Published on March 6, 2014
The Plastics Polystryrene Polyurethane Polyethylene
Description: • Polystyrene is a synthetic polymer made from the monomer styrene, a liquid petrochemical. • Polystyrene can be rigid or foamed. • General polystyrene is clear, hard and brittle. • It is a very inexpensive resin per unit weight. • It is a rather poor barrier to oxygen and water vapor.
Origin and history: • Polystyrene was discovered in 1839 by Eduard Simon, in Berlin. • From the resin of a tree, he distilled an oily substance, a monomer that he named styrol. • Days later, Simon found that the styrol had thickened, presumably from oxidation, into a jelly he dubbed styrol oxide. • They called their substance metastyrol. • But later the substance receiving its present name, polystyrene.
Properties: PS Polystyrene • Thermal properties: The "compact" polystyrene presents the lowest thermal conductivity of all thermoplastics. • Optical properties: While the PS shock is fully opaque, the PS Crystal is transparent. • Electrical properties: Polystyrene has very low electrical conductivity, in other words, it is an insulator.
Aplicattions: Polystyrene shock Crystal polystyrene Expanded form Extruded shape
Recycling: • In general, polystyrene is not accepted in recycling programs, and is not separated and recycled where it is accepted. • In Germany, polystyrene is collected, as a consequence of the packaging law that requires manufacturers to take responsibility for recycling or disposing of any packaging material they sell.
Ampliation: • Polystyrene foam is a major environmental problem. Used in the packaging of products and transportation industry, occurs in the world tons of it each year. The fact that it is not recyclable increases the ecological impact. Contamination by polystyrene foam in landfills.
POLYURETHANE • JOSÉ MIGUEL PÉREZ HITA MORENO • 1ºB ACH
WHAT IS POLYURETHANE ? • Polyurethane (PUR and PU) is a polymer composed of a chain of organic units joined by carbamate (urethane) links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are also available.
HISTORY OF POLYURETHANE • Polyurethanes can be found in liquid coatings and paints, tough elastomers such as roller blade wheels, rigid insulation, soft flexible foam, elastic fiber or as an integral skin. No matter how polyurethane is transformed, the underlying chemistry is the result of one man’s genius, Prof. Dr. Otto Bayer (1902-1982). Prof. Dr. Otto Bayer is recognized as the “father” of the polyurethanes industry for his invention of the basic diisocyanate polyaddition process. • The origin of polyurethane dates back to the beginning of World War II, when it was first developed as a replacement for rubber. The versatility of this new organic polymer and its ability to substitute for scarce materials spurred numerous applications. During World War II, polyurethane coatings were used for the impregnation of paper and the manufacture of mustard gas resistant garments, highgloss airplane finishes and chemical and corrosion-resistant coatings to protect metal, wood and masonry.
HOW POLYURETHANE IS MADE • Polyurethane chemistry is complex, but the basics are relatively easy to understand. Polyurethanes are formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. Because a variety of diisocyanates and a wide range of polyols can be used to produce polyurethane, a broad spectrum of materials can be produced to meet the needs for specific applications.
POLYURETHANE APPLICATIONS • Heating and cooling costs amount to about 56 percent of the energy used in the average American home, according to the U.S. Department of Energy. The nature of the chemistry allows polyurethanes to be adapted to solve challenging problems, to be molded into unusual shapes and to enhance industrial and consumer products. • Polyurethanes are formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. Because a variety of diisocyanates and a wide range of polyols can be used to produce polyurethane, a broad spectrum of materials can be produced to meet the needs of specific applications.
PROPERTIES OF POLYURETHANE • Continuous insulation with joints: eliminates thermal bridges. • Waterproofing (high density). • “Autoahderente “ , to any surface or material used in construction. • Light weight: no “sobre caraga “structures. • Indefinite Duration. • Total sealing. • Chemical resistance. • Fire resistance.
POLYURETHANE FORMS • Polyurethanes exist in a variety of forms, including flexible foams, rigid foams, chemicalresistant coatings, specialty adhesives and sealants, and elastomers. • Rigid : Flexible:
The Accident ! • Polyethylene was first synthesized by German chemist Hans von Pechmann who prepared it by accident in 1898, while heating diazomethane on the stove. When his colleagues Eugen Bamberger and Friedrich Tschirner investigated the white oily substance created, they discovered long chains composed of-CH2-and called it polymethylene. March 27, 1933, in England, was synthesized as we know it today, by Reginald Gibson and Eric Fawcett who worked for ICI Laboratories.
Characteristics • Excellent electrical insulator. • . Transparent, opaque or attractive colors. • . Resistant to low temperatures. • . Hygienic and safe. • . Inert to chemical attack. • . Excellent moisture barrier. • . Economic.
Its Uses • All sorts of bags : supermarkets, boutiques,bakery,frosts etc. • Coating ditches • Automatic food packaging and industrial products, such as Milk, water, plastics, etc. • Base for disposable nappies. • Serum bags. • Domestic airtight containers • Pipes and knobs: cosmetics, medicines and food • Irrigation pipes • Bottles , draws
Recycling ! The Polyethylene is recyclable,it means, that we can melt it again and transform it in new products such as plastic wood for sticks film for agriculture etc.
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