Tuning of accelerator and curing system in devulcanized green natural rubber compounds

Abstract These days sustainable ecosystem warrants cleaner, safer and easier mobility of resources in a production cycle. In a response of such call, in this present work, sulphur crosslinked natural rubber (NR) is successfully devulcanized using bis(3-triethoxysilyl propyl) tetrasulfide (TESPT) - a dual function disulfide chemical. It is observed that the mono-, di- and poly sulfide crosslinks, those determine the final performance of the composites, can be controlled by using various chemicals like N-cyclohexyl-benzothiazyl-sulphenamide (CBS), tetramethylthiuram disulfide (TMTD), 2-mercaptobenzothiazol (MBT) and N-tert-butyl-2-benzothiazyl-sulphonamide (TBBS). Subsequently different vulcanizing systems like conventional, efficient and semi efficient vulcanization systems were also studied. Furthermore, in the optimization of vulcanizing system, semi-EV showed the highest mechanical properties compared to that of the CV and EV system. The study shows a unique correlation between the crosslink density, (mono-, di- and polysulfide) and the mole % uptake of the solvent with time. It also shows the dependence of the fraction of immobilized polymer chain and the segmental dynamics of the composites on the crosslink density.