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Styrene Production- Concerns and Responsibilities Reactant and Product information
Benzene is a colorless to light-yellow liquid with an aromatic odor. It is
highly toxic with a tolerance of 25ppm in air. Benzene is derived from
many sources, including distillation of coal tar and hydrodealkylation of
toluene. It is used in industry as the building block for countless organic
molecules and also as a solvent. Recent spot prices per metric ton of benzene
were $392 in the US, $378 in Europe, and $420 in Asia. Benzene is within the 15
highest volume output chemicals in the US. Ethylbenzene is a colorless liquid
with an aromatic odor. It is moderately toxic with a tolerance of 100ppm in air.
Ethylbenzene is derived either by distillation of raw petroleum products, or by
the heating of benzene and ethylene in the presence of aluminum chloride. It's
only common industrial use is as an intermediate in the styrene production
process. Recent spot prices for ethylbenzene were $473/mt in the US and $445/mt in Europe. Ethylbenzene is the 19th highest volume
chemical produced in the US. Toluene, also known as methylbenzene, is a
colorless liquid with a benzene-like odor. It is similarly toxic to ethylbenzene.
It is also explosive in small parts with air, like styrene. The explosive limits
are 1.27% to 7% in air. It is derived predominantly by distillation of coal-tar
light oil. Toluene is used for many purposes from detergents to solvents to
resins to a common organic reagent. Recent spot prices per metric ton for
toluene were $310 in the US, $325 in Europe, and $340 in Asia. Styrene, our main
product, is an oily colorless liquid with an aromatic odor. It is similarly
toxic in air to ethylbenzene. A further danger of styrene is that its explosive
limits in air are a mere 1.1% to 6.1% in air. The styrene production process was described in detail earlier
in this report. Recent spot prices per metric ton for styrene were $601 in the
US, $615 in Europe, and $662 in Asia. Styrene's main use is as the monomer for
polystyrene, a common plastic. It is also a component of various resins and
coatings. Reasons
for choosing Styrene as the research work
Styrene plastics are easy to process and offer excellent price/performance ratios. Polystyrenes are used everywhere: as packaging materials or containers, and in a wide range of appliance and equipment housings. Polystyrene compounds are the third largest production plastics in use. Polystyrene is used in food packaging materials such as egg cartons, coffee cups, trays and other disposable products. Two styrene products commonly found in the home are styrofoam insulation panels and polystyrene vapor barriers. Styrene is co-polymerized with other materials to make products such as styrene butadiene rubber (SBR), acrylonitrile butadiene styrene plastics (ABS), styreneated alkyd coatings and as a reactive diluent in polyester/fiber glass products. Other co-polymers of styrene are used for adhesives, foams, coatings and rigid plastics. When polystyrene is burned it degrades to styrene which is a system toxin and benzene which is a toxin and carcinogen. As with most plastics, polystyrene compounds can out-gas and be broken down by UV causing them to release toxic materials. Styrene polymers have evolved as more than commodity polystyrene. Even with ABS reaching commodity status with volumes over one billion pounds and prices in the $.80/lb. range, other styrene polymers have become successful and important commercial products. Styrene polymers have found use in almost every plastic application and are available as rigid thermoplastic films, sheet, foams, and elastomers. Furthermore, styrene polymers form an important part of alloys/blends and thermoplastic elastomers (TPEs). Styrene polymers comprise about 12% of total U.S. resin sales; 15% of thermoplastic sales; and have equivalent volumes with poly-propylene -- the third ranking resin behind polyethylene and PVC. Styrene in PlasticsStyrene-Plastics: Plastics
based on resins made by the polymerization of styrene or co-polymerization of
styrene with other unsaturated compounds the styrene being in greatest amount by
weight. Styrene-Rubber Plastics: Compositions based on rubbers and styrene plastics the styrene plastics being in greatest amount by weight. Acrylonitrile Onitrile-Butadiene-Styrene(ABS): Plastics containing polymers or blends of polymers, or both, in which the minimum butadiene content is 6%, the minimum acrylonitrile content is 15%, the minimum styrene or substituted content, or both, is 15%, and the maximum content of all other monomers is not more than 5%; plus lubricants, stabilizers and colorants.
Styrofoam is kind of plastic, a polymer made of (an inter-linked network
of) styrene molecules. Styrene is a compound composed of carbon and hydrogen.
When manufactured as an insulating material, the liquid form of the polymer is
"blown" into a foam by in-situ generation of a large number of VERY
tiny bubbles of gas. The polymer
and the entrapped gas interfere with heat flow through the material. Thus, it
shows an insulating property. Uses
Of Styrene Plastics
Styrene monomer is used to make a variety of styrene plastics, from
expandable foam to higher end engineering plastics. End uses of styrene include
disposable food service products, cabinets for electronics, CD holders, paper
coatings, boat hulls, and interior automotive components. In the construction
industry it is used to produce pipe products, tanks, lighting fixtures,
insulation, and various corrosion resistant and rubber products. Uses
of Styrene in Food Packaging
The performance and price factor of polystyrene makes it idle for using
it as a packaging material. Packaging materials need to prevent food from
spoiling as well as protect it from damage during transport, storage as well as
through the process of sale, and all of this while maintaining the strictest
hygiene. Here polystyrene meets all these demands hence making it a suitable
material for packaging. When it comes to selecting the best food service packaging products, many
educational food service systems recognize that polystyrene packaging delivers!
No other food service packaging material provides polystyrene's unique
combination of performance, economic, and environmental benefits. Polystyrene
food service packaging is extremely strong yet lightweight, provides excellent
insulation, enhances food service sanitation and contributes to protecting
public health. It is less expensive than many other food service packaging
options, and has less environmental impact during its manufacture and transport
than paperboard food service packaging Appearance is also important, and
transparent food packaging plays a part in purchasing decisions. Various blends
with Styrolux allow tailored solutions to be produced for particular
applications. These include films, trays and cups. In Refrigeration
Polystyrene's tailored properties and easy processing combined with its
unbeatable cost-effectiveness make it an ideal material for use in refrigeration
equipment. Whether for superb high-gloss surfaces or for any of the wide variety of
accessories inside the refrigerator, the properties of polystyrene are equal to
the task. Matt or colored, transparent or opaque In Home
Styrenic plastics are used in a broad variety of kitchen appliances both
as a primary material of construction as well as for component use.
The inner linings of fridges and freezers are typically made of products
such as ABS or HIPS (High Impact Polystyrene), where toughness, chemical
resistance and stiffness are all required. Where transparency is a requirement,
such as for the transparent compartments found within these appliances SAN can
be used. For items such as microwaves, cookers and extraction units for cooking
odors (kitchen range vent), styrenic plastics are more likely to be used just as
components such as buttons and dials. In smaller articles such as mixers and
blenders, the housing, the exterior components and the accessories can all make
good use of the properties available from styrenic plastics. Consumer
Electronics
The tasks of writing letters, drawing, painting, and relying on sturdy
luggage for your travels also depend on styrenic plastics. So do listening to
music, watching television, playing video tapes or filming your family: consumer
electronics is a rapidly growing market with a wide array of end uses where the
versatility of styrenic plastics can be fully exploited. In
Offices
Most of the office furnishings and equipment you've inherited are made
from styrenic plastics; materials that have become indispensable in our working
environment. Whether for your wood-finished desktop, computer monitor, letter
trays, or the coat hanger behind your door, the properties of styrenic plastics
products are equal to the task. In neutral shades or brightly colored, transparent or opaque, they are
not simply pleasing to the eye or touch -- they have important qualities that go
far beyond mere aesthetics. Polystyrene (PS), acrylonitrile-butadiene-styrene
(ABS) or styrene-acrylonitrile (SAN) are amongst the products that make computer
casings and monitors strong and heat-resistant; staplers resilient enough to
withstand repeated impacts; jewel boxes a cost-effective solution to protect
valuable CD-ROMs; and your desktop scratch-resistant despite years of use.
Styrenic plastics' tailored properties and easy processing, combined with their
remarkable cost-effectiveness, make them an ideal material for the intensively
used equipment present in our modern offices. In
Construction
As the importance of energy conservation grows, the need for highly
effective insulation materials also increases. Expanded (EPS) or extruded (XPS)
polystyrene insulation provides the long-term energy efficiency now demanded by
the construction industry. Heating and cooling account for 50-70% of the energy
costs for the average home. The stable thermal performance of these insulation
materials can result in significantly lower heating and cooling costs - savings
that really add up over the life of the structure. And their design flexibility
means that their benefits can be used in every part of a building - from
foundation, to walls, to roof. In addition to reducing energy costs, reducing
energy use helps conserve non-renewable fuel supplies. And using more energy
efficient materials and products in our construction, to decrease the use of
fuel and energy, translates into reduced air pollution. As a
life saver
Bicycle helmets made from impact-absorbing polystyrene-based plastics and
composites contributed to a 60% decline in the U.S. death rate from
bicycle-related injuries among children 14 and under during the period 1979-97. Ring life floaters and children's pool toys stay afloat because they are
made from polystyrene foam plastic, which has a highly buoyant closed-cell
structure. (Closed cell foams totally encase the air bubbles that make up the
foam and don't allow water to penetrate into the structure.) Even entire
floating docks are kept safely afloat with polystyrene foam. But tough, polyester resins are also used to make lifeboats for Coast
Guard rescue operations as well as pleasure boats and cruise ships. And police
keep the peace on motorcycles of the water, patrolling on jet skis that are made
from styrenic materials. Using personal watercraft really cuts down on the
accidents and fatalities. In
Medicines
Many vaccines must be maintained at low temperatures. Easy enough when
you have a refrigerator or freezer handy, but a big challenge when your task is
to transport a batch of vaccines to another continent in tropical climates.
Thanks to a special expanded polystyrene package, vaccines are being transported
safely from one country to another. For example, each shipping unit can hold 400
freeze-dried 3ml vaccines together with 4 kg (10 pounds) of dry ice. The thermal
insulation properties of expanded polystyrene maintain the required temperature
inside the sealed package for 72 hours. In hospital settings, single use food service materials are the preferred
option, and the sanitary qualities of polystyrene single serve containers are a
primary benefit of polystyrene food packaging and service materials for hospital
use ABS (acrylonitrile-butadiene-styrene) resin is used for the housing of a
state-of-the-art blood analyzer because of its proven performance in
applications that require strength, durability and a high-gloss surface to help
ensure cleanliness in hospital settings. The hand-held system provides
clinicians with a portable, nearly instantaneous analyzer that requires just two
drops of whole blood to provide a wide range of tests needed in medical
diagnoses. Styrene-based boxes also help to save lives by protecting organs
while they are being transported for donation. In
Transportation
The convenience and safety you enjoy in driving your car - as well as the
benefits of lorry (truck) transport, aircraft, and construction machinery - all
depend on styrene. Styrene-based plastic materials are not only used in the automotive
industry for their easy processability or the reduction of the vehicle assembly
time and costs they help achieve. The weight savings achieved through plastics
use are impressive, which helps minimize environmental impact (among other
things through fuel savings) and save resources like cutting fuel. Styrene is
also used to give tires better road-hugging ability, especially on wet roads. New Scientist magazine reports that chemists have taught single molecules
of polystyrene an impressive new trick - how to snatch and store energy from
light in the way that plants do. Researchers are working on a new breed of
polystyrene-based battery. They say that because polystyrene derivatives are
inexpensive, the batteries could be used to power anything from cars to cellular
telephones. The project is to find simple materials that can mimic the complex
chemistry of photosynthesis, which allows plants to store energy from sunlight
in chemical bonds In
Computers
Toughness, heat-, scratch-, impact-resistance, smart surface finish,
creative design, cost-effectiveness; these aren't the only qualities of styrenic
plastics. One of the world leaders in computer design and manufacture conducted
a case study on the need to combine in their products top quality, ease of
manufacture, and cost-effectiveness - but with environmental responsibility.
Their decision, justified by reduced cost and increased recyclability, was to
use an integral acrylonitrile-butadiene-styrene (ABS) top cover for their latest
model. In making their decision, the manufacturer considered ABS' key
environmental performance attributes, including energy conservation, ease of
disassembly of materials and recyclability of components and materials. A study comparing housings for electrical and electronic equipment
demonstrated that the environmental costs in production and at the end of life
for styrene-based housings were one tenth those of aluminum alternatives. Health and Safety
The safety of employees is obviously an important factor to consider when designing a production process that utilizes potentially dangerous substances. According to the US Department of Labor Occupational Safety and Health Administration the following substances present in the production of styrene are considered hazardous air contaminants: styrene, ethyl benzene, benzene, toluene, and propane. The chart below shows the limits placed on emissions of these substances.
(1) The TWA is the total
weighted average over a typical eight-hour workday.
The employee should not be exposed to an amount of the substance above
the acceptable ceiling concentration at any time during the eight-hour shift.
If a maximum peak concentration is given, exposure is allowed up to but
not exceeding that concentration, but for no more than a set time limit (usually
10 minutes). Any exposure above the
TWA concentration must be compensated for by exposure suitably below the TWA
concentration. Care should be taken in storage of flammable substances. Listed in order of increasing flash point these substances are: the hydrocarbon fuel mixture, benzene, toluene, ethylbenzene, and styrene. These substances are extremely flammable in both liquid and vapor state, therefore it is important that they be stored in a well ventilated area away from heat, ignition sources and open flame. Outside storage is recommended (3). (1) Data obtained from www.osha.gov (2) Data obtained from www.epa.gov/ttnchiel/le/styrene.pdf (3) Data obtained from http://siri.org/msds/gn.cgi Environmental Concerns The primary environmental concern associated with the production of styrene is the combustion of the hydrogen-hydrocarbon fuel mixture. Though the hydrocarbon fuel mixture is relatively clean burning when compared to other sources such as coal(which contributes to acid rain), it does produce large amounts of greenhouse gases when combusted. According to the Energy Information Administration, in the year 2000 twenty-two thousand metric tons of methane were emitted from the production of styrene in the United States alone making it the second highest source of methane emissions among chemical production processes. Even more abundant than the methane is impact from the release of carbon dioxide into the atmosphere. Carbon dioxide in the atmosphere has increased approximately 10% since 1958 largely due to the burning of fossil fuels (4). Though the emission of some amount of these gases is inevitable, there are steps that can be taken to reduce the environmental impact.
By making energy efficiency a focus in the design of the styrene production plant one can decrease the amount of fuel consumed. This results not only in the reduction of greenhouse gas emissions but also reduces the long-term cost of production. Another way to help compensate for the environmental damage due to carbon dioxide emissions is the implementation of carbon sinks. Plants and trees which consume carbon dioxide as a part of their metabolic cycle are examples of natural carbon sinks. By making an effort to plant trees and keep up the environmental areas in the community we can help reduce the effect of greenhouse gases until a permanent solution is found. (4) Data obtained from http://www.wikipedia.org
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Copyright IPRO 304 fall ALeksandar Leposavic.
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