Methods for Polymer Material AnalysisPosted by beauty33 on February 24th, 2021
The composition analysis of polymer materials is characterized by a variety of separation techniques and various analytical instruments, and then the detection results are reversely deduced by technicians, and finally the process of qualitative and quantitative analysis of the unknown components of the sample to be tested is completed. It can be seen that the polymer materials analysis is a process of comprehensive analysis, and the analysis method is very important. The composition determines the performance, workers may need to confirm the material through composition analysis during material evaluation, quality control, failure analysis, etc. The composition analysis of polymer materials is characterized by a variety of separation techniques and various analytical instruments, and then the detection results are reversely deduced by technicians, and finally the process of qualitative and quantitative analysis of the unknown components of the sample to be tested is completed. It can be seen that the composition analysis of polymer materials is a comprehensive analysis process. It is necessary to formulate a comprehensive analysis plan to implement it based on the knowledge of the material to be analyzed, and the analysis method is very important. In view of the characteristics of polymer materials, its analysis methods are also pertinent. This article summarizes the common methods and characteristics of polymer material composition analysis, hoping to provide reference for related workers.
Infrared spectroscopy uses the wavelength position of the infrared absorption band and the intensity and shape of the absorption band to characterize the molecular structure, so it is mainly used to identify the structure of unknowns or for the qualitative identification of chemical groups and compounds. Because the absorption intensity of the infrared absorption band is related to the molecular composition or the content of its chemical groups, it can also be used for quantitative analysis and compound purity identification. At present, infrared detection is mainly used for qualitative analysis. Usually, the spectrum of the sample is compared with the spectrum of the standard or the spectrum in the literature. Computer library search can also be used to identify by similarity. Infrared spectroscopy analysis runs through the entire process of analysis. The initial collection of information, the subsequent monitoring of the components of each compound, and the analysis of the compound structure after purification all require infrared spectroscopy.
GC-MS is mainly used for the separation, qualitative and quantitative of additives in polymer materials. Generally, the additives in the polymer materials are separated from the resin, and then the different additives are separated through a gas chromatographic column, and then compared with the standard spectrum in the mass spectrometer for qualitative, combined with the standard sample for quantitative. In the composition analysis of polymer materials, it is mainly used to analyze some organic additives with low boiling point and good thermal stability.
Thermogravimetric analysis is to measure the change of sample weight with temperature or time under program temperature control. Polymer materials decompose, oxidize, volatilize, etc. as the temperature rises, and accompanied by changes in quality, through the relationship between the recorded quality and temperature and the analysis results of other instruments to infer the cause of the quality change, the main components, additives, fillers, carbon etc. for quantification.
DSC is a direct measurement of the energy absorbed or released by the sample during the process of heating, cooling or constant temperature under programmed temperature control. Polymer materials undergo physical changes with increasing temperature and are accompanied by changes in heat flow. The physical changes, such as melting point and glass transition temperature, are detected by recording the relationship between heat flow and temperature, so as to realize the qualitativeness of the material.
X-rays excite the surface elements of the polymer material to cause energy band transitions, and then return to the ground state to emit fluorescence. By detecting the emitted fluorescence, some elements in the polymer material are qualitatively and semi-quantified. This method is simple and easy to operate. It is a qualitative and semi-quantitative method that can be used to confirm the basic information in the early stage of polymer material composition analysis.
Nuclear magnetic resonance spectroscopy and carbon spectroscopy, that is, the chemical shift value, coupling constant and absorption peak area of hydrogen or carbon atoms are used to determine the structure of organic compounds. It is recommended for the accuracy of structure information and for unknown structures. Predictability is one of the best methods. Nuclear magnetic resonance spectroscopy can accurately provide information about hydrogen and carbon in organic compounds, as well as the functional groups, structural units, and connection methods that are composed of them. In the analysis of the composition of polymer materials, nuclear magnetic resonance can be used to accurately characterize some separated and purified substances, which requires high sample purity.
ICP-OES is a commonly used method for analyzing metal elements, and it does not seem to be suitable for polymer materials. However, because general qualitative and semi-quantitative element analysis methods cannot be used for quasi-group quantification, the detection limit is not enough for the resolution of some trace elements. ICP-OES is qualitative based on a series of characteristic wavelengths generated by atoms from the ground state to the excited state, and then quantified based on the intensity of the spectrum and the standard working curve. It has the characteristics of low detection limit and high accuracy. In the composition analysis of polymer materials, the inorganic components are mainly quantitatively analyzed.
PY-GC-MS is connected to a GC-MS sampler with a cracker. The high polymer enters the high-temperature cracker for cracking into volatile small molecules and low-molecular compounds into the GC-MS for separation and detection. Compared with infrared absorption spectroscopy, it has an irreplaceable role in analyzing various forms of polymer samples, including identifying infusible thermosetting resins, identifying homopolymers of similar composition, and distinguishing copolymers and blends. In addition, some additives in polymer materials can also be analyzed. In the actual analysis process, in order to reduce the blindness of the analysis, it is necessary to have an understanding of the cleavage spectra of common polymer materials or added systems in order to do more with less.
HPLC is based on the classic chromatography method, which improves column efficiency by changing the mobile phase to high pressure delivery. This method has a wide application range and can make up for the shortcomings of GC-MS. It can analyze some high boiling point, poor thermal stability and relatively large molecular weight. Organic additives. However, compared with GC-MS, because there is no assistance of MS, other means are needed for qualitative analysis in the actual analysis process, which is not conducive to blind sample analysis or preliminary collection of information.
XRD uses the diffraction phenomenon of X-rays in the crystal to obtain the characteristics of the X-ray signal after diffraction, and after processing, the diffraction pattern is obtained to analyze the phase or compound structure. It is a method to determine the phase and crystalline state of a compound. Component analysis is mainly used to identify the structure of inorganic compounds. In addition, XRD is suitable for the analysis of crystalline, microcrystalline or quasicrystalline compounds, but not suitable for the analysis of amorphous compounds.
XPS uses X-rays to act on the surface of the sample to generate photoelectrons. The photoelectron spectrum is obtained by analyzing the energy distribution of the photoelectrons to study the composition and structure of the sample surface. This method is commonly used to determine the valence state of a compound, thereby obtaining the structure of the compound. XRD cannot identify amorphous inorganic compounds, and XPS can make up for this deficiency. About T, C& A LAB T, C& A LAB is a branch of Alfa Chemistry, headquartered in New York, USA. Today, T, C& A LAB is an independent lab providing quality or custom testing, characterization and analysis of a variety of materials. We can help with troubleshooting, R&D screening, raw materials retest and diagnosis, etc., to most industries worldwide. We can also assist clients in testing data interpretation and simulation by advanced data analysis techniques. Like it? Share it! More by this author |
