Mixing, Curing and Reinforcement of NR/BR/EPDM Blends for Tire Sidewall Applications

2009 ◽  
Vol 82 (3) ◽  
pp. 379-399 ◽  
Author(s):  
H. Zhang ◽  
R. N. Datta ◽  
A. G. Talma ◽  
J. W. M. Noordermeer
Keyword(s):  
Natural Rubber ◽  
Butadiene Rubber ◽  
High Concentration ◽  
Ethylene Propylene ◽  
Ethylene Propylene Diene Rubber ◽  
Filler Distribution ◽  
Diene Rubber ◽  
Ozone Resistance

Abstract Tire sidewalls generally consist of blends of natural rubber (NR) and butadiene rubber (BR), containing a high concentration of antiozonants to provide ozone resistance. However, the most widely used antiozonant, N-(1, 3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine (6PPD), is a staining, toxic and environmentally unfriendly substance. Incorporation of Ethylene-Propylene-Diene rubber (EPDM) into NR/BR is a way of achieving non-staining ozone resistance. But blending of dissimilar rubbers is severely restricted due to viscosity mismatch, thermodynamic incompatibility, cure incompatibility and heterogeneous filler distribution. This chapter gives an overview of the various research approaches in the field of blending dissimilar rubbers so far, as well as the mechanism of ozone protection by incorporation of EPDM in tire sidewall applications.

Mechanisms Involved in the Recycling of NR and EPDM

1999 ◽  
Vol 72 (4) ◽  
pp. 731-740 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
J. W. M. Noordermeer ◽  
M. van Duin ◽  
H. J. Manuel
Keyword(s):  
Natural Rubber ◽  
Crosslink Density ◽  
Main Chain ◽  
Chain Scission ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Lower Reactivity ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber ◽  
Crosslink Densities

Abstract The thermochemical recycling of natural rubber (NR) and ethylene-propylene-diene rubber (EPDM) vulcanizates with disulfides was studied. NR sulfur vulcanizates were completely plasticized when heated with diphenyldisulfide at 200 °C. It could be concluded that both main chain scission and crosslink scission caused the network breakdown. NR peroxide vulcanizates were less reactive towards disulfide at 200 °C, and only reacted through main chain scission. For EPDM a temperature range of 200–275 °C was studied. In the presence of diphenyldisulfide at 200 °C there was almost no devulcanization of EPDM sulfur vulcanizates, and at 225 and 250 °C there was only slightly more devulcanization. A decrease in crosslink density of 90% was found when 2×10−4 mol diphenyldisulfide/cm3 vulcanizate was added and the EPDM sulfur vulcanizates were heated to 275 °C. EPDM peroxide vulcanizates showed a decrease in crosslink density of ca. 40% under the same conditions. The lower reactivity of EPDM towards disulfide compared with NR is the result of higher crosslink densities, the presence of a higher percentage of more stable monosulfidic crosslinks and the fact that EPDM is less apt to main chain scission relative to NR.

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