�ݺ�ߣ

Rayon
-the first man-made fibre.
Name: Nikita Negi
Class: 8th A
Roll no.: 40

Introduction
Rayon is technically neither
an
artificial fibre or a natural
fibre. It is derived from
cellulose which is a natural
product but it requires a lot
of
processing to become Rayon.

Rayon
Production:
• Wet spun rayon (viscose)
• High wet modulus (HWM) rayon
Physical structure:
• Natural bright
• Can be solution dyed
• Regular rayon: Serrated cross section.
• HWM rayon: Rounder cross section and better performance.

Viscose Process
The vast majority
of rayon is
fabricated using
the viscose
process. This
process started in
the early 1900’s.

Manufacturing Process
• Purification of Cellulose: The purified cellulose that is used in
the fabrication of rayon comes from processed wood pulp that is
of a higher grade that that used for paper. Also known as
“dissolving cellulose” or “dissolving pulp”. It is composed of long
chain molecules.
• Steeping Process: The sheets of cellulose are saturated in
sodium hydroxide and left to set so that the sodium hydroxide
can penetrate the sheets and transform it into “soda cellulose”.
• Shredding or cutting process: The sheets of cellulose are
shredded so they can be processed easier. Shredded cellulose is
commonly referred to as “white crumb”.

• Ageing Process: Because white crumb has such a high alkalinity,
so it is oxidized to lower molecular weights.
• Churning Process or Xanthation: The cellulose crumbs are
allowed to react with carbon disulphide to form cellulose
xanthate.
• Mixing or dissolving Process: The yellow crumb is dissolved in an
aqueous solution.
• Ripening Process: The viscose is allowed to stand for a period of
time.
• Filtering: It’s filtered to remove any undissolved materials that
could cause defects.

• Degassing: Bubbles of air that could also cause defects are
removed.
• Spinning Process: The material is moved into a bath containing;
sodium sulphate, sulphuric acid and zinc sulphate. This causes the
rayon filaments to bond together tightly.
• Drawing: The newly bonded rayon filaments are stretched.
• Washing: The rayon gets washed to remove any impurities that
may remain.
• Cutting: To be made usable the rayon is passed through a rotary
cutter to create a fibre that can be processed the same as any
other.

Rayon-The first man made fiber

Rayon Properties
• Physical: Fluid drape, soft hand, control lustre, length, diameter.
• Mechanical:
Regular: Weak, especially wet.
HWM: Stronger, adequate breaking elongation.
• Chemical: Absorbent, dyes well, high regain, smooth, soft, good heat & static
conductor.
• Appearance retention: Moderate
Regular: poor resiliency, progressive shrinkage
HWM: less wrinkling, accepts durable press & dimensional stability finishes, can be
mercerized
• Care:
Regular: limited wash ability (wrinkling, loss of sizing, excessive shrinkage) dry clean
HWM: greater wash ability, less wrinkling, shrinkage may be controlled

Environmental Impacts of Fabric:
Rayon
• Rayon requires raw wood, usually hemlock or pine, and a great
deal of water and energy to process.
• Here's a fun fact: Port Angeles, WA was once home to a pulp mill
that produced the raw cellulose needed to make rayon and a
number of other products. Today, it's a toxic clean-up site. The
company's name? Rayonier.
• This is another artificial fibre, made from wood pulp, which on
the face of it seems more sustainable. However, old growth
forest is often cleared and/or subsistence farmers are displaced
to make way for pulpwood plantations. Often the tree planted is
eucalyptus, which draws up phenomenal amounts of water, causing
problems in sensitive regions. To make rayon, the wood pulp is
treated with hazardous chemicals such as caustic soda and
sulphuric acid.

�ݺ�ߣ

Rayon-The first man made fiber

Recommended

More Related Content

What's hot (20)

Similar to Rayon-The first man made fiber (20)

Recently uploaded (20)

Rayon-The first man made fiber