Investigations on matrix network characteristics in NBR/silica nanocomposites: Resolving matrix bulk density and network molecular weight and their alterations due to filler-curing agent interactions

摘要

Presence of filler in an elastomeric composite can affect curing characteristics due to possible interaction with curing agents. Alteration of the curing characteristics can change intrinsic properties of elastomer including its bulk density and swelling behavior. In this study, a series of acrylonitrile butadiene rubber (NBR) with various curing levels was prepared. From the experimental data the bulk density and network molecular weight (M-c,M-sw) were specified and a relationship was established between these parameters. In order to determine the swelling characteristics of NBR in presence of filler, another series of NBR/silica nanocomposites was prepared with various nanosilica loadings under a constant content of curing agents and curing conditions. With the use of the swelling data and applying the obtained relationship, the M-c,M-sw and bulk density of the filled NBR matrix were resolved. The M-c,M-sw values obtained by considering the influence of nanosilica on curing characteristics of NBR were compared with those obtained simply based on bulk density of raw rubber. This comparison confirmed that there are considerable differences between these values. With increasing nanosilica contents, and hence, increasing the negative impact of the filler on reducing curing degree of NBR, the bulk density of filled NBR matrix was decreased. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46170.