Polyethylene or polythene is the most common plastic. As of 2017, over 100 million tonnes of polyethylene resins are produced annually, accounting for 34% of the total plastics market, its primary use is in packaging. Many kinds of polyethylene are known, with most having the chemical formula n. PE is a mixture of similar polymers of ethylene with various values of n. Polyethylene is a thermoplastic. Polyethylene was first synthesized by the German chemist Hans von Pechmann, who prepared it by accident in 1898 while investigating diazomethane; when his colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance that he had created, they recognized that it contained long –CH2– chains and termed it polymethylene. The first industrially practical polyethylene synthesis was again accidentally discovered in 1933 by Eric Fawcett and Reginald Gibson at the Imperial Chemical Industries works in Northwich, England. Upon applying high pressure to a mixture of ethylene and benzaldehyde they again produced a white, waxy material.
Because the reaction had been initiated by trace oxygen contamination in their apparatus, the experiment was difficult to reproduce at first. It was not until 1935 that another ICI chemist, Michael Perrin, developed this accident into a reproducible high-pressure synthesis for polyethylene that became the basis for industrial low-density polyethylene production beginning in 1939; because polyethylene was found to have low-loss properties at high frequency radio waves, commercial distribution in Britain was suspended on the outbreak of World War II, secrecy imposed, the new process was used to produce insulation for UHF and SHF coaxial cables of radar sets. During World War II, further research was done on the ICI process and in 1944 Bakelite Corporation at Sabine, Du Pont at Charleston, West Virginia, began large-scale commercial production under license from ICI; the landmark breakthrough in the commercial production of polyethylene began with the development of catalyst that promoted the polymerization at mild temperatures and pressures.
The first of these was a chromium trioxide–based catalyst discovered in 1951 by Robert Banks and J. Paul Hogan at Phillips Petroleum. In 1953 the German chemist Karl Ziegler developed a catalytic system based on titanium halides and organoaluminium compounds that worked at milder conditions than the Phillips catalyst; the Phillips catalyst is less expensive and easier to work with and both methods are used industrially. By the end of the 1950s both the Phillips- and Ziegler-type catalysts were being used for high-density polyethylene production. In the 1970s, the Ziegler system was improved by the incorporation of magnesium chloride. Catalytic systems based on soluble catalysts, the metallocenes, were reported in 1976 by Walter Kaminsky and Hansjörg Sinn; the Ziegler- and metallocene-based catalysts families have proven to be flexible at copolymerizing ethylene with other olefins and have become the basis for the wide range of polyethylene resins available today, including low density polyethylene and linear low-density polyethylene.
Such resins, in the form of UHMWPE fibers, have begun to replace aramids in many high-strength applications. The properties of polyethylene can be divided into mechanical, electrical and thermal properties. Polyethylene is of low strength and rigidity, but has a high ductility and impact strength as well as low friction, it shows strong creep under persistent force. It feels waxy; the commercial applicability of polyethylene is limited by its comparably low melting point. For common commercial grades of medium- and high-density polyethylene the melting point is in the range 120 to 180 °C; the melting point for average, low-density polyethylene is 105 to 115 °C. These temperatures vary with the type of polyethylene. Polyethylene consists of nonpolar, high molecular weight hydrocarbons. Therefore, its chemical behavior is similar to paraffin; the individual macromolecules are not covalently linked. Because of their symmetric molecular structure, they tend to crystallize. Higher crystallinity increases mechanical and chemical stability.
Most LDPE, MDPE, HDPE grades have excellent chemical resistance, meaning they are not attacked by strong acids or strong bases, are resistant to gentle oxidants and reducing agents. Crystalline samples do not dissolve at room temperature. Polyethylene can be dissolved at elevated temperatures in aromatic hydrocarbons such as toluene or xylene, or in chlorinated solvents such as trichloroethane or trichlorobenzene. Polyethylene absorbs no water; the gas and water vapour permeability is lower than for most plastics. PE can become brittle when exposed to sunlight, carbon black is used as a UV stabilizer. Polyethylene burns with a blue flame having a yellow tip and gives off an odour of paraffin; the material produces a drip. Polyethylene can not be bonded with adhesives without pretreatment. H
The 22945 / 46 Mumbai Central Okha Veraval Saurashtra Mail is an Express train belonging to Indian Railways - Western Railway zone that runs between Mumbai Central and Okha, Veraval in India. It operates as train number 22945 from Mumbai Central to Okha, Veraval and as train number 22946 in the reverse direction serving the state of Maharashtra & Gujarat; this train is started in 1 oct 1925 and name is kathiawad express after the name is changed saurashtra mail. The 22945 / 46 Mumbai Central Okha Saurashtra Mail presently has 1 AC 1st Class cum AC 2 tier, 1 AC 2 tier, 3 AC 3 tier, 11 Sleeper Class, 4 General Unreserved and 2 SLR coaches, it does not have a Pantry car coach. As is customary with most train services in India, Coach Composition may be amended at the discretion of Indian Railways depending on demand; the 22945 Mumbai Central Okha, Veraval Saurashtra Mail covers the distance of 990 kilometres in 18 hours 00 mins & in 18 hours 00 mins as 22946 Okha Mumbai Central Saurashtra Mail. As the average speed of the train is above 55 km/hr, as per Indian Railway rules, its fare includes a Superfast surcharge The 22945 / 46Mumbai Central Okha Saurashtra Mail runs from Mumbai Central via Palghar, Vadodara Junction, Ahmedabad Junction, Rajkot Junction, Jamnagar to Okha.
The slip coaches of the Veraval bound Link Express are attached / detached at Rajkot Junction. Prior to February 2012, Dual traction Valsad based WCAM 1 locomotives would haul the train between Mumbai Central & Ahmedabad Junction handing over to a Ratlam or Vatva based WDM 3A locomotive for the remainder of the journey. Western Railway completed DC Electric Conversion to AC on 5 February 2012 & it is now hauled by a Vadodara based WAP 4 or WAP 5 locomotive until Ahmedabad Junction handing over to a Ratlam or Vatva based WDM 3A locomotive which powers the train for the remainder of the journey. 22945 Mumbai Central Okha Saurashtra Mail leaves Mumbai Central on a daily basis at 21:35 hrs IST and reaches Okha at 15:35 hrs IST the next day. 22946 Okha Mumbai Central Saurashtra Mail leaves Okha on a daily basis at 13:10 hrs IST and reaches Mumbai Central at 07:10 hrs IST the next day. "Caller threatens to blow up Saurashtra Mail - The Times of India". Timesofindia.indiatimes.com. Retrieved 30 May 2014.
"Additional coaches in Saurashtra mail, Abu road demu trains | DeshGujarat". Deshgujarat.com. Retrieved 30 May 2014. "Mumbai-bound Saurashtra mail derails near Rajkot - The Times of India". Timesofindia.indiatimes.com. Retrieved 30 May 2014. "Saurashtra Mail engine derails at Okha station". Asiarailjobs.com. Retrieved 30 May 2014. "Welcome to Indian Railway Passenger reservation Enquiry". Indianrail.gov.in. Retrieved 5 April 2014. " Welcome to IRFCA.org, the home of IRFCA on the internet". Irfca.org. Retrieved 5 April 2014
Rosemary Gladstar is an American herbalist. She began her work in herbalism in California, she founded the California School of Herbal Studies in Forestville, the first herbal school in California, in 1978. Gladstar taught at the school with the help of herbalists such as Christopher Hobbs, she co-founded Sage Mountain Herbs. Gladstar founded United Plant Savers out of concern over the ecological sustainability of the herb trade. Gladstar helped found the Northeast Herb Association in 1991, she is the co-founder of the International Herb Symposium and The New England Women's Herbal Conference. The New England Women's Herbal Conference os held yearly in August ar Camp Wicosuta in Newfound Lake, New Hampshire. Gladstar announced her retirement from being the director of the conference during the 2018 event. Gladstar is the author of several books, including Herbal Healing for Women, Herbs for Natural Beauty, Herbs for the Home Medicine Chest, Herbal Recipes for Vibrant Health and Planting the Future: Saving Our Medicinal Herbs.
She has taught herbs extensively throughout the U. S, she organizes the International Herb Symposium and the United Plant Savers conference, speaks at other herbal conferences including the Southwest Conference, Medicines from the Earth, the Green Nations Gathering and Breitenbush. She leads herbal travel adventures in various parts of the world. Gladstar, Rosemary. Rosemary Gladstar's family herbal a guide to living life with energy and vitality. North Adams, Mass.: Storey Books, c2001.vii, 400 p.: ill.. Gladstar, Rosemary. Planting the future: saving our medicinal herbs / edited by Rosemary Gladstar and Pamela Hirsch. Rochester, Vt.: Healing Arts Press, c2000.x, 310 p. p. of plates: ill.. Sage Mountain United Plant Savers