Polyurethane (PU) fiber is an elastic fiber with good resistance to chemical degradation. As a fiber solution provider, Alfa Chemistry offers polyurethane fiber products to meet your fiber material requirements.
Properties
- High elongation (500% ~ 700%)
- Low elastic modulus (200% elongation, 0.04 ~ 0.12 g/denier)
- High elastic recovery rate (200% elongation, 95% to 99%)
- Lower breaking strength (polyether type is stronger than polyester type)
- Excellent chemical stability
- Good thermal stability
- Good acid and alkali resistance
- Good wear resistance
- Low moisture absorption range (generally 0.3-1.2%)
- Not resistant to chlorine bleach
Chemical Structure
PU fibers are alternately composed of flexible long segments (soft segments) and rigid short segments (rigid segments). The soft segment is a low molecular weight polyester or polyether segment without crystallinity, which is easily deformed under the action of stress, so that the obtained fiber can be stretched and deformed. The rigid segment is an aromatic diisocyanate segment that is crystalline and can generate lateral cross-linking, does not deform under stress, can prevent lateral slip, and make the obtained fiber have sufficient resilience. The content of soft segment in the segment structure of PU fiber is generally not less than 80% to 85%. According to the composition of the soft segment, they can be divided into polyester type and polyether type. The polyester type is obtained from block copolymers of aromatic diisocyanates and hydroxyl-containing polyester segments. The polyether type is obtained from block copolymers of aromatic diisocyanates and polyether segments containing hydroxyl groups.
Schematic diagram of hard segment and soft segment of PU structure [1]
Preparation Method
Spinning methods of PU elastic fibers include solution dry spinning, solution wet spinning, melt extrusion, and reaction spinning. The first step of these four methods involves the chemical reaction of monomers to produce prepolymers. The resulting prepolymer is further reacted in various ways and subsequently drawn to produce long fibers. Among them, solution dry spinning is a relatively mature method for preparing PU fibers in the industry. The technology has become mature, can be continuously produced, has high efficiency, good product performance and is widely used.
Applications
PU elastic fibers are generally not used alone because of their special elasticity, but are incorporated into fabrics in a small amount. Depending on the actual use, the product form is also different, including bare yarn, core yarn, covered or twisted yarn and other types.
In the field of chemical research, polyurethane fibers also have many functionalization applications. For example, Guan-Jun Zhu et al. developed a flexible strain sensor based on PU fibers. In this work, the researchers integrated silver nanowires (AgNWs) into PU fibers and formed a fully conductive network. The obtained PU/AgNW fibers can be used as wearable devices to detect various human movements and drive light-emitting diodes at a lower voltage (2.7 V). [2]
References
- J.U. Otaigbes, et al. Handbook of Textile Fibre Structure, 2009, 325-351.
- Guan-Jun Zhu, et al. ACS Appl. Mater. Interfaces, 2019, 11, 26, 23649-23658.
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