The chemical properties of "Epoxy Hardener," typically referring to the compounds that undergo chemical reactions with epoxy resins to crosslink and cure them, can be outlined from several aspects:

Reactivity

One of the most significant chemical properties of epoxy hardeners is their high reactivity. The active functional groups in the hardener (such as amine groups, anhydrides, hydroxyl groups, etc.) can react with the epoxy groups in the epoxy resin to form an insoluble and infusible three-dimensional network structure, thereby curing the epoxy resin. This reaction is usually exothermic and can be accelerated by heating.

Types and Structures

Epoxy hardeners are diverse in types and structures. Common hardeners include amine-based hardeners, anhydride-based hardeners, phenolic hardeners, etc. The structural characteristics of these hardeners determine their reactivity, curing speed, curing temperature, and the properties of the cured product.\
 

Physical States

Epoxy hardeners are usually liquids or solids at normal temperature and pressure. Liquid hardeners are convenient for mixing uniformly with epoxy resins, while solid hardeners may require heating or dissolution before use. The physical state of the hardener has a certain impact on its mixing uniformity with the epoxy resin and the curing process.

Stability and Storage

Epoxy hardeners should maintain their chemical stability during storage to avoid reacting with oxygen, moisture, etc., in the air and causing deterioration. Therefore, they should be stored in a cool, dry place, away from direct sunlight and high-temperature environments. Additionally, different types of hardeners may require different storage measures to ensure their stability.

Properties of Cured Products

The chemical properties of epoxy hardeners are also reflected in the properties of their cured products. The hardness, strength, toughness, heat resistance, chemical resistance, etc., of the cured products are related to the type, structure, and curing conditions of the hardener. Therefore, when selecting a hardener, comprehensive consideration should be given based on specific application scenarios and requirements.

Safety and Environmental Protection

During use, attention should be paid to safe operation to avoid direct contact with skin, eyes, etc., when handling epoxy hardeners. Additionally, harmful gases or vapors may be generated during the curing process, so operations should be carried out in a well-ventilated environment. Furthermore, with the increasing awareness of environmental protection, more and more hardeners are being prepared using low-toxicity, low-volatility raw materials to reduce pollution to the environment.

In summary, the chemical properties of epoxy hardeners involve reactivity, types and structures, physical states, stability and storage, properties of cured products, as well as safety and environmental protection. These properties collectively determine the role and application scope of the hardener in the curing process of epoxy resins.