Leszek Nikiel

Filler dispersion, network density, and tire rolling resistance

Abstract The filler dispersion is an essential rubber compound characteristic. Traction, treadwear, and rolling resistance are affected by filler dispersion. The quantification of dispersion is a length scale phenomenon. The existing experimental tools, which are capable of measuring dispersion, for example transmission electron microscopy (TEM), mechanical scanning microscopy (MSM), optical microscopy, and reflectometry, have limitations and the information they provide may not probe the relevant scale length. The recent advance in instrumentation allows one to include electrical measurements in the arsenal of tools available to quantify the dispersion. This paper reviews the range of dispersion measurements and the correlation with compound dynamic properties is presented.

Reflectometry—A New Method of Measuring Filler Dispersion

Abstract A new method of measuring carbon black dispersion in rubber is presented. This method is based on the measurement of the light reflectivity from the rubber sample using standard equipment used in the evaluation of the tint strength of carbon black (ASTM D3265 procedure). This method can be applied for both uncured and cured samples; however, the uncured sample measurement has significant advantages in the simplicity of the sample preparation and obtaining important filler dispersion information of the compound. It is shown that samples with better dispersed carbon black reflect less light as compared to samples with poor carbon black dispersion.

Furnace Carbon Black Characterization: Continuing Saga

Abstract A summary of the latest efforts to characterize carbon black and the latest findings using state-of-the-art scientific instrumentation is presented. Over the years, advanced studies of furnace carbon black formation and characterization have helped the rubber technologist to better predict the performance of the end product (i.e., a tire) but still today these characteristics are not totally sufficient and more work is necessary to better define and describe the exact nature of carbon black produced using the furnace process.

The Significance of Percolation on the Dynamics of Polymer Chains Bound to Carbon Black

A critical need in the fundamental understanding of reinforcement in filled polymers is the characterization of the polymer-filler interface and the dynamics of the polymer in this interfacial regime. In carbon black filled polymers, one of the central themes in the mechanism of reinforcement is that of “bound” polymer. Understanding the dynamics of this bound polymer may be key to arriving at an understanding of reinforcement mechanisms in filled polymers. The interactions between polymers and filler surfaces are also key in the development of more advanced nanocomposite materials. We have previously utilized inelastic neutron scattering methods to examine the variation of bound polymer dynamics as a function of carbon black type for a single, initial carbon black concentration. An apparent change in the distribution in backbone motions was observed in the bound polymer compared with the pure polymer. In this study, we extend our prior work to examine the bound polymer dynamics as a function of the type of carbon black and the initial concentration of carbon black. The results suggest that two types of dynamic behavior are observed as a function of the initial carbon black concentration. This critical cutoff concentration may be related to the percolation threshold of the carbon black and suggests that quantifying the amount of bound polymer is insufficient for understanding the relationship between mechanical behavior and bound polymer content.