Remember me. Steinheil, Paris, Davy to E. He was astonished by the analogies between muriatic acid chlorhydric acid and fluoric acid fluorhydric acid and concluded that an element first called oxy-fluoric and then fluorine in French must exist, once he had understood that fluorhydric acid did not contain any oxygen. Among the letters that he exchanged with Davy during the war raging between their two nations, he even suggested on 1st November the possibility of isolating the element fluorine through the electrolysis of anhydrous fluorhydric acid . The isolation of this new element continued to occupy many researchers for most of the nineteenth century.
US6225382B1 – Fluorine-containing resin composition – Google Patents
It is best known for its role in efforts to prevent tooth decay. It may be added to toothpastes or mouthwashes or to municipal water supplies for this purpose. Although the practice of fluoridating water is now widespread in the United States , it remains the subject of controversy regarding its potential health effects on humans. Sodium fluoride occurs naturally as the mineral villiaumite, although the compound is not produced commercially from that source.
Some sodium fluoride is obtained as a byproduct of the manufacture of phosphate fertilizers.
Fluorine-containing diols represented by the following formula are provided: diisocyanate for use in the present invention, any diisocyanate known to date is.
The present invention relates to a fluorine-containing copolymer which has functional groups, and a curable composition containing the copolymer and a curing agent. Conventionally, in room temperature curing fluoro-resin paints which do not require backing at high temperatures upon curing the paints, there has been employed a fluorine-containing copolymer prepared by copolymerizing a fluorolefin, cyclohexyl vinyl ether, and the like as one component of the room temperature curing paints [Japanese Unexamined Patent Publication Tokkyo Kokai Nos.
However, the conventional copolymers have the defect of being poor in compatibility with acrylic resins. The present inventors have found incorporation of acrylic resins into the room temperature curing fluoro-resin paint of the invention improves the weatherability, transparency and pigment dispersibility of the paints. It is an object of the present invention to provide a novel fluorine-containing copolymer having a functional group, which has an excellent transparency and moreover has an excellent compatibility with an acrylic resin.
A further object of the present invention is to provide a curable composition containing the fluorine-containing copolymer and a curing agent. These and other objects of the present invention will become apparent from the description hereinafter. In accordance with the present invention, there is provided a fluorine-containing copolymer comprising structural units of the formula a :. The present invention also provides a curable composition comprising a fluorine-containing copolymer having structural units of the formulas a , b and c and a curing agent.
When the content of the structural units b in the copolymers is from 0. The structural unit c is effective in improving the solubility in solvents of the copolymers. The fluorine-containing copolymers of the present invention are generally prepared by copolymerizing a monomer of the formula a’ :. When Y is a lower fluoroalkyl group, trifloromethyl group is preferable.
Typical examples of the monomer of the formula b’ are, for instance, STR7 and the like.
Who Invented Fluorine Dating
The pro-fluoride side had more money, more support from officials and more diverse backers, but when the votes were tallied, 60 percent of the city voted against adding fluoride to their water. Fluoride was first added to drinking water in Grand Rapids, Michigan in , just a decade or so after scientists first identified its teeth-saving properties. In , a dentist named Dr. After years of treating patients, McKay figured that the stain must be coming from the water supply they shared.
But he also noticed something interesting. People with the brown stains had less tooth decay.
Collaborations between Emile Rivière and Adolphe Carnot in the s led to the development of the.
The present invention relates to a kind of polyvinylidene fluoride resin, this polyvinylidene fluoride resin has fluorine-containing ether end-group structure, and has the characteristics of high flexibility, high impact and high thermal stability. The invention still further relates to the method for manufacture of said polyvinylidene fluoride resin. In all fluoro-resin, the homopolymer of vinylidene VDF is the very high fluoro-resin of a kind of hardness, but it is not good around Qu Xingneng.
In order to improve this performance, mode that generally can be through adding comonomer to be reducing its percent crystallinity, thereby improves around Qu Xingneng. Usually side chain is long more, helps the reduction of percent crystallinity more, just helps the improvement around Qu Xingneng. For example; U. But because this method has adopted hydrocarbon type the organic initiators and the chain-transfer agent of lipid, the end group of the polyvinylidene fluoride ene product that the result obtains is a hydrogeneous type of end group, causes the stability of this polymeric articles general.
Pat 6; ; B2 discloses a kind of method of manufacture of polyvinylidene fluoride resin; It comprises that the joining day of Quality Initiative transfer agent obtains the polyvinylidene fluoride resin of a part of non-chain transfer, thereby can make polyvinylidene fluoride resin have extraordinary shock strength performance not adding softening agent or impact under the condition of activator. But the molecular weight of product wider distribution of this patented process gained, adopting no organic initiators and hydrocarbon class simultaneously is that main chain-transfer agent also is faced with end group stabilization property general problem.
Pat 4,, disclose that to adopt Virahol be the thermostability that chain-transfer agent improves vinylidene copolymerization product and homopolymerization product, but compare fluorine-containing end group, and owing to the bond energy of the C-F key bond energy greater than c h bond, so its stability still is apparent not enough.
Facts About Fluorine
This invention relates to a novel method of preparing non-ionic inorganic fiuoro compounds. This invention further relates to certain novel inorganic compounds. It is an object of this invention to prepare non-ionic inorganic fluoro compounds in a novel manner. It is another object of this invention to employ novel reaction conditions whereby fluorine groups can be introduced selectively into inorganic compounds.
9 F Fluorine Atomic Number: 9. Atomic Weight: Melting Point: K (°C or °F). Boiling Point: K.
This invention relates to a novel curable composition consisting essentially of a fluorine rubber and an amino acid. The fluorine rubber is well known, and finds a wide range of applications because of its superior thermal stability and outstanding resistances to chemicals and oils. Organic peroxides such as dicumyl peroxide, polyamines such as triethylene tetramine, and polyisocyanates are among known vulcanizing agents for fluorine rubbers.
The present inventor has now found that specific amino acids are new and useful vulcanizing agents for fluorine rubbers. The present invention thus provides a curable composition consisting essentially of a fluorine rubber and at least one amino acid selected from the group consisting of arginine, lysine, ornithine, hydroxylysine, glutamine, cystine, asparagine and citrulline. The accompanying drawing shows the cure curves of compositions illustrated in Example to be given hereinbelow.
Various types of fluorine rubbers are known, and for example, vinylidene fluoride-type fluorine rubbers, fluorinated silicone-type fluorine rubbers, fluorinated nitroso-type fluorine rubbers, fluorinated acrylate-type fluorine rubbers, fluorinated polyester-type fluorine rubbers, fluorinated vinyl ether-type fluorine rubbers, fluorinated triazine-type and fluorinated phosphonitrile-type fluorine rubbers are commercially available.
Suitable fluorine rubbers for use in the composition of this invention are the vinylidene fluoride-type, fluorinated nitroso-type and fluorinated acrylate-type fluorine rubbers. On the other hand, a polymer of 1,1-dihydroperfluorobutyl acrylate is an example of the fluorinated acrylate-type fluorine rubber.
The most reactive element on the Periodic Table, fluorine has a violent history in the quest for its discovery. Despite the difficult and sometimes explosive properties of fluorine, it is a vital element for humans and animals, which is why it is commonly found in drinking water and toothpaste. Early chemists tried for years to isolate the element from various fluorides.
However, fluorine does not occur free in nature and no chemical substance is capable of freeing fluorine from any of its compounds due to its reactive nature. For centuries, the mineral fluorspar was used in metal refining.
Who Invented Fluorine Dating. Item the in fluoride absorbed of amount the From underground, been has object an time of amount the determine to used method.
The fluorine that is found in products such as toothpaste was likely formed billions of years ago in now dead stars of the same type as our sun. Fluorine can be found in everyday products such as toothpaste and fluorine chewing gum. However, the origins of the chemical element have been somewhat of a mystery. There have been three main theories about where it was created. The findings now presented support the theory that fluorine is formed in stars similar to the sun but heavier, towards the end of their existence.
The sun and the planets in our solar system have then been formed out of material from these dead stars. By analysing the light emitted by a star, it is possible to calculate how much of different elements it contains.
Development of radioactive dating methods and their application
Conventional methods for producing a fluorine-containing olefin involving a 1,1-dihydrofluorovinyl group generally comprise the following steps: the hydroxyl group of a 1,1-dihydro-2,2-difluoro alcohol referred to as a “fluoroalcohol” hereinafter is substituted by a halogen atom; and then the resulting halide is dehalogenated with zinc. A method for halogen substitution of a fluoroalcohol has been reported, e.
The reaction scheme is indicated below.
It has been assumed that there is only form of fluoride in serum, the inorganic F ion. , The U.S. Environmental Protection Agency is created, -, – Long-term exposure to C8 “has not been directly factored into any risk estimation to date.
Federal Register Open Comments. This timeline is still in draft form. We hope to complete it in the not too distant future! We welcome contributions, suggestions, or corrections from anyone who would like to add to this Timeline. We especially would appreciate the dates for the first-time use of PFOA and PFOS chemicals used in pesticides or as “inerts” – and data that can confirm that the substances used in “inerts” are waste products from the production of these chemicals.
Thanks – EC. Taves DR Evidence that there are two forms of fluoride in human serum.
Dentists Discovered the Tooth-Saving Properties of Fluoride by Accident
The present invention relates to a process for converting a fluoride of a metal to free fluorine gas or to a fluoride of an element other than the metal. Finely ground fluorspar is reacted with con- centrated sulfuric acid to yield hydrogen fluoride. This is dried and then reacted with potassium fluoride to form potassium hydrogen fluoride, KF. Anhydrous potassium hydrogen fluoride is subjected to electrolysis and fluorine gas is obtained at the anode.
At present fluorine is an expensive chemical, particularly when purchased in small quantities.
Properties and uses of the element fluorine. Fluorine is created in sun-like stars towards the end of their lifetime, according to a Stay up to date on the coronavirus outbreak by signing up to our newsletter today.
Previous Element Oxygen. Next Element Neon. What’s in a name? From the Latin and French words for flow, fluere. Say what? Fluorine is the most reactive of all elements and no chemical substance is capable of freeing fluorine from any of its compounds. For this reason, fluorine does not occur free in nature and was extremely difficult for scientists to isolate.
The first recorded use of a fluorine compound dates to around to a set of instructions for etching glass that called for Bohemian emerald CaF 2. Chemists attempted to identify the material that was capable of etching glass and George Gore was able to produce a small amount of fluorine through an electrolytic process in Unknown to Gore, fluorine gas explosively combines with hydrogen gas. That is exactly what happened in Gore’s experiment when the fluorine gas that formed on one electrode combined with the hydrogen gas that formed on the other electrode.
Ferdinand Frederic Henri Moissan, a French chemist, was the first to successfully isolate fluorine in He did this through the electrolysis of potassium fluoride KF and hydrofluoric acid HF. He also completely isolated the fluorine gas from the hydrogen gas and he built his electrolysis device completely from platinum.
US2409372A – Removal of organic fluorine – Google Patents
On this day in , Teflon, the polymer commonly found in non-stick pans, was patented. Teflon is the chemical found in some brands of saucepans that helps to prevent your meal from sticking to them during the cooking process. The discovery of PTFE actually happened completely by accident. When working in a team trying to develop non-toxic refrigerants in the s at chemical company Dupont, Dr.
By the early twentieth century there was a growing need within palaeoanthropology and prehistoric archaeology to find a way of dating fossils and artefacts in order to know the age of specific specimens, but more importantly to establish an absolute chronology for human prehistory. The radiocarbon and potassium-argon dating methods revolutionized palaeoanthropology during the last half of the twentieth century.
However, prior to the invention of these methods there were attempts to devise chemical means of dating fossil bone. The invention of the fluorine dating method marked a significant advance in the quest for absolute dating in palaeoanthropology, but it also highlights interesting problems and issues relating to the ability of palaeoanthropologists and chemists to bring together different skills and bodies of knowledge in order successfully to develop and apply the fluorine dating method.
Abstract By the early twentieth century there was a growing need within palaeoanthropology and prehistoric archaeology to find a way of dating fossils and artefacts in order to know the age of specific specimens, but more importantly to establish an absolute chronology for human prehistory. Publication types Historical Article. Substances Fluorine.
International Bamboo and Rattan Organisation
As has been seen, the geologic time scale is based on stratified rock assemblages that contain a fossil record. For the most part, these fossils allow various forms of information from the rock succession to be viewed in terms of their relative position in the sequence. Approximately the first 87 percent of Earth history occurred before the evolutionary development of shell-bearing organisms.
This invention, relates to, a new class of iron-fluorine compounds and compositions The iron-fluorine composition obtained by reacting the siderite and aqueousHF in Publication number Priority date Publication date Assignee Title.
Allotropes Some elements exist in several different structural forms, called allotropes. Each allotrope has different physical properties. For more information on the Visual Elements image see the Uses and properties section below. Group A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell. Period A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.
Block Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp s , principal p , diffuse d , and fundamental f. Atomic number The number of protons in an atom. Electron configuration The arrangements of electrons above the last closed shell noble gas. Melting point The temperature at which the solid—liquid phase change occurs.