Morphological structure of nylon


Release time:

2023/05/19

The morphological structure observed in the microscope of the nylon fiber produced by the melt spinning method has a circular cross section and no special longitudinal structure.

The morphological structure observed in the microscope of the nylon fiber produced by the melt spinning method has a circular cross section and no special longitudinal structure. Filamentous fibrils can be observed under the electron microscope, and the width of the fibrils of nylon 66 is about 10-15nm. If special-shaped spinnerets are used, it can be made into nylon with special cross-section shapes, such as polygonal, multi-leaf, hollow and other special-shaped cross-sections. Its focused state structure is closely related to the stretching and heat treatment of the spinning process. The main chains of macromolecules of different nylon fibers are all connected by carbon atoms and nitrogen atoms.
Shaped fiber can change the elasticity of the fiber, make the fiber have special luster and bulkiness, and improve the cohesion and covering ability of the fiber, as well as anti-pilling and static reduction. For example, the triangular fiber has a flash effect; the five-leaf fiber has a fat-like luster, has a good hand feeling, and is anti-pilling; the hollow fiber has a cavity inside, has a low density, and has good warmth retention.
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. The main chain of polyamide contains many repeated amide groups. It is called nylon when it is used as a plastic, and it is called nylon when it is used as a synthetic fiber. Cyclic lactams are synthesized. According to the number of carbon atoms contained in diamines and dibasic acids or amino acids, a variety of different polyamides can be prepared. There are dozens of polyamide varieties, among which polyamide-6, polyamide-66 and polyamide Amide-610 is the most widely used.
The chain link structures of polyamide-6, polyamide-66 and polyamide-610 are [NH(CH2)5CO], [NH(CH2)6NHCO(CH2)4CO] and [NH(CH2)6NHCO(CH2)8CO] respectively ]. Polyamide-6 and polyamide-66 are mainly used for spinning synthetic fibers, called nylon-6 and nylon-66. Nylon-610 is a thermoplastic engineering plastic with excellent mechanical properties.
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 to enhance modification, improve performance and expand application range.
There are many varieties of PA, including PA6, PA66, PAll, PA12, PA46, PA610, PA612, PA1010, etc., as well as many new varieties such as semi-aromatic nylon PA6T and special nylon developed in recent years. Nylon-6 plastic products can use metal sodium, sodium hydroxide, etc. as the main catalyst, and N-acetyl caprolactam as a co-catalyst, so that δ-caprolactam can be directly produced by negative ion ring-opening polymerization in the model, which is called cast nylon. This method facilitates the manufacture of large plastic parts.

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