Mechanisms of rubber abrasion

Abstract

SynopsisRates of wear have been determined for several elastomer materials, using a razor-blade abrading apparatus based on one described by Champ, Southern, and Thomas. Measurements have been carried out a t different levels of frictional power input, corresponding to different severities of wear, a t both ambient temperature and a t lOO"C, and both in air and in an inert atmosphere. It is concluded that wear occurs as a result of two processes: local mechanical rupture (tearing) and general decomposition of the molecular network to a low-molecular-weight material (smearing). Marked differences were shown by different elastomers. Carbon-black-filled natural rubber, SBR (styrene-butadiene copolymer) and EPR (ethylene-propylene copolymer) were particularly susceptible to decomposition and smearing, but for natural rubber and SBR the decomposition process was not observed in an inert atmosphere. It is attributed to molecular rupture under frictional forces followed by stabilization of the newly formed polymeric radicals by reaction with oxygen, if present, or with other polymer molecules, or with other macroradicals. Cis-polybutadiene and trans-polypentenamer did not appear to undergo smearing to a significant degree. The reactive radicals formed in these materials by molecular rupture are assumed to undergo rapid addition to other molecules so that the network structure is maintained. Rates of wear have been found to increase with the applied frictional force raised to a power n. The value of n was between 2.5 and 3.5 for unfilled materials a t ambient temperature, in agreement with Champ, Southern, and Thomas, who pointed out a general correlation with mechanical fatigue. Filled materials were found to be less sensitive to the frictional force, whether wear took place by tearing or by smearing, having values of the index n of 1.5-1.8. Several observations suggest that wear, even in the absence of smearing, is not fully correlated with mechanical fatigue: the markedly lower wear rates for carbon-black-filled materials, the anomalous rankings of unfilled materials, and the relatively small effects of raising the test temperature to 100°C. It is concluded that abrasive wear by small-scale tearing is not accounted for solely by the crack growth properties of the material but involves other failure processes as well.

A numerical investigation on mechanical property improvement of styrene butadine rubber by static straight blade indentation

“…The stress field on the rubber material by blade indentation shows that the stress that occurs around the blade tip is tensile stress, not compressive stress. It is different to compressive test on the rubber that the compressive stiffness of the rubber compound has a large increase if compared to unfilled rubber [2]. Besides, indentation by sharp blade indenter is the initial process for rubber cutting that requires a small contact area in order to get a small force for cutting.…”

“…The incorporation of reinforcing fillers, such as carbon black, improves the stiffness and the strength of the rubber [1]. Hence, the abrasion resistance of the rubber is also improved to suppress the tearing of the rubber under sliding contact [2].…”

Rubber Abrasion Resistance

“…Theories of abrasion thus require details of the local stresses, which together with the strength properties of the rubber may enable the rate of abrasion to be predicted. Gent and Pulford (Gent & Pulford, 1983) reported the reversal in the relative rates of wear of unfilled polybutadiene rubber comparing to those of unfilled natural rubber and styrene butadiene rubbers as frictional force increased. Fukahori and Yamazaki (Fukahori & Yamazaki, 1994) investigated the mechanism of the formation of the periodic ridges in rubber abrasion by designing the razor blade abrader.…”

“…Incorporation of reinforcing fillers such as carbon black improves stiffness and strength of rubber (Tabsan et al, 2010). Hence, the abrasion resistance is improved by suppressing tearing of the rubber under the sliding contact (Gent & Pulford, 1983). Arayapranee at el.…”

Wear Behavior of C/B filled NR Compounds using a Blade-type Abrader

“…Schallmach 와 Grosch 는 이러한 복잡한 마모·마찰 메커니즘을 밝히는데 크게 기여하였으며 [3][4][5][6][7][8] , Gent 등은 인열에너지 이론 을 기초로 칼날형 마모시험기를 제작하여 마모 현상을 연구하 였다.…”