Aging mechanism of PP non-woven fabric

In the processing of PP non-woven fabrics, due to the material's own structure and the influence of factors such as temperature, light and oxidation during processing, it is prone to aging and degradation, and phenomena such as powdering, discoloration and brittleness appear, resulting in elongation at break and fracture. The reduction in strength not only shortens the service life of the product, but also causes a large waste of materials, and the waste products are difficult to effectively explain under natural conditions, which easily causes environmental pollution. From the perspective of its aging mechanism, it is mainly caused by the aging of its matrix resin PP material. In addition to the structure of the PP material itself, residual impurities, and the use of inorganic fillers, additives, etc., the material is easily affected by temperature and oxygen during processing. Thermal oxygen aging, screw shearing, etc. At the same time, during use, if exposed to ultraviolet light and oxygen for a long time, photo-oxidative aging is also prone to occur.


(1) Among them, thermal oxidative aging and mechanical shearing are mainly due to the fact that the PP material is subjected to the shearing and extruding of the barrel and screw during processing, causing the carbon-carbon chemical bond on the macromolecular chain to break, plus Under the influence of temperature, the macromolecular carbon free radicals after the molecular chain breaks react with oxygen to form hydroperoxides, which are further decomposed into RO? Oxygen-containing free radicals and -OH hydroxide free radicals accelerate the auto-oxidation reaction, reduce the relative molecular weight of the material, and reduce its breaking strength and breaking elongation.


(2) Photo-oxygen aging. Ultraviolet rays can cut the PP molecular chain, and under the action of oxygen, a photooxidation reaction occurs, which reduces the anti-photooxidative aging performance of PP. From the perspective of the production of PP non-woven fabrics, it is mainly made of spinnerets, and its diameter is small, and it is easy to contact with oxygen and ultraviolet light in a large area, which will cause photo-oxidative aging and cause the PP molecular chain to break.