Nylon morphology and structure

The morphological structure of nylon made by melt spinning method observed in the microscope has a circular cross section and no special longitudinal structure. The filamentous fibril structure can be observed under the electron microscope, and the fibril width of nylon 66 is about 10-15nm. If the special-shaped spinneret is used, it can be made into nylon with various special cross-sectional 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 nylons 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 cohesive performance and covering ability of the fiber, as well as anti-pilling, reducing static electricity and other properties. For example, the triangular fiber has a flashing effect; the five-lobed fiber has a plump luster, has a good hand feel, and is resistant to pilling; the hollow fiber has a low density and good warmth retention due to the cavity inside.

Polyamide (PA, commonly known as nylon) is the first resin developed by DuPont in the United States for fiber, and it was industrialized in 1939. In the 1950s, it began to develop and produce injection molded products to replace metal to meet the requirements of downstream industrial products to reduce weight and reduce costs. The main chain of polyamide contains many repeating amide groups. It is called nylon when used as plastics, and we called nylon when used as synthetic fibers. Polyamides can be made from diamines and dibasic acids, or omega-amino acids or rings. Lactam to synthesize. According to the number of carbon atoms contained in diamine and diacid or amino acid, many 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 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 to spin 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, abrasion resistance, chemical resistance and self-lubrication, and has low friction coefficient, certain flame retardancy, easy processing, suitable for glass fiber and Other fillers are filled to enhance modification, improve performance and expand the scope of application.

There are many varieties of PA, including PA6, PA66, PAll, PA12, PA46, PA610, PA612, PA1010, etc., as well as many new varieties of semi-aromatic nylon PA6T and special nylon developed in recent years. Nylon-6 plastic products can use sodium metal, sodium hydroxide, etc. as the main catalyst, and N-acetyl caprolactam as the co-catalyst, so that δ-caprolactam can be produced directly in the model through anion ring-opening polymerization, which is called cast nylon. This method facilitates the manufacture of large plastic parts.