Isocyanates with two or more functional groups are required for the formation of polyurethane polymers. Volume wise, aromatic isocyanates account for the vast majority of global diisocyanate production. Aliphatic and cycloaliphatic isocyanates are also important building blocks for polyurethane materials, but in much smaller volumes. There are a number of reasons for this. First, the aromatically linked isocyanate group is much more reactive than the aliphatic one. Second, aromatic isocyanates are more economical to use. Aliphatic isocyanates are used only if special properties are required for the final product. For example, light stable coatings and elastomers can only be obtained with aliphatic isocyanates. Even within the same class of isocyanates, there is a significant difference in reactivity of the functional groups based on steric hindrance. In the case of 2,4-toluene diisocyanate, the isocyanate group in the para position to the methyl group is much more reactive than the isocyanate group in the ortho position.
Phosgenation of corresponding amines is the main technical process for the manufacture of isocyanates. The amine raw materials are generally manufactured by the hydrogenation of corresponding nitro compounds. For example, toluenediamine (TDA) is manufactured from dinitrotoluene, which then converted to toluene diisocyanate (TDI). Diamino diphenylmethane or methylenedianiline (MDA) is manufactured from nitrobenzene via aniline, which is then converted to diphenylmethane diisocyanate (MDI).
The two most important aromatic isocyanates are toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI consists of a mixture of the 2,4- and 2,6-diisocyanatotoluene isomers. The most important product is TDI-80 (TD-80), consisting of 80% of the 2,4-isomer and 20% of the 2,6-isomer. This blend is used extensively in the manufacture of polyurethane flexible slabstock and molded foam.12 TDI, and especially crude TDI and TDI/MDI blends can be used in rigid foam applications, but have been supplanted by polymeric MDI. TDI-polyether and TDI-polyester prepolymers are used in high performance coating and elastomer applications. Prepolymers are available that have been vacuum stripped of TDI monomer, which greatly reduces their toxicity. Diphenylmethane diisocyanate (MDI) has three isomers, 4,4'-MDI, 2,4'-MDI, and 2,2'-MDI, and is also polymerized to provide oligomers of functionality three and higher.
Only the 4,4'-MDI monomer is sold commercially as a single isomer. It is provided either as a frozen solid or flake, or in molten form, and is used to manufacture high performance prepolymers. Monomer blends, consisting of approximately 50% of the 4,4'-isomer and 50% of the 2,4'-isomer, are liquid at room temperature and are used to manufacture prepolymers for polyurea spray elastomer applications. 4,4'-MDI blends containing MDI uretonimine, carbodiimide, and allophonate moieties are also liquid at room temperature, and are used in the manufacture of integral skin and microcellular foams. 4,4'-MDI-glycol prepolymers offer increased mechanical properties in the same applications, but are prone to freezing at temperatures below 20�C. Polymeric MDI (PMDI) is used in rigid pour-in-place, spray foam, and molded foam applications. Polymeric MDI that contains a very high portion of high-functionality oligomers is used to manufacture polyurethane and polyisocyanurate rigid insulation boardstock. Modified PMDI, which contains high levels of MDI monomer, is used in the production of polyurethane flexible molded and microcellular foam. The relative percentage of the 4,4'- and 2,4'- isomers is adjusted to change the reactivity and storage stability of the isocyanate blend, as well as the firmness and other physical properties of the finished goods. Other aromatic isocyanate include p-phenylene diisocyante (PPDI), naphthalene diisocyanate (NDI), and o-tolidine diisocyanate (TODI).
The most important aliphatic and cycloaliphatic isocyanates are 1,6-hexamethylene diisocyanate (HDI), 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), and 4,4'-diisocyanato dicyclohexylmethane (H12MDI). They are used to produce light stable, non-yellowing polyurethane coatings and elastomers. Because of their toxicity, aliphatic isocyanate monomers are converted into prepolymers, biurets, dimers, and trimers for commercial use. HDI adducts are used extensively for weather and abrasion resistant coatings and lacquers. IPDI is used in the manufacture of coatings, elastomeric adhesives and sealants. H12MDI prepolymers are used to produce high performance coatings and elastomers with optical clarity and hydrolysis resistance. Other aliphatic isocyanates include cyclohexane diisocyanate (CHDI), tetramethylxylene diisocyanate (TMXDI), and 1,3-bis(isocyanatomethyl)cyclohexane (H6XDI).
The pioneering work on polyurethane polymers was conducted by Otto Bayer and his coworkers in 1937 at the laboratories of I.G. Farben in Leverkusen, Germany.1 They recognized that using the polyaddition principle to produce polyurethanes from liquid diisocyanates and liquid polyether or polyester diols seemed to point to special opportunities, especially when compared to already existing plastics that were made by polymerizing olefins, or by polycondensation. The new monomer combination also circumvented existing patents obtained by Wallace Carothers on polyesters.2 Initially, work focused on the production of fibres and flexible foams. With development constrained by World War II (when PUs were applied on a limited scale as aircraft coating2), it was not until 1952 that polyisocyanates became commercially available. Commercial production of flexible polyurethane foam began in 1954, based on toluene diisocyanate (TDI) and polyester polyols. The invention of these foams (initially called imitation swiss cheese by the inventors2) was thanks to water accidentally introduced in the reaction mix. These materials were also used to produce rigid foams, gum rubber, and elastomers. Linear fibres were produced from hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO).
The first commercially available polyether polyol, poly(tetramethylene ether) glycol, was introduced by DuPont in 1956 by polymerizing tetrahydrofuran. Less expensive polyalkylene glycols were introduced by BASF and Dow Chemical the following year, 1957. These polyether polyols offered technical and commercial advantages such as low cost, ease of handling, and better hydrolytic stability; and quickly supplanted polyester polyols in the manufacture of polyurethane goods. Another early pioneer in PUs was the Mobay corporation.2 In 1960 more than 45,000 tons of flexible polyurethane foams were produced. As the decade progressed, the availability of chlorofluoroalkane blowing agents, inexpensive polyether polyols, and methylene diphenyl diisocyanate (MDI) heralded the development and use of polyurethane rigid foams as high performance insulation materials. Rigid foams based on polymeric MDI (PMDI) offered better thermal stability and combustion characteristics than those based on TDI. In 1967, urethane modified polyisocyanurate rigid foams were introduced, offering even better thermal stability and flammability resistance to low density insulation products. Also during the 1960s, automotive interior safety components such as instrument and door panels were produced by back-filling thermoplastic skins with semi-rigid foam.
In 1969, Bayer AG exhibited an all plastic car in Dusseldorf, Germany. Parts of this car were manufactured using a new process called RIM, Reaction Injection Molding. RIM technology uses high-pressure impingement of liquid components followed by the rapid flow of the reaction mixture into a mold cavity. Large parts, such as automotive fascia and body panels, can be molded in this manner. Polyurethane RIM evolved into a number of different products and processes. Using diamine chain extenders and trimerization technology gave poly(urethane urea), poly(urethane isocyanurate), and polyurea RIM. The addition of fillers, such as milled glass, mica, and processed mineral fibres gave arise to RRIM, reinforced RIM, which provided improvements in flexural modulus (stiffness) and thermal stability. This technology allowed production of the first plastic-body automobile in the United Sates, the Pontiac Fiero, in 1983. Further improvements in flexural modulus were obtained by incorporating preplaced glass mats into the RIM mold cavity, also known as SRIM, or structural RIM.
Starting in the early 1980s, water-blown microcellular flexible foam was used to mold gaskets for panel and radial seal air filters in the automotive industry. Since then, increasing energy prices and the desire to eliminate PVC plastisol from automotive applications have greatly increased market share. Costlier raw materials are offset by a significant decrease in part weight and in some cases, the elimination of metal end caps and filter housings. Highly filled polyurethane elastomers, and more recently unfilled polyurethane foams are now used in high-temperature oil filter applications.
Polyurethane foam (including foam rubber) is often made by adding small amounts of volatile materials, so-called blowing agents, to the reaction mixture. These simple volatile chemicals yield important performance characteristics, primarily thermal insulation. In the early 1990s, because of their impact on ozone depletion, the Montreal Protocol led to the greatly reduced use of many chlorine-containing blowing agents, such as trichlorofluoromethane (CFC-11). Other haloalkanes, such as the hydrochlorofluorocarbon 1,1-dichloro-1-fluoroethane (HCFC-141b), were used as interim replacements until their phase out under the IPPC directive on greenhouse gases in 1994 and by the Volatile Organic Compounds (VOC) directive of the EU in 1997 (See: Haloalkanes). By the late 1990s, the use of blowing agents such as carbon dioxide, pentane, 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1,1,3,3-pentafluoropropane (HFC-245fa) became more widespread in North America and the EU, although chlorinated blowing agents remained in use in many developing countries.3
Building on existing polyurethane spray coating technology and polyetheramine chemistry, extensive development of two-component polyurea spray elastomers took place in the 1990s. Their fast reactivity and relative insensitivity to moisture make them useful coatings for large surface area projects, such as secondary containment, manhole and tunnel coatings, and tank liners. Excellent adhesion to concrete and steel is obtained with the proper primer and surface treatment. During the same period, new two-component polyurethane and hybrid polyurethane-polyurea elastomer technology was used to enter the marketplace of spray-in-place load bed liners. This technique for coating pickup truck beds and other cargo bays creates a durable, abrasion resistant composite with the metal substrate, and eliminates corrosion and brittleness associated with drop-in thermoplastic bed liners.
The use of polyols derived from vegetable oils to make polyurethane products began garnering attention beginning around 2004, partly due to the rising costs of petrochemical feedstocks and partially due to an enhanced public desire for environmentally friendly green products.4 One of the most vocal supporters of these polyurethanes made using natural oil polyols is the Ford Motor Company.5
Pawling designs and manufactures rubber and plastic seals, actuators, clamps and structural bumpers and barriers for global industrial (1,2,3, 4), scientific (5) and architectural applications (6,7,8). The company?? Engineered Products Division has been IS0 9001 certified since 1994.
General industrial; building and construction; medical/lab/scientific; material handling; transportation; aerospace; energy; semiconductor processing; nuclear power. History
In 1945, a small rubber extrusion business with fifteen employees opened in Pawling, NY, to make gaskets for military ammunition cases. After WW II, the company diversified into plastics processing and launched several consumer products. In the mid-50s, Pawling Rubber Corporation entered into two strategic alliances. It acquired Presray Corporation, which had developed a successful inflatable gripper to handle fragile unfired grinding wheels, and formed an extrusion licensing agreement with the French firm FLT.
In the 1960s, the combined companies established a line of standard wall and corner guards for the architectural market; introduced fabric-reinforced rubber seals and expanded their inflatable seal, actuator and gripper business. Midway through the decade, Pawling diversified into mill mixing and extruding of high-purity silicone, then a leading-edge elastomer for electrical wire and cable insulation. By the end of the decade, the company had branched out into molding of silicone and plastics.
For the next thirty years, all three business areas grew steadily. Reflecting the diversification, the company shortened its name to Pawling Corporation in 1987.he next thirty years, all three business areas grew steadily. Reflecting the diversification, the company shortened its name to Pawling Corporation in 1987.
More recently, the company has focused on high-value branded product lines for demanding growth markets such as healthcare, medical and scientific, nuclear power, solar energy and semiconductor processing. Continuing that focus, in 2006 the company created the strategic business unit Pawling Scientific Products, which provides high-purity elastomeric products (5) to the environmental testing, analytical, and pharmaceutical lab markets.
The Greenpeace flagship Rainbow Warrior lay moored at Auckland's Marsden Wharf on Wednesday, 10 July 1985. It had arrived in New Zealand from Vanuatu three days earlier - a week after President Haruo Remeliik had been assassinated in Belau. Greenpeace campaigners were preparing the former North Sea fishing trawler for the environmental group's biggest-ever protest voyage to Moruroa Atoll, one which they hoped would embarrass France over nuclear testing. On board, supporters celebrated the 29th birthday of Steve Sawyer, the American co-ordinator of the Pacific Peace Voyage.
Unknown to the Greenpeace activists, French secret agents Jacques Camurier and Alain Tonel, had set off in an inflatable dinghy across the 2 km stretch of the harbour from Mechanics Bay. When they arrived, they both swam underwater with the bombs, clamp and rope to the stern of the Rainbow Warrior. Tonel attached the smaller, 10 kilo bomb to the propeller shaft. Camurier fixed the clamp on to the keel and ran out a rope to pinpoint a spot to attach the larger bomb next to the engineroom.
The hull explosive would sink the ship, the propeller mine would cripple it. Both bombs were timed to explode in just over three hours, at 11.50 pm. The explosives laid, the Frenchmen headed back to their hidden Zodiac.
The first blast ripped a hole the size of a garage door in the engine room. The force of the explosion was so powerful that a freighter on the other side of Marsden Wharf was thrown five metres sideways. As the Rainbow Warrior rapidly sank until the keel touched the harbor floor, the shocked crew scrambled on to the wharf. But Pereira dashed down a narrow stairway to one of the stern cabins to rescue his expensive cameras. The second explosion probably stunned him and he drowned with his camera straps tangled around his legs.
Fernando's daughter, Marelle, then aged eight, in June 1995 appealed in the French newspaper Libration to anybody who was involved in the bombing operation to tell her fully what had happened in the bombing. "Now I am 18, I am an adult and I think by now I have the right to know exactly what events transpired surrounding the explosion which cost my father his life", she wrote. She also travelled to New Zealand to interview former Prime Minister David Lange and Greenpeace campaigners who sailed on the Rainbow Warrior.
A Sengstaken-Blakemore tube is an oro- or nasogastric tube used occasionally in the management of upper gastrointestinal hemorrhage due to bleeding from esophageal varices (distended veins in the esophageal wall, usually as a result of cirrhosis). It was originally described in 1950.1 The use of esophageal tamponade in the treatment of bleeding varices has been known since Westphal described it in 1930.2
It consists of a multiluminal plastic tube with two inflatable balloons. Apart from the balloons, two lumens serve the proximal esophagus and the gastric tip of the device, respectively (although earlier devices had no oesophageal lumen, requiring the parallel insertion of a nasogastric tube3). It is passed down into the oesophagus and the distal balloon is inflated in the stomach. Distension of the proximal balloon is used to stop bleeding from the varices. The gastric lumen is for aspirating stomach contents.
Generally it is used only in emergencies where bleeding from presumed varices is impossible to control by administration of medication. It may be difficult to position, particularly in an unwell patient, and may inadvertently be inserted in the trachea, hence endotracheal intubation before the procedure is strongly advised to secure the airway. The tube is often kept in the refrigerator in the hospital's emergency department, intensive care unit and gastroenterology ward. It is a temporary measure: ulceration and rupture of the esophagus and stomach are recognized complications.34
A related device with a larger gastric balloon capacity, the Linton-Nachlas tube, is used for isolated gastric hemorrhage (such as with gastric varices).
Andrew J. Toti (24 July 1915 ??20 March 2005 ) was a world-renowned American inventor. Toti was born in Visalia, California, and died in Modesto, California. He held more than 500 U.S. patents at the time of his death. Toti was honored by the Edison Society in 1995.
Among his many inventions, the most famous include an inflatable lifejacket (nick-named the Mae West), an automated chicken plucker, light-weight construction beam (commonly used in Australia), and the EndoFlex endotracheal tube (co-invented with Michael H Wong and Jay Kotin). He invented a combination lock when he was 12 years old.
Toti attended Modesto High School through tenth grade. He completed his education through correspondence courses.
Toti related that his mother was the inspiration for the invention of the Mae West life vest. He had built a boat, and his mother was worried because he couldn't swim. He designed a personal life preserver filled with duck feathers. However, that was too bulky and heavy, so he used air. Toti sold the rights to the Mae West life vest to the US War Department in 1936 for $1,600.
Toti owned and operated Tro-Pic-Kal Manufacturing Company of Modesto for approximately 60 years.
Pink Floyd's market strategy for the In the Flesh Tour was very aggressive, filling pages of The New York Times and Billboard magazine. To promote their four-night run at Madison Square Garden in New York City, there was a Pink Floyd parade on 6th Avenue featuring pigs and sheep.2
This was the first tour since their 1972 tour that Pink Floyd didn't use female backing singers. The musicians that augmented the band for the tour was sax player Dick Parry (occasionally playing keyboards too out of view of the audience) and guitarist Snowy White (who would also help out on bass guitar on some of the songs).
In the first half of the show, Pink Floyd played all of the Animals album in a slightly different sequence to the album starting with "Sheep" then "Pigs On the Wing (Part 1)", "Dogs", "Pigs On the Wing (Part 2) and "Pigs (Three Different Ones)". During "Pigs (Three Different Ones)", Waters would shout the number of the concert on the tour, such as "1-5!" for the fifteenth show. The second half of the show comprised the Wish You Were Here album in its exact running order ("Shine On You Crazy Diamond (Parts 1-5)", "Welcome to the Machine", "Have a Cigar", "Wish You Were Here" and "Shine On You Crazy Diamond (Parts 6-9)"). The encores would usually consist of either "Money" or "Us and Them" from Dark Side of the Moon or both. At the Oakland, California show on 09 May they played "Careful with That Axe, Eugene" as a third encore; it was the last time it was ever performed live. The final night of the tour on 06 July at Montreal's Olympic Stadium had a third encore of "More Blues" which saw David Gilmour sit out the final encore as he was unhappy with the band's performance that night. Snowy White played a bluesy guitar solo with the rest of Pink Floyd in Gilmour's place.
During the tour Waters began to exhibit increasingly aggressive behaviour, and would often yell abusively at disruptive audiences who wouldn't stop yelling and screaming during the quieter numbers.2 In the New York shows they had to use local workers as lighting technicians due to union problems with their own crew. They had several difficulties with the workers; for example, Waters once had to beckon one of the spotlights to move higher when it only illuminated his lower legs and feet while he was singing. He eventually became exasperated, brought the whole band to a halt to remark "I think you New York lighting guys are a fucking load of shit!", and then continued the song.3
The Montreal show, 06 July 1977, the final performance of the tour, ended with Pink Floyd performing a blues jam as the roadies dismantled the instruments in front of the insatiable audience who refused to let the band leave the stadium. A small riot at the front of the stage followed the band's eventual exit. That night, Waters spat in the face of a disruptive fan; The Wall grew out of Waters' thoughts about this incident, particularly his growing awareness that stardom had alienated him from his audience.4 Three unofficial audience recordings are known to exist (one aptly named Who Was Trained Not To Spit On The Fan?, a pun referencing a lyric in the song Dogs, played that night, and the spitting incident); during "Pigs on the Wing (pt. 2)" Roger halts the performance to yell this at the rather rowdy crowd:3
The Severn class lifeboat is the largest lifeboat used by the Royal National Lifeboat Institution (RNLI), a UK charity dedicated to saving life at sea. The class is named after the River Severn, the longest river in Great Britain.
There are forty-six Severn class lifeboats serving the RNLI around the coast of the UK and Ireland since the introduction of the class in 1996. It carries a Y Class inflatable boat, which can be deployed by an on-board crane for use in shallow water.
Severns have a comprehensive electronics fit including full MF and VHF DSC radio equipment, DGPS Navigator, an electronic chart system, VHF/DF, radar and weather sensors. For added manoeuvrability, in addition to twin engines, the Severn also has a bow thruster fitted. The propellers are enclosed so the Severn can take ground without damaging them.
The Severn is constructed of fibre reinforced composite material, and the hard chine semi-displacement hull built to a two compartment standard, meaning it can stay afloat with two of its five compartments flooded. Provision for survivors includes comprehensive first aid equipment including stretchers, oxygen and Entonox.
Severns carry a portable salvage pump in a water-tight container, and can also carry out pumping and fire fighting tasks using the engine driven general service pump.
The 2000s have seen a giant leap forward in snowkite-specific technologies, skill levels and participants in every possible snow-covered country. The development of snowkite specific, de-powerable, foil kites have allow snowkiters to explore further and push the limits of windpowered expions. Recent crossings in record times of large snowfields and even Greenland have been accomplished through the use of snowkites.
On the forefront of extreme kiting, dedicated snowkiting communities from Utah to Norway are pushing the freestyle envelope and documenting their efforts through films like Something Stronger and Dimensions by SnowkiteFilm.com and Drift Snowkite Magazine which is available as a digital magazine. The extreme envelope of snowkiting is being pushed by Chasta, a French kiter sponsored by Ozone Kites now based in New Zealand.
Better equipment, safety practices, community know-how and qualified instructors are readily available in many areas, allowing people to learn properly and safely through different means than trial and error. The sport is currently being enjoyed by kiters of all ages and in a wide variety of activities ranging from mellow jaunts on a lake, to kitercross events, from multi-day expions, to flying off mountains, from freestyle jib tricks, to huge cliff jumps.
As a child Dieter Strasilla, inspired by Otto Lilienthal, practiced gliding around Berchtesgaden and in the 1960s he began parapente experiments (also with his brother Udo in USA) in Germany and Switzerland, parachute-skiing in 1972 and later perfected a kiteskiing system using self-made paragliders and a ball-socket swivel allowing the pilot to kitesail upwind or uphill, but also to take off into the air at will, swivelling the body around to face the right way (SKYWING).
In the mid 1980s e.g. some alpine skiers used a rebridled square parachute to ski upwind on a frozen bay in Erie, PA.citation needed Kiteskiers began kiteskiing on many frozen lakes and fields in the US midwest and east coast. Lee Sedgwick and a group of kiteskiers in Erie, PA were early ice/snow kiteskiers. In 1982 Wolf Beringer started developing his shortline Parawing system for skiing and sailing. This was used by several polar expions to kite-ski with sleds, sometimes covering large distances.1 Ted Dougherty began manufacturing 'foils' for kiteskiing and Steve Shapson of Force 10 Foils also began manufacturing 'foils' using two handles to easily control the kite. In the mid 1980's Shapson, while icesailing, took out an old two line kite and tried to ski upwind on a local frozen lake in Wisconsin. Shapson demonstrated the sport of 'kiteskiing' in Poland, Germany, Switzerland and Finland. He also used grass skis to kiteski on grassy fields. Early European kiteskiers were Keith Stewart and Theo Schmidt, who also was among the first to waterski with kites. American Cory Roeseler together with his father William developed a Kiteski system for waterskiing and began winning in windsurf races featuring high following winds, such as in the gorge of the Columbia river. The following terms describe the sport of 'Traction Kiting' or some refer to as 'Power Kiting': Kite buggying, kite skiing, kitesurfing, kiteboarding.
In the late 1990s small groups of French and North American riders started pushing the boundaries of modern freestyle snowkiting. The Semnoz crew from France began hosting events at the Col du Lautaret and other European sites where the mountainous terrain lent itself to "paragliding" down the hills. In North America, riders were mainly riding snow-covered lakes and fields where tricks were being done on the flat ground, jumps, rails and sliders.
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