Long carbon chain nylon

Long-chain nylon generally refers to nylon with a methylene length of more than 10 in the segment chain. In addition to common nylon characteristics, it also has the characteristics of good toughness and flexibility, low water absorption, good dimensional stability, and excellent dielectric properties.

On October 27, 1938, DuPont announced the synthesis of the world's first synthetic fiber, and named it polyamide 66 (nylon 66); nylon 66 was completely industrialized at the end of 1939, from the initial clothing products to the follow-up engineering It has a development history of more than 80 years, and Orinko Plastics has very unique advantages in engineering plastics.

The well-known nylon 66 and nylon 6 belong to the range of short-chain nylon, while long-chain nylon can largely compensate for the size of short-chain nylon due to its high water absorption due to the low ratio of amide bonds and methylene groups. The shape is easy to change and so on.

At the same time, long carbon chain nylon has excellent toughness and softness, and long carbon chain nylon has the general properties of most nylons, such as lubricity, wear resistance and compression resistance, and easy processing. It can be said that long carbon chain nylon has unique advantages, making it have unique application space and future development potential.

Properties of Long Carbon Chain Nylon

Generally, nylon has the characteristics of high tensile strength, high toughness, good self-lubrication, and friction resistance. For example, nylon 6 and nylon 66 account for almost 90% of the world's nylon production.

In addition, long-chain nylon also has the advantages and characteristics of low water absorption, good toughness, good flexibility, low density, and excellent dielectric properties. The physical parameters of each nylon are listed in Table 1.

1. Water absorption and dimensional stability

The lower water absorption of long carbon chain nylon is one of its important properties different from short chain nylon. Since the amide group (—NHCO—) in the nylon molecule is a hydrophilic group, nylon has a strong hydrophilicity. properties, and the greater the density of amide groups, the higher the water absorption.

However, long carbon chain nylon has a large number of methylene groups, resulting in a low ratio of amide bonds to methylene groups, and a low concentration of amide bonds, which leads to low water absorption of long carbon chain nylon compared with short chain nylon. As a comparison, the water absorption rate of PA6 is 1.8%, while the water absorption rate of PA11 can reach 0.3%.

The impact of water absorption on nylon products is mainly reflected in the crystal structure, mechanical properties, dielectric properties and dimensional stability. Therefore, long carbon chain nylon will play an irreplaceable role in environments such as humidity and high dimensional stability requirements.

2. Toughness and flexibility

Due to the large amount of methylene (-CH2-) in long-chain nylon, it has the characteristics of free extension and rotation, which makes the molecular chains more flexible and thus has higher toughness. Elongation at break is an important mechanical index, which can characterize fiber toughness and softness.

At 23°C, the elongation at break of PA6 is 180%, while that of PA11 reaches 330%. In order to improve the mechanical strength of nylon, materials such as glass fiber and carbon fiber have been added to nylon in many scientific studies.

However, the increase of glass fiber and carbon fiber will reduce the toughness of the material to varying degrees. Toughener is a good choice in some cases, however, excessive toughener will lead to problems such as larger particle size and poor dispersion.

Long carbon chain nylon still has good toughness and flexibility under low temperature conditions, so long carbon chain nylon can be used to prepare soft products and cold-resistant parts in low temperature regions.

3. Electrical properties

As we all know, nylon is a typical insulating material. Dielectric strength is an important indicator for insulating materials. It refers to the ratio of breakdown voltage to the thickness of the insulator, that is, the maximum field strength that the material can withstand for a long time.

As mentioned earlier, generally nylon has a high water absorption rate due to the high concentration of amide bonds. High water absorption will cause a decrease in the dielectric strength of nylon.

Therefore, the water absorption capacity has an impact on all links in the dielectric strength industry, such as manufacturing, storage, and use, and the selection of materials is of great significance for safety and long-term use. The relatively low water absorption of long carbon chain nylon allows it to still play the role of a material with excellent dielectric properties in a humid environment.