Sulfur Dispersion Quantitative Analysis in Elastomeric Tire Formulations by Using High Resolution X-Ray Computed Tomography

Abstract

Good dispersion of compounded ingredients in a rubber formulation is important for mechanical performance. After mixing, certain materials can remain undispersed within the rubber matrix, which could lead to critical flaws, influencing performance according to the Griffith failure criteria. High resolution X-ray computed tomography (XCT) offers a unique opportunity to measure phase domain size and distributions. Fillers such as carbon black or silica can be differentiated from sulfur or zinc oxide, providing an opportunity to determine dispersion characteristics of the various phases. The XCT technique has become an important characterization tool for three-dimensional and higher dimension material science due to the availability of polychromatic micro-focus x-ray sources and efficient high spatial resolution detectors with superior scintillators. High resolution XCT provides very rich data quantifying mixing efficiency of particulates in a matrix, such as insoluble sulfur or silica particles in rubber. Imaging with X-rays provides attenuation, phase, or scattering contrast and will prove to be a critical method for evaluating the field of rubber crosslinking, considering realistic environments in situ. This paper highlights methodology development and validation and provides insight on the dispersion of polymeric (insoluble) sulfur in rubber formulations. Dispersion assessment is compared using three techniques: high resolution XCT, population survival analysis in tensile testing, and optical microscopy.

Construction of a rough surface in EPDM/CB composite through peroxide curing: A mechanism for optimizing physico‐mechanical properties in automotive paint‐compatible applications

“…The consistent variation in percentage elongation and similar tear resistance values can be attributed to the differences in the percentage of mono-sulfidic, disulfide, and poly-sulfidic cross-links formed between the polymeric chains in these composites. 6,23,29 Additionally, the nature of carbon black reinforcement in rubber relative to the original polymer has also been explored in the literature. 23 In addition to the curing characteristics responsible for the physico-mechanical properties of EPDM composites, the nature and composition of the carbon filler, as well as the processing oil content, play significant roles in shaping these properties.…”

“…Common diene units include dicyclopentadiene, ethylidenenorbornene (ENB), and vinyl norbornene. 3,[6][7][8] In this study, EPDM rubber composites were prepared using both sulfur and peroxide vulcanization methods. The properties, including hardness, tensile strength, elongation percentage, and tear resistance, for composites A, B, C, D, and E are detailed in Table 2.…”

“…Rubber components for automobiles are typically manufactured using either injection molding or compression molding techniques, and the choice of processing EPDM rubber involves options such as sulfur or peroxidebased curing methods. [6][7][8] The specific composition of these rubber composites, including additional ingredients, is tailored to the particular characteristics and applications of the automotive parts. These rubber composites derive their distinctive properties from a range of specialized additives.…”

“…5 Penumadu et al studied sulfur dispersion quantitative analysis in elastomeric tire formulations using high-resolution X-ray computed tomography. 6 Mousavi et al analyzed polypropylene/ethylene propylene diene monomer/cellulose nanocrystal ternary blend nanocomposites, focusing on the effects of different parameters on mechanical, rheological, and thermal properties. 9 Mohamed et al examined the effect of gamma irradiation and particle size of CaCO 3 on the properties of high-density polyethylene/EPDM blends.…”

Thermally Activable Bistetrazoles for Elastomers Crosslinking

“…However, the low solubility of sulfur in elastomeric compounds together with the mild mixing conditions make not always optimal the sulfur dispersion. For example, in the case of mixtures of elastomers with different polarity, undesired accumulation of sulfur can occur in the more affine elastomeric phase [ 11 , 12 ]. Because of an unsatisfactory distribution of sulfur, the cross-linked final material may not have the desired properties, in particular it can be characterized by a marked hysteresis, i.e., showing an increase in the heat dissipated under dynamic conditions.…”