The ontology of polymers

Almost no industry branch has developed as quickly as the polymer industry in the last decades. Many properties of new developed polymers showed to be ideal for the tasks of the matrix in polymer composites. Thus, progress in composite technology was mainly linked to improvements in polymer chemistry. The main target was the development of new high temperature plastics-especially thermoplastics-with outstanding chemical and mechanical properties.

Polymers can be classified under four different aspects, like:

1. Manufacturing process  

   polymerisation

   The chemical conversion of one or several chemically different and active low-molecular connections (monomers) to a linear branched, meshed or cyclic polymer. The most common polymerisation is the radical polymerisation.

   polycondensation

   Chemical reaction where bi- or higher functional low-molecular connections (monomers) are converted to linear or meshed macromolecular substances (polycondensates) by proceeeding condensation reactions. This is always combined with a separation (condensation) of low-molecular products, like water, ammonia, hydrochlorgas and methanol.

   copolymerisation (polyaddition)

   With copolymerisation, monomers are directly added to the basic structure, in contrast to a polycondensation, where low-molecular parts are separated.

2. Origin of raw materials  

   modified natural materials

   Materials which originate from a natural material and have been modified for an industrial use.

   synthetic materials

   Materials which do not originate from a natural material and have been produced artficially.

3. Composition of the macromolecules  

   amorphous structure

   Macromolecular design of a material, which only shows a short range order of the atoms (e.g. glass) in contrast to a wide range order of cristalline structures.

   semi-cristalline structure

   Materials with a partial wide range order of atoms but also a coexisting irregular, amorphous structure.

   liquid-cristalline structure

   An intermediate state between the amorphous and cristalline state of high-molecular polymers, which are liquid but nevertheless have a regular, cristalline molecular structure.

4. Processing technology and polymer properties  

   thermoplastics

   Polymers with a loose connection of the molecule chains to each other. They can be melt open again by heat.

   thermosets

   Polymers with a fixed meshed net of polymer chains to one big molecule which cannot be separated again after the meshing reaction (curing).

   elastomers

   Polymers with irregular orientated molecule chains, which in contrast to thermoplastics and thermosets are able to move slightly against each other. After a deformation they automatically return to their initial position.

In contrast to the general subdivision of materials, the above main criteria are not unequivocal, i.e. a polymer is not belonging to only one single group but needs to be classified by all of them. The resulting ontology is sketched in figure 7.

  
Figure 7: The plastics ontology

The (9) leaves of the hierarchy do by no way represent the complete set of existing polymers with fixed properties and chemical composition. However, each of them may be regarded as a representative of the possible combination of the characteristics 1, 2, and 4 as mentioned above. Hence, we omitted characteristic 3 since it would complicate the layout of the hierarchy and it is not important for our application. The pure definition of the classes without properties can be found in appendix C.