Natural plastics are obtained directly from raw vegetable materials
— for example, cellulose or latex, or from animal proteins.

Synthetic plastics are made from compounds extracted from
petroleum, natural gas and carbon.The majonty of plastics belong
to this group.

We can incorporate chemical additives to increase flexlbility and to
strengthen the polymers, , and we can add pigments to give colour to
the plastics.

ENERGETIC. We can incinerate plastics and the energy that
is produced is used tn industry, for heating or producing electricity.

CHEMICAL. We apply chemical processes to make new
matetials from the origtnal components of plastic residues.

They' re made up of weakly formed molecular chains When we heat them, they become soft, which allows them to be formed into different shapes.
The heating and cooling process
can be repeated many times.

These plastics are made from compounds derived from petroleum.They are formed by strongly-linkedchams runmng in different directions

Made by vulcanisation mixing sulphur and rubber, and heating to 160ºC
They are hard, resistant and very elastic — stretching easily under
force

We put thermoplastic Into a previously heated cyhnder

We apply pressure by means of a large, rotattng screw, which forces
the melted matenal out, through a nuzzle

We cool the shaped material slowly In a refngerated water bath until
lt's solid.

Finally, we collect the pieces of plastic through a feeder system.

Thermoplastic produced by the extrusion method ls passed through a
series of hot cylinders to produce sheets of varying thickness

We put thermoplastic into a mould

then use a heater to heat the mould and soften the plastic

We extract the air below the sheet so that the plastic ts pulled against
the instde walls of the shaped mould, and the desired form is created

We leave the mould to cool, then remove the object

1. We inject melted thermoplastic into a mould
2. When the material has cooled and solidified, we extract tt from the
   mould

1. We put a tubular-shaped piece of plastic into a hollow mould which has the same shape as the oblect that we want to make
2. We close the mould and blow pressurised air into it, so that the
   plastic adheres to the sides of the mould and takes its shape.
3. When the object is cold, we remove it from the mould.

1. We put thermostable plastic,which can be in granular form, into the base of a cavity mould.
2. The outer part of the cavity
   mould, shaped the same, isclosed to compress the material inside We then heat it and itbecomes soft and mafleable.

We can join and then separate objects with mechanical fasteners. For example nut and bolt, standard screw or double ended screw

We use this type of joint when we don't want to separate or dismantle
the piece, we can use adhesives or soldering

It can be vegetable origin, animal origin or mineral origin

Synthetic fibres such as nylon, polyester, rayon and Lycra' are plastics.They are long-lasting, resistant and waterproof.A mixture of natural and synthetic fibres is often used to make textiles.

STONE. These are materials found in nature as large blocks of rock within the
Earth.

STONE BINDERS. Sand and gravel are used directly to make asphalt and also for binders,
which are used to 'bind' or join other matenals together

PHSYCAL AND CHEMICAL PROPERTIES
Clay is a fine-grained earth composed of aluminium silicates and other substances We can mould it easily when it's wet.

making ceramics: Preparing the clay, mixing, modelling, drying, baking and glazing and enamelling

There are two large groups: structural ceramics and whiteware ceramics. Structural ceramics are permeable; whiteware ceramics are impermeable

SHAPING TECHNIQUES
We make glass by mixing sand, soda (which acts as a flux) and limestone.
We heat this mixture to I 400'C; it then melts tn form a paste. There are 3 shaping techniques: mould blowing, float glass making and lamination