How to enhance nylon's anti-aging ability?
TIME：2021-10-7
The structural characteristics and physical state of polymer materials and the external factors such as heat, light, thermal oxygen, ozone, water, acid, alkali, bacteria and enzymes in the process of use will lead to the decline or loss of performance in the process of application, such as yellowing, decline of relative molecular weight, cracking of product surface, loss of luster, and more seriously, impact strength The mechanical properties such as tensile strength and elongation decreased significantly, and even lost their use value. This phenomenon is called aging for short.
Aging may occur in all stages of polymer material synthesis, storage, processing and final application, which can lead to the end of material service life and massive waste, resulting in great waste of resources and serious environmental pollution.
Aging classification of polymer materials
In general, the aging of polymer materials can be divided into the following four types of changes:
(1) Changes in appearance. Such as stains, spots, crazes, cracks, etc.
(2) Changes in physical properties. Such as changes in quality, size, heat resistance, cold resistance and other performance indicators.
(3) Changes in mechanical properties. Such as the change of tensile, bending and compressive properties.
(4) Changes in electrical properties. Such as insulation resistance, dielectric loss, breakdown voltage, etc.
Polymer materials and their products play a very important role in practical application. Once aging failure occurs in use, it will inevitably cause economic losses, even environmental damage, personal casualties and so on.
Therefore, polymer products must be replaced before aging and failure. With the principle of energy saving, low carbon and ecological development, and giving full play to the function of polymer products, the reliability and durability of materials have attracted more and more attention.
Aging of nylon
PA6 and PA66 have the advantages of light weight, high toughness, good electrical insulation and thermal insulation. They are widely used in the electronic industry, such as electrical machinery or power tool housing, electrical tuning parts, machine housing, automobile engine blades, etc.
However, as the basic raw material of electronic devices, it is required not only to maintain good mechanical strength within a certain service life, but also that the appearance and color of products can not change too much after aging, especially some light colored nylon products with strict appearance requirements, otherwise the performance of electronic products will be reduced and the normal use of devices will be affected.
PA6 and PA66 materials for electronic and electrical appliances used indoors will face high local temperature in practical use, so the long-term thermal effect is one of the important factors for the aging of PA6 and PA66; In the actual use environment and conditions, in most cases, oxygen will participate in the aging process of nylon, and the joint action of heat and oxygen will greatly accelerate the aging process. Therefore, it is very necessary to take anti-aging measures for PA6 and PA66.
Anti aging method of reinforced nylon
It has been found that the addition of antioxidants and blending modification can improve the heat aging resistance of PA materials and greatly extend the service life of PA materials.
Commonly used reinforced nylon has thermal oxygen stabilizer, including copper stabilizer, amine and hindered phenol antioxidant, hydroperoxide decomposition agent, etc.
According to some data introduction and a large number of experiments, the anti-aging effects of different antioxidant systems are as follows: copper salt antioxidant > 1098 + 626 antioxidant system > 1098 antioxidant system > 1010 + 626 antioxidant system. Carbon black has good ultraviolet absorber, so black reinforced nylon material is more resistant to aging than other color reinforced nylon.
It has been found that POE-g-MAH elastomer can resist thermal aging to a certain extent in toughened PA6 system. The combination of antioxidant 1098 and phosphite antioxidant 626 has a synergistic effect in PA6 system.
Copper salt antioxidant, antioxidant 1098 and their composite antioxidants are high-efficiency antioxidants in PA6 resin system. Copper salt antioxidant has more obvious anti-aging effect on toughened PA6 system. Antioxidant 1010 blending system has limited anti-aging effect on PA6 resin. Reinforced nylon and copper salt antioxidant and 1098 complex antioxidant toughened PA6 material can meet the requirements of thermal oxidation aging.
