Polymers
Polymers
by definition consist of a number of repeat units called monomers.
Polymers can be formed by a condensation process (for example polyesters,
polyurethanes, etc) or an addition process (for example polystyrene,
PVC, etc). The polymerization process is random in nature. In other
words, rather than a single molecular weight species, normal polymerization
processes yield a distribution of different molecular weights.
Molecular weight of a polymer influences its physical, chemical,
mechanical properties. The methods employed to measure the molecular
weights generally give the "average" values. These include
viscosity measurements. However, the average molecular weight does
not give the total information about the polymer. One may have two
polymers of similar average molecular weights but totally different
properties. Besides the average values, the distribution of molecular
weights within a polymer drastically affects its end-properties.
Gel Permeation
Chromatography (GPC) is used to measure the molecular weight and the
molecular weight distribution of polymers. This is a powerful tool
for QC, manufacturing and R&D. In a simplistic view, a polymer
solution is injected in the instrument; the material passes through
a series of column and is separated by its size. Dolph has
acquired a state-of-the-art GPC and we are now gearing up to use this
powerful tool to help with production of our base resins for consistency
and reproducibility; for verifying the quality of purchased raw materials,
and for analyzing the competitive products. For information on this
new, powerful tool, contact the Dolph laboratory.
