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75-405: For the analysis, polystyrene markers are placed at specific points on the horse's limbs, mainly over the joints . Then the horse is walked and trotted in-hand, and filmed with a video camera from all angles on a hard, flat surface. The information is then collated and downloaded on to a CD or DVD, which is analyzed on a computer by an accredited individual. The specialist software program records

150-481: A chemical compound that is widely used as a food preservative . In 1865, inspired by Auguste Laurent , Hofmann suggested a systematic nomenclature for hydrocarbons and their derivatives. It was adopted internationally by the Geneva Congress, with some modifications, in 1892. Hofmann was apparently the first to introduce molecular models into organic chemistry, following August Kekule 's introduction of

225-475: A polymerisation process. About 80 years later it was realized that heating of styrol starts a chain reaction that produces macromolecules , following the thesis of German organic chemist Hermann Staudinger (1881–1965). This eventually led to the substance receiving its present name, polystyrene. The company I. G. Farben began manufacturing polystyrene in Ludwigshafen , about 1931, hoping it would be

300-462: A "blowing agent", a material that enables the beads to be expanded. Pentane is commonly used as the blowing agent. The beads are added to a continuously agitated reactor with the blowing agent, among other additives, and the blowing agent seeps into pores within each bead. The beads are then expanded using steam. EPS is used for food containers , molded sheets for building insulation , and packing material either as solid blocks formed to accommodate

375-563: A US patent for polystyrene foam as an insulation product in 1935 (USA patent number 2,023,204). PS foams also exhibit good damping properties, therefore it is used widely in packaging. The trademark Styrofoam by Dow Chemical Company is informally used (mainly US & Canada) for all foamed polystyrene products, although strictly it should only be used for "extruded closed-cell" polystyrene foams made by Dow Chemicals. Foams are also used for non-weight-bearing architectural structures (such as ornamental pillars ). Expanded polystyrene (EPS)

450-485: A basis for systematising and categorising both organic and inorganic compounds by exploring the substitution of one or more atoms of hydrogen for an equivalent atom or group. Hofmann himself had focused on researching ammonia, but discussed all four models in his book. In it, he also first introduced the term valence , under its longer variant quantivalence, to describe the combining capacity of an atom. His textbook strongly influenced introductory textbooks in both Europe and

525-466: A chain of polystyrene, giving a molar mass of 100,000–400,000 g/mol. Each carbon of the backbone has tetrahedral geometry , and those carbons that have a phenyl group (benzene ring) attached are stereogenic . If the backbone were to be laid as a flat elongated zig-zag chain, each phenyl group would be tilted forward or backward compared to the plane of the chain. The relative stereochemical relationship of consecutive phenyl groups determines

600-468: A grey/black color which distinguishes it from standard EPS. Several EPS producers have produced a variety of these increased thermal resistance EPS usage for this product in the UK and EU. Water vapor diffusion resistance ( μ ) of EPS is around 30–70. ICC-ES ( International Code Council Evaluation Service) requires EPS boards used in building construction meet ASTM C578 requirements. One of these requirements

675-516: A major contributor to the development of techniques for organic synthesis, which originated at Liebig's laboratory in Giessen. Hofmann and John Blyth were the first to use the term "synthesis", in their paper "On Styrole, and Some of the Products of Its Decomposition," predating Kolbe's use of the term by some months. What Blyth and Hofmann called "synthesis" enabled them to make inferences about

750-672: A metallocene catalyst for the polymerisation reaction. Polystyrene is relatively chemically inert. While it is waterproof and resistant to breakdown by many acids and bases, it is easily attacked by many organic solvents (e.g. it dissolves quickly when exposed to acetone ), chlorinated solvents, and aromatic hydrocarbon solvents. Because of its resilience and inertness, it is used for fabricating many objects of commerce. Like other organic compounds, polystyrene burns to give carbon dioxide and water vapor , in addition to other thermal degradation by-products. Polystyrene, being an aromatic hydrocarbon , typically combusts incompletely as indicated by

825-520: A method of fractional distillation of coal tar and separated out benzene , xylene , and toluene , an essential step towards the development of products from coal tar. In 1856, Hofmann's student William Henry Perkin was attempting to synthesize quinine at the Royal College of Chemistry in London, when he discovered the first aniline dye , mauveine . The discovery led to the creation of

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900-722: A smoke-developed index of less than 450. ICC-ES requires the use of a 15-minute thermal barrier when EPS boards are used inside of a building. According to the EPS-IA ICF organization, the typical density of EPS used for insulated concrete forms ( expanded polystyrene concrete ) is 1.35 to 1.80 pounds per cubic foot (21.6 to 28.8 kg/m ). This is either Type II or Type IX EPS according to ASTM C578. EPS blocks or boards used in building construction are commonly cut using hot wires. Extruded polystyrene foam (XPS) consists of closed cells. It offers improved surface roughness, higher stiffness and reduced thermal conductivity. The density range

975-566: A split via a channel system of gates and runners. EPS is colloquially called "styrofoam" in the Anglosphere , an genericization of Dow Chemical's brand of extruded polystyrene . Sheets of EPS are commonly packaged as rigid panels (common in Europe is a size of 100 cm x 50 cm, usually depending on an intended type of connection and glue techniques, it is, in fact, 99.5 cm x 49.5 cm or 98 cm x 48 cm; less common

1050-496: A sprayed-on coating is necessary to prevent saturation. Oriented polystyrene (OPS) is produced by stretching extruded PS film, improving visibility through the material by reducing haziness and increasing stiffness. This is often used in packaging where the manufacturer would like the consumer to see the enclosed product. Some benefits to OPS are that it is less expensive to produce than other clear plastics such as polypropylene (PP), (PET), and high-impact polystyrene (HIPS), and it

1125-513: A suitable replacement for die-cast zinc in many applications. Success was achieved when they developed a reactor vessel that extruded polystyrene through a heated tube and cutter, producing polystyrene in pellet form. Ray McIntire (1918–1996), a chemical engineer of Dow Chemical, rediscovered a process first patented in early 1930s by Swedish inventor Carl Munters . According to the Science History Institute, "Dow bought

1200-719: A symptom of that decline, and with him gone, the Royal College of Chemistry lost its focus. Later, the Royal College of Chemistry, under the School of Mines, became part of Imperial College London as part of a drive to stop Britain falling behind Germany in science and technology. In 1864 Hofmann was offered a chair of chemistry at the University of Bonn , and another at the University of Berlin . While taking his time to decide which offer to accept, Hofmann designed laboratory buildings for both universities, which were both subsequently built. In 1865 he succeeded Eilhard Mitscherlich at

1275-404: A visit to his alma mater at Bonn, found his old rooms now occupied by Hofmann and his chemical apparatus. In 1845 Hofmann was approached by Sir James Clark , physician to Queen Victoria with the offer of the directorship. With the support of Prince Albert, and funding from a variety of private sources, the institution opened in 1845 with Hofmann as its first director. The financial position of

1350-756: A wide range of artificially created colourful textile dyes, revolutionising the fashion world. Hofmann's researches on rosaniline , which he first prepared in 1858, were the beginning of a series of investigations on colouring matter. In 1863, Hofmann showed that aniline blue is a triphenyl derivative of rosaniline and discovered that different alkyl groups could be introduced into the rosaniline molecule to produce dyes of various purple or violet colours, which became known as 'Hofmann's violets'. In 1864, Hofmann confirmed that magenta can only be made by oxidation of commercial aniline in which isomeric orthotoluidine and paratoluidine are present as impurities, not from pure aniline. Other students of Hofmann's who became involved in

1425-984: A young man, he travelled widely with his father. August Wilhelm matriculated at the University of Giessen in 1836. He originally took up the study of law and philology at Giessen . He may have become interested in chemistry when his father enlarged Liebig's Giessen laboratories in 1839. August Wilhelm changed his studies to chemistry , and studied under Justus von Liebig . He obtained his PhD there in 1841. In 1843, after his father's death, he became one of Liebig's assistants. His association with Liebig eventually became personal as well as professional. Both his first wife, Helene Moldenhauer (m. 12 August 1846), and his third wife, Elise Moldenhauer (m. 19 May 1866), were nieces of Liebig's wife, Henriette Moldenhauer. Hofman reportedly courted Elise after Liebig's daughter Johanna refused him. In between, he married Rosamond Wilson (m. 13 December 1856), and later Bertha Tiemann (m. 11 August 1873) He had eleven children. As president of

1500-497: Is 120 x 60 cm; size 4 by 8 ft (1.2 by 2.4 m) or 2 by 8 ft (0.61 by 2.44 m) in the United States). Common thicknesses are from 10 mm to 500 mm. Many customizations, additives, and thin additional external layers on one or both sides are often added to help with various properties. An example of this is lamination with cement board to form a structural insulated panel . Thermal conductivity

1575-481: Is a distinct compound). By 1845 Jamaican-born chemist John Buddle Blyth and German chemist August Wilhelm von Hofmann showed that the same transformation of styrol took place in the absence of oxygen. They called the product "meta styrol"; analysis showed that it was chemically identical to Simon's Styroloxyd. In 1866 Marcellin Berthelot correctly identified the formation of meta styrol/Styroloxyd from styrol as

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1650-524: Is a rigid and tough, closed-cell foam with a normal density range of 11 to 32 kg/m . It is usually white and made of pre-expanded polystyrene beads. The manufacturing process for EPS conventionally begins with the creation of small polystyrene beads. Styrene monomers (and potentially other additives) are suspended in water, where they undergo free-radical addition polymerization. The polystyrene beads formed by this mechanism may have an average diameter of around 200 μm. The beads are then permeated with

1725-449: Is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene . Polystyrene can be solid or foamed . General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to air and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics , with the scale of its production being several million tonnes per year. Polystyrene

1800-450: Is about 28–34 kg/m . Extruded polystyrene material is also used in crafts and model building, in particular architectural models. Because of the extrusion manufacturing process, XPS does not require facers to maintain its thermal or physical property performance. Thus, it makes a more uniform substitute for corrugated cardboard . Thermal conductivity varies between 0.029 and 0.039 W/(m·K) depending on bearing strength/density and

1875-437: Is commonly injection molded , vacuum formed , or extruded, while expanded polystyrene is either extruded or molded in a special process. Polystyrene copolymers are also produced; these contain one or more other monomers in addition to styrene. In recent years the expanded polystyrene composites with cellulose and starch have also been produced. Polystyrene is used in some polymer-bonded explosives (PBX). Polystyrene (PS)

1950-489: Is exploited for extrusion (as in Styrofoam ) and also for molding and vacuum forming , since it can be cast into molds with fine detail. The temperatures behavior can be controlled by photocrosslinking. Under ASTM standards, polystyrene is regarded as not biodegradable . It is accumulating as a form of litter in the outside environment , particularly along shores and waterways, especially in its foam form, and in

2025-468: Is generally considered to be non-biodegradable. However, certain organisms are able to degrade it, albeit very slowly. In 2015, researchers discovered that mealworms , the larvae form of the darkling beetle Tenebrio molitor , could digest and subsist healthily on a diet of EPS. About 100 mealworms could consume between 34 and 39 milligrams of this white foam in a day. The droppings of mealworm were found to be safe for use as soil for crops. In 2016, it

2100-410: Is initiated with free radicals . Ziegler–Natta polymerization can produce an ordered syndiotactic polystyrene with the phenyl groups positioned on alternating sides of the hydrocarbon backbone. This form is highly crystalline with a T m (melting point) of 270 °C (518 °F). Syndiotactic polystyrene resin is currently produced under the trade name XAREC by Idemitsu corporation, who use

2175-501: Is known as the Hofmann rearrangement . While primary, secondary, and tertiary amines were stable when distilled at high temperatures under alkaline conditions, the quaternary amine was not. Heating quaternary tetraethylammonium hydroxide yielded tertiary triethylamine vapour. This became the basis of what is now known as the Hofmann elimination , a method for converting quaternary amines into tertiary amines. Hofmann successfully applied

2250-419: Is less hazy than HIPS or PP. The main disadvantage of OPS is that it is brittle, and will crack or tear easily. August Wilhelm von Hofmann August Wilhelm von Hofmann (8 April 1818 – 5 May 1892 ) was a German chemist who made considerable contributions to organic chemistry. His research on aniline helped lay the basis of the aniline-dye industry, and his research on coal tar laid

2325-560: Is measured according to EN 12667. Typical values range from 0.032 to 0.038 W/(m⋅K) depending on the density of the EPS board. The value of 0.038 W/(m⋅K) was obtained at 15 kg/m while the value of 0.032 W/(m⋅K) was obtained at 40 kg/m according to the datasheet of K-710 from StyroChem Finland. Adding fillers (graphites, aluminum, or carbons) has recently allowed the thermal conductivity of EPS to reach around 0.030–0.034 W/(m⋅K) (as low as 0.029 W/(m⋅K)) and as such has

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2400-548: Is naturally transparent , but can be colored with colorants. Uses include protective packaging (such as packing peanuts and optical disc jewel cases ), containers, lids, bottles, trays, tumblers, disposable cutlery , in the making of models, and as an alternative material for phonograph records . As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature . It becomes rigid again when cooled. This temperature behaviour

2475-412: Is not produced commercially. [REDACTED] The only commercially important form of polystyrene is atactic , in which the phenyl groups are randomly distributed on both sides of the polymer chain. This random positioning prevents the chains from aligning with sufficient regularity to achieve any crystallinity . The plastic has a glass transition temperature T g of ~90 °C. Polymerization

2550-732: Is often done to introduce polar groups. Much of modern biomedical research relies on the use of such products; they, therefore, play a critical role in pharmaceutical research. Thin sheets of polystyrene are used in polystyrene film capacitors as it forms a very stable dielectric , but has largely fallen out of use in favor of polyester . Polystyrene foams are 95–98% air. Polystyrene foams are good thermal insulators and are therefore often used as building insulation materials, such as in insulating concrete forms and structural insulated panel building systems. Grey polystyrene foam, incorporating graphite , has superior insulation properties. Carl Munters and John Gudbrand Tandberg of Sweden received

2625-415: Is open at the top to allow addition of water and an ionic compound to improve conductivity, such as a small amount of sulphuric acid . A platinum electrode is placed inside the bottom of each of the two side cylinders, connected to the positive and negative terminals of a source of electricity. When current is run through Hofmann's Voltameter, gaseous oxygen forms at the anode and gaseous hydrogen at

2700-404: Is that the limiting oxygen index of EPS as measured by ASTM D2863 be greater than 24 volume %. Typical EPS has an oxygen index of around 18 volume %; thus, a flame retardant is added to styrene or polystyrene during the formation of EPS. The boards containing a flame retardant when tested in a tunnel using test method UL 723 or ASTM E84 will have a flame spread index of less than 25 and

2775-723: Is used for producing disposable plastic cutlery and dinnerware , CD "jewel" cases , smoke detector housings, license plate frames, plastic model assembly kits, and many other objects where a rigid, economical plastic is desired. Production methods include thermoforming ( vacuum forming ) and injection molding . Polystyrene Petri dishes and other laboratory containers such as test tubes and microplates play an important role in biomedical research and science. For these uses, articles are almost always made by injection molding, and often sterilized post-molding, either by irradiation or by treatment with ethylene oxide . Post-mold surface modification, usually with oxygen -rich plasmas ,

2850-471: The CPK colour scheme and is in use even today. After 1874, when van't Hoff and Le Bel independently suggested organic molecules can be three-dimensional, molecular models began to assume their modern appearance. The Hofmann voltameter is an apparatus for electrolyzing water , invented by August Wilhelm von Hofmann in 1866. It consists of three joined upright cylinders, usually glass. The inner cylinder

2925-647: The Royal Society in London, Albert, Prince Consort to Queen Victoria , was determined to foster scientific advancement in Britain. In 1845, he proposed to start a school of practical chemistry in London, under the style of the Royal College of Chemistry . Liebig was approached for advice, and recommended Hofmann to the directorship of the new institution. Hofmann and the Prince met when Prince Albert, on

3000-484: The University of Giessen , Hofmann became the first director of the Royal College of Chemistry , now part of Imperial College London , in 1845. In 1865 he returned to Germany to accept a position at the University of Berlin as a teacher and researcher. After his return he co-founded the German Chemical Society ( Deutsche Chemische Gesellschaft ) (1867). In both London and Berlin, Hofmann recreated

3075-450: The cathode . Each gas displaces water and collects at the top of the two outer tubes. Hofmann was multilingual and published extensively, particularly about his work on coal tar and its derivatives. In 1865 Hofmann published An Introduction to Modern Chemistry , summarising type theory and emerging ideas about chemical structure. Type theory modelled four inorganic molecules, hydrogen, hydrogen chloride, water, and ammonia, and used them as

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3150-401: The sooty flame. The process of depolymerizing polystyrene into its monomer , styrene , is called pyrolysis . This involves using high heat and pressure to break down the chemical bonds between each styrene compound. Pyrolysis usually goes up to 430 °C. The high energy cost of doing this has made commercial recycling of polystyrene back into styrene monomer difficult. Polystyrene

3225-428: The tacticity , which affects various physical properties of the material. In polystyrene, tacticity describes the extent to which the phenyl group is uniformly aligned (arranged at one side) in the polymer chain. Tacticity has a strong effect on the properties of the plastic. Standard polystyrene is atactic. The diastereomer where all of the phenyl groups are on the same side is called isotactic polystyrene, which

3300-626: The British dyestuffs industry include Edward Chambers Nicholson , George Maule , and George Simpson . After his return to Germany, Hofmann continued to experiment with dyestuffs, finally creating quinoline red in 1887. Hofmann studied nitrogen bases, including the development of methods for separating mixtures of amines and the preparation of large numbers of "polyammonias" (diamines and triamines such as ethylenediamine and diethylenediamine). He worked with Auguste Cahours on phosphorus bases between 1855 and 1857. With him, in 1857, Hofmann prepared

3375-602: The Pacific Ocean. Polystyrene was discovered in 1839 by Eduard Simon , an apothecary from Berlin. From storax , the resin of the Oriental sweetgum tree Liquidambar orientalis , he distilled an oily substance, that he named styrol, now called styrene . Several days later, Simon found that it had thickened into a jelly, now known to have been a polymer , that he dubbed styrol oxide ("Styroloxyd") because he presumed that it had resulted from oxidation ( styrene oxide

3450-529: The United States. In addition to his scientific works, Hofmann wrote biographical notices and essays on the history of chemistry, including a study of Liebig. He was elected a fellow of the Royal Society in 1851. He was awarded the society's Royal Medal in 1854 and their Copley Medal in 1875 "for his numerous contributions to the science of chemistry, and especially for his researches on

3525-461: The University of Berlin as professor of chemistry and director of the chemical laboratory. He held the position until his death in 1892. Following his return to Germany Hofmann was the principal founder of the German Chemical Society (Deutsche Chemische Gesellschaft zu Berlin) (1867) and served 14 terms as its president. Hofmann's work covered a wide range of organic chemistry . Hofmann was

3600-416: The average value is ~0.035 W/(m·K). Water vapor diffusion resistance (μ) of XPS is around 80–250. Commonly extruded polystyrene foam materials include: Although it is a closed-cell foam, both expanded and extruded polystyrene are not entirely waterproof or vapor proof. In expanded polystyrene there are interstitial gaps between the expanded closed-cell pellets that form an open network of channels between

3675-694: The bonded pellets, and this network of gaps can become filled with liquid water. If the water freezes into ice, it expands and can cause polystyrene pellets to break off from the foam. Extruded polystyrene is also permeable by water molecules and can not be considered a vapor barrier. Water-logging commonly occurs over a long period in polystyrene foams that are constantly exposed to high humidity or are continuously immersed in water, such as in hot tub covers, in floating docks, as supplemental flotation under boat seats, and for below-grade exterior building insulation constantly exposed to groundwater. Typically an exterior vapor barrier such as impermeable plastic sheeting or

3750-409: The constitution of styrole . A subsequent paper, Muspratt and Hofmann's "On Toluidine ", described some of the first "synthetical experiments" (synthetische Versuche) in the field of organic chemistry. While the ultimate goal of such experiments was to artificially produce naturally occurring substances, such a goal was not practically attainable at the time. The immediate purpose of the technique

3825-550: The death of Prince Albert in 1861, the institution lost one of its most significant supporters. Hofmann felt the loss deeply, writing in 1863, "[Albert's] early kindness exercised so powerful an influence upon the destinies of my existence. Year by year do I feel more deeply the debt of gratitude which I owe to him... it is to him, I feel, that I owe my opportunities through life." Without the Prince's encouragement, British government and industry lost interest in science and technology. Hofmann's decision to return to Germany can be seen as

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3900-612: The derivatives of ammonia". On his 70th birthday, in 1888, he was ennobled, enabling him to add the prefix "von" before his last name. In 1900, the German Chemical Society built the "Hofmann-Haus" at Berlin and in 1902 created the August Wilhelm von Hofmann Gold Medal in his honour, to be awarded for outstanding achievements in chemistry. The first recipients were Sir William Ramsay of England and Professor Henri Moissan of Paris. Hofmann died in 1892 and

3975-412: The first aliphatic unsaturated alcohol , allyl alcohol , C3 H5OH. He also examined its derivative, allyl isothiocyanate (mustard oil), in 1868, and studied various other isocyanates and isonitriles (isocyanides, or carbylamines). Hofmann also developed a method for determining the molecular weights of liquids from vapour densities . Hofmann isolated sorbic acid from rowanberries' oil in 1859,

4050-442: The groundwork for his student Charles Mansfield's practical methods for extracting benzene and toluene and converting them into nitro compounds and amines . Hofmann's discoveries include formaldehyde , hydrazobenzene , the isonitriles , and allyl alcohol . He prepared three ethylamines and tetraethylammonium compounds and established their structural relationship to ammonia . After studying under Justus von Liebig at

4125-430: The gut of superworms that contain encoded enzymes associated with the degradation of polystyrene and the breakdown product styrene. The bacterium Pseudomonas putida is capable of converting styrene oil into the biodegradable plastic PHA . This may someday be of use in the effective disposing of polystyrene foam. It is worthy to note the polystyrene must undergo pyrolysis to turn into styrene oil. Polystyrene

4200-442: The institution became successful for a time, and was an international leader in the development of aniline dyes. Many of the men who studied there made significant contributions to chemical history. In 1853, the Royal College of Chemistry became part of the governmental Department of Science and Art, under the new School of Mines, putting it in a position to receive governmental funding on a somewhat more secure basis. However, with

4275-471: The item being protected or as loose-fill "peanuts" cushioning fragile items inside boxes. EPS also has been widely used in automotive and road safety applications such as motorcycle helmets and road barriers on automobile race tracks . A significant portion of all EPS products are manufactured through injection molding. Mold tools tend to be manufactured from steels (which can be hardened and plated), and aluminum alloys. The molds are controlled through

4350-460: The method to coniine , the cholinergic poison of hemlock , to derive the first structure of an alkaloid. His method became extremely significant as a tool for examining the molecular structures of alkaloids, and was eventually applied to morphine, coca amine, atropine, and tubocurarine, among others. Coniine eventually became the first of the alkaloids to be artificially synthesised. In 1848, Hofmann's student Charles Blachford Mansfield developed

4425-467: The molecules consist of thousands of atoms, the cumulative attractive force between the molecules is large. When heated (or deformed at a rapid rate, due to a combination of viscoelastic and thermal insulation properties), the chains can take on a higher degree of confirmation and slide past each other. This intermolecular weakness (versus the high intramolecular strength due to the hydrocarbon backbone) confers flexibility and elasticity. The ability of

4500-492: The movement of the markers and produces data that can be used to quantify stride length, body symmetry, joint flexion and extension, and soundness. The resulting baseline of facts - which is presented in a hard-copy portfolio of information for future reference - then provides the horse owner with a valuable 'baseline measurement' of movement and soundness. A 2011 study published in the Journal of Equine Veterinary Science found

4575-433: The natural alkaloids. Hofmann drew an analogy between aniline and ammonia . He wanted to convince chemists that organic bases could be described in terms of derivatives of ammonia. Hofmann successfully converted ammonia into ethylamine and the compounds diethylamine , triethylamine , and tetraethylammonium . He was the first chemist to synthesize the quaternary amines. His method of converting an amide into an amine

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4650-712: The new institution was somewhat precarious. Hofmann accepted the position on the condition that he be appointed as extraordinary professor at Bonn, with leave of absence for two years, so that he could resume his career in Germany if the English appointment did not go well. The college opened in 1845 with 26 students at 16 Hanover Square, moving to cheaper premises at 299 Oxford Street in 1848. Hofmann himself relinquished his free personal accommodation in Hanover Square and gave up part of his salary. Despite this rocky start,

4725-457: The plant dye indigo . In his first publication (1843) he demonstrated that a variety of substances which had been identified in contemporary chemical literature as obtainable from coal tar naphtha and its derivatives were all a single nitrogenous base, aniline. These included Kyanol , Carl Julius Fritzsche 's Anilin , Otto Unverdorben 's Krystallin , and Nikolai Zinin 's Benzidam . Much of his subsequent work further developed understanding of

4800-434: The polymerization, the carbon-carbon π bond of the vinyl group is broken and a new carbon-carbon σ bond is formed, attaching to the carbon of another styrene monomer to the chain. Since only one kind of monomer is used in its preparation, it is a homopolymer. The newly formed σ bond is stronger than the π bond that was broken, thus it is difficult to depolymerize polystyrene. About a few thousand monomers typically comprise

4875-455: The processes by which they were formed. Hofmann's first research investigations, carried out in Liebig's laboratory at Giessen, was an examination of the organic bases of coal tar . Hofmann successfully isolated Kyanol and Leucol , bases previously reported by Friedlieb Ferdinand Runge , and showed that Kyanol was almost entirely aniline, previously shown to be a decomposition product of

4950-676: The raw material for molding parts or extruding sheets. BASF and Stastny applied for a patent that was issued in 1949. The molding process was demonstrated at the Kunststoff Messe 1952 in Düsseldorf. Products were named Styropor. The crystal structure of isotactic polystyrene was reported by Giulio Natta . In 1954, the Koppers Company in Pittsburgh , Pennsylvania, developed expanded polystyrene (EPS) foam under

5025-423: The rights to Munters's method and began producing a lightweight, water-resistant, and buoyant material that seemed perfectly suited for building docks and watercraft and for insulating homes, offices, and chicken sheds." In 1944, Styrofoam was patented. Before 1949, chemical engineer Fritz Stastny (1908–1985) developed pre-expanded PS beads by incorporating aliphatic hydrocarbons, such as pentane. These beads are

5100-686: The style of laboratory instruction established by Liebig at Giessen, fostering a school of chemistry focused on experimental organic chemistry and its industrial applications. Hofmann received several significant awards in the field of chemistry, including the Royal Medal (1854), the Copley Medal (1875) and the Albert Medal (1881). He was elected as a member of the American Philosophical Society in 1862. He

5175-448: The system did not produce repeatable data from day to day, and was therefore not sufficiently reliable for use in clinical evaluations of equine lameness . This equine-related article is a stub . You can help Misplaced Pages by expanding it . This veterinary medicine –related article is a stub . You can help Misplaced Pages by expanding it . Polystyrene Polystyrene ( PS ) / ˌ p ɒ l i ˈ s t aɪ r iː n /

5250-458: The system to be readily deformed above its glass transition temperature allows polystyrene (and thermoplastic polymers in general) to be readily softened and molded upon heating. Extruded polystyrene is about as strong as an unalloyed aluminium but much more flexible and much less dense (1.05 g/cm for polystyrene vs. 2.70 g/cm for aluminium). Polystyrene is an addition polymer that results when styrene monomers polymerize (interconnect). In

5325-593: The theory of chemical structure in 1858, and Alexander Crum Brown 's introduction of printed structural formulas in 1861. At a Friday Evening Discourse at London's Royal Institution on April 7, 1865, he displayed molecular models of simple organic substances such as methane, ethane, and methyl chloride, which he had had constructed from differently colored table croquet balls connected together with thin brass tubes. Hofmann's original colour scheme ( carbon = black, hydrogen = white, nitrogen = blue, oxygen = red, chlorine = green, and sulphur = yellow) has evolved into

5400-523: The trade name Dylite. In 1960, Dart Container , the largest manufacturer of foam cups, shipped their first order. In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating carbon centers are attached to phenyl groups (a derivative of benzene ). Polystyrene's chemical formula is (C 8 H 8 ) n ; it contains the chemical elements carbon and hydrogen . The material's properties are determined by short-range van der Waals attractions between polymer chains. Since

5475-478: Was also reported that superworms ( Zophobas morio ) may eat expanded polystyrene (EPS). A group of high school students in Ateneo de Manila University found that compared to Tenebrio molitor larvae, Zophobas morio larvae may consume greater amounts of EPS over longer periods of time. In 2022 scientists identified several bacterial genera, including Pseudomonas , Rhodococcus and Corynebacterium , in

5550-539: Was ennobled on his seventieth birthday. His name is associated with the Hofmann voltameter , the Hofmann rearrangement , the Hofmann–Martius rearrangement , Hofmann elimination , and the Hofmann–Löffler reaction . August Wilhelm Hofmann was born at Giessen , Grand Duchy of Hesse , on 8 April 1818. He was the son of Johann Philipp Hofmann, privy councillor and provincial architect to the court at Darmstadt. As

5625-414: Was the application of known reactions to a variety of materials to discover what products could be formed. Understanding a substance's method of formation was an important step in placing it within a developing taxonomy of substances. This technique became the basis of Hofmann's research program. He used organic synthesis as a method of investigation, to increase chemical understanding of reaction products and

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