Knowledge Of The Industry| Plastic Anti-Aging 4 Must-See Guides

Polymer materials are now widely used in high-end manufacturing, electronic information, transportation, building energy saving, aerospace, national defense and many other fields because of their excellent properties such as light weight, high strength, temperature resistance and corrosion resistance. This not only provides a broad market space for the new polymer material industry, but also puts forward higher requirements for its quality performance, reliability level and guarantee capability.

Therefore, how to maximize the function of polymer material products in line with the principle of energy saving, low carbon and ecological development is getting more and more attention. And aging is an important factor that affects the reliability and durability of polymer materials.

Next, we will look at what is aging of polymer materials, aging types, factors causing aging, the main methods of anti-aging and the anti-aging of five general plastics.

A. Plastic aging
The structural characteristics and physical state of polymer materials themselves and their external factors such as heat, light, thermal oxygen, ozone, water, acid, alkali, bacteria and enzymes in the process of use make them subject to performance degradation or loss in the process of application.

This not only causes a waste of resources, and may even cause greater accidents due to its functional failure, but also the decomposition of the material caused by its aging may also pollute the environment.

The aging of polymer materials in the process of use is more likely to cause great disasters and irreparable losses.

Therefore, the anti-aging of polymer materials has become a problem that the polymer industry has to solve.

B. Types of polymer material aging
There are different aging phenomena and characteristics due to different polymer species and different usage conditions. In general, the aging of polymer materials can be categorized into the following four types of changes.

01 Changes in appearance
Stains, spots, silver lines, cracks, frosting, chalking, stickiness, warping, fish eyes, wrinkling, shrinkage, scorching, optical distortion and optical color changes.

02 Changes in physical properties
Including solubility, swelling, rheological properties and changes in cold resistance, heat resistance, water permeability, air permeability and other properties.

03 Changes in mechanical properties
Changes in tensile strength, bending strength, shear strength, impact strength, relative elongation, stress relaxation and other properties.

04 Changes in electrical properties
Such as surface resistance, volume resistance, dielectric constant, electric breakdown strength and other changes.

C. Microscopic analysis of aging of polymer materials
Polymers form excited states of molecules in the presence of heat or light, and when the energy is high enough, the molecular chains break to form free radicals, which can form chain reactions within the polymer and continue to initiate degradation and may also cause cross-linking.

If oxygen or ozone is present in the environment, a series of oxidation reactions are also induced, forming hydroperoxides (ROOH) and further decomposing into carbonyl groups.

If residual catalyst metal ions are present in the polymer, or if metal ions such as copper, iron, manganese and cobalt are brought in during processing or use, the oxidative degradation reaction of the polymer will be accelerated.

D. The main method to improve the anti-aging performance
At present, there are four main methods to improve and enhance the anti-aging performance of polymer materials as follows.

01 Physical protection (thickening, painting, outer layer compound, etc.)

The aging of polymer materials, especially photo-oxidative aging, starts from the surface of materials or products, which is manifested as discoloration, chalking, cracking, gloss decrease, etc., and then gradually goes deeper to the interior. Thin products are more likely to fail earlier than thick products, so the service life of the products can be extended by thickening the products.

For products prone to aging, a layer of weather-resistant coating can be applied or coated on the surface, or a layer of weather-resistant material can be compounded on the outer layer of the products, so that a protective layer can be attached to the surface of the products to slow down the aging process.

02 Improvement of processing technology

Many materials in the synthesis or preparation process, there is also the problem of aging. For example, the influence of heat during polymerization, thermal and oxygen aging during processing, etc. Then accordingly, the influence of oxygen can be slowed down by adding deaerating device or vacuum device during polymerization or processing.

However, this method can only guarantee the performance of the material at the factory, and this method can only be implemented from the source of material preparation, and cannot solve its aging problem during reprocessing and use.

03 Structural design or modification of materials

Many macromolecule materials have aging groups in the molecular structure, so through the design of the molecular structure of the material, replacing the aging groups with the non-aging groups can often play a good effect.

04 Adding anti-aging additives

At present, the effective way and common method to improve the aging resistance of polymer materials is to add anti-aging additives, which are widely used because of the low cost and no need to change the existing production process. There are two main ways of adding these anti-aging additives.

The anti-aging additives (powder or liquid) and resin and other raw materials directly mixed and mixed after extrusion granulation or injection molding, etc.. This is a simple and easy way of addition, which is widely used by the majority of pelletizing and injection molding plants.

Post time: Oct-26-2022

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