Perusviskositeetti

Perusviskositeetti, also known as intrinsic viscosity, is a measure of a polymer's contribution to the viscosity of a solution. It quantifies the effective volume occupied by a polymer molecule in a dilute solution. This property is related to the size, shape, and interactions of the polymer chains with the solvent.

The concept of perusviskositeetti is crucial in polymer science for determining molecular weight and understanding polymer behavior. It is defined as the limit of the specific viscosity divided by the concentration as the concentration approaches zero. Mathematically, it is represented by the symbol [η] and is typically expressed in units of volume per mass, such as deciliters per gram (dL/g).

Perusviskositeetti is influenced by factors such as temperature, solvent quality, and the polymer's molecular weight. In good solvents, polymer chains are more expanded, leading to a higher perusviskositeetti. Conversely, in poor solvents, chains coil more tightly, resulting in a lower value.

The Mark-Houwink equation is a well-known relationship that connects perusviskositeetti to the polymer's molecular weight: [η] = K * M^a, where K and a are constants specific to the polymer-solvent system. By measuring perusviskositeetti and knowing the constants K and a, researchers can accurately determine the average molecular weight of a polymer sample. This makes perusviskositeetti a fundamental tool for polymer characterization and analysis in various industries, including materials science, biotechnology, and pharmaceuticals.