Polypropylene

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Polypropylene 2016-12-06T05:35:22+00:00

Polypropylene

       

Polypropylene is a highly crystalline thermoplastic polymer produced by the chain growth polymerisation of propylene, a gas obtained from petroleum cracking. It has properties related to polyethylene but has a much higher melting temperature and is much stiffer. Polypropylene can be produced with different molecular chain structures under controlled conditions (stereo-specific) but only the "isotactic" form is produced in large quantities. Here the methyl side groups are arranged on the same side of the polymer chain.

Isotactic polypropylene was discovered in 1954 by the Italian chemist Guilio Natta and his assistant Paulo Chini, working in conjunction with the Italian company Montecatini. Catalysts of the type invented by Karl Ziegler, the German chemist, for the production of polyethylene at ambient pressure were used. (See K. Ziegler, G. Natta.)

Commercial production of polypropylene began in 1957 with Hercules Incorporated, Montecatini and Farbwerke Hoechst AG. ICI produced polypropylene resin as Propathene in 1954. Natta and Ziegler were awarded the Nobel Prize for Chemistry in 1963 in recognition of their work on "Ziegler-Natta" catalysts.

Polypropylene is an important plastic and is used in many different forms and applications through a range of manufacturing processes. A large proportion of polypropylene is used in fibres as constituents of fabrics, upholstery and carpets. Many industrial uses involve ropes, woven and non-woven fabrics and reinforcements. Blow moulded containers, such as bottles for foods, shampoos and other liquids, form part of everyday experience. A wide range of injection moulded items exists in appliance housings, resistant containers, car components, toys and furniture. The remarkable fatigue resistance properties of polypropylene has seen valuable applications in long life hinge designs in packaging containers and elsewhere.

Since the 1980s the production, consumption and applications of this important polymer have increased through the application of even more efficient catalysts and property enhancements.