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Polyester

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Polyester

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Polyester

  1. 1. Polyester Polyester Polyester fibres are formed from synthetic polymers, manufactured by the action of poly-functional acids with poly-functional alcohols. The fibre forming polymer substance is a long linear polymer with repeating ester groups in its structure. According to “FTC (Federal Trade Commission of USA)”, Polyester fibres are manufactured fibers in which the fiber forming substance is any long chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted Terephthalate units P(-R-O-CO-C6H4-CO-O-) and para-substituted hydroxybenzoate units P(-R-O-CO- C6H4-CO-O-).DuPont Company of USA first produced polyester fibres on commercial scale in 1953. Commercial or trade names of polyester • Terelene (UK) • Dacron (USA) • Tetron (Japan) • Torital (Italy) • Lavson (Russia) • Terenca (Holland) • Diolen (France) Classification of Polyester fibres and their manufacturing process There are different types of polyester- Polyethylene terephthalate (PET) The most important and widely used polyester is known as polyethylene terephthalate. It is produced from the polymer manufactured by the reaction of terephthalic acid (TPA) and ethylene glycol (EG). The reaction can be shown as below- n HOOC- --COOH + n OH-CH2-CH2-OH HO-[-OC- -COO-(CH2)2O-]n-H TPA EG PET or Dacron + (2n-1) H2O Page 1
  2. 2. In USA, PET is known as Dacron but in UK, it is known as Terylene and produced from the polymer manufactured by the reaction of dimethyl terephthalate (DMT) and ethylene glycol (EG) as shown below- n CH3OOC- --COOCH3 + n OH-CH2-CH2-OH CH3O-[-OC- -COO-(CH2)2O-]n-H DMT EG Terylene + (2n-1) CH3OH Poly-1,4-cyclohexylene dimethylene terephthalate (PCDT) or Kodel II (200) This type of polyester is derived from the polymer manufactured by the reaction of terephthalic acid (TPA) and 1,4-cyclohexane dimethanol which can be shown as below- n HOOC- -COOH + n HOCH2- -CH2OH TPA HO-[-OC- -COO-H2C- -CH2O-]n-H + (2n-1) H2O PCDT Vyron For this type polyester, fibre forming polymer is produced from ethylene glycol and a mixture of terephthalic and isophthalic acid. m HOOC- -COOH + n HOOC- -COOH + (m+n) OH-CH2-CH2-OH TPA EG HO-[-OC- -COO-(CH2)2-OOC- -COO-(CH2)2-O-](m+n)-H Vyron Flow chart of Polyester production Preparation of raw material (Terephthalic acid, DMT, ethylene glycol preparation) Mixing tank Polymerization in reactor (Ester interchange and poly condensation) Temperature: 260-2800 C, Time: 3-6 hours Polymer chips Melt spinning Page 2
  3. 3. Polyester filament produced from spinneret holes (Monofilament, multifilament) Drawing Reeling onto a package or Texturization Page 3
  4. 4. Polymer system Polyester fibre forming polymer is a long linear polymer and it’s degree of polymerization is 115 to 140 where molecular weight is around 20000. Important groups are –CH2, -CO, -OCO and held in polymer together by Vander Walls force, H-bond. Polyester polymer length is 120 to 150µm and 0.6µm thick. It is 65 to 85% crystalline. -OH, -COOH are the functional groups of polyester. Macro structure of polyester Length: It can be made in both staple and filament form. Fibre diameter: 12 to 25 µm Length width ratio: 2000:1 Appearance: Smooth Cross section: Generally have round cross section but may be triangle, oval and rectangle shaped. Color: Generally white Physical properties of polyester Specific gravity: 1.38 Moisture Regain: 0 to 0.4% at standard condition due to having extremely crystallinity and lack of polarity. Tenacity (dry/wet): 7-8 gm/denier for high tenacity filament 4.5-5.5 gm/denier for normal tenacity filament 3.5-4 gm/denier for staple fibres Elongation: 8-11% for high tenacity 15-30% for medium tenacity 25-45% for staple fibre Bending recovery: Good Abrasion resistance: Not good. Abrasion resistance of normal polyester is less than that of high tenacity one. Resiliency: very good. Page 4
  5. 5. Chemical properties polyester 1. Effects of moisture:N Polyester absorbs only a very small amount of moisture and the tenacity and elongation are unaffected by moisture. 2. Effects of bleaches:Not affected by oxidizing and reducing bleaches. 3. Effects of acids: Polyester fibres are highly resistant to mineral and organic acids. Weak acid can not effect on them even on boiling. Strong mineral acid such as H2SO4 can only hydrolyze them on boiling for hours together. 4. Effects of alkali: Polyester is very much resistant to alkalis. Only strong hot alkalis results in a slow thinning of the diameter by saponification. 5. Effects of organic solvents: Resistant to all dry cleaning solvents. 6. Dye ability: Disperse dye and some pigments can be used for coloration. 7. Effects of sunlight: Have good resistance to sunlight but becomes weak when expose in sunlight for long time. Thermal properties of Polyester Polyester fibre is the most thermally stable synthetic fibre. If heat setting is not done properly then shrinkage occurs. At high temperature polyester melts and burns. Softening temperature: 690 C Melting temperature: 250-2650 C Sticking temperature: 230-2400 C Ironing temperature: 1350 C Thermo plasticity ‘Thermo plasticity’ means capable of being shaped or moulded when heated. Thermoplastic fibres heated under strictly controlled temperatures soften and can then be made to conform to a flat, creased or pleated configuration. When cooled, thermoplastic fibres will retain the desired configuration that is remain flat, pleated or creased. Polyester textile materials can be permanently heated. Textile fibres classed as thermoplastic are acetate, triacetate, acrylic, nylon and polyester. Polyesters retain a heat set permanently where as acetate fibres do not hold a set as satisfactory. Biological properties of Polyester Polyesters have good resistance against micro organisms, larvae, fungi, mildew and moulds. Page 5
  6. 6. End uses of Polyester 01. As apparel: Men’s wear, women’s wear, children’s wear, trousers, skirts, suits, jackets, blouses and every form of clothing are made by polyester fibres. Besides ties, lingeries etc can also be made by polyester fibres. 02. As blended fabrics: Polyesters are widely used in blends with cotton, wool, acrylic, nylon etc fibres for making quality fabrics. Blends with cotton and virgin wool are very popular. They are often referred to as the "classical blend". This is normally a combination of 55% polyester and 45% wool. 03. As home furnishings: Carpets, curtains, draperies, sheets, pillow covers, wall coverings, upholstery etc are made of polyester fibres. 04. As industrial use: Polyester fibres are used in manufacturing of tire cord, power belt, ropes, tarpaulin, nets, hoses, conveyor belt etc. It is also used in making floppy disk, liners etc. Use of polyester higher than any other synthetic fibre The use of polyester is higher than any other synthetic fibre due to low cost, more durable, no fading, easy care, no ironing. Page 6
  7. 7. End uses of Polyester 01. As apparel: Men’s wear, women’s wear, children’s wear, trousers, skirts, suits, jackets, blouses and every form of clothing are made by polyester fibres. Besides ties, lingeries etc can also be made by polyester fibres. 02. As blended fabrics: Polyesters are widely used in blends with cotton, wool, acrylic, nylon etc fibres for making quality fabrics. Blends with cotton and virgin wool are very popular. They are often referred to as the "classical blend". This is normally a combination of 55% polyester and 45% wool. 03. As home furnishings: Carpets, curtains, draperies, sheets, pillow covers, wall coverings, upholstery etc are made of polyester fibres. 04. As industrial use: Polyester fibres are used in manufacturing of tire cord, power belt, ropes, tarpaulin, nets, hoses, conveyor belt etc. It is also used in making floppy disk, liners etc. Use of polyester higher than any other synthetic fibre The use of polyester is higher than any other synthetic fibre due to low cost, more durable, no fading, easy care, no ironing. Page 6

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