There are mainly three methods to recycle PET fiber wastes. These methods can be classi- fied into three groups, respectively; mechanical methods, chemical methods, and thermo-mechanical methods. Some special applications are also avail- able.
Mechanical methods can be applied to all kind of wastes including natural originated wastes such as wool wastes, cotton wastes, etc. and synthetic and regenerated polymers originated wastes such as polyester wastes and nylon wastes. The general pro- duction steps of the method are cutting, blending and opening. The opened material, which is in web form, is fed into the spinning plants to obtain coarse yarns or fed into the non-woven plants. The mechanical method is the simplest and the most universal one when compared to the other methods. The costs are low, however generally the economical value of the product is also low.
The chemical methods are widely used to recycle PET fiber production wastes in the plants, which have large capacities, and to recycle PET bottle wastes. The most common methods are glycolysis and methanolysis. Hydrolysis and steam cracking can also be used, however they have not been common yet. The processes in the chemical methods are complicated and the costs are high but the economic value of the final product is also high.
Thermo-mechanical method can be used in PET fiber wastes, polypropylene wastes, polyamide wastes, etc. Thermo-mechanical method is based on re-melt- ing of thermoplastic wastes to obtain re-granules. Re-granules can be used in staple fiber production or in plastic industry. Due to the degradations and viscosity drops, re-granules are used in staple fiber production. Solid state post-condensation can be used to increase viscosity, however the process requires very high energy.
There are mainly three methods to recycle PET fiber wastes. These methods can be classi- fied into three groups, respectively; mechanical methods, chemical methods, and thermo-mechanical methods. Some special applications are also avail- able.Mechanical methods can be applied to all kind of wastes including natural originated wastes such as wool wastes, cotton wastes, etc. and synthetic and regenerated polymers originated wastes such as polyester wastes and nylon wastes. The general pro- duction steps of the method are cutting, blending and opening. The opened material, which is in web form, is fed into the spinning plants to obtain coarse yarns or fed into the non-woven plants. The mechanical method is the simplest and the most universal one when compared to the other methods. The costs are low, however generally the economical value of the product is also low.The chemical methods are widely used to recycle PET fiber production wastes in the plants, which have large capacities, and to recycle PET bottle wastes. The most common methods are glycolysis and methanolysis. Hydrolysis and steam cracking can also be used, however they have not been common yet. The processes in the chemical methods are complicated and the costs are high but the economic value of the final product is also high.Thermo-mechanical method can be used in PET fiber wastes, polypropylene wastes, polyamide wastes, etc. Thermo-mechanical method is based on re-melt- ing of thermoplastic wastes to obtain re-granules. Re-granules can be used in staple fiber production or in plastic industry. Due to the degradations and viscosity drops, re-granules are used in staple fiber production. Solid state post-condensation can be used to increase viscosity, however the process requires very high energy.
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