Rheological analysis as a means for determining the silane crosslink network structure and content in crosslinked polymer composites

For evaluating the crosslink content of a polymer, gel content determination is a commonly used method. However, for crosslinked polymer composites containing particulate filler, the gel content may be overestimated due to partly trapping filler inside the gel portion. In this paper, parallel-plate rheology was used, together with the gel determination and FTIR measurement, for determining the silane crosslink network structure and content in crosslinked ethylene-octene copolymer composites. The effects of filler surface property on structure and content of silane crosslink are also discussed. The results show that a correlation plot between gel content, IR absorption index and crosslink density provides useful information on changes in silane network structure and properties of the crosslinked composites. The network structure formed (loose or tight network) shows a strong influence on the final tensile properties of the crosslinked products.