Polymer Engineering

Polymer Engineering

Polycarbonate

Contents

History

Polycarbonate structure

Polymer production

Processing

Manufacturing diagram

Properties

Applications

History

Dr. Hermann Schnell and his team at Bayer company discovered polycarbonate in 1953, forever changing how we live our lives.

PC was introduced in United States Of America in 1960 by general electric company

As the next 63 years have shown, polycarbonate has evolved, finding its way into a multitude of products that touch our lives every day.

What is polycarbonate?

Polycarbonates received their name because they are polymers containing carbonate groups (-O-(C=O)-O-).

Its most popular trade name is LEXAN.

PC is a good material choice in industry not only due to its characteristics, but also because its processing is environmentally friendly, and it can be recycled.

About 2.7 million tons of polycarbonate are produced annually worldwide.

Structure

Polycarbonates are long-chain linear polyesters of carbonic acid and dihydric phenols, such as bisphenol A.

Take a look at the above diagram. In it, you will see two six-sided structures. These are called phenyl groups. You will also see two groups identified by the label CH3. These are methyl groups. The presence of the phenyl groups on the molecular chain and the two methyl side groups contribute to molecular stiffness in the polycarbonate. This stiffness has a large effect on the properties of polycarbonate. First, attraction between of the phenyl groups between different molecules contributes to a lack of mobility of the individual molecules. This results in good thermal resistance but relatively high viscosity (i.e., low melt flow) during processing. The inflexibility and the lack of mobility prevent polycarbonate from developing a significant crystalline structure. This lack of crystalline structure (the amorphous nature of the polymer) allows for light transparency.

Polymer Production

The main polycarbonate material is produced by the reaction of bisphenol A and phosgene (COCl2). The overall reaction can be written as follows:

Bisphenol A Phosgene PC polymer

Polycarbonate is transformed from pellets into the desired shape.

Processing

Polycarbonate

Extrusion Moulding

The molten PC is passed through a die The PC melt is pressed into a mold with

that gives the material its final shape. the defined shape of the final product.

After this, the melt is cooled rapidly. the melt is then cooled inside the mold.

Block flow Diagram

Manufacturing

Properties

excellent physical properties

excellent toughness

transparent

fair processing

good electrical insulating properties

Light weight

Good scratch resistance

Excellent thermal properties

Very durable

The addition of glass fibers to polycarbonate significantly increases the tensile strength, and heat deflection temperature . The greater the amount of glass fiber added to the polycarbonate, the greater the effect on each property will be.

How do strength property in PC compare to other plastics?

ABS: Acrylonitrile butadiene styrene

PPO: Polyphenylene Oxide

PBT: Polybutylene terephthalate

PET: Polyethylene terephthalate

The characteristics of polycarbonate are quite like those of polymethyl methacrylate (PMMA, acrylic), but polycarbonate is stronger, usable in a wider temperature range but more expensive.

Strength test

Applications

bullet proof glass lenses bottles face shield

Safety glasses

Applications

Electronic components Construction headlamp lenses

Riot shields Data storage

High institute of engineering and technology in new Damietta (NDETI)

Chemical Engineering Department

Supervisor: DR, Reham Atef

Prepared by,

Amr Rashad