A Complete Guide to ISO 188 Pamantayan: International Core Specification for Accelerated Ageing and Heat Resistance Testing of Rubber

In the field of quality control and performance evaluation of rubber materials and products, the ISO 188 standard is a globally recognized core technical specification. Its full name is “Rubber, vulcanized or thermoplastic—Accelerated ageing and heat resistance tests”, compiled and released by the Technical Committee on Rubber and Rubber Products (ISO/TC 45) under the International Organization for Standardization (ISO). It is an indispensable technical basis for R&D, production, testing and international trade in the rubber industry. Its core function is to quickly evaluate the performance stability of rubber materials under high-temperature conditions by artificially simulating accelerated ageing environments, predict their service life in practical use, and provide scientific support for product design, material selection and quality verification.

I. Development Background and Core Positioning of ISO 188 Pamantayan

As a polymer material, rubber will undergo chemical reactions such as oxidation and degradation under the influence of environmental factors such as temperature, oxygen and humidity during long-term use, leading to ageing phenomena such as hardness change, decreased tensile performance and loss of elasticity, which in turn affect the reliability and safety of products. The traditional natural ageing test cycle is as long as several months or even years, which cannot meet the needs of enterprises for rapid R&D and mass production. The ISO 188 standard emerged as the times require. Through accelerated ageing technology, it simulates the long-term ageing effect of rubber in a short time, filling the gap in rapid performance evaluation.
Since its release, the ISO 188 standard has been revised and improved many times to continuously adapt to new rubber materials and industry development needs. Sa kasalukuyan, the mainstream versions include ISO 188:2011 released in 2011 and the latest ISO 188:2023 released in 2023. Kabilang sa mga ito, ISO 188:2011, as a long-term and widely used version, has been equivalently adopted by many countries. The corresponding national standard in China is GB/T 3512-2014 (equivalent to ISO 188:2011). Ang 2023 new version has optimized and upgraded equipment control, detection accuracy and scope of application, further improving the scientificity and practicality of the standard.
In terms of core positioning, ISO 188 is a globally accepted product performance testing standard with no mandatory binding force. Gayunpaman, due to its accurate coverage of the core needs of rubber ageing testing, it is widely adopted by global rubber manufacturers, testing institutions and purchasers. Especially for import and export rubber products, passing the ISO 188 standard test is an important prerequisite for proving the product’s ageing resistance and obtaining market access. The scope of application of this standard covers all types of vulcanized rubber and thermoplastic rubber, including natural rubber, synthetic rubber (styrene-butadiene rubber, chloroprene rubber, silicone rubber, atbp.) and their composite materials. It is suitable for the ageing performance evaluation of various rubber products such as tires, seals, hoses and rubber accessories, and explicitly excludes the ageing testing of non-rubber materials.

II. Core Test Principles and Classification of ISO 188 Pamantayan

(I) Core Test Principles
The test principle of ISO 188 standard is based on two cores: “accelerated ageing” at “heat resistance testing”. It simulates the ageing environment of rubber in practical use by controlling key parameters such as temperature, air flow rate and ventilation frequency: Accelerated ageing test accelerates the oxidative degradation rate of rubber by increasing the environmental temperature, and obtains performance change data equivalent to natural ageing in a short time; Heat resistance test places the sample at a temperature consistent with the actual service environment, evaluates its performance stability after long-term exposure, and directly reflects the heat resistance of the product in actual working conditions.
The core logic of the test is: place the rubber sample in a standardized hot air ageing oven, expose it for a certain period of time under specified temperature, ventilation frequency and air flow rate conditions, then measure the physical properties of the aged sample (such as tensile strength, elongation at break, hardness, atbp.), compare it with the properties of the unaged sample, and evaluate the ageing resistance and heat resistance grade of the rubber through the performance change rate. The standard clearly recommends that, in the absence of special requirements, priority should be given to testing tensile properties (measured in accordance with ISO 37) and hardness (measured in accordance with ISO 48), which can most intuitively reflect the ageing degree of rubber.
(II) Classification of Core Test Methods
The ISO 188 standard clearly specifies two core test methods. The main differences lie in the type of ageing oven and air flow rate control, which can be flexibly selected according to the characteristics of rubber materials and testing needs. The ventilation frequency of both methods is required to be 3~10 times per hour to ensure the stability of the ageing environment:
Method A: Low Air Flow Oven Method
This method uses a multi-cell or cabinet-type hot air ageing oven without forced ventilation device, and the air flow rate is low, which is only determined by the ventilation frequency. The multi-cell ageing oven is composed of one or more vertical cylindrical cells with a height of not less than 300mm, and each cell is independently ventilated to avoid cross-influence of air in different cells; The cabinet-type ageing oven is a single chamber without a ventilation fan, and the air flows naturally and slowly. This method is suitable for rubber materials sensitive to air flow rate and requiring simulation of mild ageing environment, such as some soft rubber seals and rubber gaskets.
Method B: Forced Ventilation Air Oven Method
This method uses a cabinet-type hot air ageing oven with fan forced ventilation. The fan promotes air circulation to improve the temperature uniformity in the ageing oven, and the air flow rate is relatively high. According to the air flow state, it can be divided into two types: Type 1 laminar air ageing oven, where the air is in a uniform laminar state, the flow rate is controlled at 0.5~1.5m/s, and the sample placement should avoid disturbing the air flow; Type 2 turbulent air ageing oven, where the air forms turbulence around the sample, and the sample is hung on a bracket rotating at 5~10r/min to ensure uniform heating, with an average air flow rate of 0.5±0.25m/s. This method is suitable for most rubber materials, especially industrial rubber products that require rapid and uniform ageing, such as tires and rubber hoses.

III. Core Test Requirements of ISO 188 Pamantayan

The ISO 188 standard puts forward clear requirements for test equipment, sample preparation, test condition control, performance testing and result evaluation to ensure the operability, reproducibility and accuracy of the test. The core requirements are as follows:
(I) Test Equipment Requirements
The core test equipment is a hot air ageing oven, whose performance directly affects the accuracy of test results. The standard has strict regulations on the structure, material and parameter control of the equipment:
•Material of ageing oven: Copper or copper alloy shall not be used in the heating chamber structure to avoid the material affecting the ageing process of rubber; The box material shall be high-temperature resistant, corrosion resistant and shall not have chemical reaction with rubber samples.
•Volume and sample placement: The total volume of samples shall not exceed 10% of the effective volume of the ageing oven; The distance between suspended samples shall be at least 10mm, and in cabinet-type and forced ventilation-type ageing ovens, the distance between samples and the box wall shall be at least 50mm to ensure uniform heating of samples and avoid mutual influence.
•Temperature control: Equipped with a temperature sensor installed near the sample to record the real ageing temperature in real time; During the entire test, the sample temperature shall be kept within the allowable tolerance of the specified temperature, and the air entering the ageing oven shall be heated to within ±1℃ of the set temperature before contacting the sample.
•Ventilation and flow rate: The ventilation frequency is controlled at 3~10 times per hour, and the ventilation rate can be calculated by the volume of the ageing oven and the air flow rate; The forced ventilation-type ageing oven shall be equipped with an anemometer to regularly measure the air flow rate to ensure compliance with standard requirements.
•Equipment calibration: The standard clearly requires regular calibration of test equipment, including temperature sensors, anemometers, ageing ovens, atbp. The calibration cycle shall comply with relevant specifications to ensure the accuracy and stability of equipment parameters. ISO 188:2011 also specially added provisions and calibration schedules for equipment calibration.
(II) Sample Preparation Requirements
Sample preparation shall comply with the relevant provisions of ISO 23529 (General procedures for preparation and conditioning of test pieces for physical testing of rubber). The core requirements include:
•Samples shall be randomly selected from rubber products or materials to ensure representativeness, and samples with defects, damage or impurities shall be avoided;
•Prepare samples according to the size and shape specified by the standard. The size of samples for different performance tests (such as tensile strength and hardness) shall meet the requirements of corresponding standards (ISO 37, ISO 48) to avoid size errors affecting test results;
•After sample preparation, pretreatment shall be carried out, including cleaning and drying, to remove surface oil, dust and other impurities to ensure that the surface is free of damage and moisture; Vulcanized rubber samples shall be placed for a specified time interval after vulcanization before ageing test to avoid insufficient vulcanization affecting the results.
(III) Test Condition Control
The stability of test conditions is the key to ensuring the reliability of test results. The core control indicators include temperature, exposure time and environmental humidity:
•Temperature: Determined according to the service environment and test purpose of rubber materials, usually divided into accelerated ageing temperature (higher than the actual service temperature, such as 70℃, 100°C, 150°C, atbp.) and heat resistance test temperature (consistent with the actual service temperature). The temperature deviation shall be controlled within ±2℃, and the temperature shall be recorded at least twice a day (with an interval of not less than 7 mga oras).
•Exposure time: The standard does not specify a unified exposure cycle, which shall be determined according to product use, material characteristics and relevant agreements, usually ranging from dozens of hours to hundreds of hours; The time of accelerated ageing test can be calculated by Arrhenius equation or WLF equation, and the long-term service life of rubber can be predicted by combining test results at multiple temperatures.
•Humidity: The ISO 188:2023 version further emphasizes the control of humidity. Some tests need to be carried out in a specified humidity or steam environment to simulate the humid working conditions in actual use, making the test results closer to the real situation.
(IV) Performance Testing and Result Evaluation
After the ageing test, the samples shall be taken out of the ageing oven and placed in a standard environment for a certain period of time (usually 24 mga oras) to return to room temperature before performance testing. The core test items include:
•Tensile properties: Measure tensile strength, tensile stress at a given elongation and elongation at break in accordance with ISO 37, and calculate the performance change rate after and before ageing;
•Hardness: Measure Shore hardness (10~100 IRHD) in accordance with ISO 48 to evaluate the hardening degree of rubber after ageing;
•Other properties: According to product requirements, additional tests such as mass change, volume change and elastic recovery can be carried out to comprehensively evaluate the ageing characteristics of rubber.
Result evaluation shall be clear: Judge the ageing resistance grade of rubber through the performance change rate. The smaller the change rate, the better the ageing resistance of rubber; Kasabay nito, abnormal conditions during the test (such as sample cracking, deformation, discoloration, atbp.) shall be recorded, and a detailed test report shall be finally formed, clarifying the test conditions, process and result judgment to ensure the traceability and authority of the report. ISO 188:2011 also added the results of precision tests, providing a more scientific reference for result evaluation.

IV. Correlation and Differences Between ISO 188 and GB/T 3512

China’s national standard GB/T 3512-2014 is equivalent to ISO 188:2011. The two are completely consistent in core technical requirements, test methods and result evaluation, and only adaptively adjusted in the form of standard expression and normative reference documents — GB/T 3512-2014 refers to China’s corresponding national standards (such as GB/T 528-2009 corresponding to ISO 37:2005, GB/T 6031-1998 corresponding to ISO 48:1994), which is more in line with China’s industry usage habits.
The subtle differences between the two are mainly reflected in the focus of application scenarios: As an international standard, ISO 188 is applicable to the import and export, international cooperation and high-end product R&D of various rubber products worldwide; As China’s national standard, GB/T 3512 is mainly applicable to the production, testing and quality control of China’s rubber industry, especially widely used in the testing of high-temperature and high-pressure rubber materials in fields such as electric power, machinery and aviation. Bukod pa rito, compared with the old version, GB/T 3512-2014 added relevant requirements for multi-cell, cabinet-type and forced ventilation-type ageing ovens, achieving complete synchronization with ISO 188:2011.

V. Practical Application Scenarios of ISO 188 Pamantayan

With its international universality and scientificity of testing, the ISO 188 standard is widely used in various fields of the rubber industry, becoming an important support for product quality control, R&D innovation and market access. The core application scenarios include:
1.Automotive Industry: This is one of the most widely used fields of the ISO 188 pamantayan, used for the ageing resistance testing of automotive tires, engine seals, rubber hoses, shock absorbers and other components. Automotive rubber components are in high-temperature, oil-polluted and vibrating environments for a long time. Through the ISO 188 pagsubok, their performance stability during use can be evaluated, avoiding safety hazards such as seal failure and tire cracking caused by ageing. Mainstream domestic and foreign automakers all take ISO 188 testing as a supplier access threshold.
2.Electronic and Electrical Industry: Used for the testing of rubber insulators, seals, buttons and other products in electronic equipment, simulating the high-temperature environment during equipment operation, evaluating the changes of rubber’s insulation performance and sealing performance over time, and avoiding circuit short circuits and equipment failures caused by ageing.
3.Construction Industry: Used for the testing of rubber products for construction, such as door and window seals, waterproof rolls, shock-absorbing rubber mats, atbp., simulating outdoor high temperature, day and night temperature difference and other environments, evaluating their ageing resistance and service life, and ensuring the sealing, waterproofness and safety of building structures.
4.Rubber Product R&D: Used for formula optimization and performance testing of new rubber materials. Through the ISO 188 pagsubok, the ageing resistance of rubber under different formulas and processes is compared, the optimal scheme is selected, and the R&D and application of ageing-resistant rubber materials are promoted, such as new silicone rubber and high-temperature resistant synthetic rubber.
5.International Trade and Quality Certification: As the core testing basis for the import and export of rubber products, products passing the ISO 188 standard test can be recognized by the global market, reduce trade barriers and enhance the international competitiveness of products.

VI. Precautions for the Use of ISO 188 Pamantayan

In the actual application of the ISO 188 standard for testing, the following points shall be noted to ensure the accuracy and effectiveness of test results:
•Rational selection of test methods: Select the appropriate test method (Method A or Method B) according to the type, service environment and test purpose of the rubber material to avoid the loss of reference value of test results due to improper method selection; Halimbawa na lang, for soft rubber sensitive to air flow rate, Method A is preferred.
•Correct operation and maintenance of equipment: Operate the ageing oven in strict accordance with standard requirements, conduct regular calibration and maintenance to ensure that parameters such as temperature, air flow rate and ventilation frequency meet the standard; Avoid temperature unevenness and air flow disorder in the ageing oven.
•Representativeness and consistency of samples: Sample preparation shall be standardized to ensure that the samples are representative. The size and pretreatment conditions of samples in the same batch of tests shall be consistent to avoid test result deviation caused by sample differences.
•Update of standard version: Pay attention to the latest revision dynamics of the ISO 188 pamantayan, and preferentially adopt the latest version (ISO 188:2023) for testing to ensure that the test results meet the current industry and market requirements; Kasabay nito, be familiar with the relevant provisions of the corresponding national standard (GB/T 3512-2014) to adapt to domestic testing needs.
•Safe operation: The test involves a high-temperature environment. Operators shall wear protective equipment and formulate reasonable safety protection measures; Rubber samples in the ageing oven may produce volatile harmful substances, so it is necessary to ensure good ventilation in the test environment to avoid safety accidents and health risks.

VII. Buod

As the international core specification for accelerated ageing and heat resistance testing of rubber, the ISO 188 standard has formed a scientific, systematic and operable testing system after decades of revision and improvement. Its two test methods cover the testing needs of different types of rubber materials, which can accurately simulate the ageing process of rubber in practical use, and provide reliable technical support for quality control and R&D innovation in the rubber industry.
For rubber manufacturing enterprises, mastering the core requirements and application methods of the ISO 188 standard can not only improve the ageing resistance and quality stability of products, optimize material formulas and production processes, but also help products smoothly enter the global market and enhance market competitiveness; For testing institutions, carrying out testing work in strict accordance with this standard can ensure the accuracy and authority of test results and provide professional technical services for enterprises.
With the continuous innovation of rubber materials and the expansion of application scenarios, the ISO 188 standard will also be continuously optimized and upgraded, further improving test methods, enhancing detection accuracy, adapting to the testing needs of new rubber materials and complex working conditions, and promoting the global rubber industry to develop in the direction of high quality and high reliability.

Our Product GA-2014 Ventilation Aging Chamber meets this standard.

GA-2014 Ventilation Aging Chamber
Pamantayan sa pagsusulit:
In accordance with the standard GB/ t3512-2014 /ISO 188 2011 “vulcanized rubber or thermoplastic rubber/hot air accelerated aging and heat resistance test” turbulence design.

Gamitin ang
The hot air aging test box is suitable for the heat resistance test of electrical insulation materials, the air exchange aging test of electronic spare parts, plasticized products, etc.The adaptability of the sample to storage and use in high temperature environment was evaluated and judged. The performance of the sample after aging in air under simulated high temperature and atmospheric pressure was measured and compared with the performance of the non-aging sample.

Enclosure structure
1. Panloob na sukat: 600(lapad ng katawan)×600(lalim)×650(taas)mm;
2. External dimension: 1300(lapad ng katawan)×850(lalim)×1700(taas)mm, subject to the actual object;
3. Panel ng operasyon: the control panel is located on the right side of the machine (as shown in the figure);
4. Opening mode: single door is opened from right to left;
5. Observation window: toughened glass window on the door, size W250*H350mm;
6. Inner material: 304# stainless steel sand board: thick 1.2mm;
7. Panlabas na materyal: malamig na bakal na plato, 1.0mm thick powder baking paint treatment;(beige)
8. Product materials: two built-in turntables with a diameter of 300mm;
9. One set of speed-regulating motors with adjustable speed of 3-20 RPM;
10. Thermal pagkakabukod materyal: high temperature resistant fiber rock wool, good thermal insulation effect;
11, the door sealing material is: high temperature resistant silicone strip;
12. The machine is equipped with movable casters and fixed feet, which can be pushed and fixed at any time.

Temperature control system
1. Temperature control is PID digital display instrument (Taiwan taisong instrument GB705), single point temperature control, automatic calculation, simultaneous display of PV/SV, setting ng pindutan;
2. Timing function: mula sa 1 sa 9999 (hour, minute and second can be set), the temperature reaches the timer, when the time arrives, the heating and power supply will stop, and the alarm will be given;
3. Linya ng temperatura (K) uri ng;
4. The output is 3-32v;
5. The current controller is: SSR solid state relay;
6. Pag init ng materyal: stainless steel high-temperature heating tube;
7. Saklaw ng temperatura: adjustable from normal temperature +15 to 300℃;
8. Rate ng pag init: tungkol sa 18 minutes at 100℃;
9. Control accuracy: ±0.5o C;
10. Display accuracy: 0.1°C;
11. Temperature deviation: RT+15 ~ 200℃±2.0℃, 201 ~ 300℃±3.0℃ (walang load na pagsubok)

Product link:

https://www.gonoava.com/product/ga-2014-ventilation-aging-chamber/

Contact:

Mag-email: arlenliu@gonoava.com
WhatsApp: 0086 18670728798(We chat)
If you have any questions you can send me a message or email.