I know a few students out there who are taking classes in polymer science this term at Kettering University and I thought I would provide some study materials. Of course I'm happy to take suggestions or answer questions from students as they arise.
On the topic of polymer classification, this is one of the first things that students should be learning about polymers. This of course assumes that we all are of the understanding that polymers are chemically based materials comprised of long chains of carbon atoms that may also have side-chains that affect the properties of the material as a whole. Polymers are created via chemical reaction of a monomer or a mix of reactants each with at least two active sites on the molecules. During the reaction, the chains grow until there is little or no monomer (or reactant) available to continue the reaction. The size of the chain determines the molecular weight of the polymer.
The first thing everyone should know about any polymer is whether it's a thermoplastic or a thermoset. Thermoplastics, as the name suggests, are polymers that can be melted and reformed again and again. This is like candle wax, butter, or chocolate. Thermosets, as the name suggests, set with heat and do NOT remelt. Think of an egg; once it's cooked, it's done. There's no remelting an egg once cooked. This is because the reaction involves cross-linking between polymer chains. Heating the set polymer will cause expansion of the molecules but the cross linking will prevent the chains from slipping past one another. Thermoplastics are polymerized from monomers with two and ONLY two active sites on the molecules. Thermosets are formed from monomers and reactants with three or more active sites on the molecules.
SO...
When it comes to recycling, Thermoplastics have many uses after recycling where-as thermosets are good for little more than road asphalt filler.
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