Medical research

The key role of astrocytes in cognitive development

Astrocytes have long been considered as mere support cells for neurons. In recent years, the study of astrocytes has grown, gradually revealing their importance in brain function. Researchers from Inserm, CNRS and Collège ...

Pediatrics

Plastic drapes reduce hypothermia in premature babies

Most babies born prematurely or with health problems are quickly whisked away to the Neonatal Intensive Care Unit (NICU) where they might require assisted heating devices to regulate their temperature. A University of Houston ...

Medical research

Shootin1a—the missing link underlying learning and memory

In neurons, changes in the size of dendritic spines—small cellular protrusions involved in synaptic transmission—are thought to be a key mechanism underlying learning and memory. However, the specific way in which these ...

Neuroscience

Synaptic transmission: Not a one-way street

Information flows in a well-defined direction in the brain: Chemical and electrical signals are passed from one neuron to the other across the synapse, from the pre-synaptic to the post-synaptic neuron. Now, Peter Jonas and ...

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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