Natural rubber compositions with the partial/total replacement of carbon black/naphthenic oil by renewable additives: Rice husk ash and cashew nut oil

Abstract

The aim of this work was to use additives from renewable sources to develop an elastomeric formulation with reduced environmental impact and lower rolling resistance. Twelve compositions containing various proportions of rice husk ash—RHA (20, 40, 60, 80, and 100 phr to replace carbon black [CB]) and a combination of RHA with CB (30CB/10RHA and 20CB/20RHA) using cashew nut oil (3 phr) as a processing aid were prepared and characterized based upon their rheometric and physical–mechanical properties. The combined use of CB and RHA after the silanization process (30CB/10RHAS) increased wet grip by 3.6%, reduced rolling resistance by 17.3%, and improved abrasion resistance by 7.3%. Therefore, the use of these alternative raw materials represents an important contribution for the technological development of rubber compounds, with a combination of durability, safety, economy, and reduction in CO2 emissions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48314.

Torrefied agro‐industrial residue as filler in natural rubber compounds

“…Thus, TAS60 and TRH60 exhibited the lowest viscosity within the samples. A similar reduction in viscosity was observed when rice hull ash was used as a filler (40 phr) in Hevea NR compounds 29 . Nevertheless, all compounds exhibited melt viscosities and shear thinning behavior predicting favorable processing ease for molding and extrusion requirements.…”

“…Mechanical properties for the vulcanizates are shown in Figures 12(a)‐(d). Partial replacement of N550 with TAS (40CB/20TAS) had no effect on tensile strength, but at 50% replacement (30CB/30TAS) the tensile strength dropped about 35% (Figure 12(a)) Similar results with rice hull ash fillers were attributed to a reduction in carbon black below the percolation threshold 29 . However, at higher loadings and when TRH filler was used, tensile strength decreased with increasing torrefied filler content, indicating a lower reinforcing effect of the non‐CB fillers, except at 20 CB/40 TRH.…”

“…In general, mechanical properties for compounds replacing carbon black with TAS and TRH show similar trends to reports for other biobased fillers. Lower modulus and tensile strength was seen for NR compounds when replacing carbon black with rice hull ash 8,9,29,30 and other biobased fillers 2,5 . This trend is mirrored in the storage modulus‐strain data.…”

“…The residual basic hydroxyl and carbonyl groups on the surface of the torrefied fillers could have partially deactivated the curing system, which occurred with silica‐filled NR composites 30 . In contrast, addition of rice hull ash as a filler has been shown to decrease scorch and cure times, 8,9,29 attributed to acceleration by surface metal oxides. Based on the cure results, we conclude that the torrefied rice hull fillers used here have more of a basic surface character than acidic.…”

Waste cooking oils as processing aids for eco-sustainable elastomeric compounding

“…The decrease of G' at increasing strain can be explained by the rupture of the three-dimensional network formed by aggregates and agglomerates of filler (CB). 56 Increasing the strain amplitude, the rigid network starts to fragment, follows a decrease in the modulus G'. When the strain is high enough, the aggregates network is destroyed, and G' decreases to almost the same level as that of the elastomeric matrix.…”