Dispersity ( lat. Dispergere dissipate ',' propagate ') denotes the scientific property distribution of two or more phases or particles in a mixture or of a mixture . Colloquially, a distribution can also be meant in general. The associated adjective is "disperse". There is a strong relationship to the concept of dispersion in terms of content .
A collection of particles or individual parts with the same properties (physical, chemical or organic) is called monodisperse. According to IUPAC , the term uniform is preferable in polymer chemistry for polymers that do not have a molar mass distribution (accessible e.g. through step-by-step solid-phase synthesis according to Robert Bruce Merrifield ). Depending on the permissible standard deviation , application or size class, only one property can be the same. (e.g. inner surface )
Distribution of particles or individual parts in a mixture with different (mostly widely distributed) properties.
For polymer chemistry , polydispersity is a property of the molar mass distribution of a sample, see there. The IUPAC has recently recommended using the term dispersity with the symbol Đ .
The term describes the degree of distribution, the mass dispersion of several chains in polymer production. The dispersity is calculated using the ratio of the weight average to the number average. The distribution can be well described with the help of the Poisson distribution . (See molar mass distribution )
The term is used in connection with two-phase systems as well as in particle size analysis. He describes
- the extent and uniformity of the distribution of one disperse phase within the other, e.g. B. of quartz particles in water or of dust particles in the air, or
- the distribution of the particles in a phase to different particle size classes . If all particles are in one size class, one speaks of monodisperse, in other cases of polydisperse. Particle size analysis deals with the investigation of this distribution .
The adjective "disperse" is used to describe the audience to which the mass media address. What is meant is an audience whose parts (individuals) are different in terms of interests, worldview, demographic features and other characteristics. It is part of the often quoted definition of mass communication by Gerhard Maletzke : "Mass communication is that form of communication in which statements are communicated publicly, indirectly and one-sidedly, to a dispersed audience through technical means of dissemination."
In the current discussion in communication studies, the attribution of dispersity to the mass media audience is being questioned, as this is becoming increasingly segmented in the course of the increase in media offers (e.g. through the Internet, but also the expansion of TV offerings).