Rate of Cure of Reclaimed Rubber—II

F. L. Kilboura; G. W. Miller

doi:10.5254/1.3535489

Rate of Cure of Reclaimed Rubber—II

Rubber Chemistry and Technology ◽

10.5254/1.3535489 ◽

1930 ◽

Vol 3 (2) ◽

pp. 315-327

Author(s):

F. L. Kilboura ◽

G. W. Miller

Keyword(s):

Physical Properties ◽

Sodium Hydroxide ◽

Rapid Rate ◽

Oven Test ◽

Rubber Compounds ◽

Aging Resistance

Abstract Residual alkali in reclaim is chiefly responsible for the faster rate of cure of stocks containing reclaimed rubber as compared with those containing new rubber only. Reclaim prepared in water can be made to cure as fast as alkali reclaim by the addition of sodium hydroxide to the extent that this is present in the alkali reclaim. The determination of residual alkali requires a very long extraction, in this case approximately 60 days. Of five possible theories accounting for the rapid rate of cure of reclaim, only that of residual alkali is tenable. There still remains in certain cases, however, a difference in rate of cure between stocks containing new rubber and those containing water-cooked reclaim for which no explanation has been found. Sodium hydroxide of itself is not deleterious to rubber compounds, for, in addition to its value as an accelerator in certain cases, it tends to improve physical properties and aging resistance, as judged by the Geer oven test.

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

Tire Science and Technology ◽

10.2346/tire.14.420404 ◽

2014 ◽

Vol 42 (4) ◽

pp. 290-304

Author(s):

Rajarajan Aiyengar ◽

Jyoti Divecha

Keyword(s):

Physical And Mechanical Properties ◽

Second Order ◽

Simultaneous Optimization ◽

Order Effects ◽

Elongation At Break ◽

Five Factors ◽

Rubber Compounds ◽

Polybutadiene Rubber ◽

Contour Plots

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.

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