Schematic view of a polyaddition reaction

If A is an oxygen atom, polyepoxides are obtained if the ring reacts with another bifunctional group like diols, diamines or carbonic acid anhydrides, epoxy resins are formed. 

The characteristic of these processes closely follows those of polycondensation reactions thus, a stepwise growth with all the limitations as described in Section 2.3.2 can be observed. An advantage - also from an environmental point of view - is that there are no low molecular weight products formed. 

Generally, the reaction of monomers to polymers may be carried out discontinously or continously by one of the following processes  

In suspension polymerisation, the chemical reaction takes places in droplets that are in suspension in a solvent. Suspension polymerisation is characterised by a good transfer of the reaction heat, a low dispersion viscosity and low separation costs on the one side but also by the fact that it is a discontinuous process, and there are relatively high amounts of waste water, significant reactor wall fouling and suspension agents remaining in the final product and in the waste streams. 

Suspension polymerisation produces latex particles in the size range from 1 to 1000 pm. This process comprises monomer + initiator + solvent (usually water) + surfactant. The monomer and the initiator are both insoluble in the solvent (water), e.g. styrene and benzoyl peroxide hence the monomer is dispersed as droplets (as in emulsion polymerisation), but the initiator is present in these droplets (and not in the aqueous phase). The role of the surfactant is purely to stabilise these droplets. 

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