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Vinalon
Vinylon, also known as Vinalon (more common in Korean sources), is a synthetic fiber produced from reaction between polyvinyl alcohol (PVA) fiber and formaldehyde. Chemically it is polyvinyl formal (PVF). Vinylon was first developed in Japan in 1939 by , Ri Sung-gi, and H. Kawakami. In North Korea, Ri Sung-gi found a route to produce PVA from domestic anthracite (black coal) and limestone as raw materials. Trial production began in 1954 and in 1961 the massive "Vinylon City" was built in Hamhung, North Korea. Vinylon's widespread usage in North Korea is often pointed to as an example of the implementation of the ''Juche'' philosophy, and it is known as the ''Juche'' fiber. PVF, in fiber form, is a useful thermoplastic resin on its own, most commonly used as electric wire insulation. Applications Vinylon is the national fiber of North Korea and is used for the majority of textiles, outstripping fiber such as cotton or nylon, which is produced only in small amounts in North Kor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ri Sung-gi
Ri Sung-gi, also often spelled Lee Sung-ki, Lee Seung-gi or Yi Sung-gi (October 1, 1905 – February 8, 1996), was a North Korean chemist. He is best remembered as one of the inventors of Vinalon. He has also been accused of involvement in North Korea's North Korea and weapons of mass destruction, chemical and nuclear weapons programs. Ri was born in Damyang, South Jeolla Province, Korean Empire in 1905. He graduated from the local ''pot'ong hakkyo'' and received his degree in chemistry from Kyoto University in 1931. He developed Vinalon in 1939 alongside Ichiro Sakurada and Hiroshi Kawakami. In 1946, after Korean independence from Japanese occupation, he participated in the development of Keijo Imperial University, Gyeongseong University, but strongly opposed the university's official conversion to Seoul National University under the American military government. Following the outbreak of the Korean War in 1950, he South Korean defectors, defected to the North. Ri received the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Fiber
Synthetic fibers or synthetic fibres (in British English; see spelling differences) are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants like cotton or fur from animals. They are the result of extensive research by scientists to replicate naturally occurring animal and plant fibers. In general, synthetic fibers are created by extruding fiber-forming materials through spinnerets, forming a fiber. These are called synthetic or artificial fibers. The word polymer comes from a Greek prefix "poly" which means "many" and suffix "mer" which means "single units". (Note: each single unit of a polymer is called a monomer). The first synthetic fibres Nylon was the first commercially successful synthetic thermoplastic polymer. DuPont began its research project in 1927. The first nylon, nylon 66, was synthesized on February 28, 1935, by Wallace Hume Carothers at DuPont's research facili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Korea - Myohyang Mountains (5015252383)
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north'' is related to the Old High German ''nord'', both descending from the Proto-Indo-European unit *''ner-'', meaning "left; below" as north is to left when facing the rising sun. Similarly, the other cardinal directions are also related to the sun's position. The Latin word ''borealis'' comes from the Greek ''boreas'' "north wind, north" which, according to Ovid, was personified as the wind-god Boreas, the father of Calais and Zetes. ''Septentrionalis'' is from ''septentriones'', "the seven plow oxen", a name of ''Ursa Major''. The Greek ἀρκτικός (''arktikós'') is named for the same constellation, and is the source of the English word ''Arctic''. Other languages have other derivations. For example, in Lezgian, ''kefer'' can mean bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and the Sea of Japan to the east. Like North Korea, South Korea claims to be the sole legitimate government of the entire peninsula and List of islands of South Korea, adjacent islands. It has Demographics of South Korea, a population of about 52 million, of which half live in the Seoul Metropolitan Area, the List of largest cities, ninth most populous metropolitan area in the world; other major cities include Busan, Daegu, and Incheon. The Korean Peninsula was inhabited as early as the Lower Paleolithic period. Gojoseon, Its first kingdom was noted in Chinese records in the early seventh century BC. From the mid first century BC, various Polity, polities consolidated into the rival Three Kingdoms of Korea, kingdoms of Goguryeo, Baekje, and Sil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kyoto University
, or , is a National university, national research university in Kyoto, Japan. Founded in 1897, it is one of the former Imperial Universities and the second oldest university in Japan. The university has ten undergraduate faculties, eighteen graduate schools, and thirteen research institutes. The university's educational and research activities are centred in its three main campuses in Kyoto: Yoshida, Uji and Katsura. The Kyoto University Library Network, consisting of more than 40 libraries spread across its campuses, has a collection of more than 7.49 million books, making it the second largest university library in the country. In addition to these campuses, the university owns facilities and lands for educational and research purposes around the country. As of 2024, Kyoto University counts List of prime ministers of Japan by education, two prime ministers of Japan amongst its alumni. Additionally, three prime ministers of Japan attended the Third Higher School, a university p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Second Sino-Japanese War
The Second Sino-Japanese War was fought between the Republic of China (1912–1949), Republic of China and the Empire of Japan between 1937 and 1945, following a period of war localized to Manchuria that started in 1931. It is considered part of World War II, and often regarded as the beginning of World WarII in Asia. It was the largest Asian war in the 20th century and has been described as The Asian Holocaust, in reference to the scale of Japanese war crimes against Chinese civilians. It is known in China as the War of Resistance against Japanese Aggression. On 18 September 1931, the Japanese staged the Mukden incident, a false flag event fabricated to justify their Japanese invasion of Manchuria, invasion of Manchuria and establishment of the puppet state of Manchukuo. This is sometimes marked as the beginning of the war. From 1931 to 1937, China and Japan engaged in skirmishes, including January 28 incident, in Shanghai and in Northern China. Chinese Nationalist and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korea Under Japanese Rule
From 1910 to 1945, Korea was ruled by the Empire of Japan under the name Chōsen (), the Japanese reading of "Joseon". Japan first took Korea into its sphere of influence during the late 1800s. Both Korea (Joseon) and Japan had been under policies of isolationism, with Joseon being a Tributary system of China, tributary state of Qing China. However, in 1854, Perry Expedition, Japan was forcibly opened by the United States. It then rapidly modernized under the Meiji Restoration, while Joseon continued to resist foreign attempts to open it up. Japan eventually succeeded in opening Joseon with the unequal Japan–Korea Treaty of 1876. Afterwards, Japan embarked on a decades-long process of defeating its local rivals, securing alliances with Western powers, and asserting its influence in Korea. Japan Assassination of Empress Myeongseong, assassinated the defiant Korean queen and intervened in the Donghak Peasant Revolution.Donald Keene, ''Emperor of Japan: Meiji and his World, 1852� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemiacetal
In organic chemistry, a hemiacetal is a functional group the general formula , where is a hydrogen atom or an organic substituent. They generally result from the nucleophilic Addition reaction, addition of an Alcohol (chemistry), alcohol (a compound with at least one hydroxy group) to an aldehyde () or a ketone () under acidic conditions. The addition of an alcohol to a ketone is more commonly referred to as a hemiketal. Common examples of hemiacetals include cyclic Monosaccharide, monosaccharides. Hemiacetals have use as a protecting group and in synthesizing oxygenated heterocycles like Tetrahydrofuran, tetrahydrofurans. Nomenclature According to the IUPAC definition of a hemiacetal, the R1 and R2 groups may or may not be hydrogen. In a hemiketal, both of these R-groups must not be hydrogen. Thus, hemiketals are regarded as a subclass of hemiacetals. The prefix ''hemi,'' meaning half, refers to the one alcohol added to the carbonyl group. This is half of the required alcohols to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetal
In organic chemistry, an acetal is a functional group with the connectivity . Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments not hydrogen. The two R' groups can be equivalent to each other (a "symmetric acetal") or not (a "mixed acetal"). Acetals are formed from and convertible to aldehydes or ketones and have the same oxidation state at the central carbon, but have substantially different chemical stability and reactivity as compared to the analogous carbonyl compounds. The central carbon atom has four bonds to it, and is therefore saturated and has tetrahedral geometry. The term ketal is sometimes used to identify structures associated with ketones (both R groups organic fragments rather than hydrogen) rather than aldehydes and, historically, the term acetal was used specifically for the aldehyde-related cases (having at least one hydrogen in place of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyvinyl Acetate
Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate)), commonly known as wood glue (a term that may also refer to other types of glues), PVA glue, white glue, carpenter's glue, school glue, or Elmer's Glue in the US, is a widely available adhesive used for porous materials like wood, paper, and cloth. An aliphatic rubbery synthetic polymer with the formula (C4H6O2)''n'', it belongs to the polyvinyl ester family, with the general formula − COOCHCH2��. It is a type of thermoplastic. Properties The degree of polymerization of polyvinyl acetate is typically 100 to 5000, while its ester groups are sensitive to base hydrolysis and slowly convert PVAc into polyvinyl alcohol and acetic acid. The glass transition temperature of polyvinyl acetate is between 30 and 45 °C depending on the molecular weight. PVAc dispersions such as Elmer's Glue-All contain polyvinyl alcohol as a protective colloid. In alkaline conditions, boron compounds such as boric acid or borax cause the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds, polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects. In more straightforward polymerizations, alkenes form polymers through relatively simple radical reactions; in contrast, reactions involving substitution at a carbonyl group require more complex synthesis due to the way in which reactants polymerize. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and polyvinyl chloride (PVC), which are produced in high tonnages each year due to their usefulnes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinyl Acetate
Vinyl acetate is an organic compound with the Chemical formula, formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, ethylene-vinyl acetate copolymers, polyvinyl alcohol, and other important industrial polymers. Production The worldwide production capacity of vinyl acetate was estimated at 6,969,000 tonnes/year in 2007, with most capacity concentrated in the United States (1,585,000 all in Texas), China (1,261,000), Japan (725,000) and Taiwan (650,000). The average list price for 2008 was US$1600/tonne. Celanese is the largest producer (ca 25% of the worldwide capacity), while other significant producers include China Petrochemical Corporation (7%), Chang Chun Group (6%), and LyondellBasell (5%). Vinyl acetate is mainly (80%) polymerized, and the resulting polymer is hydrolyzed to give polyvinvyl alcohol. Preparation Vinyl acetate is the acetate ester of vinyl alcohol. Since vinyl alcohol is highly unstable (with respect to acetaldehyde), the prepara ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
