Granulator machine：The nylon family in engineering plastic , do you know them all?

Nylon plastic pelletizing line：

Polyamide (Nylon) includes aliphatic nylon and aromatic nylon (aromatic nylon have semi-aromatic nylon and fully aromatic nylon).

There are many kinds of aliphatic nylon, and it has great capacity and wide application. It named by the number of carbons of each monomer, like PA66, PA12 and so on.

Most kinds of the aromatic nylon are high-temperature nylon, the demand is not so much. But its excellent performance caused more and more application areas, such as PA9T, PA6T.

Part I: Aliphatic nylon

Classification of aliphatic nylon

1、According to the number of carbons of diamine and dicarboxylic acid, the nylon formed from two monomers: PA46, PA66, PA610, PA612, PA1010, etc.;

2、Named by the number of carbons of the monomer: PA6, PA11, PA12, etc.

Properties

Nylon has many advantages: good toughness, wear resistance, chemical resistance, colorfastness, Excellent abrasion resistance and oil resistance, Better weathering properties, better sunlight resistance and non-toxic, so it has wide application. It has a higher impact resistance (higher than ABS, POM ), a rapid moisture absorption, greater elasticity, and elastic recovery, poor dimensional stability.

We usually use PA66, because that it has the stronger structure among nylon all kinds of nylon, and PA6 has the best processing properties.

Plastic pellets extrusion machine : Processing characteristics

Rheological behavior

Most kinds of nylon is crystalline resin. When the temperature over the melting point, because of its small melt viscosity and the excellent flowability , so we need to prevent the overflowing edge. Besides, with the fast condensation speed of the melt, we should prevent the material from blocking the nozzles, runner, gate and other insufficient phenomenon of product.

The data of mold overflow is 0.03, and melt viscosity is much sensitive to temperature and shear changes, more sensitive to temperature. So we should control the barrel temperature to reduce melt viscosity.

Super absorbent and drying

Nylon is super absorbent. Wet nylon material in the forming process, expresses that a sharp decrease in viscosity and air bubble that makes products appear on the surface of the silver wire. All of them caused the results that the product mechanical strength decreased. So we need to dry the material before making products.

Crystallinity

Except transparent nylon, the rest is almost crystalline polymer with high crystallinity, tensile strength, abrasion resistance, hardness, lubricity and other improved properties of nylons. Although the coefficient of thermal expansion and water absorbent would decline, it is unfavorable for the transparency and impact resistance is unfavorable.

The mold temperature has a great influence on crystallization. High mold temperature has high crystallinity, low temperature has low crystallinity.

Systolicity

Like other crystalline plastics, nylon resin has the large shrinkage problem. Usually, between the shrinkage of nylon and crystallization have the close relation, so when the product crystallization is larger, the shrinkage will larger. If we reduce the mold temperature / increase injection pressure / reduce the material temperature, the shrinkage will be smaller. But the product internal stress will increase so that the product easy to deform.

For example, the range of the shrinkage of non-glass fiber reinforced PA6 and PA66 is 1.5-2%, and after the addition of glass fiber, it can reduce to 0.3%-0.8%.

Part II: Aromatic nylon

As we mentioned in this article, aromatic nylon can be divided into semi-aromatic nylon and all-aromatic nylon.

All-aromatic nylons : For example, poly-p-phenylene terephthalamide (PPTA) and poly-m-toluoyl-m-phenylene terephthalamide (PMIA). They have good mechanical properties, insulation, chemical stability and superb thermal properties because of the aromatic groups in the molecular chains.

Nowadays, all-aromatic nylon is mainly used in electrical and electronic industries aerospace, atomic energy industry aerospace and atomic energy industry and so on. However, the ultra-high melting point of fully aromatic nylon makes it impossible to melt extrusion and injection molding, and it only can be formed and processed by special ways. So that it limits its application in daily engineering plastics and makes it very difficult to recycle and reuse.

Semi-aromatic nylon: Contains aryl and methylene groups in the molecular chain, that makes it has the properties od aliphatic polyamides and all-aromatic nylon. Due to the excellent mechanical and thermal properties, conventional melt extrusion and injection molding, it is suitable for using widely in high temperature resistance fields.

With the rapid development of the automotive area and the electronic industry, and the demand of the environmental protection industry in recent years, we have increased demand and advanced application development. Semi-aromatic nylon includes PA9T, PA6T, PA10T and so on, and now let’s we know these guys better.

PA6T-high temperature resistant nylon

PA6T is a typical representative sample of nylon, which is composited by hexamethylene diamine and terephthalic acid. The melting point of pure PA6T 370°C. Under this temperature, the nylon has changed and cannot be thermoplasticized. So the PA6T in the market is a copolymer or compound material that has been copolymerized with other monomers.

PA6T adds a large number of benzene rings on the basis of aliphatic chains. And compared with the traditional PA6 and PA66, PA6T has higher Tg, lower water absorbent, materal stability and good heat resistance.

PA6T needs to introduce other monomers for copolymerization to reduce the processing temperature, so that different monomer ratios become the key to PA6T modification. We can say that the high temperature resistance modification of PA6T has a bright future.

Plastic profile extruder-product application:

Due to its excellent welding resistance, low water absorption, excellent flowability, etc., it is widely used in automotive parts, mechanical parts and electrical/electronic parts such as cell phones, drones, etc.

PA9T-high temperature resistant nylon

PA9T was developed by Kuraray Corporation of Japan. It is produced by condensation of nonanediamine and terephthalic acid. The name is Genestar.

Although it is the semi-aromatic nylon, PA9T does not need to be modified by copolymerization to lower the melting temperature PA6T, pure PA9T melting temperature is 306 ℃. PA9T high glass transition temperature (125 ℃) and high crystallinity give it good toughness in high temperature environments.

Comprehensive performance of PA9T is better than traditional heat-resistance nylon, and with the continuous expansion of production scale, the cost will be close to normal PA, so PA9T has great potential for development.

Application:

The product is mainly used in the electrical and electronic industry, the automotive industry and the fiber industry.

PA10T-high temperature resistant nylon

PA10T is made by terephthalic acid and decanediamine monomers and polymerized by condensation. It has excellent heat resistance, melting point 316℃, good chemical corrosion resistance, good material stability. In one word, PA10T has excellent overall performance.

Compared with other short-chain high temperature nylons: PA46, PA4T, PA6T, PA6I, etc., PA10T has a longer diamine flexible long chain. That makes the macromolecule have a certain flexibility with higher crystallization rate and crystallinity. It is suitable for rapid molding and making some small electronic components, such as LED reflection brackets, connectors, etc.

Also because of the excellent properties-rigidity and corrosion resistance come from the benzene ring structure in the main chain of its molecule, the modified granules of PA10T can also be applied to some chemical reagents, or heat-resistant environments, such as water treatment, nano-injection molding NMT, engine periphery, etc.

Plastic Pelletizer – product application:

LED reflection bracket, connector, water treatment, nano-injection NMT, engine periphery, etc.

PA4T-high temperature resistant nylon

PA4T introduced by DSM, which holds the world’s only industrialized solution for butylenediamine. It is the first synthetic high-temperature nylon since the 21st century. Like PA6T, it has a high melting temperature (430°C) and is also generally copolymerized with other nylons, such as nylon 66 or nylon 6.

PA4T has excellent spatial stability, lead-free solder compatibility, high melting point, high stiffness and mechanical strength at elevated temperatures, and it shows ultra-low water absorption than DSM’s original PA46 products, even PA9T.

Applications:

PA4T usually used in the electrical and electronics and automotive industries. In the electrical and electronics field, PA4T can be used to produce electronic components with small size, light weight and long service life, such as circuit boards, memory card connectors, memory module connectors, CPU sockets, current steering, high temperature resistant spools and other products for smartphones, tablet PCs, PC computers, wearable devices and other fields. In the automotive industry, PA4T can be used to produce high temperature resistant auto parts such as electrical system, fuel system, cooling system, and hood. In addition, PA4T is also in need in the aerospace area.

PA5T-high temperature resistant nylon

PA5T melting temperature is lower than PA6T. The main reason that previously limited its development is that the industrialization of glutamine is still in the research stage, but in the second half of 2018 there are domestic companies have successfully put into production 50,000 tons of bio-based glutamine. That stuff indicates that the industrialization of PA5T is closer.

PA12T-high temperature resistant nylon

PA12T is a kind of product made by homopolymerization of dodeca-carbon diamine and terephthalic acid.