materialsscienceandengineering: Polymers: Polyketones A ketone, shown in the bottom left image above
materialsscienceandengineering: Polymers: Polyketones A ketone, shown in the bottom left image above, is an organic compound with the structure RC(=O)R’, wherein R and R’ are place holders for other elements, compounds, or polymer chains, and the carbon double bonded to the oxygen is technically a carbonyl group. Polyketones (PK), therefore, are any polymer chains in which the ketone structure is present. Carbonyl groups are polar, which gives polyketone polymers a variety of properties not seen in polymers consisting mostly or completely of carbon and hydrogen. Polyketones thus have higher melting temperatures than many plastics, and higher chemical resistance. This is because they are highly crystalline, making them strong but brittle, and variations in the structure and composition are often preformed to achieve the desired properties. These polymers are classified as high-performance thermoplastics. Polyketones are fairly new polymers, in terms of their discovery and usage, but simple polyketones can be cheaply made with only ethylene, carbon monoxide, and a good catalyst, making them an attractive option. Because of their newness, however, their applications are not as numerous as they might one day become. Carilon is a polyketone created by Shell (now made by a different company) which adds a bit of propylene in during polymerization, separating the carbonyl groups and preventing high levels of crystallization, creating a tougher and less brittle material (but also lowering the melting temperature and the strength of the polymer). Other polyketones include polyaryletherketones (already discussed on this blog) such as PEK, PEKK, and PEEK. Sources: ( 1 - images 2 and 3 ) ( 2 - image 4 ) ( 3 ) ( 4 ) ( 5 ) Image 1. -- source link