Nylon (polyamide) types and application introduction

1. Polyamide resin (polyamide), referred to as PA, commonly known as Nylon

2. Main naming method: according to the number of carbon atoms in each repeated amide group. The first digit of the nomenclature refers to the number of carbon atoms of the diamine, and the following number refers to the number of carbon atoms of the dicarboxylic acid.

3. Types of nylon:

3.1 Nylon-6 (PA6)

Nylon-6, also known as polyamide-6, is polycaprolactam. Translucent or opaque milky white resin.

3.2 Nylon-66 (PA66)

Nylon-66, also known as polyamide-66, is polyhexamethylene adipamide.

3.3 Nylon-1010 (PA1010)

Nylon-1010, also known as polyamide-1010, is polyseramide. Nylon-1010 is made of castor oil as the basic raw material, which is a unique variety in my country. Its biggest feature is its high ductility, which can be stretched to 3 to 4 times the original length, and has high tensile strength, excellent impact resistance and low temperature resistance, and is not brittle at -60°C.

3.4 Nylon-610 (PA-610)

Nylon-610, also known as polyamide-610, is polyhexamethylene diamide. It is translucent creamy white. Its strength is between nylon-6 and nylon-66. Small specific gravity, low crystallinity, little influence on water and humidity, good dimensional stability, self-extinguishing. Used in precision plastic parts, oil pipelines, containers, ropes, conveyor belts, bearings, gaskets, insulating materials in electrical and electronic and instrument housings.

3.5 Nylon-612 (PA-612)

Nylon-612, also known as polyamide-612, is polyhexamethylene dodecylamide. Nylon-612 is a kind of nylon with better toughness. It has a lower melting point than PA66 and is softer. Its heat resistance is similar to that of PA6, but it has excellent hydrolysis resistance and dimensional stability, and low water absorption. The main use is as monofilament bristles for toothbrushes.

3.6 Nylon-11 (PA-11)

Nylon-11, also known as polyamide-11, is polyundecalactam. White translucent body. Its outstanding features are low melting temperature and wide processing temperature, low water absorption, good low temperature performance, and good flexibility that can be maintained at -40°C to 120°C. Mainly used in automobile oil pipeline, brake system hose, optical fiber cable coating, packaging film, daily necessities, etc.

3.7 Nylon-12 (PA-12)

Nylon-12, also known as polyamide-12, is polydodecamide. It is similar to Nylon-11, but has a lower density, melting point, and water absorption than Nylon-11. Because it contains a large amount of toughening agent, it has the properties of combining polyamide and polyolefin. Its outstanding features are high decomposition temperature, low water absorption and excellent low temperature resistance. Mainly used in automotive fuel pipes, instrument panels, accelerator pedals, brake hoses, noise-absorbing components of electronic appliances, and cable sheaths.

3.8 Nylon-46 (PA-46)

Nylon-46, also known as polyamide-46, is polybutylene adipamide. Its outstanding features are high crystallinity, high temperature resistance, high rigidity and high strength. Mainly used in automobile engine and peripheral components, such as cylinder head, oil cylinder base, oil seal cover, transmission.

In the electrical industry, it is used in contactors, sockets, coil bobbins, switches and other fields that require high heat resistance and fatigue resistance.

3.9 Nylon-6T (PA-6T)

Nylon-6T, also known as polyamide-6T, is polyhexamethylene terephthalamide. Its outstanding features are high temperature resistance (melting point is 370°C, glass transition temperature is 180°C, and can be used for a long time at 200°C), high strength, stable size, and good welding resistance. Mainly used in automotive parts, oil pump cover, air filter, heat-resistant electrical parts such as wire harness terminal board, fuse, etc.

3.10 Nylon-9T (PA-9T)

Nylon-9T, also known as polyamide-6T, is polynonanediamide terephthalamide. Its outstanding features are: low water absorption, water absorption rate of 0.17%; good heat resistance (melting point is 308°C, glass transition temperature is 126°C), and its welding temperature is as high as 290°C. Mainly used in electronics, electrical appliances, information equipment and auto parts.

3.11  Transparent nylon (semi-aromatic nylon)

Transparent nylon is an amorphous polyamide with a chemical name: polyhexamethylene terephthalamide. The transmittance of visible light is 85% to 90%. It inhibits the crystallization of nylon by adding components with copolymerization and steric barriers to the nylon component, thereby producing an amorphous and difficult-to-crystallize structure, which maintains the original strength and toughness of nylon, and obtains transparent thick-walled products. The mechanical properties, electrical properties, mechanical strength and rigidity of transparent nylon are almost at the same level as PC and polysulfone.

3.12 Poly(p-phenylene terephthalamide) (aromatic nylon abbreviated as PPA)

Polyphthalamide (Polyphthalamide) is a highly rigid polymer with a high degree of symmetry and regularity in its molecular structure, and strong hydrogen bonds between macromolecular chains. The polymer has the characteristics of high strength, high modulus, high temperature resistance, low density, small thermal shrinkage, and good dimensional stability, and can be made into high-strength, high-modulus fibers (the fiber trade name of DuPont DUPONT: Kevlar, Is the military bulletproof clothing material).

3.13 Monomer cast nylon (monomer cast Nylon referred to as MC nylon)

MC nylon is a kind of nylon-6. Compared with ordinary nylon, it has the following characteristics:

A. Better mechanical properties: The relative molecular weight of MC nylon is twice that of ordinary nylon (10000-40000), about 35000-70000, so it has high strength, good toughness, impact resistance, fatigue resistance and good creep resistance. .

B. Has a certain sound absorption: MC nylon has sound absorption function, and is a relatively economical and practical material for preventing mechanical noise, such as making gears with it.

C. Good resilience: MC nylon products do not produce permanent deformation when bent, and maintain strength and toughness, which is a very important feature for conditions subject to high impact loads

D. It has better wear resistance and self-lubricating properties;

E. It has the characteristics of not bonding with other materials;

F. The water absorption rate is 2 to 2.5 times lower than that of ordinary nylon, the water absorption speed is slower, and the dimensional stability of the product is also better than that of ordinary nylon;

G. Forming processing equipment and molds are simple. It can be cast directly or processed by cutting, especially suitable for the production of large parts, multi-variety and small-batch products that are difficult for injection molding machines to produce.

3.14 Reaction Injection Molded Nylon (RIM Nylon)

RIM nylon is a block copolymer of nylon-6 and polyether. The addition of polyether improves the toughness of RIM nylon, especially the low-temperature toughness, excellent heat resistance, and the ability to improve the baking temperature when painting.

3.15 IPN nylon

IPN (Interpenetrating Polymer Network) nylon has similar mechanical properties to basic nylon, but has improved to varying degrees in terms of impact strength, heat resistance, lubricity and processability. IPN nylon resin is a blended pellet made of nylon resin and pellets containing silicone resin with vinyl functional groups or alkyl functional groups. During processing, two different functional groups on the silicone resin undergo a cross-linking reaction to form an IPN ultra-high molecular weight silicone resin, which forms a three-dimensional network structure in the basic nylon resin. However, crosslinking is only partially formed, and the finished product will continue to crosslink during storage until it is complete.

3.16 Electroplated nylon

Electroplated nylon is filled with mineral fillers and has excellent strength, rigidity, heat resistance and dimensional stability. It has the same appearance as electroplated ABS, but far exceeds electroplated ABS in performance.

The electroplating process principle of nylon is basically the same as that of ABS, that is, the surface of the product is first roughened by chemical treatment (etching process), and then the catalyst is adsorbed and reduced (catalytic process), and then chemical electroplating and electroplating are performed to make copper, nickel, Metals such as chromium form a dense, uniform, tough and conductive film on the surface of the product.

3.17 Polyimide (Polyimide referred to as PI)

Polyimide (PI) is a polymer containing imide groups in the main chain. It has high heat resistance and radiation resistance. It has non-combustibility, wear resistance and good dimensional stability at high temperatures. Poor sex.

Aliphatic polyimide (PI): poor practicality;

Aromatic polyimide (PI): practical (the following introduction is only for aromatic PI).

A. PI heat resistance: decomposition temperature 500℃～600℃

(Some varieties can maintain various physical properties in a short period of time at 555°C, and can be used for a long time at 333°C);

B. PI is resistant to extremely low heat: it will not break in liquid nitrogen at -269°C;

C. PI mechanical strength: Unreinforced elastic modulus: 3 ~ 4GPa; fiber reinforced: 200 GPa; above 260°C, the tensile change is slower than aluminum;

D. PI radiation resistance: stable under high temperature, vacuum and radiation, with less volatile matter. High strength retention rate after irradiation;

E. PI dielectric properties:

a. Dielectric constant: 3.4

b. Dielectric loss: 10-3

c. Dielectric strength: 100~300KV/mm

d. Volume resistivity: 1017

F, PI creep resistance: at high temperature, the creep rate is smaller than that of aluminum;

G. Friction performance: When PI VS metal rubs against each other in a dry state, it can transfer to the friction surface and play a self-lubricating role, and the coefficient of dynamic friction is very close to the coefficient of static friction, which has a good ability to prevent crawling.

H. Disadvantages: high price, which limits the application in ordinary civilian industries.

All polyamides have a certain degree of hygroscopicity. Water acts as a plasticizer in polyamides. After absorbing water, most of the mechanical and electrical properties decrease, but the toughness and elongation at break increase.

Nylon (polyamide) types and application introduction