Application of ATR Infrared Spectroscopy in Surface Composition Analysis of Polymer Materials

Application of Infrared Spectroscopy in the Analysis of Surface Composition of Polymer Materials PAN Chun-hua ZHANG Wei-hong CHEN Fen CHEN Xi-nong LIN Shao-yue (Test Center, Sun Yat-sen University, Guangzhou 510275) Introduce some new practical examples of infrared spectroscopy—attenuation of total reflection. Application of surface composition analysis of polymer materials.

Infrared spectroscopy, attenuated total reflection, and surface composition analysis are among the most important experimental methods for infrared spectroscopy. From the very beginning, it shows its unique advantages and broad application prospects. Because it does not need to pass the signal through the sample, but through the reflection signal of the sample surface to obtain the structural information of the organic composition of the sample surface. It not only simplifies the sample preparation process, but also greatly expands the application of infrared spectroscopy. It is possible to make many experiments that cannot be sampled using the traditional transmission method, or the sample preparation process is very complicated, difficult, and the effect is not ideal. Therefore, it is widely used in surface composition analysis of polymer materials such as plastics, fibers, rubbers, coatings, and adhesives.

In this paper, the ATR accessory of the Fourier transform infrared spectrometer is applied to analyze the surface composition of a variety of polymer materials. The experimental results show that using the attenuated total reflection accessory and the experimental method, the conventional detection effect that can not be obtained by infrared spectroscopy can be obtained. Not only successfully for the business community, quality supervision, commodity inspection, public security, criminal investigation and other departments to solve a variety of quality and technical issues, but also produced a good social benefits.

1 Experimental section (1) Materials: Rubber tube of unknown composition Industrial labor protection products Cotton yarn gloves Different brands of polyester film used for surface over-molding (2) Purpose of test: Rubber tube, analysis of product composition Yarn gloves, for yarn gloves of different origins Ingredient Analysis and Criminal Investigation Identification of Polyester Films, Quality Identification, and Component Analysis Fourier Transform Infrared Spectroscopy Infrared Microscopy Couplers, the instrument's horizontal ATR attachments are used primarily in this experiment. Among them, the detection of some samples was also compared with the results obtained by infrared spectroscopy. (4) The experimental process and the results were recorded: The surface of the sample was cleaned with appropriate treatment methods, and the sample was carefully fixed on the ATR. The attachment reflects on the surface of the crystal. Then through the computer software, according to the operation requirements of the ATR attachments for experiments. The results (spectra) are processed by the computer and stored on the hard disk. The final result can be printed out by a printer connected to a computer, or it can be directly clipped into other files as a graphic file, as illustrated in this article.

2 Results and discussion 2.1 Component analysis of rubber tubing Vulcanized rubber products are difficult to measure due to their insoluble and infusible nature. Before ATR technology is put into practical use, the infrared spectrum of thermal degradation products is usually determined by thermal cracking method, and the chemical structure of the original sample is deduced.

Since the thermal degradation product of a polymer is often a mixture of various components, it is difficult to confirm the sample structure from its infrared spectrum.

However, using ATR technology for infrared spectroscopy analysis of such samples is very convenient. In fact, only a small piece (80mm x 10mm, or less) of a clean sample is pressed against the ATR accessory wafer. The sample signal is then acquired with a dedicated ATR operating software to obtain the sample's ATR spectrum. Illustration. It can be said that the ATR method is applied to the uniqueness of the above-mentioned samples and is difficult to replace by other methods. In general, the ATR spectrum and the usual infrared absorption spectrum are also basically the same. Therefore, the sample can also be confirmed by searching the standard spectrum.

An ATR spectrum obtained for a 10 mm platelet sample. The absorption peak can be seen at the position where the out-of-plane bending vibration of =CH absorbs the bending vibration absorbed by 1446 cm and the absorption peak absorbed by 1661 cm absorbs the stretching vibration of aliphatic C=C. Absorption at the above locations is a characteristic absorption of polyisoprene rubber. The absorption peak at the outlet is due to the absorption contribution of the additive talc.

Looking at the entire spectrum, we can conclude that the material of the rubber tube is cis-1,4-polyisoprene rubber with talc added, indicating that our conclusion is correct.

2.2 Analysis and Identification of Yarn Gloves The ATR method is one of the means by which infrared spectroscopy is applied to forensic science. In this case, the ATR method can be used to directly determine the type of physical evidence without destroying the sample or subjecting it to special treatment.

ATR spectra obtained from different sources of yarn gloves.

The absorption spectrum line B shows the infrared absorption spectrum of the polyester and cotton fiber blend (poly/cotton) and the spectrum line C also shows the infrared absorption spectrum of the polyester and cotton fiber blend (poly/cotton) [ 3]. It can be seen that the only difference between the two is that the relative content of polyester in the C sample is less than that of the B sample.

The ATR spectrum obtained from the physical evidence is exactly the same as that of the B sample in FIG. 2 , indicating that the source of the evidence may be the same as the source of the B sample, thereby excluding its relationship with the A and C samples. It is necessary to point out at the same time that the analytical results obtained by applying the ATR method are completely consistent with the results of the analysis using the SEM/X-ray energy spectrum analyzer. Obviously, the above test results not only provide important clues for the relevant departments to detect cases, but also reduce the scope of investigations, which can save manpower and material resources and effectively shorten the detection time of cases.

2.3 Polyester film surface composition analysis Polyester film is widely used in insulation materials, recording tapes, adhesive tape tape base, film and photographic film base, and packaging materials. In order to meet the specific requirements of different materials for different applications, the surface of the film is usually subjected to some special treatment.

However, in many cases, it is almost impossible to separate it from the film surface because the thickness of this layer is very small. In this case, applying the ATR method and directly identifying the chemical composition of the surface coating from the ATR spectrum of the sample is not only simple and quick, but also obtains satisfactory results.

ATR spectra. From the results shown in line A, the surface coating was EAA resin and line B indicated that the surface coating was EVA resin capillary gas chromatography for the separation and detection of optical isomers in the synthetic pyrethroid product. Zhang Jingxia (Zhongshan Medical University) , Guangzhou 510089, China) After hydrolysis of ethyl chrysanthemate and borneol chrysanthemum bromide, the esters of chrysanthemum chrysanthemate were hydrolyzed and reesterified to form 1-menthyl chrysantate. The content of optical isomers was determined by capillary column chromatography to obtain d-trans-chrysanthemic acid, 1 The relative content of trans- chrysanthemic acid and cis-racemic chrysanthemic acid, and the ratio of cis and anti- chrysanthemic acid in the chrysanthemum asymmetric catalytic synthesis reaction, the trans-form of ethyl chrysanthemum, chrysanthemate The enantiomeric excesses were: 7.79 and 15.84.

Capillary column chromatography, chrysanthemic acid, enantiomeric excess pyrethroids are highly efficient, low-toxicity, broad-spectrum, low-residue insecticides that can be effected by diazoacetate under the action of chiral catalysts2, 5 dimethyl 2, 4 hexadiene addition obtained. The molecule contains two chiral carbon atoms, so there are four optical isomers: d Shun