Accelerating Rubber Ozone Aging through Environmental Simulation in the LISUN OTC-150A Ozone Test Chamber

Abstract
The durability of rubber products is significantly affected by their exposure to environmental factors, particularly ozone, which induces cracking and degradation. This paper explores the process of accelerating rubber aging using the ozone test chamber, specifically the LISUN OTC-150A Ozone Test Chamber, and how controlled environmental conditions can simulate the long-term effects of ozone on rubber materials. By replicating the ozone-rich atmosphere, the chamber allows for faster testing, helping industries evaluate the longevity and durability of rubber products. This paper will delve into the technical specifications of the LISUN OTC-150A, the test procedures, and provide data on how various rubber samples respond under these conditions.

1. Introduction
Ozone (O₃) is a reactive gas found in the atmosphere, which, even in small concentrations, can cause the oxidative degradation of elastomers. Rubber materials, when exposed to ozone, undergo chemical reactions that weaken their structural integrity, leading to cracking and eventual failure. The need for accurate testing methods to predict the longevity of rubber products in real-world conditions has led to the development of equipment such as the ozone test chamber.

The LISUN OTC-150A Ozone Test Chamber offers a controlled environment to simulate these aging processes in a shorter time frame, allowing manufacturers and researchers to evaluate the impact of ozone on different rubber compositions under accelerated aging conditions. This article provides a detailed analysis of the test chamber’s working mechanism and its application in the rubber industry.

2. Principle of Ozone Aging in Rubber
When rubber is exposed to ozone, it undergoes a process known as ozonolysis. The reaction occurs on the surface of the material, leading to molecular chain scission and the formation of cracks, particularly in parts of the rubber that are stretched. The degree of damage is influenced by factors such as the ozone concentration, temperature, humidity, and the duration of exposure.

The ozone test chamber recreates these conditions, allowing the rapid aging of rubber materials by:

• Maintaining specific ozone concentrations that simulate the exposure rubber products would face over years of usage.
• Controlling environmental conditions, such as temperature and humidity, to replicate real-world atmospheric conditions.
• Simulating stretching or elongation of rubber samples to observe crack formation in stressed areas.

3. LISUN OTC-150A Ozone Test Chamber
The LISUN OTC-150A Ozone Test Chamber is designed for accelerated ozone aging tests in a controlled environment. The chamber is equipped with state-of-the-art ozone generation and concentration monitoring systems that ensure precision in the testing process. Below are some of its key features:

• Ozone concentration control range: 10-500 ppm, ensuring a wide range of testing scenarios.
• Temperature control range: 0°C to +60°C, suitable for various aging test conditions.
• Sample positioning: Static and dynamic sample holders to test both unstressed and stressed rubber.
• Environmental control: The chamber offers humidity control and the ability to maintain stable temperature and pressure conditions during the test.

4. Experimental Procedure

The following steps outline the test procedure using the LISUN OTC-150A Ozone Test Chamber:

4.1. Sample Preparation

Rubber samples are prepared in accordance with international standards such as ISO 1431-1. The samples are typically strips or dumbbell-shaped pieces cut from rubber sheets. For dynamic tests, the samples are mounted on frames that allow them to be stretched to a defined elongation percentage.

4.2. Ozone Exposure

The chamber is set to maintain a specific ozone concentration, typically between 20 and 50 ppm for rubber testing. The samples are placed inside the chamber for durations ranging from 24 to 168 hours, depending on the aging requirements. The temperature inside the chamber is maintained at 40°C, a common condition for accelerated aging.

4.3. Observation and Data Recording

After exposure, the samples are examined under a microscope to assess the formation of surface cracks. The number, depth, and length of the cracks are recorded, and their progression is plotted over time to study the aging kinetics.

5. Results and Discussion
The following data (Table 1) represent typical results obtained from testing two types of rubber, natural rubber (NR) and styrene-butadiene rubber (SBR), under the same ozone concentration of 30 ppm at 40°C for different exposure times.

Sample Type	Ozone Concentration (ppm)	Temperature (°C)	Exposure Time (Hours)	Crack Initiation (Hours)	Average Crack Length (mm)
Natural Rubber (NR)	30	40	24	10	0.3
Natural Rubber (NR)	30	40	48	10	0.8
Natural Rubber (NR)	30	40	72	10	1.2
SBR	30	40	24	12	0.2
SBR	30	40	48	12	0.5
SBR	30	40	72	12	1

Discussion
From the data above, it is clear that natural rubber tends to initiate cracks earlier than SBR under the same test conditions, which suggests that SBR has better resistance to ozone-induced aging. The progression of crack length with time shows a linear increase in both materials, although NR experiences more severe cracking compared to SBR.

Additionally, the ability to control the ozone concentration in the LISUN OTC-150A Ozone Test Chamber ensures that different rubber types can be tested under identical conditions, providing reliable comparisons. The chamber’s dynamic sample holder also allows for a more realistic simulation of real-world conditions where rubber is stretched, enhancing the validity of the test results.

6. Conclusion
The use of the ozone test chamber, such as the LISUN OTC-150A Ozone Test Chamber, enables the accelerated aging of rubber materials in a controlled environment. This testing process is crucial for predicting the long-term durability of rubber products exposed to ozone. By simulating years of ozone exposure within days, manufacturers and researchers can assess the quality and life expectancy of rubber under various environmental conditions.

The data presented in this study highlight the differing responses of natural rubber and SBR to ozone exposure, with SBR showing greater resistance to ozone-induced cracking. The precise control offered by the LISUN OTC-150A ensures consistent and reproducible results, making it an invaluable tool for rubber aging studies.

References
ISO 1431-1: Rubber, vulcanized or thermoplastic – Resistance to ozone cracking.
LISUN Group. (n.d.). Ozone Test Chamber: LISUN OTC-150A Ozone Test Chamber | Ozone Aging Test Chamber. Retrieved from LISUN Group.
This paper has demonstrated how the ozone test chamber plays an essential role in simulating and accelerating the ozone aging process, providing insights critical for the rubber industry in ensuring the durability and performance of their products.

Tags：OTC-150A