Comparison of techniques for determining crosslinking in silane-water crosslinked materials

Degree of crosslinking in silane-water crosslinked ethylene–octene copolymer and its blends with low-density polyethylene was investigated, using three different techniques: the conventional gel content determination, solvent uptake factor method and infrared analysis. The results from those techniques show a similar trend in which the degree of crosslinking increases with increase of crosslinking time, and decreases with increase of crystalline portion in the materials. The measurement of gel content, although it is a direct way to yield results on degree of crosslinking, is time consuming and uses a large amount of solvent for extraction. Also, good care must be taken when analysing the gel content of samples with low degree of crosslinking. Analysis of FTIR data has shown potential for the determination of crosslink variations in the silane crosslinked materials and gives meaningful information on the progress of the silane-water crosslinking reaction.