Curing characteristics, mechanical properties and morphology of butyl rubber filled with ground tire rubber (GTR)

Krzysztof Formela,Józef T Haponiuk

doi:10.1007/s13726-013-0214-7

Abstract

The results on testing application of ground tire rubber (GTR), as potential filler for butyl rubber, are presented. The GTR content variation, within the range of 10–90 phr, was studied with respect to the vulcanization process, static mechanical properties (tensile strength, elongation-at-break, hardness and resilience), dynamic mechanical properties and the morphology of the obtained vulcanizates. Butyl rubber was characterized by its low compatibility to other elastomers [i.e., natural rubber and styrene–butadiene rubber (SBR)—the main ingredients of tires] and low degree of unsaturation. To evaluate the impact of these factors on curing characteristics and mechanical properties of butyl rubber vulcanizates filled with GTR, the same compositions of SBR compounds, cured under identical conditions, were used as reference samples. Based on the obtained data, it can be stated that butyl rubber vulcanizates containing 30 phr of GTR as filler revealed the highest tensile strength and elongation-at-break. The microstructural analysis of a sample containing 30 phr of GTR revealed strong interactions between the butyl rubber matrix and GTR. This phenomenon resulted mainly from two factors. First, the cross-link density of the butyl rubber matrix was affected by its competition against GTR for cross-linking agents. Secondly, the migration of carbon black particles from GTR into the butyl rubber matrix had a significant impact on properties of the obtained vulcanizates.

Highlights

There are numerous research works which have attempted to design novel methods of resolving the recycling problem of scrap rubbers and to achieve alternative products based on recycled polymeric materials
Swelling degree increased with ground tire rubber (GTR) content in butyl vulcanizates, which was due to low cross-linking of butyl rubber matrix and lowering of cross-linking density of GTR arising from partial devulcanization of GTR
Tetramethylthiuram disulfide accelerator (TMTD) was used as vulcanization accelerator which might have acted as a devulcanization agent for GTR [36

Summary

Introduction

There are numerous research works which have attempted to design novel methods of resolving the recycling problem of scrap rubbers and to achieve alternative products based on recycled polymeric materials. The studies in this area have focused mainly on searching new methods of material recycling and on improving the existing methods. The economic and environmental factors related to the reduction of energy and materials costs for manufacturing of new products recommend a direct application of ground tire rubber (GTR) This is the most justifiable way because in this case GTR does not require any additional processing, for it compensates the production cost of novel materials. Ground tire rubber has been mainly used as filler in polymer compositions [8,9,10,11], thermoplastic elastomers [12,13,14,15] and as modifier of bitumen [16,17,18] and cements [19]

Methods

Results

Conclusion