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lecture 2, examples( methane CH4, ethylene C2H4, acetylene C2H2), ethylene…
lecture 2
hydrocarbon molecules
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saturated hydrocarbon, all bonds are single ones, and no new atoms may be joined without the removal of others that are already bonded
introduction
the word plastic is commonly used as synonym for polymers, plastic are polymeric material
advantages of polymers: low cost, resistance corrosion, low thermal and electrical conductivity, low density, high strength to weight ratio, noise reduction and ease manufacturing
disadvantages of polymers: low strength and stiffer, high coefficient of thermal expansion, low operation temperature (less than 35^c) and low dimension stability in service over a period of time
due to unique and diverse properties, polymers have replaced metallic components in many applications
polymerization
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addition polymerization
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it also known as chain-reaction or chain growth polymerization because polymer molecule grows step by step until all of one reactant is consumed
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An initiator or catalyst species (R.), added to open the double or triple bonds between carbons and beings the linking process by adding many more monomers to a growing chain
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bonding
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during polymerization, monomers are linking by covalent bonds forming polymer chain
types of polymers
branched polymers
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branching interferes with the relative movement of the molecular chain which results in increasing the resistance to deformation
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cross-linked polymers
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cross linking has a major influence on the properties of polymers ( hardness, strength, stiffness, brittleness, batter stability dimensional)
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examples( methane CH4, ethylene C2H4, acetylene C2H2)
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