms that the sample is chlorosulfonated polyethylene.

Claims

1. A method for qualitatively identifying chlorinated polyethylene and chlorosulfonated polyethylene using infrared spectroscopy, characterized in that... The test can distinguish between uncured and cured rubber. The specific steps are as follows: (1) Directly sourced uncured or non-black-cured chlorinated polyethylene and chlorosulfonated polyethylene rubber Detection was performed using infrared spectroscopy with ATR (total reflectance attenuation). (2) Black vulcanized chlorinated polyethylene (CPE) and chlorosulfonated polyethylene (CSM) rubber: First, cut the sample into small particles and extract it with acetone. Then, bake the extracted sample at 70°C for 2 hours. Place the baked sample in a test tube and burn the test tube with an alcohol lamp until the sample produces cracked oil. Apply the cracked oil to an infrared carrier and test it. (3) Analysis of the spectrum showed that CPE was between 1500 and 1520 cm⁻¹ -1 It has a unique absorption peak at 1350–1400 cm⁻¹, while CSM does not. CSM contains S=O and SO₂ groups, therefore it has a unique absorption peak at 1350–1400 cm⁻¹. -1 There will be an absorption peak of S=O stretching vibration at 1150–1200 cm⁻¹. -1 The three stretching vibration absorption peaks generated by SO2 are used to distinguish between qualitative CPE and CSM.

2. The method for qualitative identification of chlorinated polyethylene and chlorosulfonated polyethylene by infrared spectroscopy according to claim 1, characterized in that... This method can qualitatively distinguish between uncured CPE and CSM rubber, and can also qualitatively identify and distinguish between cured CPE and CSM rubber.

3. The method for qualitative identification of chlorinated polyethylene and chlorosulfonated polyethylene by infrared spectroscopy according to claim 1, characterized in that... Infrared spectra are obtained by passing through 1500–1520 cm⁻¹. -1 CPE special absorption Peak, 1350~1400cm -1 The S=O absorption peak and the 1150–1200 cm⁻¹ peak are also present. -1 The three absorption peaks of the SO2 group were used to qualitatively identify CPE and CSM rubber.

4. The method for qualitative identification of chlorinated polyethylene and chlorosulfonated polyethylene by infrared spectroscopy according to claim 1, characterized in that, The infrared spectroscopy test conditions are as follows: scanning range 400–4000 cm⁻¹ -1 The resolution is 4cm. -1 The number of scans was 32.

5. The method for qualitative identification of chlorinated polyethylene and chlorosulfonated polyethylene using external spectroscopy according to claim 1 is characterized in that uncured or non-black vulcanized chlorinated polyethylene and chlorosulfonated polyethylene rubber are directly detected using infrared spectroscopy (ATR, total reflectance attenuation). However, vulcanized black chlorinated polyethylene and chlorosulfonated polyethylene require identification by burning and applying the resulting cracked oil.

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