Condom industry waste mainly consists of light magnesium carbonate (LMC), which is extensively used as a finishing powder during the final stages of condom production. This LMC waste (LW) is usually disposed of as a landfill, causing an increase in the hardness of water. LW generated in HLL Lifecare Limited, India, was procured, characterized by analytical techniques, and reutilized in natural rubber (NR) as a reinforcing filler. The prepared composites were subjected to rheological, mechanical, thermal and sorption characterizations. In comparison to NR neat, the composite with 3 phr (parts per hundred of rubber) LW showed a rise in tensile strength, tear strength, and modulus at 300% elongation by 22%, 20%, and 28%, respectively. A remarkable decrease in abrasion loss is also evidenced. The activation energy (Ea) for degradation, calculated by the Coats-Redfern (CR) method, showed 10 kJmol-1 increase for composite with 3 phr LW, proving its better thermal stability. It also exhibited higher solvent uptake resistance, as established by sorption experiments. The superior properties of this composite have been attributed to the uniform LW distribution and ameliorated NR-LW interaction. Hence, the prepared composites find considerable potential in manufacturing industrial NR components accomplishing a circular economy.
Reutilization of industrial waste is one of the emerging strategies to combat solid waste disposal for the protection of our environment. The present work describes a novel and economic approach to reutilize finely ground shoe sole scrap, a thermoset polyurethane-based waste (PUW) material generated during shoe sole production in footwear industries as an efficient reinforcing filler in natural rubber (NR). Shoe sole scrap was ground to fine powder and characterized by various analytical techniques. NR-PUW composites were prepared using 0–20 phr (parts per hundred of rubber) of PUW. The cure characteristics, mechanical, thermal, and morphological properties of prepared composites were studied. Composite with 5 phr PUW showed a remarkable improvement in tensile strength by 10% and modulus at 300% elongation increased by 9% compared to that of neat sample. A considerable increase in abrasion resistance and tear strength was also observed in 5 phr PUW loaded composites. Other mechanical properties like hardness, heat build-up and compression set showed a regular increase with further filler loading. To estimate the level of interfacial adhesion between the filler and the matrix, the experimental values of tensile strength were compared with Nicolais–Narkis (N–N), Lu, and Turcsányi–Pukànszky–Tüdõs (T–P–T) models and elastic modulus values with Einstein and Guth and Smallwood models. The tensile strength values are in agreement with T-P-T model (B = 4), up to 5 phr PUW proving the better adhesion between NR and PUW at lower filler loadings. At higher PUW loading, the experimental results are approaching Lu and N–N models indicating that this adhesion is collapsed. The incorporation of PUW as a filler in NR does not adversely impact the thermal stability of prepared composites. The results obtained are not only promising from a circular economy perspective, but also is contributive in production of high-performance, low-cost NR composites for various industrial applications.
Benzyl chloride, benzyl bromide and their para substituted derivatives were selectively oxidized to corresponding benzaldehydes by acidified monochromate in toluene and ethyl acetate with the help of phase transfer catalysts like tetrabutylphosphonium bromide (TBPB), tetrabutylammonium bromide (TBAB), tetrabutylammonium hydrogen sulphate (TBAHS), cetyltrimethylammonium bromide (CTMAB) and tricaprylmethylammonium chloride (TCMC). The reaction was carried out by simple magnetic stirring for about 2 h at 60 ºC. The products were recrystallized and analyzed by infrared and UV-visible spectral techniques. Benzaldehyde and substituted benzaldehydes were formed in good yield (> 90%) on oxidation of benzyl chlorides and benzyl bromides. The reaction is proved to be highly selective due to the absence of acids or any other products during the reaction. All the phase transfer catalysts were highly effective in bringing out the reaction in both the solvents. This is highly significant as the oxidation reaction will not occur in non-polar solvents without the presence of phase transfer catalysts.
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