Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Oct 2019

Modified Soybean Oil as a Processing Oil for Styrene-Butadiene Rubber Tire Tread Compounds

,
,
,
, and
Page Range: 280 – 291
DOI: 10.2346/tire.18.470105
Save
Download PDF

ABSTRACT

Soybean oil (SBO) was modified with polystyrene via a radical graft polymerization reaction for use as a processing oil in tire tread compounds. Poly(styrene-butadiene)/polybutadiene rubber compounds with silica and carbon black, containing different processing oils including naphthenic oil (NO), aromatic oil (AO), SBO, and polystyrene-modified SBO (SBO-PS), were formulated, vulcanized, and tested. The curing behavior, mechanical properties, and dynamic properties were investigated. The cure test results showed that all SBO-based rubbers had a shorter scorch time and cure window than the NO- and AO-based rubbers.

The tensile tests demonstrated that partial and complete replacement of NO with SBO led to reduced tensile modulus but increased elongation of rubber. For the rubbers compounded with SBO-PS and with a 50/50 mixture of NO/SBO-PS, tensile strength and elongation were higher than for the NO-based rubber. The same tendency was observed when SBO-PS–based rubbers were compared with SBO- and AO-based rubbers. SBO-PS–based rubbers demonstrated better tensile properties than AO-based rubbers and far better properties than SBO-based rubbers. In the tear resistance test and durometer hardness test, SBO-PS contained rubbers that showed similar properties to NO-containing rubber.

The dynamic mechanical analysis of SBO-PS–containing rubbers demonstrated that use of this compound in tire treads is expected to improve both rolling resistance and wet traction when compared with an AO-based rubber. The modification of SBO with grafted PS is a promising method of making processing oil, which can replace petroleum-based processing oils with bio-based renewable oils in tire tread compounds while improving their properties.

Keywords: rubber; tire tread compound; processing oil
FIG. 1
FIG. 1

Schematic representation of polystyrene grafting.

FIG. 2
FIG. 2

Rheological data for the tread compounds containing different oils.

FIG. 3
FIG. 3

Average stress-strain curves for the samples of base compound formulation.

FIG. 4
FIG. 4

Tensile property retention of tread compounds prepared with NO, SBO-PS, and NO/SBO-PS mixture after thermal aging.

FIG. 5
FIG. 5

Acetone soluble fraction (in wt%) for base compounds prepared with different oils, unaged and aged for 72 hours at 80 °C.

FIG. 6
FIG. 6

Tear resistance (A) and Shore A hardness (B) for the aged and unaged tread compound vulcanizates compounded with different oils.

FIG. 7
FIG. 7

Tan delta versus temperature curves for vulcanizates compounded with different oils (base compound formulations).

Contributor Notes

2 Corresponding author. Department of Coatings and Polymeric Materials, North Dakota State University, Department 2760, P.O. Box 6050, Fargo, North Dakota 58108-6050, USA. Email: dean.webster@ndsu.edu
  • Download PDF