3.3 Petrochemical intermediates and monomers

About 80 per cent of all petrochemicals end up in polymers, the most important building blocks being ethylene, propylene, butadiene and benzene. The first three can be polymerized directly but an important slice of their production is used to create more complex monomers. Ethylene is the progenitor of most vinyl monomers (Figure 35), so the pressure on ethylene supply is particularly strong compared for example to propyle
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3.2.2 Ethane cracking

Although ethane can be cracked thermally, the reaction is slow and does not necessarily yield ethylene at high severity. Careful control of reaction conditions, however, allows the reaction to occur

The yield of ethylene is typically nearly 50 wt% with the rest composed of unreacted ethane (40 per cent) and some methane and hydrogen (10 per cent). T
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3.2.1 Thermal cracking

The bulk of the major monomer and intermediate, ethylene (C2H4), is still produced in the UK by steam cracking without the use of catalysts. Paraffinic feedstocks are best for optimising ethylene yields, and the severity of cracking is specified by the rate of disappearance of a marker compound, usually n-pentane. The severity of the reaction can then be defined as follows:

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2.1.2 Understanding
How do we learn? Understanding ‘how’ is the key to learning more effectively. This unit looks at the three main categories of theories: the acquisitive, constructivist and experiential models of learning. There is no right way to learn but developing an active approach will ensure that you are open to new ideas.
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1 Learning to learn
How do we learn? Understanding ‘how’ is the key to learning more effectively. This unit looks at the three main categories of theories: the acquisitive, constructivist and experiential models of learning. There is no right way to learn but developing an active approach will ensure that you are open to new ideas.
Author(s): The Open University

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Author(s): The Open University

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Sunset Song was written in the early 1930s and is still one of the best-known and most-debated Scottish novels. In this unit, we discuss whether Sunset Song succeeds as critique of capitalism and whether it has value as a work of literature separate from its propagandistic ambitions.
Author(s): The Open University

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8.7.1 Summing up
Sunset Song was written in the early 1930s and is still one of the best-known and most-debated Scottish novels. In this unit, we discuss whether Sunset Song succeeds as critique of capitalism and whether it has value as a work of literature separate from its propagandistic ambitions.
Author(s): The Open University

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Author(s): Harvard-Smithsonian Center for Astrophysics

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Titre : JALPES 2010 Strasbourg : Motiver par la simulation
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Physicists use the concept of a system to trace and quantify the flow of energy. In this session, take a close look at a number of energy systems and see how this concept is closely linked to the Law of Conservation of Energy.,This segment explores the question "What are some practical applications of energy systems?" by visiting classrooms as well as interviewing students and scientists.
Author(s): Harvard-Smithsonian Center for Astrophysics

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Author(s): Harvard-Smithsonian Center for Astrophysics

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Author(s): Baerlecken, Daniel; Kobiella, Olaf

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