Ultrasonic Aided Extrusion of Carbon Black-Filledsbr Compounds

Abstract

Ultrasonically assisted single screw extrusion of carbon black (CB)-filled styrene–butadiene rubber (SBR) compounds up to 60 phr was carried out and its processing characteristics were measured. The effects of ultrasonic amplitude on rheology, extractable amount, vulcanization behavior, mechanical properties, abrasion, electrical resistivity, and morphology were investigated. Increasing ultrasonic amplitude led to a reduction of extractable content with the effect diminishing with increasing CB loading. Treated compounds showed an increase in viscosity at certain amplitudes. Cure curves revealed reduced induction times with increasing amplitude, except at the highest CB content. The maximum torque of the cure curve, crosslink density, and mechanical properties of vulcanizates all showed an increase at certain ultrasonic amplitudes. An increase in the glass transition temperature (Tg) and a decrease in tan δ at Tg were observed with increasing amplitude. Ultrasonically treated unfilled and CB-filled compounds led to vulcanizates with significant and slight improvements in abrasion, respectively. Ultrasonic treatment caused a significant reduction in the electrical percolation threshold of vulcanizates. Morphological study by atomic force microscope revealed a creation of unique CB agglomerates, suggesting the strong interactions between the SBR and CB aggregates in treated compounds, leading to reinforcing effects in vulcanizates.

Effect of ultrasonic extrusion of star styrene‐butadiene rubber on properties of carbon black‐ and silica‐filled compounds and vulcanizates

“…The bound rubber content of star SBR/CB, star SBR/Silica, and star SBR/Silica/Silane compounds as a function of the ultrasonic amplitude is shown in Figure . Also, Figure reports the bound rubber content of the untreated linear SBR/CB compound, taken from the previous study, indicating the higher level of bound rubber content compared with that of the star SBR/CB compounds. Among the untreated star SBR/CB, star SBR/Silica, and star SBR/Silica/Silane compounds, star SBR/Silica/Silane compound has the highest bound rubber content, followed by star SBR/CB and star SBR/Silica compound.…”

“…Bound rubber content of star SBR/CB, SBR/Silica, and SBR/Silica/Silane compounds as a function of ultrasonic amplitude and untreated linear SBR/CB compound (Data points for untreated linear SBR/CB compound are from Ref. ).…”

“…It has 23.5% bound styrene, a number‐averaged molecular weight of 86 000, a weight‐averaged molecular weight of 330 000, and a polydispersity index of 3.8 . This SBR was used to prepare filled and unfilled compounds and vulcanizates. Carbon black N330 was supplied by Sid Richardson Carbon Corp. (Fort Worth, TX), which has a specific surface area of 78 m 2 /g.…”

“…The testing methods of all unfilled and filled star SBR compounds and vulcanizates are described in the following. The testing methods for all filled and unfilled linear SBR compounds and vulcanizates were described in earlier literature …”

“…The processing procedures for the filled and unfilled linear SBR compounds and vulcanizates are described earlier . The star SBR was masticated using a 1.2 litter Farrel Banbury mixer (Farrel Connecticut Division, Ansonia, CT), at a filling factor of ~70%.…”