Cross-linking agents are chemical compounds that are used to chemically bond two or more polymer chains together. This creates a three-dimensional network of interconnected polymer chains, resulting in a cross-linked polymer. Cross-linking agents can be used to modify the properties of polymers, such as increasing their thermal stability, improving their mechanical properties, and reducing their solubility. Some common cross-linking agents include epichlorohydrin, bifunctional isocyanates, and divinyl sulfone.
Epichlorohydrin is an organic chemical compound with the chemical formula C3H5ClO. It is a colorless, low viscosity liquid with a strong, disagreeable odor. It is used as a monomer in the production of epoxy resins, which are widely used in adhesives, coatings, composites, and other applications. It is also used in the production of glycerol, surfactants, and water treatment chemicals.
Bifunctional isocyanates are chemical compounds that contain two isocyanate groups (-N=C=O) attached to a common backbone. They are used in various applications such as the synthesis of polyurethanes, adhesives, coatings, and elastomers. Bifunctional isocyanates are reactive compounds and readily form covalent bonds with hydroxyl groups, making them useful as cross-linking agents. In the context of modified starches, bifunctional isocyanates can be used to cross-link the starch molecules, resulting in a more robust and thermally stable starch network.
Divinyl sulfone is a chemical compound with the formula (CH2CH)2SO2. It is a bifunctional reagent that contains both an ether and a sulfone functional group. Divinyl sulfone is widely used as a cross-linking agent in the production of various materials, such as resins, coatings, and polymers. It reacts with various hydroxyl-containing compounds, such as polyvinyl alcohol, starch, and cellulose, to form three-dimensional networks through chemical bonds, resulting in improved mechanical and thermal properties of the final product.