Lab Services | Crosslink Density Determination

Crosslinking is the process of bonds forming to link one polymer chain to another. This process can be triggered accidentally or on purpose by heat, pressure, change in pH, and much more. Often times in certain industries crosslinked polymers are desired and extremely useful. Cross-link bonds affect the physical properties of polymers to make the polymers more favorable for a variety of applications. The cross-link density of polymers is defined as the density of the cross-link bonds in the polymer. The cross-link density of a polymer can be determined by using ASTM-D2765 as a method guideline. The method determines the gel content and swell ratio for a known mass of polymer extracted in an appropriate solvent at a specific temperature for a specific amount of time. The material is then removed from the solvent, and then reweighed both before and after drying. The less of the material that is extracted and the less the material swells, then the greater the cross-link density.