How To Distinguish Between Polyester And Polyether PU Pipes?

PU tubes, also known as Polyurethane tubes, combine the flexibility of rubber with the strength of plastic, demonstrating exceptional wear resistance, corrosion resistance, and tear resistance. This makes PU tubes an ideal choice for applications in industrial production, logistics transportation, construction facilities, automotive, and electronics.

PU tubes are mainly made from two different types of polyurethane materials: polyester-based polyurethane and polyether-based polyurethane. Their molecular structures and compositions differ significantly, leading to notable variations in specific properties.What are their performance comparisons? Polyester vs Polyether.

Performance Differences

Molecular Structure

◆ Polyester PU Tubes: Synthesized from diols (such as ethylene glycol, propylene glycol) and diisocyanates through esterification, these tubes have ester groups (-COO-) in their molecular chains, providing high rigidity and wear resistance.

◆ Polyether PU Tubes: Made from diols (like polyether diols) and diisocyanates (like TDI or MDI) through etherification, these tubes contain ether groups (-O-) instead of ester groups, making the molecular chains more flexible.

Hydrolysis Resistance

◆ Polyester PU Tubes: The ester groups are prone to decomposition in the presence of water, leading to chain breakage and the formation of alcohols and acids, particularly in high humidity or prolonged water exposure. Therefore, their hydrolysis resistance is relatively poor.

◆ Polyether PU Tubes: With ether groups that are less reactive with water, polyether PU tubes have significantly better hydrolysis resistance, making them suitable for humid or water-contact environments.

Oil Resistance

◆ Polyester PU Tubes: The ester groups can be easily penetrated by oils, especially mineral oils and certain lubricants, potentially leading to expansion, softening, aging, or strength reduction.

◆ Polyether PU Tubes: The ether groups offer better chemical stability and are less likely to react with oils, providing strong resistance against oil degradation.

Wear Resistance

◆ Polyester PU Tubes: The ester group structure grants these tubes higher hardness and rigidity, resulting in strong wear resistance, especially under dry friction and low-speed conditions.

◆ Polyether PU Tubes: Although their wear resistance is comparatively weaker, they still perform well in many applications. However, under high-speed or heavy-load conditions, they may wear out faster than polyester PU tubes.

Weather Resistance

◆ Polyester PU Tubes: These tubes are sensitive to ultraviolet (UV) light, leading to photodegradation and potential discoloration, surface cracking, or strength reduction upon prolonged sun exposure. 

Their stability in oxidative environments is also lower, which can further accelerate aging.

◆ Polyether PU Tubes: They are less affected by UV light compared to polyester PU tubes, showing minimal photodegradation.

Additionally, they possess good oxidative stability, experiencing less aging in air and maintaining better physical properties.

Temperature resistance

◆ Polyester PU Tubes: Generally with high temperature resistance, suitable for use at higher temperature. It is typically resistant to temperatures from 80 ° C to 100 ° C and some special formulations can be even higher.

◆ Polyether PU Tubes: Relatively low temperature resistance, typically between 60 ° C and 80 ° C. Suitable for mild environments and not suitable for prolonged exposure to high temperatures.

Flexibility

◆ Polyester PU Tubes: Due to their strong rigidity from ester groups, these tubes are generally less flexible than polyether PU tubes. Their higher hardness may cause brittleness during bending or stretching, leading to potential breakage.

◆ Polyether PU Tubes: The chemical properties of ether groups grant these tubes better extensibility and flexibility, especially in low-temperature environments, where they still maintain good elasticity.

Appearance

◆ Polyester PU Tubes: Typically have a smooth surface with a certain gloss. Various colors can be produced by adding different pigments.

◆ Polyether PU Tubes: Their surfaces are generally softer and less glossy than polyester tubes, possibly exhibiting a slightly matte finish due to their more flexible molecular structure. 

They are available in various colors, such as transparent, blue, and yellow, and tend to resist fading better due to superior UV resistance.

Mechanical Properties

How to Distinguish Between Polyester and Polyether PU Tubes

◆ Touch: Polyester PU tubes feel smoother and harder when bent, while Polyether PU tubes have a slightly rough surface and a more comfortable feel when bent.

◆ Odor: Polyester PU tubes may emit a chemical smell, whereas Polyether PU tubes generally have a lighter or even odorless scent.

◆ Water Contact Test: Polyester PU tubes may absorb some water, causing surface changes. In contrast, Polyether PU tubes have a lower absorption rate and do not easily take in water.

◆ Chemical Resistance Test: If possible, conduct a small-scale chemical resistance test in a safe environment by exposing the tubes to oils or solvents. Polyester PU tubes usually withstand oils better, while polyether PU tubes may be affected.

◆ Professional Testing: Infrared spectroscopy can be used to detect ester and ether bonds in the PU tubes, allowing for differentiation between polyester and polyether types.

FOKCA is a professional manufacturer of various flexible hoses. We offer high-quality, durable PU tubes. If you have any needs, please click here to visit our product page for more information.

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