Dynamics heterogeneity in silica‐filled nitrile butadiene rubber

Abstract

Nanoparticles significantly reinforce rubbers, but their influence on polymer dynamics is far from being understood. Here a comparison study of polymer dynamics in silica‐filled nitrile butadiene rubber compounds and their bound rubber in extracted filler gels is performed. Both the compounds and filler gels contain glassy, restricted, and mobile rubber fractions. The restricted fraction detected by broadband dielectric spectra exhibits a subsegmental relaxation that is two to four orders of magnitude slower than the segmental dynamics of the mobile phase. It is significant that the extractable fraction interacts with both the restricted and mobile fractions in the bound rubber, thus improving the activation energy of restricted relaxation and reducing the fragility of segmental relaxation in the mobile fractions. Meanwhile, the influences of loading, surface nature, and specific surface area of the silica on the dynamics heterogeneity are investigated. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46223.

Dynamics Gradient of Polymer Chains near a Solid Interface

“…Because of the relatively low dielectric signal from PI, a reliable fitting was difficult to obtain for the PI/SiO 2 film. In contrast, NBR with strong polar groups (-CN) provided a well-resolved relaxation process from the interfacial region (see FigureS3in the Supporting Information) 39. This led to a reliable estimation of the segmental relaxation times of NBR both in the bulk and in the interfacial regions at various low temperatures.Figure2shows the temperature-dependence of bulk and interfacial relaxation times for NBR.…”

“…In contrast, NBR with strong polar groups (-CN) provided a well-resolved relaxation process from the interfacial region (see Figure S3 in the Supporting Information). 39 This led to a reliable estimation of the segmental relaxation times of NBR both in the bulk and in the interfacial regions at various low temperatures.…”

“…By dispersing a small amount of fillers, such as carbon black and fibers, glass fibers, silica nanoparticles, talc, and so on, into a polymer matrix, multiple macroscopic properties of the polymer can be substantially improved. − Polymer chains adsorbed onto the filler, which generally exhibit different aggregation states and relaxation dynamics from those in the bulk, are believed to play crucial roles in the improvement of mechanical properties of polymer nanocomposites. − Such can be seen in the bulk glass transition temperature ( T g b ), elastic modulus, and rheological responses for polymer nanocomposites with respect to the bulk properties. − Over the past few decades, many efforts have been devoted to gaining a better understanding of the structural and dynamic properties of adsorbed polymer chains within the interfacial layer. ,,,− …”

Influence of Carbon Black and Silica Fillers with Different Concentrations on Dielectric Relaxation in Nitrile Butadiene Rubber Investigated by Impedance Spectroscopy

“…Thus, it has been extensively employed to investigate the nature of local molecular motion associated with relaxation behavior [ 17 , 18 , 19 , 20 , 21 ]. However, limited investigations of the influence of fillers on dielectric properties in NBR have taken place thus far [ 22 , 23 ]. It is a crucial task to provide useful information on dielectric responses of NBRs blended with various filling agents in rubber applications and related academic studies.…”

Tailored higher performance silicone elastomer with nanofibrillated cellulose through acidic treatment

“…However, it can be improved by the addition of fillers, for example, natural fiber or inorganic filler materials such as glass fiber, [4] SiO 2, [5,6] Al 2 O 3, [6] and CaCO 3. [7,8] The strength of silicone polymers without filler is substandard for most applications. Thus, the addition of reinforcing fillers is required to enhance their mechanical strength.…”