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Chemicals that changed world

Chemicals that changed world. Michael Široký. Polyethylene. It was first synthesized by Hans von Pechmann in 1898 while heating diazomethane- accident, next big step was during World War II. Properties: melting point: 105-130°C, soluble in selected solvents

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Chemicals that changed world

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  1. Chemicals that changed world Michael Široký

  2. Polyethylene • It was first synthesized by Hans von Pechmann in 1898 while heating diazomethane- accident, next big step was during World War II. • Properties: melting point: 105-130°C, soluble in selected solvents • For industry it is a very common material, also used in casual life • Consists of ethylene monomers • It is formed by polymerization only upon contact with catalyst titanium(III) chloride (Ziegler- Natta), chromium(VI) oxide on silica

  3. Types of PE • There are a big number of different types of PE: HDPE, LDPE, UHMWPE, ULMWPE,PEX,.... • UHMWPE: produced by using Ziegler´s catalyst, molecular weight is between 3.1 and 5.67 million = very tough material • HDPE: produced by chromium, metallocene or Ziegler´s catalyst, density is 0.941 g/cm3, third of all toys are manufactured from HDPE, packaging • PEX: degree of cross-linking is 65-89%, three types PEX-A, B, C • Estimated time of degradation of PET bottle is 500 years

  4. Petrol • Fossil fuel formed milions years ago • Mixture of many hydrocarbons. • Consist of: naphthenes (also called cycloalkanes), alkanes(pentane- octane), alkenes and aromatics. • Isolated by fractional distillation (straight-run gasoline; reformate; cat cracked gasoline; isomerate;...) • 2 C8H18(l) + 25 O2(g) → 16 CO2(g) + 18 H2O(g) + 10.86 MJ/mol • Incomplete combustion: CO, NO, NO2,...=photochemical smog

  5. Octane rating is measurement of quality (it expresses resistance to autoignition) • Antiknock aditives for high compression combustion- tetraethyl lead found byThomas Midgley and Harry Ricardo • Nowadays are used ethers or aromatics • More volatile than diesel(caused by additives) • In USA is consumed approx. 1,3 billion liters of gasoline every day

  6. Soap • Base ingredient is sodium palmitateC15H31COOH+ NaOH = C15H31COO–Na+ • The main raw materials required for the manufacture of ordinary soap are: • Animal fat or Vegetable oil • Sodium hydroxide (Caustic soda) • Sodium chloride (Common salt) • In hard water is soap not so effective as it is in soft water because calcium an magnesium ions are present • In water sollution molecules of soap arranges into clusters called micelles.

  7. Further use of soap • Napalm • Liquid soap • Detegrents • Unusual use at household- bug repellent, deodorizer, lubricant at metal surface connection

  8. ...END? end... Thank you!

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