Ozone aging test chamber Rubber plastic aging test evaluation
The ozone aging test chamber simulates and strengthens the ozone conditions in the atmosphere, studies the effect of ozone on rubber, and quickly identifies and evaluates the rubber's anti-ozone aging performance and the protective effectiveness of anti-ozonants.
Shanghai Qianshi Precision Electromechanical Technology Co., Ltd. was established in 2012, focusing on the research and development, design, and production of textile testing instruments, providing textile testing instruments and services for academic research units and testing institutions. Shanghai Qianshi is currently one of the most competitive and R&D-capable textile testing instrument manufacturers in China. The R&D team is composed of a group of experienced engineers. We are committed to serving customers wholeheartedly and working hard to promote technological innovation in textile testing instruments.
Applicable standards:
GB/T 7762-2003 Static tensile test method for ozone cracking resistance of vulcanized rubber or thermoplastic rubber
GB/T 2951.1-2951.10-1997 General test method for cable insulation and sheath materials
When plastics are processed or used, the quality will gradually decrease. This phenomenon is called aging or deterioration. Although the term aging has long existed in the field of rubber, it mostly refers to changes over time and is not suitable for expressing a wide range of performance changes.
The main factors of aging are heat, ultraviolet rays, radiation, ozone, electrical, mechanical, chemical, microbial, etc., while oxygen, moisture, strain, etc. accelerate aging with these factors. Therefore, the changes in properties caused by this are diverse, and the specific situation is also very complicated for aging alone.
Plastic stability is generally considered to be the stability of a certain specific performance required and the stability of general performance. Usually, the requirements for physical, mechanical, electrical, and other properties are relatively high. However, it is necessary to recognize that the changes in the chemical structure caused by the aging of plastics have an impact on these properties - this is a basic problem.
The chemical aging process of plastics is molecular chain breakage, cross-linking, changes in the chemical structure of polymer chains, changes in side chain groups, etc. The combination and degree of these reactions vary with the environment.
When plastics are heated, they soften or melt. Especially when exposed to high temperatures, they are slowly oxidized by oxygen in the air. When exposed to high temperatures above the melting point, thermal decomposition occurs not only in air but also in a vacuum. It is well known that plastics age rapidly when exposed to direct sunlight outdoors, and the ultraviolet rays of sunlight and oxygen in the air are the greatest. However, if they act alone, they are weak.
Plastics are oxidized by heat and ultraviolet rays, and the physical properties change significantly as soon as the reaction begins. As mentioned above, this is because the molecular chains in the polymer break, and new bonds are generated, that is, regeneration bonds, branching, cross-linking, and cyclization.
Polymer chemistry has developed by leaps and bounds with the advancement of modern instrumental analysis technology. The research methods of chemical structure use powerful means such as infrared absorption spectrum, ultraviolet absorption spectrum, gas chromatography, mass analysis, electron spin resonance, radioisotope, etc. to identify structural changes. The degree of chain breakage and cross-linking reaction that occurs with aging, as well as the changes in polymer molecular weight caused by this, are studied by solution method, osmotic pressure method, light scattering method, sedimentation method, etc.
The melting and glass transition of polymers are reversible changes. However, heat can cause irreversible chemical changes to polymers. If there are no other active substances and effects, then the thermal stability of polymers is related to the bond dissociation energy of the various chemical structures that constitute the polymers.
In addition, photochemical reactions occur by selectively absorbing light radiation energy according to the chemical structure of the polymer. Generally, sunlight is the radiation energy source. The wavelength of sunlight that causes polymer aging is within the ultraviolet range of 300 to 400 nanometers.
Outdoor exposure aging is the result of the effects of ultraviolet radiation energy and major factors such as moisture, ozone, oxygen, heat, and other actual use conditions. Considering the complex aging mechanism, it is necessary to obtain a basic understanding of how the various main factors act on the polymer before making an overall evaluation. Therefore, to explain the complexity of polymer stability under the influence of various parameters, more basic information must be accumulated to establish practical accelerated aging test methods.