Editorial Type:
Article Category: Other
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Online Publication Date: 01 Oct 2014

Determination of Combined and Second Order Factor Effects for Simultaneous Optimization of Physical and Mechanical Properties of NR/BR Blend System

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Page Range: 290 – 304
DOI: 10.2346/tire.14.420404
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ABSTRACT

The blends of natural rubber (NR), polybutadiene rubber (BR), and other forms of rubbers are widely used for enhancing the mechanical and physical properties of rubber compounds. Lots of work has been done in conditioning and mixing of NR/BR blends to improve the properties of its rubber compounds and end products such as tire tread. This article employs response surface methodology designed experiments in five factors; high abrasion furnace carbon black (N 330), aromatic oil, NR/BR ratio, sulfur, and N-oxydiethylene-2-benzothiazole sulfenamide for determination of combined and second order effects of the significant factors leading to simultaneous optimization of the NR/BR blend system. One of the overall optimum of eight properties existed at carbon 44 phr, oil 6.1 phr, NR/BR 78/22 phr with the following values of properties: tensile strength (22 MPa), elongation at break (528%), tear resistance (30 kg/mm), rebound resilience (67%), moderate hardness (68 International rubber hardness degrees) with low heat buildup (17 °C), permanent set (12%), and abrasion loss (57 mm3). More optimum combinations can easily be determined from the NR/BR blend system models contour plots.

Keywords: CCD; NR/BR blend; second order; simultaneous optimization; RSM
FIG. 1
FIG. 1

Contour plot of tensile strength (Mpa) vs carbon, oil at NR/BR 88/12 phr.

FIG. 2
FIG. 2

Contour plot of square root transformed EB(%) vs carbon, NR/BR at oil 9 phr.

FIG. 3
FIG. 3

Contour plot of hardness (IRHD) vs carbon, oil at NR/BR 88/12 phr.

FIG. 4
FIG. 4

Contour plot of rebound resilience (%) vs carbon, NR/BR at oil 7 phr.

FIG. 5
FIG. 5

Contour plot of tear resistance (kg/mm) vs carbon, NR/BR at oil 7 phr.

FIG. 6
FIG. 6

Contour plot of heat build up (°C) vs carbon, NR/BR at oil 7 phr.

FIG. 7
FIG. 7

Contour plot of permanent set (%) vs carbon, NR/BR at oil 7 phr.

FIG. 8
FIG. 8

Contour plot of DIN abrasion (mm3) vs carbon, NR/BR at oil 7 phr.

FIG. 9
FIG. 9

Overlaid plot of TS, square root transformed EB, H, RR, TR, HBU, PS, DA vs carbon, NR/BR at oil 7 phr.

Contributor Notes

1 Corresponding author. Plastic Industries (Pty) Ltd, 7 Sigma Road, Germiston 1401, P.O. Box 4451, Johannesburg, South Africa. Email: rajanaiyenger@yahoo.com
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