anti-aging methods commonly used in plastic materials
anti-aging methods commonly used in plastic materials
In fact, polymer materials have become a necessity in every aspect of modern life. The latest progress in production and processing has further widened the application range of plastics. In some applications, polymer materials even replace other materials, such as glass, metal, paper and wood.
However, due to 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, their properties will decline or lose in the process of application, such as yellowing, decline in relative molecular weight, cracking of product surface, loss of luster, and more seriously, impact strength The mechanical properties such as tensile strength and elongation decrease greatly, which affects the normal use of polymer materials.
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. The aging of polymer materials in use is more likely to cause huge disasters and irreparable losses.
Therefore, the anti-aging of polymer materials has become a problem that the polymer industry has to solve. In fact, the anti-aging of polymer materials is an important topic in polymer chemistry. At present, there are four main methods to improve and improve the anti-aging performance of polymer materials:
1. Physical protection (such as thickening, coating, outer layer composite, etc.)
The aging of polymer materials, especially photooxidation aging, starts from the surface of materials or products, manifested as discoloration, pulverization, cracking, decline in gloss, etc., and then gradually goes deep into the interior. Thin products are easier to fail early than thick products, so the service life of products can be prolonged by thickening products.
For products that are easy to aging, a layer of coating with good weather resistance can be coated on the surface, or a layer of material with good weather resistance can be compounded on the outer layer of the product, so as to attach a protective layer to the surface of the product, so as to delay the aging process.
2. Improve processing technology
Many materials also have the problem of aging in the process of synthesis or preparation. For example, the influence of heat in the polymerization process, thermal oxygen aging in the processing process and so on. Accordingly, the influence of oxygen can be reduced by adding deaeration device or vacuum pumping device in the polymerization or processing process.
However, this method can only ensure the performance of the material when leaving the factory, and this method can only be implemented from the source of material preparation, which can not solve the aging problem in the process of reprocessing and use.
3. Structural design or modification of polymer materials
There are easily aging groups in the molecular structure of many polymer materials. Through the molecular structure design of materials, it can often play a good effect to replace easily aging groups with non easily aging groups.
4. Add anti aging additives.
At present, an effective way to improve the aging resistance of polymer materials is to add anti-aging additives. It is widely used because of its low cost and no need to change the existing production technology. There are mainly two ways to add these anti aging auxiliaries.
(1) Additive direct addition method
The anti aging additives (powder or liquid) will be directly mixed with resin and other raw materials, and then after mixing, granulating or injection molding can be done. Because of its simplicity, this addition method is widely used by the majority of granulation and injection molding plants.
(2) anti-aging masterbatch addition method
In factories with higher requirements for product quality and quality stability, more anti aging masterbatch is used in production.
The advantage of the application is that the anti-aging additives first realize the pre dispersing in the preparation process of the masterbatch. In the later stage of material processing, the anti-aging auxiliaries are dispersed for two times, which achieves the purpose of even dispersing of the auxiliaries in the polymer material matrix, not only ensuring the quality stability of the products, but also avoiding the dust pollution during the production process, making the production more green and environmental friendly.
