Method for fast and non-destructive differentiation of polyamide products

Abstract

The invention relates to a method for rapid and non-destructive differentiation of polyamide articles. The method of the present invention comprises the following steps: determine the analysis part of the product through a scanning electron microscope, use an energy spectrometer to perform elemental analysis, calculate the atomic percentage of carbon in the product, and identify the measured polyamide product according to the content of the carbon element. The first type of polyamide product is also the second type of polyamide product; among them, the first type of polyamide product is a product formed by the polymerization of amide monomers containing more than 10 carbon atoms in the largest monomer; the second type of polyamide product Amide products are products obtained by polymerizing amide monomers containing 7 or less carbon atoms in the largest monomer. Using the method of the present invention to analyze polyamide products will not cause loss to the sample, so that the sample can be retained; the method of the present invention can quickly distinguish polyamide products, and the operation is simple; the present invention also enriches the fiber identification method and provides fiber identification. new ideas.

Description

technical field [0001] The invention relates to a method for identifying physical evidence such as fibers, in particular to a method for quickly and non-destructively distinguishing polyamide products. Background technique [0002] Polyamide is also called nylon (Nylon), nylon, English name Polyamide, referred to as PA, which is the general term for polymers containing amide groups in the repeating unit of the macromolecular main chain. Polyamides can be prepared by ring-opening polymerization of lactams, or by polycondensation of diamines and dibasic acids. PA has good comprehensive properties, including mechanical properties, heat resistance, wear resistance, chemical resistance and self-lubricating properties, low friction coefficient, certain flame retardancy, easy processing, suitable for glass fiber and Other fillers are filled and modified to improve performance and expand application range. There are many varieties of PA, including PA6, PA66, PA11, PA12, PA46, PA61...

AI Technical Summary

Problems solved by technology

Among the above-mentioned standard methods, the combustion method, dissolution method, melting point method, color reaction method, etc. cannot meet the demand; using spectral means such as infrared spectroscopy can only determine the sample composition through several typical absorption bands of polyamide, but it is difficult to significantly The distinguishing components are also polyamide products, so the sample is usually characterized as polyamide by infrared spectroscopy, and then other methods are used to confirm its type

[0005] Some non-standard methods also face the same problem. The differential calorimetry scanning method can accurately distinguish polyamide products by using the difference in melting point and melting heat, etc.; the thermal cracking gas chromatography-mass spectrometry can be determined according to the difference in mass spectrum fragment ions after pyrolysis. Different cracking products can be distinguished, which can significantly distinguish the types of polyamides, but all samples must be lost; Raman spectroscopy can use the subtle differences in the spectra to distinguish samples, but because of the small peak strength, overlap, and poor repetition of the fingerprint spectra, it is difficult to determine It is difficult to distinguish significantly due to various reasons such as attribution; the use of x-ray diffraction analysis often results in poor response because the crystallinity of daily polyamide products is not high enough

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