Rubber residues present harmful impacts on health and environment, besides wasting valuable and huge amounts of rubber. Biological recycling technique is focused here to minimize this problem. A comparison of the biodegradation effect caused by Bacillus subtilis, Pseudomonas aeruginosa, and Streptomyces sp., separately, on vulcanized SBR-rubber during 4 weeks is reported. The surface and molecular analyses were studied by FTIR-ATR, TGA, DSC, TC and SEM/EDS, in addition to the contact angle and crosslinking tests. B. subtilis, P. aeruginosa, and Streptomyces sp. evoked after 4 weeks a loss in v-SBR crosslinks by 17.15, 10.68 and 43.39% and also in the contact angle with water by 14.10, 12.86 and 15.71%, respectively., if compared to Control samples. FTIR findings indicate that the polymeric chain has been partially consumed causing C-C bonds scission indicating the biodegradation and bio-devulcanization phenomena. The bacterial strains caused a carbon loss by 9.15, 5.97 and 4.55% after one week and 16.09, 16.79 and 18.13% after four weeks for B. subtilis, P. aeruginosa, and Streptomyces sp. mediums, respectively. DSC and EDS results are also promising and highlighting Streptomyces sp. strain as the most effective biodegradative one as an alternative and natural mean of degrading vulcanized rubber residues.
Flexible cement sheath can eliminate the formation of cracks caused by the thermal recovery in the EOR methods. SBR‐modified slurries were fabricated by adding Styrene‐Butadiene Rubber (SBR) in latex to the cement matrix. In this article, the influence of this latex on the hydration kinetics of the cement slurry was investigated. SBR (≈83% of Styrene) was added by 6%, 10%, and 13% (V/V) to prepare the slurries and the kinetics in both fresh and hardened states were accompanied by UCA and isothermal calorimetry. The results indicated that in the very early ages of hydration, Ca(OH)2 was consumed by SBR (demulsification phenomenon). A retarding effect was observed and the percolation threshold values were increased by 18.05%, 19.44%, and 27.77% for the SBR‐modified slurries, whereas an overall higher accumulated heat could be observed in the isothermal calorimetry curves when compared to the reference slurry.
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