Aging test methods and relevant standards of polymer materials

Date：2022-09-20 15:03:05 Views：1333

Polymer materials are widely used in almost all fields, including lunch boxes, plastic bags, instrument equipment shells, wire and cable jackets, car bumpers, clothes, films, wind turbine blades, gears, structural parts, etc., and are widely used in people's daily life. At present, there are many aging test methods to study polymer materials, mainly including climate aging test, ultraviolet aging test, ozone aging test, hot air aging test, high and low temperature alternating aging test, damp heat aging test, medium aging test, salt spray aging test, etc.

1. Climate aging test

The so-called climate aging test is a research method that exposes polymer material test samples to the atmospheric environment, so as to obtain the aging rule of material samples under the atmospheric environment, analyze the performance of polymer materials, and predict their service life.

Climate aging test can be divided into two types:

One of them is the natural exposure test, that is, the polymer material test sample is exposed to the real atmospheric environment to obtain the aging behavior of the material in the real environment. This aging test method obtains the most accurate aging information and is the most effective method to obtain the aging behavior of polymer materials. However, this test method is time-consuming and laborious. The other is artificial weather aging test. Artificial weather aging test refers to the aging test method in which people can obtain the aging behavior of materials in a short time by simulating the real atmospheric environmental conditions indoors or strengthening a certain environmental factor, which is also called artificial simulation aging or artificial accelerated aging. Artificial weathering is usually carried out in the artificial weathering chamber. The commonly used artificial climate aging chambers mainly include xenon lamp climate aging chamber, fluorescent lamp climate aging chamber and carbon arc lamp climate aging chamber. These climate aging test chambers simulate or strengthen natural environmental factors from light, temperature, humidity, rain or condensation and other major climate factors to achieve material aging. In addition, the aging test of materials shall be carried out according to certain test standards.

2. Ultraviolet aging test

Ultraviolet light in sunlight, due to its light energy equivalent to the bond energy of polymer chemical bond, can cause the fracture of polymer compound chain, which is the main factor leading to the aging and degradation of polymer materials. UV aging test refers to the test method of exposing polymer material aging test samples under UV light field to obtain the aging behavior and rules of polymer materials. Generally, the ultraviolet aging test will specify that the ultraviolet area and radiation intensity, such as 40W/m2, are within the wavelength range of 300nm - 400nm. The light sources used in ultraviolet aging test usually include xenon lamp, fluorescent lamp, tritium lamp and deuterium lamp. Among them, xenon lamp can well simulate the solar spectrum, fluorescent lamp can well simulate the ultraviolet spectrum in sunlight, and tritium lamp provides strong energy, which is generally used for accelerated aging test.

3. Ozone aging test

Ozone is a rare gas in the atmosphere, but it is extremely destructive to polymer materials. Ozone can react irreversibly with the unsaturated bonds and reducing groups in the chemical structure of polymer materials, leading to the oxidative degradation of polymer materials, thus losing their use value. Especially for rubber materials containing double bonds, it shows strong destructive power. Ozone has a strong activity. It can decompose more active atomic oxygen and react with the double bonds in rubber molecules, leading to rubber aging, cracking, embrittlement and other phenomena. The ozone aging test of polymer materials is usually carried out in the ozone aging test box. The ozone is provided by the ozone generator. Its concentration can be adjusted by mixing the mixer with air. The ozone concentration is generally determined according to the environmental conditions where the materials are actually used. In addition, the temperature, humidity and other factors in the ozone aging box can also be adjusted, so as to achieve the purpose of the test, and obtain the ozone aging resistance of materials, as well as the ozone aging behavior and law.

4. Hot air aging test

Heat is one of the main factors that lead to the aging of polymer materials. Heat can accelerate the movement of polymer chains, lead to the fracture of polymer chains, generate active free radicals, make them react with free radical chains, and lead to the degradation or cross-linking of polymers. Hot air aging test is one of the main test methods to evaluate polymer materials and study the aging resistance of polymer materials. It is usually carried out in a constant temperature air drying test box. The temperature in the drying box can be set according to the test requirements. Polymer materials are regularly sampled and tested when exposed to dryness, so as to obtain the aging behavior and rules of polymer materials, so as to modify polymer materials in a targeted way and improve their use performance.

5. Temperature alternating aging test

Temperature is another important factor leading to the aging of polymer materials. For polymer adhesives, high temperature can accelerate the movement rate of polymer adhesive chain, while low temperature can lead to the internal stress of polymer adhesives. The high and low temperature alternation can lead to the fracture of polymer adhesive chain and aging degradation. For rubber, high temperature can accelerate the thermal movement of the molecular chain, making the rubber cross-linked, and low temperature can cause the rubber molecular chain to freeze, making it brittle, elastic and aging. The high and low temperature alternating aging test is an aging test method to evaluate the temperature resistance of polymer materials. It is usually conducted in the temperature alternating aging test box. The temperature is raised from a certain temperature T1 (usually room temperature) to a certain temperature T2 at a constant heating rate, and the T2 temperature is maintained for a certain time. Then, the temperature is lowered to a certain temperature T3 at a constant cooling rate, and the T3 temperature is maintained for a certain time. Then, the temperature is raised to T1, which is a temperature cycle. The cycle length can be determined according to the specific test requirements.

6. Damp heat aging test

Damp heat aging test is an effective method to evaluate the aging resistance of polymer materials in high humidity and high temperature environments. In a high humidity environment, water can penetrate into the polymer material, causing swelling of the polymer material, hydrolysis of some hydrophilic groups, and aging and degradation of the polymer material. In addition, when water seeps into polymer materials, it can also lead to the dissolution and migration of additives in polymer materials, such as plasticizers, compounding agents and other substances, and affect the mechanical properties of polymer materials. Under the action of high heat, heat can promote the penetration of water. Heat promotes the movement of polymer chains to increase, and the intermolecular force to reduce, which promotes the penetration of water and accelerates the degradation of polymer materials. Different polymer materials have different formulations, so their hydrothermal aging mechanisms are also different. Different aging standards should be selected according to different polymer materials during the hydrothermal aging test. The damp heat aging test is usually carried out in the damp heat aging test chamber, and the temperature and humidity can be set according to the test requirements.

7. Medium aging test

Some polymer materials need to be soaked in a certain medium for a long time in the process of use. For example, polymer materials on equipment engaged in offshore operations or undersea operations need to be soaked in seawater for a long time, and some parts of aircraft need to be exposed to aviation fuel for a long time. All these require that high molecular materials have strong resistance to medium aging. The dielectric aging test is a common test method to evaluate the dielectric aging resistance of polymer materials and predict their life in a certain medium. The medium used for aging test can be prepared according to the specific environment of polymer materials, including artificial seawater, brine, rainwater, acid and alkali solutions, fuel oil and other organic solvents.

Relevant standards for aging test

GB/T16422.2 Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon arc lamps

GB/T3511-2008 Weather Resistance of Vulcanized Rubber or Thermoplastic Rubber

Paints and varnishes -- Artificial weathering and artificial radiation exposure (filtered xenon arc radiation)

GB/T16422.3-1997 Plastics - Methods of exposure to laboratory light sources - Part 3: Fluorescent ultraviolet lamps

GB/T14522-2008 Test Method for Artificial Weathering of Plastics, Coatings and Rubber Materials for Mechanical Industrial Products Fluorescent Ultraviolet Lamp

GB/T16422.4-1996 Plastics - Methods of exposure to laboratory light sources - Part 4: Open carbon arc lamps

Rubber, vulcanized -- Test method for artificial weathering (carbon arc lamp)

GB/T7762-2003 Static tensile test method for ozone cracking resistance of vulcanized rubber or thermoplastic rubber

GB/T13642-1992 Rubber, vulcanized -- Dynamic tensile test method for ozone aging resistance

GB / t12000-2003 plastics exposure to damp heat, water spray and salt

GB/T1771-2007 Paints and Varnishes Determination of Resistance to Neutral Salt Spray

GB / t12000-2003 plastics - Determination of effects of exposure to damp heat, water spray and salt spray

GB/T15905-1995 Vulcanized rubber -- Test method for damp heat aging

GB/T1740-2007 Determination of Damp Heat Resistance of Paint Films

GB/T3512-2001 Vulcanized rubber or thermoplastic rubber Accelerated aging and heat resistance test by hot air

GB/T7141-2008 Test Method for Thermal Aging of Plastics

GB/T3681-2000 Test Method for Atmospheric Exposure of Plastics

GB/T9276-1996 Test Method for Natural Weather Exposure of Coatings

Xenon arc lamp accelerated exposure test for automotive interior materials SAEJ2527:2004

Xenon arc lamp accelerated exposure test for automotive exterior decoration materials SAEJ2412:2004

Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon arc lamp ISO 4892-2:2006

Plastics for indoor use Xenon arc light exposure test method AS4459-06

Instrument operation method for xenon arc lamp aging of non-metallic materials ASTMG155-05a

Operation of Xenon Arc Type Exposure Apparatus with or without Water for Plastic Exposure Test AS2565-99 (2008)

Plastics - Exposure test methods to laboratory light sources - Part 3: Fluorescent ultraviolet lamps ISO 4892-3:2006

UV Rapid Aging Test of Automotive Exterior Decoration Materials SAEJ2020:2003

Test Method for Ultraviolet Light Exposure of Plastics AS4329-05

Instrument operation method for UV aging of non-metallic materials ASTMG154-06

Thermal aging of unloaded plastic products AS3045-92 (2003)

Plastics Determination of hygrothermal, water splash and salt spray effects ISO 4611:2008

Test Method for Tensile Properties of Plastics AS638-08