Why do sponge products turn yellow? -TMPDA-tetramethylpropylenediamine

Generally, from the perspective of additives, the yellowing of sponges includes the following four types: 1. Thermal oxygen aging yellowing caused by high temperature during sponge foaming/processing. 2. Smoke and yellowing caused by exposure to nitrogen oxides (NOx) in the air. 3. Fabric contamination caused by sponges. 4. Yellowing of the sponge caused by exposure to ultraviolet rays. Types of sponge materials: 1. Chemical sponge Polyurethane soft foam rubber. Polyurethane is the most common polymer material in life and is widely used in making various “sponge” products. As well as elastic materials for shock absorption and anti-friction purposes, such as shoe soles and tractor tank track underlays. 2. Industrial sponges: There are many types of sponges used in industrial production, including foam cotton, shaped cotton, rubber cotton, memory foam, etc. Extended information: Polyurethane is the most common polymer material in life and is widely used in making various “sponge” products. As well as elastic materials for shock absorption and anti-friction purposes, such as shoe soles and tractor tank track underlays. According to whether the product yellows under light, polyurethane adhesives are divided into general-purpose isocyanate-polyurethane adhesives and yellowing-resistant isocyanate-polyurethane adhesives. General-purpose isocyanate, that is, aromatic isocyanate, is currently the most widely used isocyanate in the polyurethane industry. Because the methylene group connected to the benzene ring in the structure is easily oxidized to form a quinone chromophoric group, the material will turn yellow.