Without Styrene, the world as we know it would be vastly different. The abilty to isolate, or rather distill Styrene was an achievement in chemistry that became a catalyst for inventions that the modern world benefit from to this day. Polystyrene and Expanded Polystyrene (EPS) would never have come into existance were it not for Styrene and its ability to be polymerize with so many different elements. The importance of Styrene can be seen all around us nearly every day of our lives. According to the Styrene Information & Research Center, this importance has brought the annual Styrene sales to over 28 billion dollars, and places in the "100 most important chemical compounds". Styrene is known by many other names including vinyl benzene, ethenylbenzene, phenylethylene, Styrol, Cinnamene, Diarex HF 77, and Styrolene. In natural forms, Styrene is found in hundreds of plants and substances in nature. Small amounts of Styrene naturally exist in many things that we eat and drink such as strawberries, coffee beans, peaches, wheat, cheese, cinnamon, wine, beer, and the balsaamic tree just to name a few.
Please remember when reading all of the information below that so much had to be stripped down, some of the essentials and details had to be condensed. There are volumes of great information about Styrene that would promote further study, and is well worth the time and effort to learn. The impact of Styrene and expanded polystyrene have forever changed the way in which we live.
About half of the annual Styrene production worldwide is used for Polystyrene production, and less than ten percent is used for Expanded Polystyrene.
Styrene is a clear organic liquid hydrocarbon that is produced mainly from petroleum products after a process of fractional distillation to extract the olefins and aromatics nesessary for the chemical materials to produce Styrene. Most petrochemical chemical plants are similar to the picture on the right. Notice the large vertical column which is called the fractional distillation column. This is where the components of the petroleum are heated to high temperatures because each of the main chemical components have different boiling points thus seperating them very accurately.
Styrene is what's known in chemistry circles as a monomer. The reaction of monomers forming "chains" and the ability to link up with other molecules are essential in the production of Polystyrene. Styrene molecules also contain a vinyl group (ethenyl) that share electrons in a reaction known as covalent bonding, this allows it to be manufactured into plastics. Frequently, Styrene is produced in a two step process. First, the alkylation of benzene (an unsaturated hydrocarbon) with ethylene to produce ethylbenzene. Aluminum chloride catalyzed alkylation is still used in many EB (ethylbenzene) plants around the world. Once that is done, the EB is put through a very precise dehydrogenation process by passing EB and steam over a catalyst like iron oxide, aluminium chloride, or lately, a fixed-bed zeolite catalyst system to get a very pure form of Styrene. Nearly all ethylbenzene that is produced around the world is used for styrene manufacturing. Recent advances in Styrene production have increased the ways in which Styrene can be produced. One way in particular uses Toluene and Methanol instead of EB. Being able to use different feedstocks makes Styrene a competitively affordable resource.
Other interesting ways in which we can obtain the Styrene monomer is through the use of LPG and NGL. According to the U.S. Energy Information Administration about 191 million barrels of LPG and NGL were also used in the United States to make plastic products in the plastic materials and resins industry, as well as 412 billion cubic feet (Bcf) of natural gas was used to make plastic materials and resins in 2010 (current figures are almost non-existant). Having these alternate sources for Styrene production reduce an over-dependancy on oil imports.
When it comes to plastics, Styrene is one of the most versitile monomers around. The list below clearly shows how the importance Styrene is measured by how many types of polymers can be manufactured from it.
For further study, a very good article on the alkylation of Ethylene and Benzene can be found here.
Simply put, Polystyrene is a synthetic polymerized thermoplastic resin using the Styrene monomer. It is known as a long-chain hydrocarbon. This stiffer type of Polystyrene is sometimes called crystal PS or general purpose polystyrene. The unique property that polystyrene has is that it can be in rigid form or foamed, and can be shaped and molded very easily because it is a thermoplastic. Polystyrene is produced in sheet form (as well as many different types and colors) or pelletized PS as pictured to the right. The rigid PS material typically can be heated and melted for molding or extrusion purposes very easily explaining why the popularity has propelled Polystyrene worldwide usage to several billion pounds of of PS per year, and has moved to the second most popular polymer in the world.
All around us are natural polymers such as, rubber, silk, wool, and cellulose. Many living organisms are also composed of natural polymers namely nucleic acids, protiens, and cellulose. Some examples of synthetic polymers among thermoplastics would be nylon, bakelite, silicone, neoprene, and polystyrene. Polystyrene is identified by the resin identification code abbreviated "PS" symbol.
Today, Styrene is polymerized into Polystyrene using what is called an radical initiator (or foamer) like Benzoyl Peroxide or AIBN, which is another organic compound used primarily in bulk processes, although there are other ways like solution and emulsion processes that are frequently used. Since it is easy to produce now, it is used in many products that we routinely use for packaging , numerous application in the medical field, toys, construction, plastic cutlery, automotive industry, consumer electronics, and thousands of household uses. Polystyrene is strong, flexible, and lightweight.The popularity and usefullness of Polystyrene has propelled worldwide usage to several billion pounds of per year.
First Commercial Polystyrene - Germany Again
So many of the most important steps in the development of Polystyrene belong to German scientists, that it was only fitting that I.G.Farben (BASF) based in Ludwigshafen Germany was the first to produce Polystyrene on a commercial scale in the early 1930's. I.G Farben also has the distinction of being able to produce Polystyrene in pellet form which EPS manufacturers all over the world use to make expanded polystyrene.
Expanded Polystyrene has been the proven answer to common packaging, insulative, and construction material solution for decades. It is unique in that it is a closed cell, rigid, polymeric material that is about 95% air. The distinctive white pre-expanded beads are very recognizable (as shown in the picture to the right), and display the resin identification code number
Expanded Polystyrene, or EPS, goes through a series of changes that take it from a small polystyrene pre-expanded bead about 1mm in width to an expanded bead fourty times that diameter. The process of pre-expansion involves very precise measurements of timing, pressure variables, and high temperature steam in our Hirsch-Gruppe pre-expander and a blowing agent called Pentane (similar in chemical structure to Methane). The process of pre-expansion is vital when it comes to determination of just how the resultant block of foam and its density is produced. For a short video demonstration of this process, go to our "About Us" page .
The magic of Pentane as a blowing agent is the vital component to making EPS foam. Pentane is a colourless organic liquid hydrocarbon, and is usually considered a "specialty solvent" that has a very distinctive smell. Pentane is used in the EPS industry to replace former CFC producing blowing agents of the past. It is an ingrediant in aerosol propellants, refrigerants, pesticides, and used for the production of other chemicals. The transformation in the bead takes place when the Pentane inside the bead changes to a gas due to the high temperature steam (approx. 270 degrees) being applied while it is revolving in the pre-expansion chamber. The beads slowly begin foaming or "puffing up" from their tiny size to 40 times their original diameter. Here the settings and parameters in the Hirsch-Gruppe pre-expander are critical to what those beads eventually become, and to what application of density the EPS foam block is to be made into.
After the expanded EPS beads are at the designated size, they are then sucked out of the pre-expander and into large storage silos like the picture on the left. Once in the silos, the beads have to dissipate excess Pentane and age anywhere from 48 to 72 hours so EPS foam block stability and the fabricating of the foam block can be done properly.
After the beads have been aged properly, they are then pumped into our state-of-the-art Hirsch-Gruppe foam block mold machine. Michigan Foam Products uses the Hirsch-Gruppe foam block mold machine because of its precision, reliability, and production capabilities. With the combined experience of our block mold techs and the computer precision quality of our Hirsch-Gruppe block mold, block consistancy is quaranteed. To make a simple EPS block, our techs program at least fourty seperate parameters into the CNC console. Each block takes anywhere from 5 minutes to 18 minutes (depending on density) to complete the high pressure forming of each block. Once again, high temperature steam and a great deal of internally applied pressure make those beads, and the rest of the Pentane in them, form into a solid block of foam. Once that block exits the block mold it is taken to a holding area, and set on end vertically to dissipate the remaining Pentane and heat within the block that occurred during the molding process. This also takes a couple days to finish.
When needed, the EPS foam blocks are transported to a variety of hot wire cutting machines. Some of the hot wire cutters such as a profile cutter, can take a 3D CAD drawing and turn that huge block of EPS foam into every shape imaginable, whether 2D or 3D, flat or round, and do it with total CNC precision. And other large hot wire cutting machines like the "Autowire Cutter"on the right, are designed to cut straight width foam sheets anywhere in size from ¼ up to the width of a full block. Each of the larger hot wire cutters have CNC controls to feed in nesessary measurements to make thousands of different sizes of parts and pieces with precision.
For a detailed examination of the way Expanded Polystyrene is manufactured, this doctoral thesis done by Olita Medne of Riga Technical University is very thorough and well worth the study if you desire details and analysis. Medne Doctoral Thesis on EPS foam
Standard EPS Foam Properties
|Foam Density - lb per cu. ft.||1 lb.||2 lb.||3 lb.|
|Compressive Strength / p.s.i.||12 - 17||31 - 37||52 -56|
|Tensile Strength / p.s.i.||22 - 27||58 - 61||92 - 95|
|Thermal Resistance / R - per in||3.8||4.2||4.3|
EPS can be formed and shaped into practically size within the dimensions of the finished block. Michigan Foam Products manufactures over twenty different densities of Expanded Polystyrene foam. Please look at the "EPS Technical Data" and foam densities chart we have made available by clicking on the image to the left. Some custom densities are not listed due to space limitations. Please contact our office for any custom densities you may need. Or download the Michigan Foam Products ESP Technical Data Sheet below
Download EPS Technical Data Sheet PDF
Many of the scientists and pharmacists listed below were instrumental in Styrene research in its earliest days of experimentation. We cannot list all those that donated their time and parts of their lives to Styrene research because it would literally take volumes of space. We have included some of those who have given proven texts and data either in publications or papers they have done for scientific societies from the late 1700's to the middle 1800's. Many European scientific societies were a close-knit, tightly connected group of individuals who regarded in-depth research as the primary goal of their vocations.
Bouillon-LaGrange did extensive research on Liquid Styrax in his study called "On the Origin and Properties of Liquid Styrax" which was delivered to the Medical Society of Paris. This study done in the late 1700's is probably the earliest done on Storax and its properties. He seemed interested mainly in what it was composed of for the use of liquid Storax for pharmaceutical purposes only. Until that time, liquid styrax was used primarily in ointments.
Among all his other achievements, Bouillon-LaGrange published around 50 publications on all subjects such as, chemistry, pharmaceuticals, and physical and chemical properties.
Eduard Simon, a pharmacist living in Berlin Germany, holds the distinction of being able to seperate Styrene (which he named Storax, or Styrol Oxide) by distillation from the sap of an Oriental Sweetgum (Liquidambar tree) in 1839. Although most of Simon's life is somewhat obscure, his discovery is one of the most important of the 1800's. Just a few days after he isolated this clear substance, it began hardening in the vial he had placed it in. Thinking that oxygen had caused this transformation he then called it styrol oxide. Little did he realize that the substance he was able to distill became polymerized styrene - or polystyrene.
In 1845 Dr. John Blyth, Professor of chemistry and August Wilhelm von Hofmann did extensive studies of Styrene taking Simon's research much further and more experimentally. Together they wrote a research paper called "On Styrole and some of the products of its decomposition" and were able to prove that Styrene (which they called Styrole and metastyrole) would polymerize in the container without the presence of oxygen and put Styrene under far more scrutiny than ever before. What they seem to endevour is to obtain styrole (styrene) through different distillation methods and to test the liquid with other newly discovered chemical substances they now had more knowledge of. The amount of testing done is one of the most thorough and a high degree of mathmatical as well as scientific research on Styrene. Their paper can be read here at "The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science"
Berthelot accomplishments are:
Berthelot published a very detailed work on the synthesis of organic chemicals in 1860,concluding that an almost infinite number of organic compounds could be synthesized he was one of the first to produce organic compounds synthetically (including the carbon compounds methyl alcohol, ethyl alcohol, benzene, and acetylene), playing a major role in dispelling the old theory of a vital force inherent in organic compounds.
In 1866 Marcelin Berthelot correctly identified the formation of metastyrol/Styroloxyd from styrol as a polymerization process.