1. Molecular weight and molecular weight distribution
Regardless of the method used to determine the molecular weight of an emulsion polymer, the emulsion must first be coagulated, then the resulting polymer washed, and then dissolved in a suitable, less polar solvent.
When measuring the viscosity-average molecular weight, a Brookfield viscometer or a format tube can be used.
When determining the number average molecular weight, use an osmometer. When measuring the weight average molecular weight, use a light scattering photometer.
Determination of polymer molecular weight and its distribution is often a matter of polymer scientific research. now
In modern polymer research, these classic methods are still used, and large-scale professional analytical instruments such as gel chromatography have also been used more and more commonly.
2. Glass transition temperature
The glass transition temperature (Tg) of a polymer is very important data. Polymer development is inseparable from this data, and polymer users also need to understand this data. As mentioned earlier, the Tg value of polymers can be checked from the data provided by the predecessors, and there are also formulas to calculate. Based on its importance, even if it is not engaged in basic research, sometimes it is necessary to measure it.
The method for determining Tg is mainly dilatometry. The instruments used are called differential thermal analyzers or thermal spectrometers, which are relatively expensive instruments. The Tg value of the homopolymer in the handbook is generally reliable, and practice has proved that the Tg value of the copolymer calculated by this method is also close to the measured value.
