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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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Polyethylene
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


Types of pe
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


Petrol
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


  • More volatile than diesel(caused by additives)

  • In USA is consumed approx. 1,3 billion liters of gasoline every day


Soap resistance to autoignition)

  • 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.


Further use of soap
Further use of soap resistance to autoignition)

  • Napalm

  • Liquid soap

  • Detegrents

  • Unusual use at household- bug repellent, deodorizer, lubricant at metal surface connection


...END? resistance to autoignition)

end...

Thank you!


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