Comparative studies using a gum formulation ( Table 1 ) on various activators were carried out. It was observed that NOVAL BD1288 reduces the cure time of gum compound indication its effectiveness not only as an activator component but also a secondary accelerator. This is commonly employed in rubber formulation to reduce cure time ( Table 2 ) but it has detrimental effect on scorch property at 5 phr level.

As indicated earlier, 5 phr of NOVAL BD1288 has a detrimental effect on scorch safety of a compound. To ensure scorch safety, experiments carried out showed that it is possible to reduce the level of NOVAL BD1288 (Figure 1).

To ensure scorch safety of a gum formulation, NOVAL BD1288 at 0.5 phr is sufficient to provide reasonable scorch and yet reduces cure time (Figure 2). The physical properties of the vulcanizates is similar as shown in Table 3.

Using a typical activator combination of 5 phr zinc oxide and 2 phr of stearic acid in a gum formulation (Table 1) NOVAL BD1288 was added at different levels. As indicated in Figure 3, 0.5 phr of NOVAL BD1288 is efficient enough to reduce cure time. Any further increase in dosage has an effect on cure characteristics.

The ability of NOVAL BD1288 to reduce cure time in the presence of stearic acid further indicates its usefulness as a secondary accelerator for example TMTD which is known to cause bloom on coloured products through the formation of zinc dimethyl dithiocarbamate (ZDMC) — the reaction product of TMTD with zinc oxide.

It is an incomplete exercise if the new material is not evaluated as a mono-accelerator (Table 4). The scorch time reduces with increasing levels of NOVAL BD1288 (Table 5).

The ability of NOVAL BD1288 to cause crosslinking of rubber chain is illustrated by the rheometer traces obtained @160°C (Figure 4). This provides the evidence that NOVAL BD1288 can behave as an accelerator/activator to affect vulcanization.

In this study, formulations as given in Table 6 were used. Figure 5 shows the effectiveness of NOVAL BD1288 as a secondary accelerator as proven by the fact that the scorch time is much shorter than a compound containing TMTD as a secondary accelerator. The advantage of using NOVAL BD1288 os further elucidated in Figure 6.

NOVAL BD1288 was also tested for its efficacy in black compounds (Table 6) and the processing characteristics are illustrated in Figures 5 and 6 in terms of scorch. The result shows that NOVAL BD1288 provides the activator /accelerator effect by reducing the scorch and cure time.

The vulcanizate properties of the black compound depicted in Table 7 indicates its ability to replace the conventional activator component stearic acid and secondary accelerator without affecting the vulcanizate properties.

The using of NOVAL BD1288 is not restricted to NR compounds only. It can also be used in synthetic rubber compounds such as SBR, chlorobutyl, butyl, EPDM and nitrile rubbers with different recipes. Results indicated that it can replace stearic acid and act as a secondary accelerator as projected by the reduction in cure time (Figure 7-11).

NOVAL BD1288 offers an alternative route in reducing material costs. It can behave as a primary/ secondary accelerator and as an activator component to replace stearic acid which is conventionally used in rubber recipe. Very low dosage of NOVAL BD1288 is sufficient to provide the effectiveness but with no compromise on physical properties vis-a-vis conventional method of compounding containing zinc oxide and stearic acid as an activator component.