massapolymerisaatioon

Massapolymerisaatio, often translated as bulk polymerization, is a method of producing polymers where the reaction occurs in the liquid monomer itself without any solvent or diluent. The monomer is typically heated, and a initiator is added to start the polymerization process. The monomer acts as both the reactant and the heat transfer medium.

This method is characterized by high monomer concentration, which can lead to a rapid increase in viscosity as the polymer forms. This viscosity increase is a significant challenge in bulk polymerization because it hinders heat dissipation and mixing. As the reaction proceeds, the increased viscosity makes it difficult for the heat generated by the exothermic polymerization to escape, potentially leading to uncontrolled temperature rises, or "runaway reactions." Furthermore, the diffusion of monomers to the growing polymer chains becomes slow, affecting the polymerization rate and molecular weight.

Despite these challenges, bulk polymerization offers several advantages. It produces a polymer of high purity as there are no solvents or additives to be removed. This also makes it an environmentally friendly process, as it avoids the use of solvents, which can be hazardous and require recovery. It is also a cost-effective method due to the absence of solvent costs. Bulk polymerization is suitable for producing polymers that are processed directly from the melt, such as in extrusion or molding. Examples of polymers often produced via bulk polymerization include polymethyl methacrylate (PMMA) and polystyrene (PS). Effective heat management and mixing techniques are crucial for successful implementation of this polymerization method.