Rubber Products The Cause Of Aging

First, the aging of rubber products

In 1885 people found that the tensile rubber in the aging process of cracking, when people thought it was due to the sun caused by the radiation, but later found that the sun without exposure to rubber products, there are also cracks. Later, after analysis, it was found that the cracks that were not exposed to the sun's rubber were due to the presence of ozone in the atmosphere.

At 20-30 km from the ground at high altitude, oxygen molecules in the sunlight will produce bulle molecules to form a layer of ozone layer. Although the surface of the ozone concentration is low, but the phenomenon of rubber talent can not be ignored, more and more audience attention.

Rubber ozone aging and other factors produced by the aging is different, mainly the following performance.

(1) The ozone aging of the rubber is a surface reaction, the stress on the surface of the rubber is not expected to be 10-40 molecules thick, or (10 ~ 50) * 10-6 square mm thick.

(2) When the undrawn rubber is exposed to the O3 environment, the rubber reacts with O3 until the double bond on the surface is completely terminated, forming a layer of frost-like gray hardcoat on the surface, making it Lose luster. Stretched rubber in the ozone aging, the surface to produce ozone cracking, but through the study that the rubber ozone cracking has a critical stress, when the rubber elongation or stress is below the critical value, in the Occurrence of ozone aging will not produce cracks, which is the inherent characteristics of rubber.

(3) rubber in the production of ozone cracking, the direction of the crack and the direction of the force perpendicular to the direction, which is the ozone cracking and light and oxygen caused by the difference between the aging, should be noted that in many directions by the stress of the rubber Ozone aging, the resulting ozone cracking is very difficult to see the direction of light, and the aging of light caused by similar cracks.

Aging is a rubber and other polymer materials in the existence of a more common phenomenon, it will degrade the performance of rubber, rubber products affect the use of value and service life, rubber protection system is to delay the aging of rubber to extend the service life of products. Rubber protection system is mainly antioxidant, anti-aging agent according to the principle of action can be divided into chemical antioxidant and physical antioxidant; according to the protection of the target is divided into antioxidants, ozone protection agent, light shielding agent, metal passivation agent, etc. Classification by chemical structure.

(1) the phenomenon of rubber aging: raw rubber or rubber products in the processing, storage or use of the process, will be subject to heat, oxygen, light and other factors and the gradual changes in the physical and chemical changes, to its performance, and Loss of use, this phenomenon is known as the aging of rubber. Rubber aging process often accompanied by some significant phenomenon, such as the appearance can be found in the long-term storage of natural rubber softening, sticky, spot; rubber products are deformed, brittle, hardened, cracked, moldy, loss of light And color changes. In the physical properties of rubber swelling, rheological properties such as changes. In the mechanical properties of tensile strength, elongation at break, impact strength, bending strength, compression rate, elasticity and other indicators decreased.

(2) the reasons for the aging of rubber: rubber aging phenomenon due to its long-term heat, oxygen, light, mechanical force, radiation, chemical media, ozone and other external factors in the air, so that its macromolecular chain chemical changes, The original chemical structure of the rubber, resulting in deterioration of rubber properties. The external factors that cause the aging of rubber are physical factors, chemical factors and biological factors. Physical factors include heat, light, electricity, stress, etc .; chemical factors include oxygen, ozone, acid, alkali, salt and metal ions; biological factors include microorganisms (mold, bacteria), insects (termites, etc.). These external factors in the rubber aging process, often not a separate role, but mutual influence, accelerate the aging process of rubber. Such as the tire sidewall in the course of the use of heat, light, alternating stress and strain, oxygen, ozone and other factors.

Different products in different conditions of use, the role of various factors vary, the aging situation is not the same. Even if the same product, due to the use of different seasons and regions, aging is also different. Therefore, the aging of rubber is caused by a variety of factors caused by a comprehensive chemical reaction. Among these factors, the most common and most important chemical factors are oxygen and ozone; physical factors are heat, light and mechanical stress. General rubber products are aging by one or several of their factors together, the most common thermal oxygen aging, followed by ozone aging, fatigue aging and photo-oxygen aging.

Second, the rubber products to prevent aging

Rubber aging method of protection: With the aging process of rubber, rubber properties gradually decline, the use of value is gradually lost. Therefore, the study of aging and protection methods have a very important practical and economic significance. As the aging of rubber is a complex process of comprehensive chemical reaction, but also to prevent the occurrence of rubber aging is impossible. Therefore, only careful study of the causes of aging of rubber causes, and according to these reasons the right medicine, take appropriate measures to delay the aging of rubber, so as to achieve the purpose of extending the life of rubber. As the factors that cause the aging of rubber products are different,

Therefore, according to different aging mechanism to take the appropriate anti-aging measures, mainly physical protection and chemical protection law. Physical protection law is to avoid the rubber and a variety of aging factors such as the use of rubber and plastic blends, surface coating or treatment, plus light shielding agent, plus paraffin and so on. Chemical protection law refers to the active addition of substances to prevent or delay the aging of the rubber to continue, such as adding amine or phenolic chemical antioxidant.

Anti-aging is mainly from the reduction of vulcanized rubber polymer chain on the chain of unsaturated double bond-based, for example, with a number of chain modification, the use of special chemical reactions, so that unsaturated bonds saturated, so that the molecular structure of the level to be improved Aging, delay aging and extend its service life.

Second, in the rubber, plastic and other processing process to add antioxidants, for example, in the vulcanized rubber formula to add UV stabilizer, anti-mildew agent, heat stabilizer, add to prevent ozone or oxygen caused by aging antioxidant.

Again, it can also be used to increase the physical protection of the coating and the protective film, such as dipping the anti-aging agent solution, painting, plating metal and so on.