Polyacrylonitrile (PAN) fiber, also known as acrylic fiber, is a fiber spun from a copolymer of acrylonitrile and other second and third monomers. In addition, PAN fiber is also an important raw material for carbon fiber formation. As a fiber solutions provider, Alfa Chemistry offers PAN fiber products to meet your fiber material requirements.
Structure
Acrylic fibers are spun from polymers made from monomers that contain at least 85% acrylonitrile in the chain. Due to the presence of polar acrylonitrile groups, the unique tensile properties and many physical properties of acrylic fibers originate from the strong interactions between the chains. However, interactions between adjacent nitrile groups on the same chain can cause some repulsion to occur. The molecular chain conception model of PAN was proposed by Hinrici Olive and Olive in 1979, as shown in the figure below. As for PAN fibers, the debate on the existence of two-phase morphology in acrylic copolymers continues. During coagulation, the long period lengths of the nascent coagulated fibers were found to be 56.1 nm (meridional) and 35.6 nm (equatorial). As solidification progresses, the long period decreases with increasing crystallinity. [1]
Performance
Acrylic and modacrylic fibers are primarily sold as tow and staple fiber products with fiber linear densities typically between 0.84 and 17 dtex. Typical values for some physical properties are given in the table. Tensile strength is much lower than polyester and polyamide fibers, but similar to cotton, higher than wool. Acrylic fibers have high electrical resistance, moderate flammability, and excellent resistance to sunlight, chemical and microbial attack. Due to the polarity, the fibers have reasonable moisture regain values of 2% to 3%. The presence of water gives the fibers a relatively low Tg value of about 70 °C.
| Property | Acrylic | Property | Acrylic |
|---|
| Specific gravity | 1.14-1.19 | Elastic recovery (%) |
| Tenacity (N/tex) | 2% | 99 |
| Dry | 0.09-0.33 | Electrical resistance | High |
| Wet | 0.14-0.24 | Static build-up | Moderate |
| Loop/knot tenacity | 0.09-0.3 | Flammability | Moderate |
| Breaking elongation (%) | Limiting oxygen index | 0.18 |
| Dry | 25-45 | Char/melt | Melts |
| Wet | 29-61 | Resistance to sun light | Excellent |
| Initial modulus (N/tex) | Resistance to chemical attack | Excellent |
| Dry | 3.5-4.9 | Abrasion resistance | Moderate |
| Wet | 3.1-4.9 | Index of birefringence | 0.1 |
| Moisture regain (%) | 1.5-2.5 |
Research Information
PAN fibers, especially PAN-based nanofibers, are also often functionalized in chemical research for various applications. For example, Qian Yang et al. modified PNA fibers with polydopamine and silver nanoparticles to develop functionalized PNA fibers with excellent adsorption properties and durable antibacterial activity. In this work, the antibacterial rate of functionalized PAN fibers can be maintained above 90% after 5 washing cycles, and can be used to remove various metal ions. [2]
References
- Bhupender S. Gupta, et al. Handbook of Properties of Textile and Technical Fibres (Second Edition), 2018, 545-593.
- Qian Yang, et al. Materials Chemistry and Physics, 2020, 245, 122755.
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