Characterization of recycled nitrile butadiene rubber industrial scraps

The amount of rubber scraps derived from rubber goods production consists of about 20-30% of the processed material, so it is necessary to enhance this material by developing new recycling techniques as well as a new market for recycled rubber products. In the present research, nitrile-butadiene rubber (NBR) scraps are reprocessed via a calendering process acting with a mechanical devulcanization. Compounds were prepared with 20%, 80%, and 100% recycled rubber content and characterized. The experimental results highlighted that the compound prepared with 20% recycled rubber content via calendering and compression molding processes shows comparable mechanical properties to that of virgin NBR. The tensile properties are the most penalized by the increasing content of recycled material (100% recycled shows - 25% and - 50% stress and strain at break, respectively). Other properties remain comparable to the standard material up to 80% recycled material: 60 +/- 5 Shore A, compression elastic modulus 8 MPa, compression set 20%. FTIR analysis revealed no changes in chemical structure from the recycling process. The results demonstrate that simple mechanical devulcanization can effectively reprocess industrial rubber waste while largely maintaining useful properties. This provides a potential pathway to enhance sustainability in rubber production through the valorization of process scraps

Steel slag as a low-impact filler in rubber compounds for environmental sustainability

This study investigates the use of electric arc furnace (EAF) slag, as a substitute for conventional filler, such as calcium carbonate, in nitrile-butadiene rubber (NBR) composites in different volume fraction. The results demonstrate that slag exhibits morphological traits comparable to calcium carbonate when used as a filler, moreover their processability and mechanical properties are similar. Specifically, at 20% v/v, slag-flled NBR exhibits slightly longer scorch times but unchanged vulcanization times. Both fillers at 20% v/v show comparable hardness, compression strength, and elastic modulus. Tensile properties are also comparable, except for the strain at break, where slag-filled NBR shows a 40% higher tensile strain at break. The environmental impact of this innovative slag application has been evaluated through a comparative life cycle assessment. All assessed impact categories demonstrate a reduction of at least 89%. The study suggests that the use of EAF slag has the potential to promote sustainable waste management

Assessment of the influence of electric arc furnace slag as a non-conventional filler for Nitrile Butadiene Rubber

Reinforcement of polymers by the addition of particles filler is a complex phenomenon that depends mainly on the hydrodynamic effect and a complex interplay between polymer, filler, and interfacial region. Mineral fillers are usually adopted as low-cost extenders due to their lower cost. In this study, the influence of a waste material such as electric arc furnace steel slag is assessed as filler for Nitrile-Butadiene Rubber following experimental procedures and analytical calculations adopted for traditional fillers. It was found that the slag content affects the static and the dynamic properties by increasing the material's capability to storage and dissipate energy. In addition to an important contribution of the hydrodynamic effect, the presence of an increasing immobilized rubber fraction around the slag particles (quantified by a differential scanning calorimetry analysis) plays a central role. The slag stiffens the NBR composite; the increase of static tensile and dynamic shear storage moduli was found to be consistent with the Halpin-Tsai and Guth-Gold prevision models respectively. Moreover, the non-linear dynamic behavior was found to be well-fitted by the Kraus equation models. The reinforcing ability of the slag particles as filler was confirmed by the negative slope of the Kraus plot on swelling data

Innovative reuse of electric arc furnace slag as filler for different polymer matrixes

The European steel industry produces about 70 million tons/year of steel by the electric arc furnace (EAF). The slag consists of about 15% by weight of the produced steel, thus from the perspective of the circular economy, it has a high potential as a co‐product. This research aims to assess an innovative reuse of EAF slag as filler in different polymer matrixes: thermoplastic (poly-propylene), thermosetting (epoxy resin), elastomeric (nitrile butadiene rubber), and recycled end of life rubber tire. A comparison between neat polymer and polymer filled with a certain amount of EAF slag has been carried out by tensile (or flexural), compression, and hardness tests. Experimental results show that slag as a filler increases the composites’ hardness and elastic modulus at the expense of toughness. For a safe reuse of the slag, the leaching of hazardous elements must comply with current legislation. It was found that, although the used EAF slag releases small amounts of Cr, Mo, and V, incorporating it into a polymer matrix reduces the leaching. The EAF slag particles distribution has been observed by scanning electron microscopy (SEM) images. The obtained results show good technical feasibility of this innovative slag application so that it could pave the way to a new industrial symbiosis between dissimilar sectors, bringing economic and environmental benefits

Reuse of Electric Arc Furnace Slag as Filler for Nitrile Butadiene Rubber

This work shows an innovative application for electric arc furnace (EAF) slag: its use as a filler for nitrile butadiene rubber (NBR). Composites with various EAF slag contents were tested. It was found that the polymer matrix significantly reduces the leaching of slag (determined according to the standard CEN-EN 12457-2) incorporated in the NBR. The processability characteristics determined by the rheometric curves highlight that the EAF slag accelerates the crosslinking kinetics, reducing the production cycle time. Mechanical characterization demonstrated that EAF slag increases hardness and compression modulus. The ability to recover an imposed deformation quantified by the compression set is reduced as the EAF slag amount increases but remains below an acceptable value. It can be stated that in sealing systems, the EAF slag as a filler for NBR positively affects the compound properties. Moreover, NBR filled with EAF slag also has magnetic properties compared with standard rubber