Scan text 2 and find the paragraph which describes

- the properties of plastics,

- the importance of the materials science,

- the application of plastics for different industrial purposes,

- consumer plastics,

- simple and complex plastics,

- engineering plastics,

- the most widespread plastics.

Read text 2 more thoroughly. Consult the list of additional vocabulary. Be ready to do the assignments after the text.

Text 2. MATERIALS SCIENCE: PLASTICS

Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials and their properties. It includes elements of applied physics and chemistry, as well as chemical, mechanical, civil and electrical engineering. With significant media attention to nanoscience and nanotechnology in the recent years, materials science has been propelled to the forefront at many universities.

Metals, polymers and ceramics constitute an important part of materials science. Polymers are the raw materials (the resins) used to make what we commonly call plastics. Plastics consisting of one polymer are referred to as simple. Thus, organic glass (plexiglass) consists of one syn­thetic resin. But in the building field we usually deal with complex plastics, e.g. plastics consisting of a polymer and other components.

As is known, the term plastics covers a range of synthetic or semi-synthetic organic condensation or polymerization products that can be molded or extruded into objects or films or fibers. Their name implies that in their semi-liquid state they are malleable, or have the property of plasticity. Plastics vary immensely in heat tolerance, hardness, and resiliency. Combined with this adaptability, the general uniformity of composition and lightness of plastics ensure their use in almost all industrial applications today.

Polymers which are in current widespread use include polyethylene, polypropylene, polyvinyl-chloride, polystyrene, nylons, polyesters, acrylics, polyurethane, and polycarbonates. Plastics are generally classified as “commodity”, “specialty” and “engineering” plastics.

PVC (polyvinyl-chloride) is a commodity plastic; it is widely used, inexpensive, and annual production quantities are huge. This plastic has an incredible array of applications, and its fabrication and processing are simple and well-established. To modify its material properties various chemicals and compounds are added to the polymer base.

Polycarbonate would be normally considered as engineering plastic. Engineering plastics are valued for their superior strengths and other special material properties. They are usually not used for disposable applications, unlike commodity plastics.

It should be noted here that the dividing line between the various types of plastics is not based on material but rather on their properties and applications. For instance, polyethylene (PE) is a cheap polymer commonly used to make disposable shopping bags and trash bags, and is considered a commodity plastic, whereas Medium-Density Polyethylene (MDPE) is used for underground gas and water pipe.

Plastics combine all the fine characteristics of a building material owing to their inherent valuable and diverse properties. The architects and engineers have also turned to them to add beauty to modern homes and of­fices. Being a comparatively recent invention plastics have found today a wide application not only in construction, but many other industrial fields (machine-build­ing, aviation, textile industry, etc.).

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