Transforming silica-silane reinforced rubber into a high quality devulcanizate

The research aims to develop a more environmentally sustainable devulcanization process for rubber sourced from silica-silane based passenger car tires to achieve a high-quality devulcanizate. A comprehensive literature review covers various aspects, including tire tread compounding, devulcanization mechanisms, and recent developments in devulcanization of ground tire rubber (GTR).A screening of devulcanization aids (DAs) for passenger car tire tread granulate chosen from commonly used rubber chemicals, is conducted to identify the most promising one: vinyl silane with peroxide (VP). Optimization of devulcanization parameters using VP is performed for model tire tread material and whole tire granulate. Further investigations involve varying combinations of DAs assessing a synergistic effect, exploring the impact of individual constituents, and investigating devulcanization solely employing peroxides. The devulcanization reaction mechanism of vinyl silane and VP is analyzed using a liquid model compound.In the next step devulcanization with variation in processing aid is carried out to pinpoint the optimal one. An examination of the influence of fillers and the effect of the silanization reaction on the devulcanizate properties is conducted.The best devulcanizate is blended with a model passenger tire tread compound, and its applicability for tires is comprehensively analyzed. A comparison between newly developed devulcanizates and commercial counterparts is conducted, establishing a correlation between tensile strength and miscibility for samples devulcanized using various DAs and process conditions.Results are transferred from a batch process and upscaled to an continuous extruder process, aiming to achieve increased productivity and to facilitate industrialization. The future of rubber recycling through devulcanization holds promise for reducing waste, conserving resources, and establishing sustainability in the rubber industry

Biosorption of Acid dye by Jackfruit Leaf Powder: Isotherm, kinetics and Response surface methodology studies

A green adsorbent derived from Jackfruit leaf powder (JLP) was used to eliminate Acid Yellow 99 (AY 99) dye from an aqueous medium in this study. We checked the effect of pH, biomass dosage, and temperature (process parameters) on the adsorption potential of AY 99 was explored using the CCD model integrating the RSM approach. At a pH of 2.5, biosorbent dosage of 4 gL-1, and a 30°C temperature, maximum removal was preferred. ANOVA was incorporated to observe the importance of experimental variables and their interactions. The solution pH (A) and biomass dose (C) had the greatest effects on the decolorization of AY 99, according to the findings. ANOVA was used to identify the most important factors, which included two independent variables (A and C) and two quadratic model terms (A2 and C2). The kinetic data were effectively interpreted using a pseudo 2nd order with film diffusion model combination, indicating the chemisorptions phenomenon. Following the model of Langmuir isotherm, the utmost capacity for adsorption was determined to be 418.15 mg g-1 in terms of initial dye concentration. The findings of the maximum adsorption capacity showed that JLP could be employed as a useful adsorbent to eliminate AY 99 from its aqueous medium

A Theoretical Approach to Demystify the Role of Copper Salts and O2 in the Mechanism of C-N Bond Cleavage and Nitrogen Transfer

C≡N bond scission accomplished by protonation, reductive cleavage and metathesis techniques are well-known to execute nitrogen transfer reactions. Herein, we have conducted an extensive computational study, using DFT and molecular dynamics simulations, to unravel the mechanistic pathways traversed in CuCN and CuBr2 promoted splitting of coordinated cyanide anion under a dioxygen atmosphere, which enables nitrogen transfer to various aldehydes. Our detailed electronic structure analysis using ab initio multi-reference CASSCF calculations reveal that both the promoters facilitate radical pathways, in agreement with the experimental findings. This is a unique instance of oxygen activation initiated by single electron transfer from the nitrile carbon, while the major driving force is the operation of the CuII/I redox cycle. Our study reveals that the copper salts act as the “electron pool” in this unique nitrogen transfer reaction forming aryl nitrile from aryl aldehydes.<br /

Exploring the Impact of Reinforcing Filler Systems on Devulcanizate Composites

Composites revolutionize material performance, fostering innovation and efficiency in diverse sectors. Elastomer-based polymeric composites are crucial for applications requiring superior mechanical strength and durability. Widely applied in automotives, aerospace, construction, and consumer goods, they excel under extreme conditions. Composites based on recycled rubber, fortified with reinforcing fillers, represent a sustainable material innovation by repurposing discarded rubber. The integration of reinforcing agents enhances the strength and resilience of this composite, and the recycled polymeric matrix offers an eco-friendly alternative to virgin elastomers, reducing their environmental impact. Devulcanized rubber, with inherently lower mechanical properties than virgin rubber, requires enhancement of its quality for reuse in a circular economy: considerable amounts of recycled tire rubber can only be applied in new tires if the property profile comes close to the one of the virgin rubber. To achieve this, model passenger car tire and whole tire rubber granulates were transformed into elastomeric composites through optimized devulcanization and blending with additional fillers like carbon black and silica–silane. These fillers were chosen as they are commonly used in tire compounding, but they lose their reactivity during their service life and the devulcanization process. Incorporation of 20% (w/w) additional filler enhanced the strength of the devulcanizate composites by up to 15%. Additionally, increased silane concentration significantly further improved the tensile strength, Payne effect, and dispersion by enhancing the polymer–filler interaction through improved silanization. Higher silane concentrations reduced elongation at break and increased crosslink density, as it leads to a stable filler–polymer network. The optimal concentration of a silica–silane filler system for a devulcanizate was found to be 20% silica with 3% silane, showing the best property profile