Study on the Effect of Zinc on the Rheological, Mechanical and Thermal Properties and Fire Hazard of Unfilled and Filled CR/BR Vulcanizates.

Aleksandra Smejda-Krzewicka,Przemysław Rybiński,Krzysztof Strzelec,Anna Słubik

doi:10.3390/polym12122904

Aleksandra Smejda-Krzewicka, Przemysław Rybiński + Show 2 more

Open Access

https://doi.org/10.3390/polym12122904

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Abstract

This paper discusses the cross-linking and functional properties of elastomer composites containing chloroprene rubber (CR) and butadiene rubber (BR) cured in the presence of zinc (Zn) and reinforced with mineral fillers. The research aimed to evaluate the effectiveness of zinc as a new cross-linking substance with the simultaneous production of elastomer materials with good mechanical properties and a reduced fire hazard. The article concerns the study and explanation of the dependencies influencing the processing and functional properties of unfilled or filled elastomer blends containing different elastomers ratio or different zinc’s amount. The following fillers were used: silica, kaolin, chalk and montmorillonite. The results revealed that the cross-linking degree of CR/BR blends decreased with the increasing amount of butadiene rubber in the blends. The mechanical properties of the cured blends depended on the proportion of elastomers in the composites, the zinc amount, and the presence and type of filler. The flammability of CR/BR/Zn vulcanizates has been investigated before and after the filling. The parameters assessed by the oxygen index method and cone calorimetry, characterizing the behavior of the tested CR/BR/Zn vulcanizates under fire conditions, have shown that they constitute a low fire hazard and can be considered as non-flammable materials.

Highlights

Butadiene rubber (BR) is one of the most important synthetic elastomers, obtained by the polymerization of 1,3-butadiene [1,2,3]
Elastomer composites containing chloroprene and butadiene rubbers (CR/BR) can be effectively cross-linked with zinc, and the obtained cross-linking density obtained largely depends on the composition of the blend, including the mass ratio of both elastomers and the amount of zinc used
The best processing and performance properties of CR/BR blends can be obtained if the amount of chloroprene rubber is not less than 60 phr and the zinc’s content is not more than 2.5 phr

Summary

Introduction

Butadiene rubber (BR) is one of the most important synthetic elastomers, obtained by the polymerization of 1,3-butadiene [1,2,3]. The participation of individual units is important for the chemical structure of BR, and for its functional properties [4,5]. Due to its low glass transition temperature (Tg ~105 ◦ C), compared to the styrene-butadiene rubber (SBR) or natural rubber (NR), this rubber is preferred, in particular, for the production of tires with low rolling resistance. Tires with low rolling resistance are characterized by lower fuel consumption in the car and result in lower emissions of carbon dioxide to the atmosphere [9,10]. Vulcanized BR reveals a poor wet skid resistance, low tear strength and tensile strength and the presence of double bonds in macromolecules

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