Polymer processing
- 1. Md. Sayedul Islam Ph.D Researcher Department of Chemistry BUET, Dhaka-1000.
- 2. Presentation on polymer processing by Fiber spin method
- 3. What is Polymer Processing? According to Tadmor and Gogos, polymer processing are the "operations carried out on polymeric materials or systems to increase their utility." Therefore, polymer processing is done to increase the value of a polymer in order to obtain the desired shape, properties, and performance for a polymer substance.
- 4. Methods of polymer processing: There are various methods of polymer processing such as -Injection modeling method -extrusion method -Fiber spin method e.t.c
- 5. Fiber Spinning method of polymer: Spinning is a manufacturing process for creating polymer fibers. It is a specialized form of extrusion that uses a spinneret to form multiple continuous filaments. This process is applied for the polymers of synthetic fibers such as nylon, polyethylene terephthalate, acrylics, polyurethanes and polypropylene.
- 6. Fig. Process of fiber spin method
- 7. Description of the process The polymer is at first converted into a fluid state. If it is a thermoplastic polymer then it is just melted otherwise it has to be dissolved in a solvent or has to be chemically treated in order to form soluble or thermoplastic derivatives. The fluid polymer is then forced through the spinneret. The polymer here cools to a rubbery state, and then finally solidifies.
- 8. Types of Polymer Spinning Processes: There are four types of spinning for polymers- wet spinning, dry spinning, melt spinning, and gel spinning
- 9. Wet Spinning: wet spinning is the oldest process. The name of the process i.e. wet spinning has got its name from this "wet" bath only. It is used for polymers that need to be dissolved in a solvent to be spun. The spinneret remains submerged in a chemical bath that leads the fiber to precipitate, and then solidify, as it emerges out of the spinneret holes. Examples of wet spinning- Acrylic fiber, rayon fiber, aramid fiber, modacrylic fiber e.t.c are manufactured through this process.
- 10. Advantage and Disadvantage of Wet Spinning: Advantage: 1. suitable for staple fiber 2. Low temp. required 3. Both organic & inorganic solvent can be used Disadvantage: 1. Slow production (150-200ft/min) speed 2. washing of fiber are needed 3. Toxic
- 11. Dry Spinning: It is also used for polymers that have to be dissolved in a solvent. However, solidification comes from the evaporation of the solvent. After dissolving the polymer in a volatile solvent, the solution is pumped through a spinneret. Air or inert gas is used to evaporate the solvent which results in solidification of the fibers. Dry spinning technique is used for such kind of Polymers which won’t melt but degrade on heating. Examples of dry spinning- Dry spinning may be used for manufacturing acetate fiber, triacetate fiber, acrylic fiber and vinyon.
- 12. Advantage and Disadvantage of Dry Spinning: Advantages 1. It is suitable for heat sensitive polymer 2. Higher spinning speeds can be easily achieved 3. The post spinning operation is simple 4. It is relatively flexible process and spinning conditions can be modified. Disadvantages 1. Flammable solvent hazards. 2. Solvent recovery is required. 3. Additional post spinning operation is required for complete removal of solvent.
- 13. Melt Spinning: It is used for the polymeric fibers or the polymers that can be melted. The polymer is melted and then pumped through a spinneret. The cooled and solidified molten fibers get collected on a take- up wheel. Melt spun fibers can be forced through the spinneret in different cross-sectional shapes such as round, pentagonal, octagonal among others. Examples of melt spinning fibers: Nylon fiber, olefin fiber, polyester fiber, saran fiber, etc. are also manufactured through melt spinning.
- 14. Advantage and Disadvantage of melt Spinning process: Advantages of Melt Spinning Process 1. Direct and simple process. 2. Low investment cost. 3. No solvent recovery process is required. 4. Can be used for both staple and continuous filament. 5. No environmental pollution. Disadvantages of Melt Spinning Process 1. It is suitable for only thermoplastic fiber. 2. Heat of input is high. 3. Accurate and precise temperature control is necessary. 4. Required more proper maintained of machine.
- 15. Gel spinning: It is also known as dry-wet spinning process because the filaments first pass through air and then are cooled further in a liquid bath. Gel spinning is used to make very strong and other fibers having special characteristics. Example of Gel Spinning: The polymer here is partially liquid or in a "gel" state, which keeps the polymer chains bound together at various points in liquid crystal form.
- 16. Conclusion: spinning process is applied to increase strength and orientation of the fiber. Man-made fibers are manufactured by spinning the polymer. There are three major types of spinning process. They are- Melt Spinning (It is used for polymers that can be melted easily.) Dry Spinning (It involves dissolving the polymer into a solution that can be evaporated.) Wet Spinning (It is used when the solvent can’t be evaporated and must be removed by chemical means.)
- 17. THANK YOU ALL