TPER: The Per
Acronym Definition
TPER Thermoplastic Elastomeric Rubber
TPER Total Primary Energy Requirement
TPER The Package-Enabled Reengineering
TPER The Packed Encoding Rules (ISO 8825-2)
TPER The Packet Encoding Rule
TPER The Packet Error Rate
TPER The Parameter Error Rate
TPER The Parity Error Rate
TPER The Parts Evaluation Report
TPER The Patrulla Especial de Rescate (Guatemala)
TPER The Peaches En Regalia
TPER The Percent Extracellular Release
TPER The Percentage Effort Ratio
TPER The Perform
TPER The Performance Evaluation Report
TPER The Performance Event Report
TPER The Periodic Electoral Review
TPER The Permanent (mathematics; group theory)
TPER The Permission
TPER The Person
TPER The Personnel
TPER The PERT Event Report
TPER The Perth, Western Australia, Australia - Perth (Airport Code)
TPER The Peru (ISO Country code)
TPER The Physical Education Recreation
TPER The Plan d'Epargne-Retraite
TPER The Polarization Extension Ratio
TPER The Port Engineer Request
TPER The Port Everglades Railway
TPER The Power Enhancement Ratio
TPER The Pre-Environmental Review
TPER The Preliminary Engineering Report
TPER The Preliminary Environmental Review
TPER The Price-to-Earnings Ratio
TPER The Probable Error in Range
TPER The Product Evaluation and Recommendation
TPER The Professional and Executive Recruitment
TPER The Proficiency Examination Review
TPER The Program Effectiveness Review
TPER The Program Element Review
TPER The Program Event Recording
TPER The Program for Ecosystem Research
TPER The Progressive Encephalomyelitis with Rigidity
TPER The Project Evaluation & Recommendation
TPER The Proposal Evaluation Report
TPER The Protein Efficiency Ratio
TPER The Provider Edge Router
TPER The Public Employees Roundtable
TPER The Public Expenditure Review (World Bank)
Per or PER can be:
* a common first name in Scandinavia. A form of Peter which means "rock" or
"cliff" in Latin.
* Per (storm), a storm in Sweden, in January 2007.
* the IOC country code for Peru.
* the IATA code for Perth Airport in Western Australia.
* PE ratio, price-to-earnings ratio, used in finance.
* Player Efficiency Rating, a basketball statistic.
* Partial equivalence relation.
* Polarization extinction ratio, used in optics and telecommunications.
* Per, the gender-neutral possessive pronoun used by the inhabitants of the
future feminist and anarchist utopia in Marge Piercy's novel Woman on the Edge
of Time.
* Packed Encoding Rules, a set of ASN.1 encoding rules for formatting data in
binary.
* Protein efficiency ratio, a method used for evaluating the quality of protein
in food.
* the official abbreviation of the Western Australian Herbarium
* an acronym for Portable Employer of Record
* Perseus (constellation) (standard astronomical abbreviation)
* the stock symbol for Perot Systems Corporation
* Period (gene)
* Packet Error Ratio, the ratio in data packet based communication systems
between valid and invalid packets.
* Pér, a village in Hungary
* Physics Education Research
Thermo Plastic Elastomeric Rubber (TPER)
A waterstop is an element of a concrete structure, intended to provide
watertightness when embedded in and running through concrete joints. Waterstops
are frequently manufactured from extruded plastics such as PVC or thermoplastic
elastomeric rubber (TPER); formed metal such as stainless steel, copper, or
carbon steel; or extruded thermosets such as natural rubber, Styrene-butadiene
rubber, or neoprene rubber.
Polymer waterstops such as PVC, TPER, or rubber are frequently supplied to
the construction site in coils (usually 50 lineal feet long), and are generally
anywhere from 4 inches to 12 inches wide in a variety of profiles that are
designed to simultaneously provide an interlock with the concrete they are
installed in and provide for a limited amount of movement within the joint. PVC
and TPER Waterstops are made continuous for the length of the concrete joint by
heat welding, using simple thermoplastic welding equipment . Thermoset rubbers
and metallic waterstops are more difficult to fabricate to continuous lengths
and are specified far less frequently by architects and engineers.
TPER waterstops are generally installed in joints of secondary containment
structures to prevent the passage of hazardous fluids other than water such as
fuel oils, acids, or process chemicals.
Plastic is the general term for a wide range of synthetic or semisynthetic
polymerization products. They are composed of organic condensation or addition
polymers and may contain other substances to improve performance or economics.
There are few natural polymers generally considered to be "plastics". Plastics
can be formed into objects or films or fibers. Their name is derived from the
fact that many are malleable, having the property of plasticity.
Overview
Plastic can be classified in many ways, but most commonly by their polymer
backbone (polyvinyl chloride, polyethylene, polymethyl methacrylate and other
acrylics, silicones, polyurethanes, etc.). Other classifications include
thermoplastic, thermoset, elastomer, engineering plastic, addition or
condensation or polyaddition (depending on polymerization method used), and
glass transition temperature or Tg.
Some plastics are partially crystalline and partially amorphous in molecular
structure, giving them both a melting point (the temperature at which the
attractive intermolecular forces are overcome) and one or more glass transitions
(temperatures above which the extent of localized molecular is substantially
increased). So-called semi-crystalline plastics include polyethylene,
polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some
polyurethanes. Many plastics are completely amorphous, such as polystyrene and
its copolymers, poly (methyl methacrylate), and all thermosets.
Plastics are polymers: long chains of atoms bonded to one another. Common
thermoplastics range from 20,000 to 500,000 in molecular weight, while
thermosets are assumed to have infinite molecular weight. These chains are made
up of many repeating molecular units, known as "repeat units", derived from
"monomers"; each polymer chain will have several 1000's of repeat units. The
vast majority of plastics are composed of polymers of carbon and hydrogen alone
or with oxygen, nitrogen, chlorine or sulfur in the backbone. (Some of
commercial interest are silicon based.) The backbone is that part of the chain
on the main "path" linking a large number of repeat units together. To vary the
properties of plastics, both the repeat unit with different molecular groups
"hanging" or "pendant" from the backbone, (usually they are "hung" as part of
the monomers before linking monomers together to form the polymer chain). This
customization by repeat unit's molecular structure has allowed plastics to
become such an indispensable part of twenty first-century life by fine tuning
the properties of the polymer.
People experimented with plastics based on natural polymers for centuries. In
the nineteenth century a plastic material based on chemically modified natural
polymers was discovered: Charles Goodyear discovered vulcanization of rubber
(1839) and Alexander Parkes, English inventor (1813—1890) created the earliest
form of plastic in 1855. He mixed pyroxylin, a partially nitrated form of
cellulose (cellulose is the major component of plant cell walls), with alcohol
and camphor. This produced a hard but flexible transparent material, which he
called "Parkesine." The first plastic based on a synthetic polymer was made from
phenol and formaldehyde, with the first viable and cheap synthesis methods
invented by Leo Hendrik Baekeland in 1909, the product being known as Bakelite.
Subsequently poly (vinyl chloride), polystyrene, polyethylene (polyethene),
polypropylene (polypropene), polyamides (nylons), polyesters, acrylics,
silicones, polyurethanes were amongst the many varieties of plastics developed
and have great commercial success.
The development of plastics has come from the use of natural materials (e.g.,
chewing gum, shellac) to the use of chemically modified natural materials (e.g.,
natural rubber, nitrocellulose, collagen) and finally to completely synthetic
molecules (e.g., epoxy, polyvinyl chloride, polyethylene).
In 1959, Koppers Company in Pittsburgh, PA had a team that developed the
expandable polystyrene (EPS) foam cup. On this team was Edward J. Stoves who
made the first commercial foam cup. The experimental cups were made of puffed
rice glued together to form a cup to show how it would feel and look. The
chemistry was then developed to make the cups commercial. Today, the cup is used
throughout the world in countries desiring fast food, namely, the United States,
Japan, Australia, and New Zealand. Freon was never used in the cups. As Stoves
said, "We didn't know freon was bad for the ozone, but we knew it was not good
for people so the cup never used freon to expand the beads."
The foam cup can be buried, and it is as stable as concrete and brick. No
plastic film is required to protect the air and underground water. If it is
properly incinerated at high temperatures, the only chemicals generated are
water, carbon dioxide and carbon ash. If burned without enough oxygen or at
lower temperatures (as in a campfire or household fireplace) it can produce
toxic vapors and other hazardous byproducts.[1][2] EPS can be recycled to make
park benches, flower pots and toys.
Cellulose-based plastics: celluloid and rayon
All Goodyear had done with vulcanization was improve the properties of a natural
polymer. The next logical step was to use a natural polymer, cellulose, as the
basis for a new material.
Inventors were particularly interested in developing synthetic substitutes for
those natural materials that were expensive and in short supply, since that
meant a profitable market to exploit. Ivory was a particularly attractive target
for a synthetic replacement.
An Englishman from Birmingham named Alexander Parkes developed a "synthetic
ivory" named "pyroxlin", which he marketed under the trade name "Parkesine", and
which won a bronze medal at the 1862 World's fair in London. Parkesine was made
from cellulose treated with nitric acid and a solvent. The output of the process
hardened into a hard, ivory-like material that could be molded when heated.
However, Parkes was not able to scale up the process reliably, and products made
from Parkesine quickly warped and cracked after a short period of use.
Englishmen Daniel Spill and the American John Wesley Hyatt both took up where
Parkes left off. Parkes had failed for lack of a proper softener, but they
independently discovered that camphor would work well. Spill launched his
product as Xylonite in 1869, while Hyatt patented his "Celluloid" in 1870,
naming it after cellulose. Rivalry between Spill's British Xylonite Company and
Hyatt's American Celluloid Company led to an expensive decade-long court battle,
with neither company being awarded rights, as ultimately Parkes was credited
with the product's invention. As a result, both companies operated in parallel
on both sides of the Atlantic.
Celluloid/Xylonite proved extremely versatile in its field of application,
providing a cheap and attractive replacement for ivory, tortoiseshell, and bone,
and traditional products such as billiard balls and combs were much easier to
fabricate with plastics. Some of the items made with cellulose in the nineteenth
century were beautifully designed and implemented. For example, celluloid combs
made to tie up the long tresses of hair fashionable at the time are now
highly-collectable jewel-like museum pieces. Such pretty trinkets were no longer
only for the rich.
Hyatt was something of an industrial genius who understood what could be done
with such a shapeable, or "plastic", material, and proceeded to design much of
the basic industrial machinery needed to produce good-quality plastic materials
in quantity. Some of Hyatt's first products were dental pieces, and sets of
false teeth built around celluloid proved cheaper than existing rubber dentures.
However, celluloid dentures tended to soften when hot, making tea drinking
tricky, and the camphor taste tended to be difficult to suppress.
Celluloid's real breakthrough products were waterproof shirt collars, cuffs, and
the false shirtfronts known as "dickies", whose unmanageable nature later became
a stock joke in silent-movie comedies. They did not wilt and did not stain
easily, and Hyatt sold them by trainloads. Corsets made with celluloid stays
also proved popular, since perspiration did not rust the stays, as it would if
they had been made of metal.
Celluloid could also be used in entirely new applications. Hyatt figured out how
to fabricate the material in a strip format for movie film. By the year 1900,
movie film was a major market for celluloid.
However, celluloid still tended to yellow and crack over time, and it had
another more dangerous defect: it burned very easily and spectacularly,
unsurprising given that mixtures of nitric acid and cellulose are also used to
synthesize smokeless powder.
Ping-pong balls, one of the few products still made with celluloid, sizzle and
burn if set on fire, and Hyatt liked to tell stories about celluloid billiard
balls exploding when struck very hard. These stories might have had a basis in
fact, since the billiard balls were often celluloid covered with paints based on
another, even more flammable, nitrocellulose product known as "collodion". If
the balls had been imperfectly manufactured, the paints might have acted as
primer to set the rest of the ball off with a bang.
Cellulose was also used to produce cloth. While the men who developed celluloid
were interested in replacing ivory, those who developed the new fibers were
interested in replacing another expensive material, silk.
In 1884, a French chemist, the Comte de Chardonnay, introduced a cellulose-based
fabric that became known as "Chardonnay silk". It was an attractive cloth, but
like celluloid it was very flammable, a property completely unacceptable in
clothing. After some ghastly accidents, Chardonnay silk was taken off the
market.
In 1894, three British inventors, Charles Cross, Edward Bevan, and Clayton
Beadle, patented a new "artificial silk" or "art silk" that was much safer. The
three men sold the rights for the new fabric to the French Courtauld company, a
major manufacturer of silk, which put it into production in 1905, using
cellulose from wood pulp as the "feedstock" material.
Art silk, technically known as Cellulose Acetate, became well known under the
trade name "rayon", and was produced in great quantities through the 1930s, when
it was supplanted by better artificial fabrics. It still remains in production
today, often in blends with other natural and artificial fibers. It is cheap and
feels smooth on the skin, though it is weak when wet and creases easily. It
could also be produced in a transparent sheet form known as "cellophane".
Cellulose Acetate became the standard substrate for movie and camera film,
instead of its very flammable predecessor.
Bakelite (phenolic)
The limitations of celluloid led to the next major advance, known as "phenolic"
or "phenol-formaldehyde" plastics. A chemist named Leo Hendrik Baekeland, a
Belgian-born American living in New York state, was searching for an insulating
shellac to coat wires in electric motors and generators. Baekeland found that
mixtures of phenol (C6H5OH) and formaldehyde (HCOH) formed a sticky mass when
mixed together and heated, and the mass became extremely hard if allowed to cool
and dry.
He continued his investigations and found that the material could be mixed with
wood flour, asbestos, or slate dust to create "composite" materials with
different properties. Most of these compositions were strong and fire resistant.
The only problem was that the material tended to foam during synthesis, and the
resulting product was of unacceptable quality.
Baekeland built pressure vessels to force out the bubbles and provide a smooth,
uniform product. He publicly announced his discovery in 1912, naming it
bakelite. It was originally used for electrical and mechanical parts, finally
coming into widespread use in consumer goods in the 1920s. When the Bakelite
patent expired in 1930, the Catalin Corporation acquired the patent and began
manufacturing Catalin plastic using a different process that allowed a wider
range of coloring.
Bakelite was the first true plastic. It was a purely synthetic material, not
based on any material or even molecule found in nature. It was also the first
thermosetting plastic. Conventional thermoplastics can be molded and then melted
again, but thermoset plastics form bonds between polymers strands when cured,
creating a tangled matrix that cannot be undone without destroying the plastic.
Thermoset plastics are tough and temperature resistant.
Bakelite was cheap, strong, and durable. It was molded into thousands of forms,
such as radios, telephones, clocks, and, of course, billiard balls. The U.S.
government even considered making one-cent coins out of it when World War II
caused a copper shortage.
Phenolic plastics have been largely replaced by cheaper and less brittle
plastics, but they are still used in applications requiring its insulating and
heat-resistant properties. For example, some electronic circuit boards are made
of sheets of paper or cloth impregnated with phenolic resin.
Phenolic sheets, rods and tubes are produced in a wide variety of grades under
various brand names. The most common grades of industrial phenolic are Canvas,
Linen and Paper.
Polystyrene and PVC
After the First World War, improvements in chemical technology led to an
explosion in new forms of plastics. Among the earliest examples in the wave of
new plastics were "polystyrene" (PS) and "polyvinyl chloride" (PVC), developed
by IG Farben of Germany.
Polystyrene is a rigid, brittle, inexpensive plastic that has been used to make
plastic model kits and similar knickknacks. It would also be the basis for one
of the most popular "foamed" plastics, under the name "styrene foam" or
"Styrofoam". Foam plastics can be synthesized in an "open cell" form, in which
the foam bubbles are interconnected, as in an absorbent sponge, and "closed
cell", in which all the bubbles are distinct, like tiny balloons, as in
gas-filled foam insulation and floatation devices. In the late 1950s "High
Impact" styrene was introduced, which was not brittle. It finds much current use
as the substance of toy figurines and novelties.
PVC has side chains incorporating chlorine atoms, which form strong bonds. PVC
in its normal form is stiff, strong, heat and weather resistant, and is now used
for making plumbing, gutters, house siding, enclosures for computers and other
electronics gear. PVC can also be softened with chemical processing, and in this
form it is now used for shrink-wrap, food packaging, and raingear.
Nylon
The real star of the plastics industry in the 1930s was "polyamide" (PA), far
better known by its trade name, "nylon". Nylon was the first purely synthetic
fiber, introduced by Du Pont Corporation at the 1939 World's Fair in New York
City.
In 1927, Du Pont had begun a secret development project designated "Fiber66",
under the direction of Harvard chemist Wallace Carothers and chemistry
department director Elmer Keiser Bolton. Carothers had been hired to perform
pure research, and he worked to understand the new materials' molecular
structure and physical properties. He took some of the first steps in the
molecular design of the materials.
His work led to the discovery of synthetic nylon fiber, which was very strong
but also very flexible. The first application was for bristles for toothbrushes.
However, Du Pont's real target was silk, particularly silk stockings. Carothers
and his team synthesized a number of different polyamides including polyamide6.6
and 4.6, as well as polyesters.
It took Du Pont twelve years and US$27 million to refine nylon, and to
synthesize and develop the industrial processes for bulk manufacture. With such
a major investment, it was no surprise that Du Pont spared little expense to
promote nylon after its introduction, creating a public sensation, or "nylon
mania". Nylon mania came to an abrupt stop at the end of 1941 when the USA
entered World War II. The production capacity that had been built up to produce
nylon stockings, or just "nylons", for American women was taken over to
manufacture vast numbers of parachutes for fliers and paratroopers. After the
war ended, Du Pont went back to selling nylon to the public, engaging in another
promotional campaign in 1946 that resulted in an even bigger craze, triggering
the so called "nylon riots".
Subsequently polyamides 6, 10, 11, and 12 have been developed based on monomers
which are ring compounds, e.g. caprolactam.
Nylons still remain important plastics, and not just for use in fabrics. In its
bulk form it is very wear resistant, particularly if oil-impregnated, and so is
used to build gears, bearings, bushings, and because of good heat-resistance,
increasingly for under-the-hood applications in cars, and other mechanical
parts.
Synthetic rubber
A polymer that was critical to the war effort was "synthetic rubber", which was
produced in a variety of forms. Synthetic rubbers are not plastics. Synthetic
rubbers are elastic materials.
The first synthetic rubber polymer was obtained by Lebedev in 1910. Practical
synthetic rubber grew out of studies published in 1930 written independently by
American Wallace Carothers, Russian scientist Lebedev and the German scientist
Hermann Staudinger. These studies led in 1931 to one of the first successful
synthetic rubbers, known as "neoprene", which was developed at DuPont under the
direction of E.K. Bolton. Neoprene is highly resistant to heat and chemicals
such as oil and gasoline, and is used in fuel hoses and as an insulating
material in machinery.
In 1935, German chemists synthesized the first of a series of synthetic rubbers
known as "Buna rubbers". These were "copolymers", meaning that their polymers
were made up from not one but two monomers, in alternating sequence. One such
Buna rubber, known as "GR-S" (Government Rubber Styrene), is a copolymer of
butadiene and styrene, became the basis for U.S. synthetic rubber production
during World War II.
Worldwide natural rubber supplies were limited and by mid-1942 most of the
rubber-producing regions were under Japanese control. Military trucks needed
rubber for tires, and rubber was used in almost every other war machine. The
U.S. government launched a major (and largely secret) effort to develop and
refine synthetic rubber. A principal scientist involved with the effort was
Edward Robbins.
By 1944 a total of 50 factories were manufacturing it, pouring out a volume of
the material twice that of the world's natural rubber production before the
beginning of the war.
After the war, natural rubber plantations no longer had a stranglehold on rubber
supplies, particularly after chemists learned to synthesize isoprene. GR-S
remains the primary synthetic rubber for the manufacture of tires.
Synthetic rubber would also play an important part in the space race and nuclear
arms race. Solid rockets used during World War II used nitrocellulose explosives
for propellants, but it was impractical and dangerous to make such rockets very
big.
During the war, California Institute of Technology (Caltech) researchers came up
with a new solid fuel, based on asphalt fuel mixed with an oxidizer, such as
potassium or ammonium perchlorate, plus aluminium powder, which burns very hot.
This new solid fuel burned more slowly and evenly than nitrocellulose
explosives, and was much less dangerous to store and use, though it tended to
flow slowly out of the rocket in storage and the rockets using it had to be
stockpiled nose down.
After the war, the Caltech researchers began to investigate the use of synthetic
rubbers instead of asphalt as the fuel in the mixture. By the mid-1950s, large
missiles were being built using solid fuels based on synthetic rubber, mixed
with ammonium perchlorate and high proportions of aluminium powder. Such solid
fuels could be cast into large, uniform blocks that had no cracks or other
defects that would cause nonuniform burning. Ultimately, all large military
rockets and missiles would use synthetic rubber based solid fuels, and they
would also play a significant part in the civilian space effort.
Plastics explosion: acrylic, polyethylene, etc.
Other plastics emerged in the prewar period, though some would not come into
widespread use until after the war.
By 1936, American, British, and German companies were producing polymethyl
methacrylate (PMMA), better known as acrylic glass. Although acrylics are now
well known for their use in paints and synthetic fibers, such as fake furs, in
their bulk form they are actually very hard and more transparent than glass, and
are sold as glass replacements under trade names such as Plexiglas and Lucite.
Plexiglas was used to build aircraft canopies during the war, and it is also now
used as a marble replacement for countertops.
Another important plastic, polyethylene (PE), sometimes known as polythene, was
discovered in 1933 by Reginald Gibson and Eric Fawcett at the British industrial
giant Imperial Chemical Industries (ICI). This material evolved into two forms,
low density polyethylene (LDPE), and high density polyethylene (HDPE).
PEs are cheap, flexible, durable, and chemically resistant. LDPE is used to make
films and packaging materials, while HDPE is used for containers, plumbing, and
automotive fittings. While PE has low resistance to chemical attack, it was
found later that a PE container could be made much more robust by exposing it to
fluorine gas, which modified the surface layer of the container into the much
tougher polyfluoroethylene.
Polyethylene would lead after the war to an improved material, polypropylene
(PP), which was discovered in the early 1950s by Giulio Natta. It is common in
modern science and technology that the growth of the general body of knowledge
can lead to the same inventions in different places at about the same time, but
polypropylene was an extreme case of this phenomenon, being separately invented
about nine times. The ensuing litigation was not resolved until 1989.
Polypropylene managed to survive the legal process and two American chemists
working for Phillips Petroleum, J. Paul Hogan and Robert Banks, are now
generally credited as the "official" inventors of the material. Polypropylene is
similar to its ancestor, polyethylene, and shares polyethylene's low cost, but
it is much more robust. It is used in everything from plastic bottles to carpets
to plastic furniture, and is very heavily used in automobiles.
Polyurethane was invented by Friedrich Bayer & Company in 1937, and would come
into use after the war, in blown form for mattresses, furniture padding, and
thermal insulation. It is also one of the components (in non-blown form) of the
fiber spandex.
In 1939, IG Farben filed a patent for polyepoxide or epoxy. Epoxies are a class
of thermoset plastic that form cross-links and cure when a catalyzing agent, or
hardener, is added. After the war they would come into wide use for coatings,
adhesives, and composite materials.
Composites using epoxy as a matrix include glass-reinforced plastic, where the
structural element is glass fiber, and carbon-epoxy composites, in which the
structural element is carbon fiber. Fiberglass is now often used to build sport
boats, and carbon-epoxy composites are an increasingly important structural
element in aircraft, as they are lightweight, strong, and heat resistant.
Two chemists named Rex Whinfield and James Dickson, working at a small English
company with the quaint name of the "Calico Printer's Association" in
Manchester, developed polyethylene terephthalate (PET or PETE) in 1941, and it
would be used for synthetic fibers in the postwar era, with names such as
polyester, dacron, and terylene.
PET is less gas-permeable than other low-cost plastics and so is a popular
material for making bottles for Coca-Cola and other carbonated drinks, since
carbonation tends to attack other plastics, and for acidic drinks such as fruit
or vegetable juices. PET is also strong and abrasion resistant, and is used for
making mechanical parts, food trays, and other items that have to endure abuse.
PET films are used as a base for recording tape.
One of the most impressive plastics used in the war, and a top secret, was
polytetrafluoroethylene (PTFE), better known as Teflon, which could be deposited
on metal surfaces as a scratch-proof and corrosion-resistant, low-friction
protective coating. The polyfluoroethylene surface layer created by exposing a
polyethylene container to fluorine gas is very similar to Teflon.
A Du Pont chemist named Roy Plunkett discovered Teflon by accident in 1938.
During the war, it was used in gaseous-diffusion processes to refine uranium for
the atomic bomb, as the process was highly corrosive. By the early 1960s, Teflon
adhesion-resistant frying pans were in demand.
Teflon was later used to synthesize the breathable fabric Gore-Tex®, which can
be used to manufacture wet weather clothing that is able to "breathe". Its
structure allows water vapour molecules to pass, while not permitting water as
liquid to enter. Gore-Tex is also used for surgical applications such as
garments and implants; Teflon strand is used to make dental floss; and Teflon
mixed with fluorine compounds is used to make decoy flares dropped by aircraft
to distract heat-seeking missiles.
After the war, the new plastics that had been developed entered the consumer
mainstream in a flood. New manufacturing were developed, using various forming,
molding, casting, and extrusion processes, to churn out plastic products in vast
quantities. American consumers enthusiastically adopted the endless range of
colorful, cheap, and durable plastic gimmicks being produced for new suburban
home life.
One of the most visible parts of this plastics invasion was Earl Tupper's
Tupperware, a complete line of sealable polyethylene food containers that Tupper
cleverly promoted through a network of housewives who sold Tupperware as a means
of bringing in some money. The Tupperware line of products was well thought out
and highly effective, greatly reducing spoilage of foods in storage. Thin-film
plastic wrap that could be purchased in rolls also helped keep food fresh.
Another prominent element in 1950s homes was Formica, a plastic laminate that
was used to surface furniture and cabinetry. Formica was durable and attractive.
It was particularly useful in kitchens, as it did not absorb, and could be
easily cleaned of stains from food preparation, such as blood or grease. With
Formica, a very attractive and well-built table could be built using low-cost
and lightweight plywood with Formica covering, rather than expensive and heavy
hardwoods like oak or mahogany.
Composite materials like fiberglass came into use for building boats and, in
some cases, cars. Polyurethane foam was used to fill mattresses, and Styrofoam
was used to line ice coolers and make float toys.
Plastics continue to be improved. General Electric introduced Lexan, a
high-impact polycarbonate plastic, in the 1970s. Du Pont developed Kevlar®, an
extremely strong synthetic fiber that was best known for its use in ballistic
rated clothing and combat helmets. Kevlar was so impressive that its
manufacturer, DuPont, deemed it necessary to release an official statement
denying alien involvement. [3]
Negative health effects
This article or section may contain original research or unverified claims.
Please help Wikipedia by adding references. See the for details.
This article has been tagged since September 2007.
Plastics #3, #6, and #7 have been associated with negative health effects.
- #3 [PVC (polyvinyl chloride)] contains numerous toxic chemicals called
adipates and phthalates ("plasticizers"), which are used to soften brittle PVC
into a more flexible form. PVC is commonly used to package foods and liquids,
ubiquitous in children's toys and teethers, plumbing and building materials, and
in everything from cosmetics to shower curtains. Traces of these chemicals can
leach out of PVC when it comes into contact with food. The World Health
Organization's International Agency for Research on Cancer (IARC) has recognized
the chemical used to make PVC, vinyl chloride, as a known human carcinogen. The
European Union has banned the use of DEHP (di-2-ethylhexyl phthalate), the most
widely used plasticizer in PVC, in children's toys.
- #6 [PS (polystyrene)] is one of the toxins the EPA (Environmental Protection
Agency) monitors in America's drinking water. Its production also pollutes the
atmosphere, destroying the ozone layer. Some compounds leaching from Styrofoam
food containers interfere with hormone functions. It's a possible human
carcinogen.
- # 7 [Other (usually polycarbonate (PC))] is a catchall group that consists
mainly of polycarbonates, whose primary building block is bisphenol A (BPA), a
hormone disrupter that releases into food and liquid and acts like estrogen.
Research in Environmental Health Perspectives finds that BPA (leached from the
lining of tin cans, dental sealants and polycarbonate bottles) can increase body
weight of lab animals' offspring, as well as impact hormone levels. A more
recent animal study suggests that even low-level exposure to BPA results in
insulin resistance, which can lead to inflammation and heart disease.
The environment
Plastics are durable and degrade very slowly. In some cases, burning plastic can
release toxic fumes. Also, the manufacturing of plastics often creates large
quantities of chemical pollutants.
By the 1990s, plastic recycling programs were common in the United States and
elsewhere. Thermoplastics can be remelted and reused, and thermoset plastics can
be ground up and used as filler, though the purity of the material tends to
degrade with each reuse cycle. There are methods by which plastics can be broken
back down to a feedstock state.
To assist recycling of disposable items, the Plastic Bottle Institute of the
Society of the Plastics Industry devised a now-familiar scheme to mark plastic
bottles by plastic type. A recyclable plastic container using this scheme is
marked with a triangle of three "chasing arrows", which enclose a number giving
the plastic type:
Plastics type marks: the Resin identification code
1. PET (PETE): Polyethylene Terephthalate - Commonly found on: 2-liter soft
drink bottles, cooking oil bottles, peanut butter jars.
2. HDPE: High Density Polyethylene - Commonly found on: detergent bottles, milk
jugs.
3. PVC: Polyvinyl Chloride - Commonly found on: plastic pipes, outdoor
furniture, shrink-wrap, water bottles, salad dressing and liquid detergent
containers.
4. LDPE: Low Density Polyethylene - Commonly found on: dry-cleaning bags,
produce bags, trash can liners, food storage containers.
5. PP: Polypropylene - Commonly found on: bottle caps, drinking straws
6. PS: Polystyrene - Commonly found on: "Styrofoam peanuts," cups, plastic
tableware, meat trays, take-away food clamshell containers
7. OTHER: Other - This plastic category, as its name of "other" implies, is any
plastic other than the named #1 – #6, Commonly found on: certain kinds of food
containers, Tupperware, and Nalgene bottles.
Unfortunately, recycling plastics has proven difficult. The biggest problem with
plastic recycling is that it is difficult to automate the sorting of plastic
waste, and so it is labor intensive. Typically, workers sort the plastic by
looking at the resin identification code, though common containers like soda
bottles can be sorted from memory. Other recyclable materials, such as metals,
are easier to process mechanically. However, new mechanical sorting processes
are being utilized to increase plastic recycling capacity and efficiency.
While containers are usually made from a single type and color of plastic,
making them relatively easy to sort out, a consumer product like a cellular
phone may have many small parts consisting of over a dozen different types and
colors of plastics. In a case like this, the resources it would take to separate
the plastics far exceed their value and the item is discarded. However,
developments are taking place in the field of Active Disassembly, which may
result in more consumer product components being re-used or recycled. Recycling
certain types of plastics can be unprofitable, as well. For example, polystyrene
is rarely recycled because it is usually not cost effective. These unrecyclable
wastes can be disposed of in landfills, incinerated or used to produce
electricity at waste-to-energy plants.
Biodegradable plastics
Research has been done on biodegradable plastics that break down with exposure
to sunlight (e.g. ultra-violet radiation), water (or humidity), bacteria,
enzymes, wind abrasion and some instances rodent pest or insect attack are also
included as forms of biodegradation or environmental degradation. It is clear
some of these modes of degradation will only work if the plastic is exposed at
the surface, while other modes will only be effective if certain conditions are
found in landfill or composting systems. Starch powder has been mixed with
plastic as a filler to allow it to degrade more easily, but it still does not
lead to complete breakdown of the plastic. Some researchers have actually
genetically engineered bacteria that synthesize a completely biodegradable
plastic, but this material is expensive at present e.g. BP's Biopol. BASF make
Ecoflex, a fully biodegradable polyester for food packaging applications. A
potential disadvantage of biodegradable plastics is that the carbon that is
locked up in them is released into the atmosphere as a greenhouse gas carbon
dioxide when they degrade, though if they are made from natural materials, such
a vegetable crop derivatives or animal products, there is no net gain in carbon
dioxide emissions, although concern will be for a worse greenhouse gas, methane
release.
So far, these plastics have proven too costly and limited for general use, and
critics have pointed out that the only real problem they address is roadside
litter, which is regarded as a secondary issue. When such plastic materials are
dumped into landfills, they can become "mummified" and persist for decades even
if they are supposed to be biodegradable.
There have been some success stories. The Courtauld concern, the original
producer of rayon, came up with a revised process for the material in the
mid-1980s to produce "Tencel". Tencel has many superior properties over rayon,
but is still produced from "biomass" feedstocks, and its manufacture is
extraordinarily clean by the standards of plastic production.
Researchers at the University of Illinois at Urbana have been working on
developing biodegradable resins, sheets and films made with zein (corn
protein).[1]PDF (96.7 KiB)
Recently, however, a new type of biodegradable resin has made its debut in the
United States, called Plastarch Material (PSM). It is heat, water, and oil
resistant and sees a 70% degradation in 90 days. Biodegradable plastics based on
polylactic acid (once derived from dairy products, now from cereal crops such as
maize) have entered the marketplace, for instance as polylactates as disposable
sandwich packs.
An alternative to starch based resins are additives such as Bio-Batch an
additive that allows the manufacturers to make PE, PS, PP, PET, and PVC totally
biodegradable in landfills where 94.8% of most plastics end up according to the
EPA According to their latest MSW report done in 2003, located under Municipal
Solid Waste in the United States: 2003 Data Tables.
It is also possible that bacteria will eventually develop the ability to degrade
plastics. This has already happened with nylon: two types of nylon eating
bacteria, Flavobacteria and Pseudomonas, were found in 1975 to possess enzymes
(nylonase) capable of breaking down nylon. While not a solution to the disposal
problem, it is likely that bacteria will evolve the ability to use other
synthetic plastics as well.
The latter possibility was in fact the subject of a cautionary novel by Kit
Pedler and Gerry Davis (screenwriter), the creators of the Cybermen, re-using
the plot of the first episode of their Doomwatch series. The novel, "Mutant 59:
The Plastic Eater", written in 1971, is the story of what could happen if a
bacterium were to evolve - or be artificially cultured - to eat plastics, and be
let loose in a major city.
In the novel, the mutant bacterium is cultured by a lone scientist experimenting
with the common germ Bacillus prodigiosus, with the intent of solving the
world's plastic waste disposal problem; it is the 59th attempted variant (hence
the novel's title), and is accidentally released when the scientist suffers a
fatal cerebral haemorrhage, dropping a test-tube containing the bacteria into a
sink as he collapses.
Needless to say, the consequences would be - and, in the novel, are -
catastrophic; a modern city such as London would be paralysed if all its plastic
suddenly began disappearing under bacterial action.
Price, environment, and the future
The biggest current threat to the conventional plastics industry is likely to be
environmental concerns, including the release of toxic pollutants, greenhouse
gas, litter, biodegradable and non-biodegrable landfill impact as a result of
the production and disposal of petroleum and petroleum-based plastics.
For decades one of the great appeals of plastics have been their low price as
compared to other materials. Yet in recent years the cost of plastics has been
rising dramatically. A major cause of the increase is the sharply rising cost of
petroleum, the raw material that is chemically altered to form commercial
plastics. As the cost of plastic hinges on the cost of petroleum, should
petroleum prices rise so will the cost of plastic. This affects the commercial
viability of some plastic products and their manfacturers.
With some observers suggesting that future oil reserves are uncertain the price
of petroleum may increase further, and thus alternatives are being sought. Oil
shale and tar oil are alternatives for plastic production but are expensive.
Scientists are seeking cheaper and better alternatives to petroleum-based
plastics, and many candidates are in laboratories all over the world. One
promising alternative on the horizon may involve processing fructose found in
simple sugar to provide an alternative for some types of plastic[4].
Common plastics and their uses
Polyethylene (PE)
Wide range of inexpensive uses including supermarket bags, plastic bottles. ;
Polypropylene (PP) :Food containers, appliances, car fenders (bumpers). ;
Polystyrene (PS) :Packaging foam, food containers, disposable cups, plates,
cutlery, CD and cassette boxes. ; High impact polystyrene (HIPS) : fridge
liners, food packaging, vending cups. ; Acrylonitrile butadiene styrene (ABS)
:Electronic equipment cases (e.g., computer monitors, printers, keyboards). ;
Polyethylene terephthalate (PET) :carbonated drinks bottles, jars, plastic film,
microwavable packaging. ; Polyester (PES) :Fibers, textiles. ; Polyamides (PA)
(Nylons) :Fibers, toothbrush bristles, fishing line, under-the-hood car engine
mouldings. ; Poly(vinyl chloride) (PVC) :Plumbing pipes and guttering, shower
curtains, window frames, flooring, erotic clothing. ; Polyurethanes (PU) :
cushioning foams, thermal insulation foams, surface coatings, printing rollers.
(Currently 6th or 7th most commonly used plastic material, for instance the most
commonly used plastic found in cars). ; Polycarbonate (PC) :Compact discs,
eyeglasses, riot shields, security windows, traffic lights, lenses. ;
Polyvinylidene chloride (PVDC) (Saran) :Food packaging. ; Bayblend (PC/ABS) :A
blend of PC and ABS that creates a stronger plastic. :Car Interior and exterior
parts
Special-purpose plastics
Polymethyl methacrylate (PMMA)
contact lenses, glazing (best known in this form by its various trade names
around the world, e.g., Perspex, Oroglas, Plexiglas, fluorescent light
diffusers, rear light covers for vehicles. ; Polytetrafluoroethylene (PTFE)
(trade name Teflon) :Heat-resistant, low-friction coatings, used in things like
non-stick surfaces for frying pans, plumber's tape and water slides. ;
Polyetheretherketone (PEEK) (Polyketone):Strong, chemical- and heat-resistant
thermoplastic, biocompatibility allows for use in medical implant applications,
aerospace mouldings. One of the most expensive commercial polymers. ;
Polyetherimide (PEI) (Ultem) :A General Electric product, similar to PEEK. ;
Phenolics (PF) or (phenol formaldehydes) : high modulus, relatively heat
resistant, and excellent fire resistant polymer. Used for insulating parts in
electrical fixtures, paper laminated products (e.g. "Formica"), thermally
insulation foams. It is a thermosetting plastic, with the familiar trade name
Bakelite, that can be moulded by heat and pressure when mixed with a filler-like
wood flour or can be cast in its unfilled liquid form or cast as foam, e.g.
"Oasis". Problems include the probability of mouldings naturally being dark
colours (red, green, brown), and as thermoset difficult to recycle. ;
Urea-formaldehyde (UF) : one of the aminoplasts and used as multi-colorable
alternative to Phenolics. Used as a wood adhesive (for plywood, chipboard,
hardboard) and electrical switch housings. ; Melamine formaldehyde (MF) : one of
the aminoplasts, and used a multi-colorable alternative to phenolics, for
instance in mouldings (e.g. break-resistance alternatives to ceramic cups,
plates and bowls for children) and the decorated top surface layer of the paper
laminates (e.g. "Formica"). ; Polylactic acid : a biodegradable, thermoplastic,
found converted into a variety of aliphatic polyesters derived from lactic acid
which in turn can be made by fermentation of various agricultural products such
as corn starch, once made from diary products. ; Plastarch Material :
biodegradable and heat resistant, thermoplastic composed of modified corn
starch.
Are you interested in mult-player
online internet games? Such as runescape and neopets?Internet
Game Online-games, tips, cheats and kids forumsAnother
good forum is the Internet Junction For Gamers IJFG.COM
Internet Junction For Gamers, Runescape Market and
More IJFG.COM Jokes, Pranks, Runescape and other cool games at IJFG.COM.
RuneScape is set in a medieval fantasy world, similar to "Guild Wars" or "EverQuest",
where players control character representations of themselves. As with most
massive multiplayer online roleplaying games (MMORPG), there is no overall
objective or end to the game. Players explore, form alliances, perform optional
tasks, and complete quests for rewards and to build character's skills.
RuneScape has often been one of
the top massive online role playing games. It is a unique game. But, with a
unique game, comes unique players. Players get bored, and then try to develop
cheats....autos or bots that will help them achieve success in their beloved
games of Runescape 2.
RuneScape is a virtual world which
is divided into two part: Members Areas and Non-Members areas. People who pay to
play (p2p), receive access to the special areas. They also have access to the
free areas. The members' places are much larger, offer "better" items for the
gameplay of rs2, and much, much more. The character that you create when you
first start playing runescape, moves around the game on foot; either by running,
or walking. Players are challenged to their utmost skills by fighting new
monsters, completing difficult quests, and manipulating marketing. As Runescape
2 is an RPG (Role playing game), there is no set path a person must take to play
rs. They can choose what to do, and when, whether it be training their
money-making skills, or fighting another player. Players usually interact with
each other by chatting through public chat, or private chat.Internet
Junction For Gamers, Runescape Market and More IJFG.COM IJFG.com was a
runescape 2 based site. They have now, however, taken another look....
Of course the king of all game
cheating websites is
trick
the trik (otherwise known as RPG Cheats Site), where you can find cheat
forums, mmorpg topsite, arcade games and any mmo game related topics.
The master of massive multiplayer
online role-playing games (MMORPG) cheats can be found at Trik.com
Trik.com; this site is one of the best today. The forum section,
Trik.com forum, originally came from IJFG.com (Internet Junction For
Gamers) , which was one of the best websites that discussed various gamers'
issues. The full name was Internet Junction For Gamers, Runescape Market and
More. This site had Jokes, Pranks, RuneScape and other cool games. RuneScape is
set in a medieval fantasy world, similar to "Guild Wars" or "EverQuest," where
players control character representations of themselves. As with most MMORPG,
there is no overall objective or end to the game. Players explore, form
alliances, perform optional tasks, and complete quests for rewards and to build
characters' skills.
Trik.com continues IJFG.com's
success, but Trik.com has more to offer. Trik Topsite can be found at
Trik Topsite; the TopSite is a great addition if you want to find the best
MMO RPG site(s) or raise your site in the rankings. Trik.com also has a
viciously competitive Arcade. If you want to be the #1 Arcade on Trik, then come
prove yourself at Trik.com arcade:
Trik arcade. Trik.com ?Trik.com/topsite ?Trik.com/forum/arcade.php
With the rising popularity of
commercial MMORPG games came the desire from ardent players of these games to
run their own servers beside the ones run by the game's creator. Since the
original server software is not usually available, the behavior of the server
has to be re-engineered. This can be done by analyzing the data stream with the
original server, or by disassembling and analyzing the client which is
available.
Ultima Online was one of the first
large MMORPGs. Due to its openness in implementation, server emulators arose
very quickly, even during the beta stage of development. The destination to
which the client connects was changeable by simply editing a text file. In beta
stage the client-server data stream was not encrypted yet. The term server
emulator became known through Ultima Online server reimplementation such as UOX,
which was the pioneer. Many forks and reimplementations followed UOX, because
its source code was released under the GNU General Public License relatively
early. RunUO is today the most widely used UO-server emulator. After RuneScape
implemented anti-cheating measures, many gamers left and started their own
private servers. The best place to discuss the private server is at
Trik- The Master of Private Server.
Another useful site is
Rune
Web ruwb.com . This site is about more serious RuneScape gold trading,
account exchange, gold for real life cash and many services. It includes tips on
how to avoid getting lured/scammed while using the marketplace. For programming,
visual basics, java, C/C++, scar and all other languages such as PHP, HTML, ASP,
Delphi. There are also sections for graphics talents, plus many cool videos and
fun stuff.
A defining moment in internet
gaming history was when a group of gamers called (hygo 7) decided to start an
ultimate game forum, which they named
hygo.com. It has the best financial backing, the friendliest game community,
and the highest quality of information. Currently Hygo.com has entered a new
phase...Hygo.com is offering the best private server game. With thousands of
members, Hygo.com is your next place to visit, as they have an amazing game with
a community and economy.
Hygo.com - The Online Adventure Game. is definitely one of the top sites you
want to join right now!
EZud is another popular site.
ezud.com. It has the best runescape bug abuse, bugs and trik.
ezud.com - The runescape bugs. is definitely one of the best sites you want
to join right now!
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