Polyether polyols are a class of polyol compounds with a certain molecular weight, usually prepared by epoxidation reaction, and are important basic raw materials for the production of polyurethane, coatings, foam materials, elastomers, etc. The properties of polyether polyols vary due to their specific molecular structure, degree of polymerization, functional groups and other factors, but some common basic properties include:
1. Chemical structure and molecular properties
Polyether group: The basic structural unit of polyether polyols is the polyether chain, which is composed of a structure composed of alternating oxygen atoms and carbon chains and repeatedly polymerized.
Molecular weight: The molecular weight of polyether polyols is usually high, ranging from hundreds to thousands, and the size of the molecular weight directly affects its physical properties and application areas.
Terminal functional group: Polyether polyols generally have multiple hydroxyl end groups, which play an important role in the crosslinking and hardness of polymers such as polyurethane.
2. Physical properties
Viscosity: The viscosity of polyether polyols is usually high, and as the molecular weight increases, the viscosity also increases. Low molecular weight polyether polyols have low viscosity and are easy to process and apply.
Melting point/freezing point: Polyether polyols have low melting and freezing points and are usually liquid at room temperature, which is easy to handle and process.
Solubility: Polyether polyols usually have good solubility and are compatible with many organic solvents, such as alcohols, ethers, and esters. However, they have poor solubility in water.
3. Chemical stability
Water resistance: Polyether polyols have good water resistance and are usually not as easy to absorb water as some polyester polyols. However, excessive moisture absorption may affect their polymerization performance.
Acid and alkali resistance: Polyether polyols usually have good stability to weak acids and weak bases, but may degrade or react in strong acid or alkali environments.
Oxidation resistance: Polyether polyols have good oxidation resistance, but over time, if exposed to air, some degree of degradation may occur.
4. Reactivity with other substances
Reaction with isocyanates: Polyether polyols react with isocyanates to form polyurethanes, which is its most important application area.
Reaction with acid: Polyether polyols may undergo some degree of hydrolysis in an acidic environment, especially at high temperatures.
Reaction with metals: Polyether polyols may react with certain metals under certain conditions, but this reaction is usually not very violent.
5. Uses
These characteristics of polyether polyols make them widely used in many industrial fields:
Polyurethane foam: Polyether polyols are the core raw materials of polyurethane foam and are used to produce soft foam, hard foam, elastomers, etc.
Coatings and adhesives: Polyether polyols are used to make coatings, paints, adhesives, etc. to enhance the wear resistance, water resistance and adhesion of products.
Elastomers and sealants: Polyether polyols have important applications in the production of polyurethane elastomers, automotive sealants, etc.
Plastics and rubber: Polyether polyols are used to make polyurethane plastics and rubber materials, providing good physical properties and durability.
Surfactants: Some types of polyether polyols are also used as surfactants and are widely used in products such as detergents and emulsifiers.
6. Environmental and health impacts
Biodegradability: Polyether polyols are usually biodegradable, especially some low molecular weight polyether polyols are more easily decomposed by microorganisms.
Toxicity and safety: Polyether polyols are usually less toxic, but during production and use, if they are exposed to high concentrations of polyether polyols for a long time, they may cause slight irritation to the skin, eyes or respiratory tract. Therefore, appropriate protective measures need to be taken during handling.
In summary, the main properties of polyether polyols include their excellent water resistance, low melting point, good chemical stability and reactivity with isocyanates, making them an important raw material in polyurethane production.
