ABSTRACT

The rubber industry is rife with problems associated with blooming of additives to the surface of rubber products; for sulfur blooms especially, this has led to the use of other forms of sulfur, particularly expensive insoluble sulfur. To tackle this issue, sulfur-encapsulated alginate beads were used in this study and the blooming characteristics in NR were compared with soluble and insoluble sulfur. At testing temperatures of 100 and 120 °C, sulfur-encapsulated beads yielded less sulfur blooming than soluble sulfur. The beads also showed relatively less blooming than insoluble sulfur at 120 °C, whereas the two were comparable at 100 °C. Statistically, the tensile strength of vulcanized rubber with the beads (mean ± SD, 18.9 ± 2.5 MPa) was not significantly different (p = 0.067) from that with insoluble sulfur (22.2 ± 2.5 MPa), although lower (p = 0.011) than that with soluble sulfur (23.3 ± 0.7 MPa). Altogether, the study results showed that the sulfur-encapsulated alginate beads could be used as a substitute for soluble sulfur and insoluble sulfur in rubber compounding.