Super absorbent polymer has been widely used in various fields of production and life in today's society. However, due to the particularity of this material, many factors will make it aging, thus losing its application performance, resulting in corresponding product damage or scrap. This paper mainly expounds the concept, main performance and main mechanism of macromolecular material aging.
In the process of forming, storage and application of super absorbent polymer, its structure may change accordingly, thus changing its original physical, chemical and mechanical properties, and gradually deteriorating, resulting in the loss of its use value. We call this phenomenon the aging of macromolecular material.
In the process of forming, storage and application of super absorbent polymer, once it is aged, its material structure and properties will change. Generally speaking, the main manifestations of aging include the following aspects: first, the changes in the surface appearance, including changes in color and shape, or problems such as becoming sticky, brittle and cracked; The second is the changes of its physical and chemical properties, including the changes of its relative molecular weight distribution, relative molecular weight, light transmittance, air permeability, cold resistance, heat resistance, solubility and melting point; The third is the change of mechanical properties, including the change of wear resistance, adhesion, elongation, strength, hardness and elasticity; The fourth is the change of its electrical properties, including the change of breakdown field strength, dielectric loss tangent, dielectric constant and insulation resistance.
Degradation chemical reaction and cross-linking chemical reaction are the main aging mechanisms of super absorbent polymer. Among them, the degradation chemical reaction will reduce its relative molecular weight, thus reducing its electrical and mechanical properties, and may lead to its pulverization and stickiness. The cross-linking chemical reaction will lead to the increase of its relative molecular weight. Before the crosslinking reaction reaches a certain degree, the heat resistance and mechanical properties will be improved. However, with the increasing degree of intermolecular crosslinking, the crosslinking network structure will be formed, which will increase its hardness and brittleness, destroy it, and make it unable to dissolve and melt.
In the process of studying the aging problem of super absorbent polymer and its prevention and control measures, researchers first need to fully understand its basic concept, main performance and main aging mechanism, so as to further clarify the main causes of the aging problem and provide a scientific and reasonable reference for the prevention and control of the aging problem of macromolecular material.
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