Polyurethane is a polymer composed of organic units joined by carbamate links. While most polyurethanes are thermosetting polymers that do not melt when heated, thermoplastic polyurethanes are available. Polyurethane polymers are traditionally and most formed by reacting a di- or triisocyanate with a polyol. Since polyurethanes contain two types of monomers, which polymerise one after the other, they are classed as alternating copolymers. Both the isocyanates and polyols used to make polyurethanes contain, on average, two or more functional groups per molecule. Polyurethanes are used in the manufacture of high-resilience foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, automotive suspension bushings, electrical potting compounds, high-performance adhesives, surface coatings and sealants, synthetic fibers, carpet underlay, hard-plastic parts and hoses. Otto Bayer and his coworkers at IG Farben in Leverkusen, first made polyurethanes in 1937.

The new polymers had some advantages over existing plastics that were made by polymerizing olefins or by polycondensation, were not covered by patents obtained by Wallace Carothers on polyesters. Early work focused on the production of fibres and flexible foams and PUs were applied on a limited scale as aircraft coating during World War II. Polyisocyanates became commercially available in 1952, production of flexible polyurethane foam began in 1954 using toluene diisocyanate and polyester polyols; these materials were used to produce rigid foams, gum rubber, elastomers. Linear fibers were produced from hexamethylene 1,4-Butanediol. In 1956 DuPont introduced polyether polyols poly glycol, BASF and Dow Chemical started selling polyalkylene glycols in 1957. Polyether polyols were cheaper, easier to handle and more water-resistant than polyester polyols, became more popular. Union Carbide and Mobay, a U. S. Monsanto/Bayer joint venture began making polyurethane chemicals. In 1960 more than 45,000 metric tons of flexible polyurethane foams were produced.

The availability of chlorofluoroalkane blowing agents, inexpensive polyether polyols, methylene diphenyl diisocyanate allowed polyurethane rigid foams to be used as high-performance insulation materials. In 1967, urethane-modified polyisocyanurate rigid foams were introduced, offering better thermal stability and flammability resistance. 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 exhibited an all-plastic car in Germany. Parts of this car, such as the fascia and body panels, were manufactured using a new process called reaction injection molding, in which the reactants were mixed and injected into a mold; the addition of fillers, such as milled glass and processed mineral fibres, gave rise to reinforced RIM, which provided improvements in flexural modulus, reduction in coefficient of thermal expansion and better thermal stability. This technology was used to make the first plastic-body automobile in the United States, the Pontiac Fiero, in 1983.

Further increases in stiffness were obtained by incorporating pre-placed glass mats into the RIM mold cavity known broadly as resin injection molding, or structural RIM. Starting in the early 1980s, water-blown microcellular flexible foams were used to mold gaskets for automotive panels and air-filter seals, replacing PVC polymers. Polyurethane foams have gained popularity in the automotive realm, are now used in high-temperature oil-filter applications. Polyurethane foam is sometimes made using small amounts of blowing agents to give less dense foam, better cushioning/energy absorption or thermal insulation. In the early 1990s, because of their impact on ozone depletion, the Montreal Protocol restricted the use of many chlorine-containing blowing agents, such as trichlorofluoromethane. By the late 1990s, blowing agents such as carbon dioxide, pentane, 1,1,1,2-tetrafluoroethane and 1,1,1,3,3-pentafluoropropane were used in North America and the EU, although chlorinated blowing agents remained in use in many developing countries.

1,1-Dichloro-1-fluoroethane was introduced in early 2000s as an alternate blowing agent in developing nations. Polyurethane products are called "urethanes", but should not be confused with ethyl carbamate, called urethane. Polyurethanes neither are produced from ethyl carbamate. Non-isocyanate based polyurethanes have been developed to mitigate health and environmental concerns associated with the use of isocyanates to synthesize polyurethanes. Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, phenolics. Polyurethanes are produced by reacting an isocyanate containing two or more isocyanate groups per molecule with a polyol containing on average two or more hydroxyl groups per molecule in the presence of a catalyst or by activation with ultraviolet light; the properties of a polyurethane are influenced by the types of isocyanates and polyols used to make it. Long, flexible segments, contributed by the polyol, give elastic polymer.

High amounts of crosslinking give rigid polymers. Long chains and low crosslinking give a polymer, stretchy, short chains with lots of crosslinks produce a hard polymer while long chains and intermed

Arturo Martín Jauretche was an Argentine writer and philosopher. Jauretche spent his adolescence in the city of Lincoln before moving to Buenos Aires, he sympathized with the new model of social integration promoted by the Radical Civic Union and allied himself with the radical faction of Hipólito Yrigoyen, the so-called personalistas. He was influenced by the poet and Tango lyricist Homero Manzi, whose working-class appeal struck Jauretche, himself of rural origin, as a positive political strategy. In 1928, when Yrigoyen assumed his second mandate following the interlude of Marcelo T. de Alvear, Jauretche was appointed to the civil service, though it was not long before the Argentine army unseated Yrigoyen in a coup, setting off the Década Infame. Jauretche joined the armed struggle against the coup, subsequently opposed the regime with intense political action. In 1933, in the province of Corrientes, he took part in a failed uprising led by Colonels Francisco Bosch and Gregorio Pomar. Jauretche was imprisoned for his role in the uprising.

In prison, he wrote a poetic account of the episode in the gauchesque style, titling the work Paso de los Libres. It was published in 1934 with a prologue by Jorge Luis Borges, with whom Jauretche differed markedly in political matters. Jauretche's clash with Alvear's leading faction radicalized him; when Alvear decided in 1934 to abandon the UCR's policy of abstentionism, a significant portion of the left split from the party. Along with Manzi, Luis Dellepiane, Gabriel del Mazo, Manuel Ortiz Pereyra and others, Jauretche founded FORJA, which pursued a democratic nationalist ideology opposed to conservative nationalism and to the economic liberal policies of Agustín P. Justo. Marginalized by the partisan political system, FORJA expressed its positions through street demonstrations and self-published literature known as Cuadernos de FORJA, or FORJA Notebooks. In them, FORJA criticized the government's measures, they argued that the Central Bank had been founded to solidify British control of the Argentine monetary and financial system, that the Transport Corporation had been established to allow British railways to operate without competition.

FORJA opposed the breaking off of relations with the Soviet Union, on the basis that the Soviet bloc was a major potential market for Argentine agricultural exports. They alleged that Justo's government had abused the policy of federal intervention to punish provinces where anti-government parties had enjoyed electoral success, blamed Justo for dropping wages and rising unemployment. One of FORJA's fundamental principles was the maintenance of Argentine neutrality in the run-up to the Second World War, it was the only party to adopt this position. Around 1940 Jauretche broke with Dellepiane and del Mazo, who realigned themselves with the UCR. FORJA became further radicalized, shifted towards more nationalistic positions. Raúl Scalabrini Ortiz, who had always shared a similar ideology, affiliated himself with the party, along with Jauretche formed a double leadership, he departed in 1943. He vehemently opposed the government of Ramón Castillo. Although he was skeptical of the motives of the coup that unseated Castillo, his firm neutrality with regard to the war led him to welcome the government of Pedro Pablo Ramírez.

When the Grupo de Oficiales Unidos unseated Ramírez after he severed relations with the Rome-Berlin-Tokyo Axis, Jauretche allied himself with the up-and-coming Colonel Juan Domingo Perón. Though he was always critical of it, Jauretche supported Peronism after October 17, 1945. With the support of Domingo Mercante, governor of Buenos Aires Province, he was named president of the Bank of the Province of Buenos Aires in 1946, he would hold the position until 1951, when Mercante's falling out with Perón led Jauretche to abandon it. Jauretche did not return to the public scene until 1955, when the Revolución Libertadora led to Perón's ouster. Having been out of government for a few years meant that, for once, he was able to avoid political persecution, he founded the periodical El Líder and the weekly El'45 to defend what he called "the ten years of popular government", to excoriate the political and social activities of the de facto regime. In 1956 he published the essay El Plan Prebisch: retorno al coloniaje, refuting the report written by Raúl Prebisch, secretary of the Economic Commission of Latin America, at the behest of Pedro Eugenio Aramburu.

The harshness of his opposition led him to be exiled to Montevideo. There in 1957 he published Los profetas del odio, a polemical study of class relations in Argentina since the rise of Peronism. In it he criticized various conceptions of Argentine political history which had enjoyed favor, in particular that of Ezequiel Martínez Estrada. Estrada had subjected Argentine history to a bio-sociological analysis in his Radiografía de la pampa, which resembled Sarmiento's Facundo, in its suggestion that the Argentine geography had imposed upon its inhabitants a life disconnected from the flow of history. In his subsequent work ¿Qué es esto? he presented a devastating critique of Peronism, in which he portrayed Perón as a "snake charmer" whose political movement had instigated the "low passions of the populace", "pornocracy". Jauretche criticized these allusions as the prejudices of a middle class sensibility irritated by the eruption of new participants in a political environment, run by the bourgeoisie since the generación del'80.

Although bour

Omar A. Aggad was a Saudi Palestinian businessman, the founder of Aggad Investment Company, the founder and former chairman of Arab Palestinian Investment Company. Aggad was born in Jaffa, Mandatory Palestine, in 1927, attended Alrashidieh College in Jerusalem, he subsequently received a scholarship to attend the University of Manchester in the UK where he graduated with degrees in electrical and mechanical engineering. After working for a few years in the UK, he moved to Saudi Arabia in 1950 where he joined the Juffali Group as a senior manager. In 1975, he ventured out on his own and created what would become one of the leading investment groups in Saudi Arabia, he established over 40 industrial and trade ventures in Saudi Arabia. He was the founder of Aggad Investment Company in 1975, the founder and former chairman of the Arab Palestinian Investment Company, he led a group of investors to purchase 25% of Smith Barney in 1982, served on its board of directors. The Wall Street Journal noted that "Aggad is considered one of Saudi Arabia's most savviest and professional managers.

In a book about Arabian merchants, British writer Michael Fields called him "bold and impulsive, an intuitive decision-taker with a huge head for detail." As a partner with other Saudi and foreign investors, Aggad operated 23 manufacturing plants scattered across Saudi Arabia."He was a founding shareholder and director of InvestCorp Bank and a founding director of the Saudi British Bank while serving on the board of directors for 20 years. After the Oslo process, having been supportive of Palestine, Aggad decided to create an entity to invest and create jobs in his historic homeland, thus he founded the Arab Palestinian Investment Company. Since its founding, APIC has become one of the largest operators in Palestine, employing over 1600 people. Subsidiaries of APIC offer a wide array of products and services through distribution rights agreements with multinational companies that include Philip Morris, Procter & Gamble, Kellogg's, Chrysler, Jeep, Alfa Romeo, Fiat Professional, XL Energy, Abbott, B.

Braun, Eli Lilly, GlaxoSmithKline, Sanofi Aventis and Nivea, among many others. APIC was registered in the British Virgin Islands in September 1994. In 1996, it was registered with Palestine's Ministry of National Economy as a foreign private shareholding company, became into a foreign public shareholding company in 2013. In March 2014, APIC shares were listed on the Palestine Exchange, its authorized capital is US$70 million, its paid-up capital is US$66 million as of December 2015. Aggad was a philanthropist, the school of engineering at Birzeit University is named after him, he served as an honorary trustee of the university, he was an honorary trustee of the Institute of Palestine Studies and other not-for-profits in Saudi Arabia and elsewhere in the Arab World. He was married to Malak Aggad, they had 4 children, Rana and Tarek. Talal Aggad manages the family holding company, Tarek Aggad is CEO of APIC. Omar Aggad died on 1 February 2018 at the age of 90