2.3.3i Modern and smart materials

Question 1

what are smart materials

Answer 1

Smart materials or intelligent textiles react to a
change in their surroundings or external stimuli
such as temperature, light, moisture or friction.
* Modern materials are continually being updated
and developed. Some are engineered for
specific purposes.

Question 2

Smart textiles

Answer 2

• Photochromic
  Photochromic dyes change colour as a result
  of changes in light intensity i.e. sunlight.
  Photochromic inks can be printed onto fabric, as
  well as dyeing it. Sewing thread and beads can also
  be photochromic.
• Thermochromic
  Thermochromic dyes in fabric change colour
  in response to a change in heat levels.
  Thermochromic liquid crystals can be encapsulated
  onto fibres and fabrics. Thermochromic
  materials could act as a warning. For example, if
  impregnated onto dressings, a rise in temperature
  and colour change could indicate infection.
• Solvation chromism
  This refers to colour change that occur as a
  reaction to a change in moisture levels.
• Microencapsulation
  Microscopic particles containing various
  substances such as essential oils, moisturisers,
  antiseptics and anti-bacterial chemicals can be
  applied to fibres and fabrics. These substances are
  released through friction alongside contact with
  the skin.

Question 3

Interactive or intelligent textiles

Answer 3

• Wearable electronics
  Electronic devices can be integrated into fashion
  and textile products or into the fabric itself. These
  devices communicate wirelessly with the user/
  wearer. Integrated devices already in use include:
  mobile phones, heart rate monitors, GPS trackers,
  LEDs, heated panels, solar panels and performance
  trackers.
  Circuits embedded into clothing or fabric rely on
  conductive fibres to carry the electricity to the
  device.
• Conductive fibres and yarns
  Fine flexible conductive fibres and threads made
  from carbon, steel and silver can be seamlessly
  woven into fabrics without interfering with the
  texture and aesthetics of the fabric. In some cases,
  conductive fibres can be washed without impeding
  future functionality.
• Optical fibres
  Optical fibres are transparent flexible fibres made
  from glass or plastic that are slightly thicker than a
  human hair. Optical fibres can be used as sensors in
  smart clothing and technical textiles. They can carry
  an enormous amount of data as pulses of light.
• Heat storage materials
  PCMs or phase changing materials change from one
  state to another by absorbing, storing and releasing
  heat over a small temperature range. PCMs are
  encapsulated into textiles or applied as a coating.
  When used in clothing, they help regulate body heat
  – store energy when it is hot (liquid) but release it
  on cooling (return to solid)

Question 4

Modern materials

Answer 4

Sun protective clothing
A very closely woven or knitted fabric will effectively
block out harmful UV rays. Synthetic fibres have a
natural lustre which reflect UV rays away.
* Rhovyl®
Rhovyl® is a synthetic fibre known as chlorofibre
derived from polyvinylchloride (PVC). It is antibacterial, waterproof, crease resistant and quick
drying. It does not retain odours and wicks away
moisture. Ideal for sportswear.
* Carbon fibres
Carbon fibres are extremely lightweight and strong
with excellent covering power. Constructed through
an electrospinning process and made into sheets
like non-woven felt. These sheets that can folded
down into very compact sizes. Carbon fibre sheets
can be used as breathable membranes.
* Aramid fibres - Kevlar and Nomex
Engineered fibres said to be 5 times stronger than
nylon. They are heat and flame resistant with no
melting point, resistant to abrasion, cutting, solvents
and chemicals. Easy to care for and comfortable to
wear.
Kevlar has high tensile strength to weight ratio
and can be manufactured to withstand extreme
conditions. Nomex is used where resistance to heat
and flames is critical.
* Biosteel
Biosteel is comparable to steel and has a high
tensile strength, and can stretch up to 20 times its
normal length. It is the strongest natural fibre and
is biodegradable. It is currently not commercially
viable but could potentially replace Kevlar.