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Engineering Plastic: Difference Of PA6 Sheet PA66 Sheet


1. Background:

PA material, polyamide or commonly called nylon, is manufactured by Ensinger in standard stock shapes for machining in sheet, rod and tube is one of the common engineering plastics. It has 2 kinds of material, PA6 and PA66, which are the most common nylon materials. The two structures are similar and have many things in common. So what is the difference between the two?

PA66 was successfully polymerized into a PA66 polymer by Wallace Hume Carothers in 1935. The process of manufacturing PA66 by melt spinning was discovered from 1936 to 1937, and was commercialized by DuPont in the United States at the end of 1939.

PA6 is a PA6 polymer synthesized by German IG Schraker using a single caprolactam as raw material ε-aminocaproic acid as initiator. The test production of PA6 fiber was carried out in 1939, and commercialization was carried out by German company Faben in 1943.

2. Structure:

To analyze the difference between them, we must start with their structure. As we all know, PA6 is formed by ring-opening polymerization of caprolactam, and nylon PA66 is obtained by condensation of hexamethylenediamine with adipic acid. PA6 and PA66 have the same molecular formula, but the structural formula is different, as shown in the following figure:

PA66 Sheet

It is precisely because of this difference that the nature of the difference, such as the intermolecular hydrogen bonding force is different.

PA6 Sheet

3. Performance

The melting point of PA66 is 260~265 °C, and the glass transition temperature (dry state) is 50 °C. The density is 1.13~1.16 g/cm3.

PA6 translucent or opaque milky crystalline polymer particles, melting point 220 ° C, thermal decomposition temperature greater than 310 ° C, relative density 1.14, water absorption (24 ° C water 24 hours) 1.8%, with excellent wear resistance and self-lubricating It has high mechanical strength, good heat resistance and electrical insulation properties, excellent low temperature performance, good self-extinguishing and chemical resistance, especially excellent oil resistance.

Compared with PA66, PA6 is easy to process and form, has good gloss on the surface of the product, and has a wide temperature range, but has high water absorption rate and poor dimensional stability. It has low rigidity, low melting point, long-term use in harsh environments, and sufficient stress in a wide temperature range. The continuous use temperature is 105 °C.

Overall, the performance differences between PA66 and PA6 are as follows:

Mechanical properties: PA66 > PA6

Heat medium performance: PA66 > PA6

Price: PA66 > PA6

Melting point: PA66 > PA6

Water absorption: PA66< PA6

Weather resistance: PA66< PA6

Condensation time: PA66< PA6

Molding performance: PA66 < PA6

4.The process conditions

Drying treatment

PA6 absorbs moisture easily, so special attention should be paid to drying before processing. If the material is supplied in a waterproof material, the container should be kept closed. If the humidity is greater than 0.2%, it is recommended to dry in hot dry air above 80 °C for 3-4 hours. If the material has been exposed to air for more than 8 hours, it is recommended to dry at 105 ° C for more than 1 to 2 hours. It is best to use a dehumidifying dryer.

PA66 If the material is sealed before processing, then there is no need to dry. If the storage container is opened, it is recommended to dry in a hot, dry air at 85 °C. If the humidity is greater than 0.2%, it is also necessary to carry out vacuum drying at 105 ° C for 1 to 2 hours. It is best to use a dehumidifying dryer. Molding temperature: 260~310 °C, 280~320 °C for enhanced varieties.

Mold temperature

PA6: 80~90 °C. The mold temperature significantly affects the crystallinity, which in turn affects the mechanical properties of the part.

For thin-walled, longer-flowing parts, it is also recommended to apply higher mold temperatures. Increasing the mold temperature increases the strength and stiffness of the part, but reduces the toughness. If the wall thickness is greater than 3mm, it is recommended to use a low temperature mold of 20~40 °C. For glass reinforcement the mold temperature should be greater than 80 °C.

PA66: 80 °C is recommended. The mold temperature will affect the crystallinity, which will affect the physical properties of the product.

For thin-walled plastic parts, if a mold temperature lower than 40 ° C is used, the crystallinity of the plastic part will change with time, and in order to maintain the geometric stability of the plastic part, annealing treatment is required.

Melting temperature

PA6: 230~280°C, 250~280°C for enhanced varieties.

PA66: 260~290 °C. The product for glass additives is 275~280 °C. The melting temperature should be avoided above 300 °C.

Injection pressure

Both are generally between 750 and 1250 bar (depending on material and product design).

Injection speed

Both are high speed (slightly lower for reinforced materials).

Runner and gate

Since the setting time of PA6 and PA66 is very short, the position of the gate is very important. The gate aperture should not be less than 0.5*t (where t is the thickness of the plastic part). If a hot runner is used, the gate size should be smaller than with a conventional runner because the hot runner can help prevent premature solidification of the material. If a submerged gate is used, the minimum diameter of the gate should be 0.75 mm.

5. Application

PA6 engineering plastics have high tensile strength, good impact resistance, excellent wear resistance, chemical resistance and low friction coefficient. They can be modified by glass fiber, mineral filler modification and flame retardant. It makes it more comprehensive, mainly used in the automotive industry and electronic appliances.

PA66 Sheet

PA66 has good comprehensive performance, high strength, good rigidity, impact resistance, oil and chemical resistance, wear resistance and self-lubrication, especially hardness, rigidity, heat resistance and creep performance. PA66 is more used for the production of industrial yarns such as cords because of its higher strength than PA6.

PA66 Sheet

PA6 and PA66 overlap in many applications, but where PA6 can be used, PA66 is generally not used.

AHD Plastic

General stock specifications for PA6 :

Sheet: 1---100 x 1000 x 2000MM (custom sizes also can be provided)

Colors: white, black, blue ,other colors can be ordered.


PA6 Sheet

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