What are the characteristics of unidirectional polyimide film
Unidirectional polyimide film is a high-performance polymer film material with the following characteristics:
1、 In terms of mechanical performance
1. High intensity
Unidirectional polyimide film has relatively high strength in the stretching direction. This is because its molecular chains are highly oriented in a unidirectional direction, which can effectively resist external stretching
Unidirectional polyimide film is a high-performance polymer film material with the following characteristics:
1、 In terms of mechanical performance
1. High intensity
Unidirectional polyimide film has relatively high strength in the stretching direction. This is because its molecular chains are highly oriented in a unidirectional direction, which can effectively resist external stretching. For example, compared to ordinary plastic films, the tensile strength of unidirectional polyimide films can reach several times or even tens of times that of ordinary plastic films. This high-strength characteristic enables it to be used as a reinforcement material for manufacturing structural components such as wings and fuselage in some fields that require high material strength, such as aerospace, and can withstand the enormous aerodynamic forces and structural loads during flight.
2. High modulus
Its modulus (the ratio coefficient of stress and strain of the material during elastic deformation) is very high, which means that the deformation of the film is very small when subjected to external forces. Taking unidirectional polyimide film as an example for manufacturing flexible circuit boards, it can maintain shape stability during bending, curling and other operations of the circuit board, and will not undergo excessive deformation due to small external forces, thus ensuring the electrical performance and mechanical reliability of the circuit board.
2、 In terms of thermal performance
1. High temperature resistance
Unidirectional polyimide film has good high temperature resistance. It can maintain stable performance over a wide temperature range and can generally be used in environments ranging from -269 ℃ to 400 ℃ for a long time. In high-temperature environments, such as in the thermal protection system of aircraft engines, it can effectively isolate high-temperature gas, prevent heat transfer to internal structures, and protect key components of the engine. Even if exposed to higher temperatures in a short period of time, such as instantaneous high temperature shocks in certain special industrial heat treatment processes, it will not undergo melting or decomposition.
2. Low thermal expansion coefficient
The thermal expansion coefficient of this film is very low, and its size changes very little when the temperature changes. This is crucial for high-precision application scenarios. For example, in optical equipment such as telescopes, unidirectional polyimide film is used in the lens support structure. When the ambient temperature changes, it will not cause the lens position to shift due to its own expansion or contraction, thus ensuring the imaging accuracy of the optical system.
3、 In terms of chemical properties
1. Chemical corrosion resistance
Unidirectional polyimide film has good resistance to most chemical substances. It can resist the erosion of various chemical substances such as acids, bases, and organic solvents. For example, in the application of anti-corrosion lining in chemical pipelines, it can effectively prevent chemical substances inside the pipeline from corroding the pipeline wall. Unidirectional polyimide film can effectively isolate and protect both acidic chemical raw materials and alkaline reaction media, thereby extending the service life of pipelines.
2. Hydrolysis resistance
It has good hydrolysis resistance and can maintain its performance stability for a long time in humid environments or in contact with water. In some underwater equipment or high humidity industrial environments, such as protective casings for marine instruments or packaging materials for humid electronic devices, unidirectional polyimide films will not experience performance degradation, such as degradation and delamination, due to the invasion of moisture, thus ensuring the normal operation of the equipment.
4、 In terms of electrical performance
1. High insulation
Unidirectional polyimide film is an excellent electrical insulation material. Its dielectric constant is low, which can effectively prevent the conduction of current. When used in insulation layers of high-voltage electrical equipment such as transformers and motors, it can avoid electrical short circuits and ensure the safe operation of the equipment. At the same time, its dielectric loss is also very low, which means that in AC electric fields, it can reduce energy loss and improve the efficiency of electrical equipment.
2. Resistance to corona discharge
It has good anti corona performance and can withstand high electric field strength without corona discharge phenomenon. In the insulation materials of high-voltage transmission lines, corona discharge may cause energy loss, electromagnetic interference, and other problems. The corona resistance of unidirectional polyimide film can effectively avoid these problems and improve the reliability of transmission lines.