ARTICLE | doi:10.20944/preprints202109.0411.v1
Subject: Chemistry And Materials Science, Polymers And Plastics Keywords: Brominated butyl rubber; Thermal decomposition; Lifetime
Online: 23 September 2021 (13:15:39 CEST)
The thermal decomposition of brominated butyl rubber under air atmosphere was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG) at various heating rates. The kinetic parameters were evaluated by TG and the isoconversional method developed by Ozawa. One prominent decomposition stage was observed in the DTG curves at high heating rates while an additional small peak was observed at low heating rates. The apparent activation energy determined using the TG method ranged from 219.31–228.13 kJ·mol-1 at various heating rates. The non-isothermal degradation was found to be a first order reaction, and the activation energy, as determined by the isoconversional method, increased with an increase in mass loss. The kinetic data suggested that brominated butyl rubber had excellent thermal stability. This study will indirectly aid in improving rubber pyrolysis methods and in enhancing the heat resistance of materials.
ARTICLE | doi:10.20944/preprints202005.0102.v1
Subject: Medicine And Pharmacology, Pharmacology And Toxicology Keywords: marine natural products; Laurencia; brominated sesquiterpenes; antimycobacterial; nontuberculous mycobacteria; tuberculosis
Online: 6 May 2020 (15:32:53 CEST)
Marine environments represent a great opportunity for the discovery of compounds with a wide spectrum of bioactive properties. Due to the privileged conditions of natural selection, marine natural products are subject to overcome the pressure put on identify novel drugs; not only in the case of newly discovered bioactive metabolites, but also in those previously known. Since drug resistance has caused an increase in infections caused by tuberculous and nontuberculous Mycobacteria, the re-evaluation of known bioactive metabolites has been suggested as a means to address this problem. In this sense, this study presents an evaluation of in vitro effect of laurinterol (1) and aplysin (2), two brominated sesquiterpenes isolated from Laurencia johnstonii against nine Mycobacterium tuberculosis strains and six nontuberculous mycobacteria. Laurinterol (1) exhibited good anti-tuberculous activity, especially against nontuberculous mycobacteria, being remarkable the effect against M. abscessus with MIC values lower than the reference drug imipenem. This study provides further evidence for the antimycobacterial activity of some sesquiterpenes from L. johnstonii, that can be considered an interesting lead compound for the discovery of novel antimycobacterial molecules to treat NTM infections.
ARTICLE | doi:10.20944/preprints202303.0516.v1
Subject: Environmental And Earth Sciences, Sustainable Science And Technology Keywords: Melt-blend extrusion; 3D filament; brominated flame retardants; solvent extraction; acetone smoothing
Online: 30 March 2023 (02:41:32 CEST)
Less than half of e-waste plastics is sorted worldwide and this rate is likely to decline as major processing countries have banned importation of e-waste plastics. This forces the development of decentralized processing facilities, also known as microfactories. The present work investigates the recyclability of different grades of acrylonitrile-butadiene-styrene (ABS) copolymer, polycarbonate, and polypropylene, which were found to be very abundant in a recycling site in the UK. The determination of the matrix relied on the resin identification code imprinted in the e-waste plastic and subsequent FTIR analysis. The melt-blend extrusion technology enabled the valorization of the wasted thermoplastics as 3D filament without significant degradation of the polymers. The recycled materials maintained the tensile strength around 2.5 MPa in agreement with the specifications offered by virgin polymers. Further characterization was done by means of laser microscope, thermogravimetric analysis, and XRF to determine the commercial viability of the recycled filament. A modified solvent-based method was developed with acetone to remove the brominated flame retardants: 25g/100mL, 30 minutes of contact time, and 4 extraction steps. The FTIR results show that the degradation of the rubbery dispersed phase corresponding to the butadiene can be accumulated in the less soluble fraction of the waste ABS.