A method for detecting the prepolymerization temperature of nylon salt

Abstract

The invention discloses a method for detecting a prepolymerization temperature of a nylon salt. The method comprises the following steps: (1) adding white powder-shaped nylon salt prepared by condensation polymerization between binary acid and diamine into distilled water according to a ratio of (1:1)-(1:2), heating to the temperature of 60-80 DEG C so as to dissolve the nylon salt, and maintaining the temperature so as to completely volatilize the distilled water, thereby obtaining a transparent nylon salt sample; (2) taking the dried nylon salt sample, preparing a sheet by adopting a KBr method, wherein the mass ratio of the sample to KBr is (1:100)-(1:300), the thickness of the sample sheet is 0.3-0.6mm, and the baseline infrared transmittance is higher than 85 percent; and (3) detecting the heated amidation of the nylon salt under a constant rate by adopting an in-situ transmission infrared spectrum, thereby obtaining the prepolymerization temperature of the nylon salt. According to the method disclosed by the invention, the structural change of the nylon salt in the polymerization process can be really monitored, the optimal prepolymerization temperature is obtained, volatilization of short carbon chain diamine components is avoided, the molar ratio of the diamine and binary acid is guaranteed, and the molecular weight of a polyamide product is improved.

Description

technical field [0001] The invention relates to a method for detecting the prepolymerization temperature of nylon salt. Background technique [0002] Polyamide (PA, commonly known as nylon) was the first resin developed by DuPont in the United States for fiber, and it was industrialized in 1939. In the 1950s, the development and production of injection molding products began to replace metals to meet the requirements of lightweight and cost-reducing downstream industrial products. Polyamide 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. [0003] There are many varieties of PA, including PA6, PA66, PA11, PA12, PA46, PA610, PA612, PA1010, etc., as well as many new varieties such as s...

AI Technical Summary

Problems solved by technology

If the selected prepolymerization temperature is low, the nylon salt will not react completely during the prepolymerization process. During the subsequent temperature rise polymerization process, the unprepolymerized nylon salt will also lose the short carbon chain diamine component, and will eventually reduce Molecular Weight of Nylon Products

In addition, there are problems such as waste of raw materials, long research cycle, and product quality depending on the quality and structure of the polymerization kettle to study the polymerization process conditions of nylon salt directly through the polymerization kettle.

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