Evaluation Methods Of Photodegradation And Thermal-Oxidation Degradation Of Non-Durable Nonwoven Fabrics

With the rapid development of non-durable nonwoven fabrics in clothing, medical, commercial and industrial areas, there has been so much waste material harmful to the environment that more and more researchers refer to the degradation of non-durable nonwoven fabrics. However, there is little research on photodegradation and thermal-oxidation degradation, and the test and evaluation methods of polyester (PET), polylactide (PLA) and viscose (CV).In order to study the test and evaluation methods of photodegradation and thermal-oxidation degradation, samples of polypropylene(PP), polyethylene(PE), polyester (PET), polylactide(PLA) and viscose(CV) nonwoven fabrics were exposed to carbon arc and xenon arc light in a covered chamber at an atmospheric condition of (65±3)℃and (50±5)%relative humidity for different periods of time, and exposed to blowing hot oven at (110±3)℃、(90±3)℃、(70±3)℃temperature conditions for different times.It’s found that the light source, temperature of thermal oxidative degradation, thickness and density of fabrics are the influence factors for the photodegradation and thermal-oxidation degradation. The retention of samples tensile strength and elongation rate decreased by irradiation times. Nonwoven fabrics changed from white to light yellow after irradiation, with some cracks appearing on the surface, and even chalking after irradiation. And, photosensitizer mixed into the non-woven fabrics can significantly increase the photodegradation rate. As photooxidation continues, the C=O and POOH indices increase non-linear with the degradation times. As photodegradation proceeds, the main molecular chain breaks, and the amount of degradation products increase, and its molecular weight decrease, all of which make the melting temperature decrease.In order to determine photodegradation and thermal-oxidation degradation of non-woven fabrics, there are several effective methods currently used, which include mechanical properties testing, SEM observation of fabrics and fibers surface changes, infrared spectroscopy for detecting the build-up of carbonyl and hydroxyl groups, and DSC curves for measuring melting point trends of samples.It’s found to characterize photodegradation and thermal-oxidation degradation by melting points changes. The mechanical properties changes can evaluate photodegradation and thermal-oxidation degradation of PP, PET, CV, and PLA. However, when fabrics break up, or, even in powder, it cannot be further determined. SEM observation cannot determine photodegradation and thermal-oxidation degradation quantitatively. Though infrared spectroscopy can detect the build-up of products quantitatively by carbonyl and hydroxyl indices, it’s not suitable for PET, PLA and CV. Similarly, the melting temperature is unsuitable for CV non-woven fabrics.Textiles-Measurement for the Photodegradation and Thermal-oxidation degradation of Nonwovens are designed as draft standards. They aim to not only provide a theoretical and application basis to detect and evaluate the degradation and thermal-oxidative degradation of non-woven fabrics, but also make a help for nonwovens production to improve the performance of photodegradation and thermal-oxidation for environmental protection.