News tagged with plastics

Cranial irradiation causes brain degeneration

(Medical Xpress)—Cranial irradiation saves the lives of brain cancer patients. It slows cancer progression and increases survival rates. Unfortunately, patients who undergo cranial irradiation often develop ...

Jul 16, 2013
popularity 4.9 / 5 (16) | comments 4 | with audio podcast report

The hippocampus as a decision-maker

(Medical Xpress) -- Synapses are modified through learning. Up until now, scientists believed that a particular form of synaptic plasticity in the brain’s hippocampus was responsible for learning spatial ...

Jul 19, 2012
popularity 5 / 5 (1) | comments 0 | with audio podcast

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs. Monomers of plastic are either natural or synthetic organic compounds.

The word plastic is derived from the Greek πλαστικός (plastikos) meaning capable of being shaped or molded, from πλαστός (plastos) meaning molded. It refers to their malleability, or plasticity during manufacture, that allows them to be cast, pressed, or extruded into a variety of shapes—such as films, fibers, plates, tubes, bottles, boxes, and much more.

The common word plastic should not be confused with the technical adjective plastic, which is applied to any material which undergoes a permanent change of shape (plastic deformation) when strained beyond a certain point. Aluminum which is stamped or forged, for instance, exhibits plasticity in this sense, but is not plastic in the common sense; in contrast, in their finished forms, some plastics will break before deforming and therefore are not plastic in the technical sense.

There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be moulded again and again; examples are polyethylene, polypropylene, polystyrene, polyvinyl chloride and polytetrafluoroethylene (PTFE). Thermosets can melt and take shape once; after they have solidified, they stay solid.

The raw materials needed to make most plastics come from petroleum and natural gas.

This text uses material from Wikipedia licensed under CC BY-SA