This page looks in ~ the formation, structure and also uses of a usual polyester sometimes recognized as Terylene if that is offered as a fibre, or pets if it supplied in, for example, plastic drink bottles. A polyester is a polymer (a chain that repeating units) wherein the individual devices are held together through ester linkages.
You are watching: Which two monomers may combine to form a polyester?
Figure: The mountain is benzene-1,4-dicarboxylic mountain (old name: terephthalic acid) and the alcohol is ethane-1,2-diol (old name: ethylene glycol).
Now imagine lining these up alternately and also making esters through each mountain group and also each alcohol group, shedding a molecule the water every time one ester linkage is made.
That would produce the chain shown above (although this time created without separating out the carbon-oxygen dual bond - write it whichever way you like).
See more: The Arctic Ocean Touches What Continents Does The Arctic Ocean Touch?
In the polymerisation stage, this is heated come a temperature of around 260°C and also at a low pressure. A catalyst is required - there are numerous possibilities including antimony compounds prefer antimony(III) oxide. The polyester creates and fifty percent of the ethane-1,2-diol is regenerated. This is removed and also recycled.
Hydrolysis that polyesters
Simple esters are quickly hydrolyzed by reaction with dilute mountain or alkalis. Polyesters are struck readily through alkalis, but much more slowly by dilute acids. Hydrolysis by water alone is therefore slow as to be totally unimportant. (You wouldn"t suppose your polyester fleece to fall to pieces if friend went out in the rain!). If you spill dilute alkali ~ above a towel made native polyester, the ester linkages are broken. Ethane-1,2-diol is formed in addition to the salt the the carboxylic acid. Because you produce small molecules fairly than the original polymer, the fibers space destroyed, and you end up v a hole! because that example, if you reaction the polyester through sodium hydroxide solution: