Record Chemistry - Other constituents

As previously mentioned the PVC in records is actually a copolymer (a mixture of two monomers) of vinyl chloride and vinyl acetate. A copolymer of the these molecules will consist of a mixture of chloride substituted and acetate substituted segments. This is produced in a reaction much like the one seen previously but with different substituents on the carbon chain. Replacing a Cl is the OOCCH3 group.

 

Vinyl Chloride: Vinyl Acetate:
Gray atoms are carbon, white hydrogen, green chlorine and red atoms are oxygen.

 

To give records the classic black vinyl colour carbon black is usually added. This consists of finely divided carbon, which is produced by incomplete combustion of natural gas or oil, normally by letting a flame touch a cold surface. Carbon black contains up to 95% carbon.

The main use of carbon black is as a strengthening agent for rubbers (eg in tires) but it is also widely used as a pigment (eg in ink, paint, and carbon paper). Other uses for carbon black include: protective coatings, plastics, and resistors for electronic circuits.
 

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dcressey@another.co.uk copyright Daniel Cressey 2001