Product Details
CasNo： 63428-84-2
Appearance： granule
Delivery Time： 15 days
Packing： 25kg/bag
Purity： 99%
1. Basic Information
1.1 Definition
Polyamide resin, abbreviated as PA, is a class of polymers with amide groups (-NHCO-) in the main chain. It is a kind of micro - molecular polycondensed by vegetable oil unsaturated fatty acid dimer and polyamine, with active groups, hydroxyl groups, and amide in its molecule.
1.2 Appearance
Generally appears as white or light - yellow granules. However, different manufacturing processes and additives may cause some changes in appearance. For example, some polyamide resins for special applications may have a slightly different color or particle shape.
1.3 Density
The density is approximately in the range of 1.01 - 1.16 g/cm³. This density range endows polyamide resin with a certain mass - to - volume ratio, which is beneficial for its applications in various fields. For instance, in the manufacturing of lightweight yet strong mechanical parts, this density property helps to balance the weight and strength requirements.
1.4 Melting Point
The melting point usually ranges from 180 to 280 °C, but it varies significantly depending on the specific type of polyamide. For example, PA66 has a relatively high melting point, which is around 260 °C, while PA6 has a melting point of about 220 °C. This difference in melting points makes them suitable for different processing conditions and applications.
2. Classification
2.1 Classification by the Hydrocarbon Group between Amide Groups
- Aromatic Polyamides: These polyamides contain aromatic rings in their molecular structure. They often exhibit excellent high - temperature resistance, high strength, and good chemical stability. For example, some aromatic polyamides are used in aerospace applications where materials need to withstand extreme temperatures and high mechanical stresses.
- Aliphatic Polyamides: The main chain of aliphatic polyamides consists of aliphatic hydrocarbon chains. They are the most common type of polyamides and are widely used in various industries due to their relatively low cost and good comprehensive performance. Examples include PA6 and PA66, which are used in large quantities in the automotive, electronics, and textile industries.
- Heterocyclic - containing Polyamides: With heterocyclic structures in their molecules, these polyamides may have unique properties such as high - temperature resistance, high electrical resistance, and good mechanical properties under special conditions. They are often used in high - tech fields such as electronics and advanced composites.
- 脂环族聚酰胺（Alicyclic Polyamides）: Containing alicyclic structures, they combine the advantages of aliphatic and cyclic structures. They usually have good mechanical properties, heat resistance, and chemical resistance, and can be used in applications that require both strength and heat resistance, such as in some high - performance coatings and engineering plastics.
2.2 Classification by Raw Materials
- MP - type Polyamides: Formed by the condensation polymerization of diamines and dibasic acids. For example, PA - 66 is synthesized from hexamethylenediamine and adipic acid. PA - 610 is made from hexamethylenediamine and sebacic acid. These types of polyamides have relatively high strength, good wear resistance, and are widely used in the manufacture of mechanical parts, such as gears and bearings.
- P - type Polyamides: Synthesized by the ring - opening polymerization of lactams. For example, PA - 6 is obtained from the ring - opening polymerization of caprolactam. P - type polyamides generally have good processability and impact resistance, and are often used in injection - molded products, such as automotive interior parts and consumer goods.
3. Performance Characteristics
3.1 Mechanical Properties
- Polyamide is a typical hard - and - tough polymer, with good tensile strength, compression strength, impact strength, and wear resistance. For example, in the automotive industry, polyamide - based components can withstand the mechanical stress during long - term use, reducing the need for frequent replacements. However, its tensile strength, bending strength, and hardness decrease with the increase of humidity and temperature, while the impact strength increases significantly. This characteristic should be considered when designing products for different working environments.
3.2 Electrical Properties
- In low - temperature and dry conditions, polyamide resin has good electrical insulation properties. But as the temperature and water absorption rate increase, its resistance value and dielectric strength decrease significantly, while the dielectric constant and dielectric loss increase significantly. For example, in electronic applications, if the operating environment has high humidity or temperature fluctuations, appropriate measures need to be taken to ensure the stable electrical performance of polyamide - based components.
3.3 Thermal Properties
- Polyamide resins generally have a relatively high and narrow melting temperature range, with a distinct melting point. Their thermal conductivity is relatively low, and the linear expansion coefficient is generally greater than 6×10⁻⁵ K⁻¹. Most polyamides are self - extinguishing, which makes them suitable for applications where fire safety is required, such as in the manufacturing of electrical enclosures.
3.4 Water Absorption
- The amide group in polyamide is a hydrophilic group, so polyamide has a relatively high water absorption rate compared to other plastics. This property can affect the dimensional stability and mechanical properties of products. For example, in precision - molded parts, excessive water absorption may lead to dimensional changes and a decrease in mechanical strength. Therefore, it is not suitable for manufacturing products with high precision and strict dimensional stability requirements. Before molding, pre - heating and drying are usually required to reduce the water content.
3.5 Chemical Resistance
- Polyamide resin is stable against the action of most chemical reagents, especially showing good oil resistance. It is also stable against the action of alkalis and most salts. However, at room temperature, it can be dissolved in phenols, inorganic acids, formic acid, and some salt solutions. This chemical resistance property determines its application scope in different chemical environments, such as in the packaging of some chemical products or in the manufacturing of parts that come into contact with oil.
4. Preparation Methods
- Usually, it is obtained by the condensation polymerization of dibasic acids and diamines. For example, in the production of PA66, hexamethylenediamine and adipic acid react under certain conditions to form the polyamide resin. It can also be synthesized through the ring - opening polymerization of lactams. For instance, caprolactam undergoes ring - opening polymerization to produce PA6. In addition, non - reactive polyamide resins can be made from the condensation polymerization of dimer acid and diamines, followed by granulation.
5. Quality Indicators
- Taking the products of Shandong Huijin Chemical Co., Ltd. as an example, different types of polyamide resins have different quality indicators. For the benzene - soluble and general - purpose HJ - 3070, the acid value is ≤5 mgKOH/g, the amine value is ≤5 mgKOH/g, the viscosity is 30 - 70 mPa·s/25 °C, the softening point is 110 - 125 °C, and the freezing point is ≤6 °C. These indicators reflect the quality and performance characteristics of the product, which are important references for customers to select products according to their specific needs.
6. Application Fields
6.1 Mechanical Field
- Widely used as mechanical parts, such as bearings, gears, etc. Polyamide - based parts do not require additional lubrication during operation and produce no noise. In addition, polyamide powder can be applied to the surface of parts to improve their friction, wear, and sealing performance. For example, in some high - speed rotating machinery, polyamide - based bearings can reduce energy consumption and improve the service life of the equipment.
6.2 Electrical Field
- Can be used to manufacture electrical parts, such as motor housings, junction boxes, etc. Its electrical insulation properties and mechanical strength can meet the requirements of electrical applications. In addition, its self - extinguishing property provides an extra layer of safety in electrical equipment, reducing the risk of fire caused by electrical failures.
6.3 Packaging Field
- Polyamide can be made into films. PA films have high mechanical strength and good airtightness, especially outstanding barrier properties against flavors, oils, and oxygen. They are mainly used for packaging high - value foods, such as vacuum - packed meats and high - end dairy products, to extend the shelf life of the products and maintain their quality.
7. Packaging and Storage
- Generally, it is packaged in a sealed manner to prevent moisture absorption and contamination. It should be stored in a cool and dry place. Under the condition of 2 - 25 °C, the original unopened packaging usually has a shelf life of 12 months. Proper packaging and storage conditions can ensure the stability of the product quality and prevent performance degradation due to environmental factors.
