Polyurethane chain extenders and catalysts are used in the production of polyurethanes. They help control final product properties such as hardness, flexibility and toughness.

Polyurethane chain extenders are low molecular weight compounds that react with isocyanate groups in polyurethane resins to form long chains. The reaction is catalyzed by a polyurethane catalyst.

The choice of chain extender and catalyst will depend on the desired properties of the final product. For example, if a hard rigid product is desired, long chain extenders and strong catalysts are required. If a soft, elastic product is desired, short chain extenders and weak catalysts will be used.

Polyurethane chain extenders and catalysts are an important part of the polyurethane manufacturing process. They help ensure that polyurethane resins are cured properly and that the final product has the desired properties.

Here are some of the most common types of polyurethane chain extenders:

Ethylene Glycol: Ethylene glycol is the most common polyurethane chain extender. They effectively extend the chain of polyurethane resins and help improve the properties of the end product.
Diamines: Diamines are also effective in extending the chains of polyurethane resins. They help improve final product properties such as hardness and toughness.
Polyol: Polyol is a chain extender composed of multiple hydroxyl groups. They effectively extend the chains of polyurethane resins and help improve the properties of the final product, such as its flexibility and toughness.
The following are some of the most common types of polyurethane catalysts:

Amines: Amines are the most common polyurethane catalysts. They efficiently catalyze the reaction between isocyanates and hydroxyl groups. However, amines also lead to the formation of undesired by-products, such as amines and amides.
Organotin compounds: Organotin compounds are also effective in catalyzing the reaction between isocyanates and hydroxyl groups. However, they are more expensive and difficult to handle than amines.
Metal salts: Metal salts, such as zinc chloride, can also be used as polyurethane catalysts. They are less expensive than amines and organotin compounds, but they are not as effective at catalyzing the reaction between isocyanates and hydroxyl groups.
The choice of polyurethane chain extender and catalyst depends on a variety of factors, including the type of polyurethane resin used, the desired properties of the final product, and the cost of the chain extender and catalyst.