POLYMERIC MATERIALS

PRESENTED BY

MAARIF RAZA

ME 3E 66

USMAN MUJAWARME 3E 52

SHAIKH MUZAMMILME 3E 80

In Engineering applications we often come across the use of various types of polymeric materials. These materials are comparatively cheaper and already replaced lot of metals in our day-to-day life. They are corrosion resistant, low weight and versatility in shape and sizes.

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.INRODUCTION

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A polymer is a chemical substance made-up of repeating units or molecule to form a long flexible chain. This is actually Greek word in which ‘poly’ means ‘many’ and ‘mer’ means a unit. i.e. having many units. Each repeating unit called as a monomer. The process of linking the monomer together to form a polymer is called polymerisation.

DEFINATION

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In the above chain the first and last mers are made stable by adding a hydrogen atom to the unused bind, a plastic material (known as

polyethylene) will be formed.

STRUCTURE

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PROPERTIES :

Plastics are light in weight. They are soft as compared to metals. Plastic have very low tensile and compressive strengths. They are excellent heat and electrical insulators. They have high corrosion resistance. They offer excellent resistance to acid , alcohols and alkalies.

TYPES OF PLASTICS :

1. Thermoplastics.

2. Thermosetting plastics.

3. Elastomers (Rubber)

PLASTICS

Substance which loose their rigidty whenever they are heated, so that they can be moulded under pressure with the new shape being retained on cooling.

This are also known as thermosoftening plastics. Thermoplastic can be reshaped with the soften state, thus the scrap can be used again & again. They may become too soft to use at temperature from 60oC to 325oC. They have linear structure. i.e cellulose nylon, polyethylene resins, vinyl plastics etc.

PROPERTIES :

1. They have excellent tensile strength (about 60MPa).

2. Good compressive strength (about 150MPa).

3. Excellent machinability.

4. Very good chemical resistance.

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THERMO PLASTICS

COMMONLY USED THERMOPLASTICS PLASTICS

Acrylic : The full name of acrylic is polymetyl methacylate. It is also known as Plexiglas or

Lucite. It is transparent with excellent clarity and high index of refraction. It can be shaped easily and widely used in sheet form. It is light in weight and tough but easily scratched.

APPLICATION : In fiber optics, contact lenses, transparent bowls, drink dispensers etc.

Nylons : It I also known as Polymides, Nylatron, Nylafil and Plaskon. It can be moulded successfully, extracted, formed into sheet as well as thin film

and can be casted easily. It is strong, tough and light in weight. It has low coefficient of friction. It is excellent to heat, abrasion and chemical reaction.

APPLICTION : For manufacturing of films, bearings, gears, machine slides, clothing rope, brush bristles etc.

EXAM QUESTIONS What is polymerism ? S-08 What are type of polymer material ? S-10 What do you mean thermosetting plastics, properties,

application & types? S-08 W-08