various types of materials used in orthotics.

1. MATERIALS
USED IN
ORTHOTICS
- By MAYANK ANTHWAL
BPO- 10TH
BATCH
PT. DDUIPH
1

2. 2
Materials
• Some common materials being
used in ORTHOTICS are:-
• Aluminium
• Rubber.
• Plastics.
• Adhesives.
• Plaster of paris.
• Leather.
• Fabrics.
• Iron.

3. 3
Materials
THERE ARE MORE than 114 different elements known
to us today. These elements can be classified into metals
and non -metals. Of these Known elements, only 22 are
non-metals. The majority of the elements are metals. They
are all solids at room temperature, except mercury, which
is
a liquid. The characteristic properties of metals are quite
different from those of non-metals. For example, metals
are
lustrous, malleable, ductile and are generally good
conductors of heat and electricity. Nonmetals do not
possess these characteristics.
METALS
Metals are widely used in our daily life
Physical Properties
(a) Metallic Lustre
In pure state, metals have a shining surface. This property
is called metallic lustre. Metals like aluminium and
magnesium appear white. Gold is yellow in colour and
copper is reddish brown.

4. 4
Materials
(b) Hardness
Metals are generally hard. But all metals are not equally
hard. The hardness varies from metal to metal. Metals
like iron, copper, aluminium, etc., are quite hard. They
cannot be easily cut with a knife. But sodium and
potassium are so soft that they can be easily cut with a
knife.
(c) Malleability and Ductility
Some metals can be beaten into thin sheets with a
hammer. This property is called malleability.Gold and
silver are the most malleable metals. They can be
hammered into very thin foils. Another important
physical property shown by metals is ductility. That is,
metals can be drawn into very thin wires. But all metals
are not equally ductile. Gold and silver are the best
ductile metals

5. 5
Materials
(d) Thermal and Electrical Conductivity
Thermal means heat. Metals are generally good conductors
of heat. Silver is the best conductor of heat, followed by
copper. Aluminium is also a good conductor of heat. Metals
also conduct electricity because they have electrons which
are free to move. They offer little resistance to the flow of
current. Silver and copper are the best conductors of
electricity, followed by gold, aluminium and tungsten.
Mercury offers a very high resistance to the passage of
electric current.
Chemical Properties
(a) Reaction with Oxygen
Almost all metals combine with oxygen to form metal
oxides. When a metal combines with oxygen, it loses its
valence electrons and forms positively charged metal ions.
Thus, oxidation of metal takes place.
(b) Reaction with Water
Metals react with water and produce a metal hydroxide or
oxide and hydrogen gas. But all metals do not react with
water.

6. 6
Materials
(c) Reaction with Acids
All metals do not react with dilute hydrochloric and
sulphuric acids. But when a metal reacts with any of
these acids,
(d) Reaction with Chlorine
Metals react with chlorine to form metal chlorides,
(e) Reaction with Hydrogen
Metals generally do not form compounds with
hydrogen because metals form compounds By the loss
of electrons, which are accepted by the other
element.
But, hydrogen usually Forms compounds with other
elements either by sharing of electrons, or by the loss
of electrons. It does not accept electrons. But a few
active metals like Na, K and Ca, can force the
hydrogen atom to accept electrons to form salts,
called hydrides.

7. 7
Materials
IRON
Pliny the Elder (AD 23-79), the Roman
naturalist and writer wrote about iron :
"Ion
mines bring man a most splendid and most
harmful tool. Iron (Fe) is the second most
abundant metal in nature after aluminium
and it is the fourth most abundant element
in the Earth's crust. Nearly 5 percent of
Earth's crust is iron. So, we have about
755,000,000,000,000,000 tons. But then
only a fortieth part of this amount that is
accumulated in deposits is fit for
development. Its chemical symbol Fe is
derived from its Latin name ferrum. Its
atomic number is 26. Depending on the
percentage of carbon, iron is classified in
different classes. For example, cast iron
which is used for manufacturing heavy
frames or machinery parts contain 18 to
4.5% of carbon. Steel contain upto 2% of
carbon.

8. 8
Materials
Depending on these percentage different
properties of iron like ductility, malleability
etc. For imparting special properties,
Different metals are added to iron like
manganese, phosphorus, silicon, cadmium
etc.
ALLOYS
Iron is the most widely used metal. But it is never used
in the pure state. It is because pure iron is very soft and
stretches easily when hot. But, if it is mixed with a
small amount of carbon (about 0.05 %), it becomes
hard and strong. When iron is mixed with nickel and
chromium, we get stainless steel. It is hard and does
not rust. Thus, if iron is mixed with some other
substance, its properties change. In fact, properties of
any metal can be changed if it is mixed with some
other substance. The substance that is added, can be
a metal or a non-metal. The mixture is known as an
alloy. An alloy is a homogeneous mixture of two or
more metals, or a metal and a non-metal. If one of the
metals is mercury, then the alloy is known as an
amalgam.

9. 9
Materials
Aluminium
Among the metals aluminium is the most abundant
One in the Earth's crust and it is the third most
abundant
element (after oxygen and silicon). Aluminium makes
up about 8.1 per cent of the Earth's crust. It is found
in
minerals bruxite, mica and cryolite and in clay. In 1809
Sir Humphry Davy had prepared an iron-aluminium
alloy by electrolysing fused aluminium oxide (alumina)
and he had named the element aluminum, which was
later modified to aluminium. Aluminium is a silvery
white metal (melting point 6600C and boiling point
about 25000C). Pure aluminium (99.996 percent) is
quite soft and weak. Commercial aluminium (99.0 to
99.6percent pure) with small amounts of silicon and
iron is hard and strong.

10. 10
Materials
The following properties of aluminium make it very
useful metal in many ways.
1. It has a low density (relative density 2.70). It is
more than three times lighter than copper and 2.9
times lighter than iron.
2. It can be easily rolled into thin sheets. It is
possible to flatten aluminium into a foil a more 3
microns thick or to draw it into wire not thicker
than a spider's web.
3. It has good electrical and thermal conductivity. In
its thermal and electrical conductivity aluminium is
inferior only to silver, gold and copper.
4. Aluminium, because of formation of a thin film of
aluminium oxide on its surface, is highly resistant
to corrosion. Because of this coating it is possible
for aluminium parts to serve for decades even in
the chemical industry.

11. 11
Materials
Other Materials
Rubber
The rubber serve the field of O & P in many ways
such
as padding and cushioning material. Natural rubber is
a hydrocarbon polymer of isoprene. Polymerization
i..e. the uniting of one or more compounds
(monomers) into very long chains polymers) is the key
to synthetic rubber manufacture.
Plastics
The term “Plastics” applies to highly polymeric
substances made by man from natural materials like
petroleum, sand, salt, and water. Plastics are cheap
and provide for ease of fabrication and appear
attractively. They can be classified as “rigid” or
“thermostting” and “flexible” or “thermoplastics”.
Plastics are weaker and less stiff in sheets of equal
thickness, lighter in weight, and good electrical and
thermal insulators, than metals.

12. 12
Materials
Plastics
Plastics are resistant to corrosion. Certain plastics are
resistant to many solvents, but generally they are
attacked by acids and bases. Plastics are usually
favored because of their superior appearance, uniform
colour, and physical properties and the ease with
which they can be casted, molded or extruded.
Adhesives
Adhesion is primarily a chemical phenomenon rather
than a mechanical one. The adhesions of one material
to another depends upon the chemical nature of the
surfaces involved.
Adhesives can be broadly categorized into three
groups.
1. Synthetic resins
2. Rubber based
3. Protien adhesives

13. 13
Materials
Plaster of Paris
The POP is obtained from crushing and grinding of
purest form of gypsum, and then heating it sufficiently
to dry out the the water. POP is the Hemi Hydrate of
Calcium Sulphate. POP forms a plastic mass, when
mixed with water, that can be molded, shaped and
cast. POP is so hungry of water that even the slightest
moisture can start the process of crystallization and
POP starts setting.
Leather
Leather is probably one material. Along with wood,
and metal, that has been in use in the field of O & P.
The properties of leather, basically, are dependent on
the type of leather, type of tannage, character of
lubrication, and the mechanical treatment. The
characteristics of leather which make it valuable for O
& P purposes are its strength, stretch, tearing
resistance, resilience, porosity, .ventilating power
make it versatile material in O & P construction
Business. Efforts are on since long to find out suitable
substitute of leather.