PART 4 LYCRA-SPANDEX - structure, properties and uses

Doc Brown's Chemistry Revision Notes - Smart Materials and Materials Science

PART 4 LYCRA-SPANDEX

• LYCRA was the first spandex fibre introduced into the clothing materials market - from fashion ware to sports ware!

• Lycra is a commercial material specially designed to have special properties for a wide variety of clothing articles.

• Lycra-Spandex polymer materials are strong fibres with elastic properties.

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  • The above diagram is an example of the molecular structure of 'Lycra-Spandex' type molecules

  • n = a very large number of repeating double 'molecular segments' in the polymer chain.

  • x is the variable number of units in the 'elastic' molecular segment, this gives differing degrees of 'stretchiness'.

  • Therefore its molecules have a stretchy section that make it soft and rubbery, and a rigid section that makes it tougher than rubber.

• Lycra is an artificial fibre that readily stretches but is still a strong material overall.

  • Parts of the long polymer molecules stretch easily i.e. elastic at the molecular level, but other sections of the polymer chain are more rigid to increase strength.

  • Lycra fibres can be stretched up to 500% (i.e. 5x) of their original length.

  • Some advanced molecular ideas

    • (i) I wouldn't have thought this stretching capacity could be totally explained by the zig-zag chain of carbon and oxygen atoms, i.e. -(-C-C-O-)_x-, so is this polyether section coiled up prior to be stretched?

      • The intermolecular forces between the relatively non-polar polyether sections of adjacent Lycra molecules are the weakest Van der Waal forces, instantaneous dipole - induced dipole attractive forces.

    • (ii) The benzene rings are much more rigid compared to a hydrocarbon/ether saturated chain of atoms, but is the strength and rigidity of this section also enhanced by hydrogen bonding between -NH-CO- groupings in adjacent Lycra molecules? (as in protein tissue and synthetic nylon polymers).

• The advantages of Lycra

  • It is used in making sports clothing such as wetsuits, and with other fibres to make comfortable clothing with a snug fit.

  • Lycra is a lightweight material but isn't damaged by sunlight, sweat or detergents - all of which can make other materials wear out.

WHERE NEXT?

INDEX of SMART MATERIALS PAGES

PART 1 CHROMOGENIC MATERIALS - Thermochromic, Photochromic & Electrochromic Materials

PART 2 SHAPE MEMORY ALLOYS e.g. Nitinol & Magnetic Shape Memory Alloys

PART 3 SHAPE MEMORY POLYMERS, pH and temperature sensitive-responsive polymers, self-healing materials

Part 4 LYCRA-SPANDEX

PART 5 High performance polymers like KEVLAR

PART 6 GORETEX, THINSULATE and TEFLON-PTFE

PART 7 PIEZOELECTRIC EFFECT (PIEZOELECTRIC MATERIALS) and PHOTOMECHANICAL MATERIALS

PART 8 CARBON FIBRES

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