How to prevent adipic acid dehydroxy when producing nylon 66 5

One is to dry as much as possible.

The second is to add corresponding antioxidants and processing aids.

The third is the appropriate processing and molding temperature.

Thermal decomposition and hydrolysis reactions.

Compared to other polyamides, nylon-66 is most susceptible to thermal degradation and three-dimensional structuring. When the thermal decomposition of nylon-66 occurs, it is first manifested as a decrease in molecular weight and melt viscosity caused by cracking of the main chain. When further degraded, the three-dimensional structuring causes the melt viscosity to rise and eventually becomes a gel, becoming an insoluble and non-meltable substance. The mechanism has not been fully elucidated, but it is believed that the main reason is the nature of nylon-66, which is closely related to the easy formation of cyclopentanone derivatives from adipic acid residues.

In an inert gas atmosphere, nylon-66 can maintain stability for a short time at 300 °C, but after a long time (e.g. 290 5 hours), obvious decomposition can be seen, producing ammonia and carbon dioxide. In the absence of oxygen, the decomposition products are cyano (-CN) and vinyl (-CH=CH2).

In the presence of oxygen and water, nylon-66 shows a significant tendency to decompose at 200. In the presence of aerobic, heating also causes cross-linking between molecular chains.

Nylon-66 is stable to room temperature and boiling water, but hydrolysis occurs at high temperatures, especially in the molten state. In addition, nylon-66 is also stable in alkaline aqueous solutions, and no significant changes can be observed even after 10% NaOH treatment at 85 for 16 hours. However, hydrolysis is susceptible to occur in acidic aqueous solutions.

This is called humidity treatment, which refers to the treatment of freshly demolded products in hot water. It can be said that the product isolates the air, prevents oxidation, accelerates the moisture absorption balance, and is the dimensional stability of the product. Nylon should be humidified because nylon is prone to oxidation and discoloration when in contact with air at high temperature (nylon is reducing).

At the same time, it is easy to absorb water and expand, making the size unstable. After debugging, the size of nylon products is stable, and at the same time, an appropriate amount of water can play a role similar to plasticizer, which can improve softness, tensile strength and so on. The treatment method is to place it in 80-100 water or acetate solution, the length of time is determined by the thickness and shape alone, and the equilibrium is generally reached after a few hours.

There is no other way to cool the waist slowly after humidification, to avoid internal stress, if the size of the product is not high, you can not deal with it, many of us do not deal with it.

Nylon 66 is formed by dehydration and condensation of hexamethylenediamine and adipic acid. The relative molecular mass of hexamethylenediamine.

is 116g mol, and the relative fractional weight of adipic acid is 146g mol. The molecular mass of the nylon-66 repeating unit is 116 146-18 2 226. Since each repeating unit contains two building blocks, the molecular mass of the building blocks is (116 146-18 2) 2 113 g mol.

Nylon 66 is also known as polyadipylhexanediamine.

Its monomer adipic acid, hexamethylenediamine and the monomer caprolactam of polyamide 6 are mainly derived from cyclohexane prepared by benzene hydrogenation.

A small amount comes from phenol.

One monomer of nylon 610 and nylon 1010 is sebacic acid, and the monomer aminoundecanoic acid of nylon 11 are prepared by the alkali decomposition of castor oil, a chemical product of agriculture and forestry. The monomer butadiene of nylon 12 is the product of C4 fraction separation, and all monomers are balanced and refined before polymerization to meet the requirements of polymerization grade.

* Structure: Nylon 6 is a polycaprolactam, while Nylon 66 is a polyhexamethylenediamine adipate. Nylon 66 is harder than nylon 612, and theoretically speaking, the harder it is, the more brittle the fiber is, and the easier it is to break.

But in carpet use, this small difference cannot be distinguished.

Cleanability and antifouling: What affects these two properties is the cross-sectional shape of the fiber and the antifouling treatment of the subsequent process. The strength and hardness of the fiber itself have little effect on cleaning and stain resistance.

Melting point and elasticity: The melting point of nylon 6 is 220C, while the melting point of Nylon 66 is 260C. However, this is not a difference when it comes to the temperature conditions at which the carpet is used.

The lower melting point makes nylon 6 have better resilience, fatigue resistance and thermal stability than nylon 66.

Color fastness: Color fastness is not a property of nylon, it is the dye in nylon and not the nylon itself that fades under light.

Abrasion and dust resistance: Clemson University conducted a two-and-a-half-year experiment at Tampa International Airport using BASF's Zeftron 500 nylon 6 carpet and DuPont Antron XL nylon 66 carpet. The carpet is in a state of extremely high amount, and the results show that:

BASF's Zeftron 500 nylon is slightly better than DuPont Antron XL in terms of color retention and pile abrasion resistance. There is no difference in the dust resistance of the two yarns.

The difference between nylon 6 and nylon 66 in engineering plastics: nylon 66 has a high melting point and high density.

Nylon 6, also known as PA6, polyamide 6. Melting point 220 degrees Celsius, density.

Nylon 66 is also known as polyamide-66; Polyadipylhexanediamine; Melting point 264 degrees Celsius, density.

Nylon 66 is made of hexamethylenediamine adipate and nylon 6 is made of caprolactam, which are similar in molecular structure. Nylon 6 has less strength and is softer, the wear resistance is worse than that of nylon 66, and it is slower to solidify when condensed after melting, and the crystalline structure is loose and the color is simple.

Nylon 66 has greater strength, good wear resistance, delicate feel, and quickly solidifies when cold after melting, it can be used as high-end clothing fabrics, which is not easy to color, and has a tight crystalline structure.

Properties of Nylon:

1. High melting point (264°C).

2. The crystalline structure is compact.

3. It is very little affected by ozone and laughing gas.

4. It is difficult to dye.

5. Fiber has the best elasticity.

6. Dense feel.

7. The most suitable fiber for engineering.

Nylon 6 Performance:

1. Low melting point (228°C).

2. The crystalline structure is loose.

3. It is easy to fade under the action of ozone and laughing gas.

4. It is easy to dye.

5. The elasticity of the fiber is poor.

6. It feels soft.

7. It is not suitable for engineering needs, unless it is implemented under the guarantee of SDN.

However, dyeing is more difficult. The difference is that the hydrogen bonds between adjacent molecules of nylon 66 are more firmly combined, such as tire cords and heat-resistant washing fabrics and woven fabrics, and the elastic modulus is also better; The nylon 6 is made of caprolactam polycondensation, the main use difference in industrial applications, not easy to color, the feel is softer than nylon 6, now the most advanced down fabrics on the market are made of nylon 66, but the melting point of nylon 66 is higher, the heat resistance is better, in fact, the difference between the two in clothing textiles is not big, these two fibers are very similar, about 40 higher than nylon 6. From the perspective of molecular structure, nylon 66 is more excellent, smooth and greasy, and can be made into microfiber, so the physical and chemical properties of the two are basically similar, and it is more suitable for manufacturing heat-resistant strain products and high-end clothing fabrics.

Nylon 66 and nylon 6 are both polyamide fibers. The weaving and sewing properties of both are not bad, they need to be dyed at high temperatures, especially in the use of cord threads, they are thin and soft, so they have a melting point of up to 260. However, this is all from the subtle aspects of the difference, nylon 66 is made of adipic acid hexamethylenediamine polycondensation, and has an anti-feather effect, heat resistance is superior, the color fastness is not very good, nylon 66 is more expensive than nylon 6.