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Polymer Chemistry....Dr M Muzaffar Mir


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POLYMER CHEMISTRY STRUCTURE OF POLYMERS Dr Mohammad Muzaffar Mir Professor of Biochemistry Al- jouf University

[PE] Polyethylene:

[PE] Polyethylene T he “monomer” unit is, Ethylene or C 2 H 4 . This is an example of a linear chain homo-polymer, where the “ X” in our model is replaced with the ethylene group. ا.د/ محمد مظفر مير

Uses of PE:

Uses of PE Polyethylene is used for flexible bottles, toys, battery parts, ice trays, and film wrapping and other packaging materials. It is tough but possesses low strength. Trade names: Ethron , Fortiflex , Hi-fax, Rigidex , Zendel etc ا.د/ محمد مظفر مير

Two types of PE polymers :

Two types of PE polymers One is when the polyethylene exists as long straight chains. The picture here shows the chains of one carbon with two hydrogen atoms repeating. The chain can be as long as 20,000 carbons to 35,000 carbons. This is called high density polyethylene (HDPE). ا.د/ محمد مظفر مير

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The other type is low density polyethylene ( LDPE ). It is made by causing the long chains of ethylene to branch. That way they cannot lie next each other, which reduces the density and strength of the polyethylene. This makes the plastic lighter and more flexible. ا.د/ محمد مظفر مير


USES OF HDPE Low density polyethylene is used to make plastic bags, plastic wrap, and squeeze bottles, plus many other things. When the chains get up to 500,000 carbons long, they are tough enough for synthetic ice, replacement joints, and bullet-proof vests USES OF LDPE ا.د/ محمد مظفر مير

Polypropylene :

Polypropylene T he “monomer” unit is Propylene or C 3 H 6 ) This is also an example of a linear chain homo-polymer, where the “X” in our model is replaced with the Propylene group. USES Polypropylene is used for such items as bottles, TV cabinets, luggage. It tends to be relatively strong and resistant to heat. It has the trade names Herculon, Meraklon, and Profax. ا.د/ محمد مظفر مير

Polyvinyl chloride [PVC]:

Polyvinyl chloride [PVC] T he “MONOMER” unit is V inyl chloride or C 2 H 3 Cl . Polyvinyl chloride is a very popular, low cost rigid material It can be made flexible by adding plasticizers. It is used as floor coverings, pipe, garden hose, electrical wire insulation, and (at one time) phonograph records. • Trade names: “PVC,” Saran, Tygon , Darvic , Geon. ا.د/ محمد مظفر مير


Polystyrene The “mono mer ” unit is S tyrene or C 6 H 5 CH = CH 2 . In the polymerization, one carbon-carbon double bond (in the vinyl group) is replaced by a much stronger carbon-carbon single bond, hence it is very difficult to depolymerize polystyrene. Produced either as a soild or as foamed plastic –polystyrene foam. Uses : Used most commonly as expanded polystyrene [EPS] Home insulation, packaging, electrical and thermal insulation, translucent window panes, storage battery cases, toilet articles etc ا.د/ محمد مظفر مير

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H O C O Polyester [a co-polymer] is made from the two monomers, terephthalic acid (note: “ph” is silent) and ethylene glycol (car antifreeze). This makes a popular plastic called PETE, which is short for Polyethylene Terephthalate. The synthesis is also a dehydration reaction because water is given off. PETE Polyester ا.د/ محمد مظفر مير

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Dehydration Reactions in polymerization of PE ا.د/ محمد مظفر مير

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Various industrial uses Clothes and home furnishings like bedspreads, sheets, pillows, furniture, carpets and even curtains. High strength ropes, thread, hoses, sails, floppy disk liners, power belting Packaging and insulation materials Toys and balloons. ا.د/ محمد مظفر مير Uses of Polyester

Molecular structure :

Molecular structure Linear polymers long, flexible chains (with only 2 ends) with some van der Waals or hydrogen bonding between chains Branched polymers Have branches Chain packing efficiency is reduced compared to linear polymers (lower density) ا.د/ محمد مظفر مير

Molecular structure :

Molecular structure Cross-linked polymers Cross linkage happens either during synthesis or in a separate process, typically involving addition of impurities which bond covalently. This is termed vulcanization in rubber ا.د/ محمد مظفر مير

Molecular structure:

Molecular structure Network polymers 3D networks made from trifunctional “monomers”. Examples: epoxies, phenolformaldehyde . These are thermosetting materials! ا.د/ محمد مظفر مير

Covalent chain configurations and strength :

Covalent chain configurations and strength ا.د/ محمد مظفر مير

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ا.د/ محمد مظفر مير

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