The essence of core indicators: why is it tensile strength retention rate rather than others?
The reason why the tensile strength retention rate (tensile strength after aging/initial tensile strength × 100%) is the core index to measure the aging resistance of spunbond nonwoven fabrics is that it directly reflects the “structural integrity” and “functional viability” of materials under environmental erosion. The core demand of anti-aging is to keep the material stable in long-term use, and the tensile strength is the basis of the bearing mechanical function of spunbonded non-woven fabrics – whether it is the reinforcement of geotechnical engineering, the crack resistance of building envelope, or the wear resistance of outdoor products, it depends on the tensile strength of the material to resist external forces and environmental stresses.
Unlike auxiliary indicators such as color difference and water absorption, the retention rate of tensile strength can accurately quantify the degree of damage to the molecular structure of materials. Aging factors such as ultraviolet radiation, humidity, and chemical media can damage the molecular chains of polypropylene (PP) or polyester (PET) filaments, leading to fiber brittleness, breakage, and ultimately a decrease in tensile strength. This performance degradation is irreversible and directly related to product life – when the tensile strength retention rate is below the critical value, the material will fail due to the inability to withstand the stress during normal use, such as geotextile cracking, tent bottom fabric damage, and building envelope detachment. Therefore, the tensile strength retention rate is not only the “quantitative data” of aging test, but also the “early warning signal” of the actual service life of the product, and has become the core judgment standard of anti-aging performance recognized by the industry.
Testing Logic and Standards: How to Scientifically Measure Retention Rate?
The testing of tensile strength retention rate should follow the rigorous logic of “pre aging benchmark test+accelerated aging test+post aging comparative test” to ensure the objectivity and reference value of the data. The core process and standard requirements are as follows:
Firstly, representative samples should be selected for the benchmark test before aging – at least 5 samples should be randomly selected from the same batch of products according to standards such as GB/T 13762 (Geotextiles) and GB/T 3923.1 (Textiles), and equilibrated in a standard environment (temperature 23 ± 2 ℃, humidity 50 ± 5%) for 24 hours. Then, a universal material testing machine should be used for tensile testing, and the average breaking strength should be taken as the initial tensile strength (unit: N/50mm or N/5 × 10cm, determined according to the product type). During testing, it is necessary to control the stretching speed (such as 50mm/min for geotextiles and 100mm/min for outdoor fabrics) to avoid data distortion caused by excessive speed.
Secondly, accelerated aging testing needs to simulate key erosion factors in the actual usage environment. The most commonly used method is xenon lamp aging testing (following standards such as GB/T 16422.2 and ASTM G155), and additional tests such as wet heat aging (GB/T 1740) and freeze-thaw cycle aging can be added according to the scenario. The aging duration should match the target service life of the product, such as using 500 hours of accelerated aging for short-term use products (1-3 years) and 2000-3000 hours of accelerated aging for long-term engineering use products (more than 10 years), to ensure that the test results can equivalently reflect the performance degradation in the natural environment.
Finally, the comparison test after aging should be conducted under the same environmental conditions and test parameters as the benchmark test. The aged samples should be subjected to repeated tensile testing to calculate the retention rate of tensile strength. The general judgment logic of the industry is: the higher the retention rate, the stronger the anti-aging performance – for example, the spunbonded non-woven fabrics for outdoor engineering require the retention rate ≥ 80% after 1000 hours of xenon lamp aging, and the retention rate ≥ 85% for major projects; Ordinary outdoor products require a retention rate of ≥ 75% after 500 hours of aging, while high-end products require a retention rate of ≥ 80%.
Key influencing factors: What factors determine the retention rate of tensile strength?
The tensile strength retention rate of spunbonded non-woven fabrics is not a fixed value, but is affected by three core factors, namely material formula, production process and use environment. Its mechanism directly determines the anti-aging performance:
In terms of material formulation, the type and amount of anti-aging additives are the core variables. Hindered amine light stabilizers (HALS) can effectively block molecular chain breakage caused by ultraviolet radiation, while quaternary pentanol ester antioxidants can inhibit oxidative degradation in humid and hot environments. The scientific ratio of the two (usually 0.2% -0.5% light stabilizer and 0.8% -1.0% antioxidant) can significantly improve retention rate – PET spunbond fabric with sufficient additives can achieve a retention rate of over 90% after 2000 hours of xenon lamp aging, while ordinary products without additives are only 40% -50%. In addition, the performance of the substrate itself is also crucial: the molecular structure of PET filament is more stable, and its anti-aging performance is better than that of PP filament. The retention rate after aging under the same conditions is usually 10% -15% higher; If the proportion of regenerated fibers is too high (over 50%), the retention rate will decrease by 8% -12% due to incomplete fiber molecular chains.
At the production process level, the spunbond forming and solidification processes directly affect the fiber bonding strength. Products using S/SS/SMS composite spunbond technology have tighter interweaving of filaments, stronger hot melt bonding, less fiber shedding and loose structure during aging, and a 5% -8% higher retention rate of tensile strength compared to ordinary spunbond technology; Accurate control of hot rolling temperature and pressure is also crucial – excessively high temperatures can lead to fiber degradation, while excessively low temperatures can result in weak bonding and lower retention rates. In addition, surface modification treatments such as silane coupling agent coatings and UV resistant coatings can further enhance the environmental resistance of materials, resulting in an additional 3% -5% increase in retention rate.
In terms of usage environment, factors such as UV intensity, temperature, humidity, and chemical media can accelerate or slow down performance degradation. Products used in high-altitude areas (where UV intensity is 2-3 times that of plains) have a 10% -15% lower retention rate after 1000 hours of aging compared to plain areas; Wet and hot environments (such as the rainy season in the south) will accelerate oxidative degradation, resulting in a 5% -8% decrease in retention rate; In chemical environments such as salt alkali and industrial pollution, materials will suffer from fiber strength loss and further decrease in retention rate due to corrosion. Therefore, in practical applications, it is necessary to adjust the formula according to the environmental intensity to ensure that the retention rate meets the usage requirements.
Industry application standard: Qualification threshold for retention rate in different scenarios
The qualified standard for tensile strength retention rate needs to be combined with the product’s usage scenario and target life. The requirements of different industries vary significantly, forming a targeted threshold system:
In the field of geotechnical engineering (water conservancy, road engineering), since the products need to be in service for more than 50 years, the requirements for anti-aging performance are extremely high. According to the “Technical Specification for Application of Geosynthetics in Water Conservancy Engineering”, spunbond non-woven fabrics used in water conservancy dams must pass a 2000 hour xenon lamp aging test with a tensile strength retention rate of ≥ 85%; Products used for highway subgrade must pass a 3000 hour test with a retention rate of ≥ 80% – for example, the PET spun clay geotextile used for the Hong Kong Zhuhai Macao Bridge has a retention rate of 92% after 3000 hours of aging, ensuring long-term resistance to water erosion and freeze-thaw.
In the field of building enclosure systems, spunbond fabrics used for roof waterproofing and exterior wall insulation need to withstand long-term exposure to sunlight and temperature cycles. Domestic standards require a retention rate of ≥ 80% after 1000 hours of xenon lamp aging; Products for planting roofs and prefabricated walls require a retention rate of ≥ 85% due to more complex environments such as soil corrosion and moisture erosion, in order to avoid cracking and water leakage in the enclosure system caused by material aging.
In the field of outdoor products, differences in scenarios lead to standard differentiation: short-term use products such as temporary outdoor tents and construction enclosures (with a lifespan of 1-3 years) can have a retention rate of ≥ 75% after 500 hours of aging; Mid term products such as sunshades and high-end camping tents (with a lifespan of 3-10 years) must have a retention rate of ≥ 80% after 1000 hours of aging; Products used in extreme environments such as plateaus and coastal areas need to be increased to ≥ 85%, such as the grass proof cloth used for cotton cultivation in Xinjiang, which has a retention rate of 88% after 1500 hours of aging and is suitable for strong ultraviolet and arid environments.
In the field of agriculture, spunbond fabrics are used for greenhouse and outdoor covering. According to the “Technical Specification for spunbond nonwoven fabrics for agricultural use”, the retention rate after 1000 hours of aging is required to be ≥ 78% in ordinary scenarios, while products for long-term planting (more than 5 years) need to be ≥ 82% to ensure that they maintain grass protection and insulation functions under wind, sun, and rain, and avoid frequent replacement.
5、 The practical value of indicators: from product selection to quality control
The retention rate of tensile strength is not only the core optimization goal of product development, but also the key basis for product selection and quality control in practical applications. For the engineering purchaser, by checking the aging test report of the product (with a focus on whether the tensile strength retention rate meets the standard), high-quality products that meet long-term use requirements can be quickly screened to avoid engineering hazards caused by the selection of low retention rate products; For manufacturing enterprises, by monitoring the retention rate index, the formulation and production process of anti-aging additives can be optimized, and the competitiveness of products can be improved. For example, adjusting the addition of light stabilizer from 0.3% to 0.4% can increase the retention rate from 82% to 88%, meeting the needs of high-end projects.
Meanwhile, the retention rate of tensile strength can also provide scientific basis for predicting product life. By accelerating aging test data, a correlation model between retention rate and service life can be established: for example, the retention rate of a certain PET spunbond fabric is 85% after 1000 hours of aging and 80% after 2000 hours. It can be estimated that the time for its tensile strength retention rate to drop to 70% (failure critical value) in a normal outdoor environment is about 15 years, providing reference for engineering design and product replacement.
It should be noted that the retention rate of tensile strength needs to be combined with other indicators (such as elongation retention rate and appearance integrity) for judgment, and cannot be relied solely on. If the tensile strength retention rate of a product reaches the standard after aging, but the elongation decreases significantly (less than 70%) or cracks and pulverization occur, it is still judged as unqualified – after all, the core of anti-aging performance is “overall stability”, rather than a single index reaching the standard.
Dongguan Liansheng Non woven Technology Co., Ltd. was established in May 2020. It is a large-scale non-woven fabric production enterprise integrating research and development, production, and sales. It can produce various colors of PP spunbond non-woven fabrics with a width of less than 3.2 meters from 9 grams to 300 grams.
Post time: Feb-27-2026