The structural characteristics and physical state of the polymer material itself, as well as the external factors such as heat, light, hot oxygen, ozone, water, acid, alkali, bacteria and enzymes that it is subjected to in the use process, will cause its performance to decline or lose in the application process. For example, yellowing, relative molecular mass decline, product surface cracking, luster loss, more serious is resulting in impact strength, tensile strength and elongation and other mechanical properties decreased significantly, and even lost use value. This phenomenon is simply called aging. Aging can occur in all stages of synthesis, storage, processing and final application of polymer materials, which can lead to the end of the service life of materials and a large amount of waste, resulting in a great waste of resources and serious environmental pollution.

Classification of aging of polymer materials In general, the aging of polymer materials can be classified into the following four types of changes:

(1) Changes in appearance. Such as stains, spots, silver lines, cracks, etc.

(2) Changes in physical properties. Such as quality, size, heat resistance, cold resistance and other performance indicators change.

(3) The change of mechanical properties. Such as tensile, bending, compressive and other properties of change.

(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 applications, once the aging failure occurs in use, it will inevitably cause economic losses, and may even lead to environmental damage, personal injury and so on. Therefore, it is necessary to replace the polymer material products before aging failure. In the principle of energy saving, low-carbon and ecological development, but also to maximize the function of polymer materials products, the reliability and durability of materials are more and more people's attention.

Nylon aging PA6, PA66 has the advantages of light weight, high toughness, good electrical insulation and thermal insulation performance, etc., widely used in the electronic industry, such as electrical machinery or power tool shell, electrical tuning parts, machine shell, automotive engine blade and so on. However, as the basic raw materials of electronic devices, it is required that in a certain period of use, not only the mechanical strength is maintained well, but also the appearance and color of products after aging can not change too much, especially some light-colored nylon products with strict appearance requirements, otherwise it will reduce the performance of electronic products and affect the normal use of devices. As PA6, PA66 materials used in indoor electronic appliances will face high local temperature in actual use, so the long-term heat effect is one of the important factors that make PA6, PA66 aging; In the actual use of the environment and conditions, in most cases will be aerobic participation in the aging process of nylon, the combined effect of heat and oxygen will greatly accelerate its aging process.

Therefore, it is necessary to take anti-aging measures for PA6 and PA66. At present, it has been found that adding antioxidants and blending modification can improve the heat aging property of PA materials and greatly extend the service life of the material. Commonly used reinforced nylon has thermal oxygen stabilizers, including copper stabilizers, amines and hindered phenol antioxidants, hydroperoxide decomposers, etc. According to some data introduction and a lot 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 a good ultraviolet absorber, so the black reinforced nylon material is more resistant to aging than other color reinforced nylon.

It has been found that POE-g-MAH elastomers can resist thermal aging to a certain extent in toughened PA6 systems. The combination of antioxidant 1098 and phosphite antioxidant 626 has a synergistic effect in the PA6 system. Copper salt antioxidants and antioxidant 1098 and their complex antioxidants are highly effective antioxidants of PA6 resin system. The antioxidant of copper salt has more obvious anti-thermal aging effect on toughening PA6 system. The antioxidant 1010 mixture system has limited anti-thermal aging effect on PA6 resin. Nylon reinforced with copper salt antioxidant and 1098 compound antioxidant toughened PA6 material can meet the requirements of thermal oxidation aging of materials.