PA has the following advantages and disadvantages in performance:


It is a crystalline material, and its advantages are as follows:

1. high mechanical strength, good toughness, high tensile strength

 and compressive strength.

2. fatigue resistance is outstanding. It can maintain its original mechanical

 strength after repeated bending.

3. smooth surface, small friction coefficient, wear-resistant.

4. corrosion resistance, alkali resistance and most salt solution, but also

 weak acid, oil and gasoline.

5. innocuity, inert to biological erosion, good antibacterial and anti toxic ability.

6. the heat resistance is strong, the temperature range is wide, it can be used 

for a long time at 45~100 C, and the heat resistance temperature is 120~150 

C in a short time.

7., it has excellent electrical properties and good electrical insulation.


The quality of the 8. parts is light, easy to dye and easy to form.


Shortcomings:


1. is easy to absorb water.


2. light resistance is poor.


3. is not resistant to strong acid and oxidizing agent.


4. the technical requirements of the design are strict.

Processing requirements: generally, low molding temperature, low material 

temperature, long time and high injection molding pressure should be taken.

The variety and overall performance of PA:

The main varieties in PA are PA6 and PA66, which are dominant, followed by 

PA11, PA12, PA610, PA 612, and PA1010, PA46, PA7, PA9, and PA13. Injection

 molding (RIM) PA, aromatic PA, transparent PA, high impact (super toughened)

 PA, electroplating PA, conductive PA, flame retardant PA, PA and other polymer

 blends and alloys, etc., meet the special requirements, and are widely used as a

 substitute for the traditional materials such as metal and wood as a variety of 

structural materials.

PA is the most important engineering plastics and its output ranks first among 

the five general engineering plastics.

Performance: PA is a tough angle translucent or milky white crystalline resin. As

 engineering plastics, the molecular weight of PA is generally 15 thousand ~3. PA

 has high mechanical strength, high softening point, heat resistance, low friction 

coefficient, wear-resistance, self lubrication, vibration absorption and silencing, oil 

resistance, weak acid, alkali resistance and general solvent, good electrical insulation

, non-toxic, odorless, good weatherability and poor dyeability. The disadvantage is

 that the water absorbency is large, which affects the dimensional stability and 

electrical properties. Fiber reinforcement can reduce the water absorption rate of

 the resin and make it work under high temperature and high humidity. Nylon has

 good affinity with glass fiber.

The hardness and rigidity of PA66 are the highest in PA, but the toughness is the

 worst. All kinds of PA were classified according to their toughness size: PA66 

< PA66/6 < PA6 < PA610 < PA11 < PA12.

The combustibility of PA is UL94 V-2, the limiting oxygen index is 24%~28%, 

the decomposition temperature of PA is 299 degrees C, and spontaneous

 combustion occurs at 449~499 C. The melt fluidity of PA is good, so the product

 wall thickness can be as small as 1 mm.

Application of PA

It is widely used as a variety of mechanical and electrical parts, including bearings,

 gear, pulley pump impeller, blade, high pressure seal ring, cushion, valve seat,

 bushing, oil pipe, oil storage device, rope, belt, grinding wheel adhesive, battery

 box, electric coil, cable joint and so on. There is also a considerable yield of 

packaging tape, food film (low-temperature film for cooked food and cool drinks).

Several common PA flame retardants are halogen / antimony or other flame

 retardant synergistic systems, red phosphorus or melamine type halogen free 

flame retardant systems. From the perspective of quantity, halogen / antimony

 synergy system is still the most widely used PA flame retardant system. In some

 parts of Europe and Asia, efforts are being made to find alternatives to halogen

 flame retardants. But generally speaking, these alternative systems usually have

 problems of low thermal stability or moisture absorption. For red phosphorus, 

there is also a problem of storage because it is inflammable. The following are the

 main flame retardants used in nylon and their respective advantages and disadvantages.

1. halogen containing flame retardant system: the most important one of them 

is the most widely used one in foreign countries is the brominated styrene polymer

, which has excellent thermal stability. And because it is mixed with PA, it has 

good fluidity during the process. In addition, the flame-retardant PA prepared 

by this method also has excellent electrical properties and better physical and 

mechanical properties. The limitation of this flame retardant is poor optical 

stability and is not completely compatible with PA. In addition, the cost is

 higher than that of the ten brominated diphenyl ethers widely used in China.

  Another kind of flame retardant used in PA for many years is the enemy 

combustible. It is a kind of chlorine containing flame retardant with high flame 

retardancy and electrical properties, but its limitation on thermal stability is only 

suitable for the nylon flame retardant system with low processing temperature.

 At present, the most widely used flame retardant in China is ten brominated

 diphenyl ether. Because of its high bromine content, it has high flame retardant

 efficiency to PA. It is the most economical flame retardant. But because it is

 a filler type flame retardant, it has a great negative impact on the processing

 fluidity and physical and mechanical properties of the product. In addition, its

 thermal stability and light stability are also poorly differentiated. In recent 

years, a new flame retardant used in the field of nylon flame retardancy has

 been developed for ten brominated two benzoethane, which has the same

 bromine content and high flame retardant efficiency as ten brominated diphenyl

 ethers, and is the same as brominated styrene polymer without DPO 

(called dioxin). In addition, it has good thermal stability and light stability. Its

 limitation is that it is the same as ten brominated diphenyl ether as a filler 

type flame retardant, which is poor in compatibility with the polymer, so the 

processing fluidity and the physical and mechanical properties of the products

 are poor. In addition, the cost is higher than that of ten brominated diphenyl ethers.

2. halogen free flame retardant