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The sustainable material—thermoplastic potato starch (TPS)—was blended with modified natural rubber–epoxidized natural rubber (ENR). The poor mechanical properties of the ENR/TPS blends limited the application. Sulfur vulcanization is a common and economical method to improve the mechanical properties in the rubber industry. To fully understand the relationship between vulcanization systems and ENR/TPS blends and the sustainability of the developed material, the effects of a vulcanization accelerator (N-cyclohexylbenzothiazole-2-sulphenamide (CBS), 2-mercaptobenzothiazole (MBT), N-tert-butylbenzothiazole-2-sulphenamide (TBBS)) and a system type (conventional vulcanization (CV), semi-efficient vulcanization (SEV) and efficient vulcanization (EV)) on curing characteristics, mechanical and thermal properties, water absorption and biodegradability were systematically evaluated. The results indicate that vulcanization significantly improves the mechanical properties of ENR/TPS blends. The performance optimization of the CBS-CV vulcanization system is the best for improving the mechanical properties and reducing the water absorption. The CBS-CV curing system makes ENR/TPS less biodegradable (12–56% of mass loss) than other accelerators and systems. TBBS-CV makes the material more biodegradable (18–66% of mass loss). The low rubber content enables the rapid biodegradation of the vulcanized blend. This has implications for research on sustainable materials. The material can be applied for eco-friendly packaging and agricultural films, etc. The investigation on performance by using common accelerators and systems provides ideas for industries and research.

Natural rubber, given its natural origin, is not composed exclusively of polyisoprene chains, but also of so-called non-rubber components such as proteins or phospholipids. Such compounds are responsible for gel formation - insoluble phase if natural rubber (NR) is in a proper solvent. Gel is one of the causes why the behavior of NR is non-standard during processing. The gel content is determined by various methods, while it is not examined in detail which method has a stronger relation to the rheological behavior of rubber. Three different methods (filtration, dissolution in toluene for three different times and Soxhlet extraction) used for determining the gel content of NR are compared in this paper. Analytical (ash content, molar mass measurement, …) and rheological (Mooney viscosity, rubber process analyzer measurements, …) measurements are performed and their results are correlated with the gel content values.