Effect of vulcanization systems on the properties of natural rubber latex films

Natural rubber latex (NRL) films have high elasticity and flexibility and are excellent protection barriers against micro-organisms. For this reason, NRL is often used in the manufacture of medical products, such as gloves, condoms, blood transfusion tubes and catheters. The objective of this study was to evaluate the effect of two accelerators, ZDEC and TMTD, of the sulphur-based curing system, on the rheometric, crosslink density, thermal and mechanical properties. For this purpose, the compositions of NRL films were designed using two-level factorial design with a centre point, considering the variation from − 1 to + 1 of the levels of sulphur and accelerators. The results indicated that the delta torque was influenced by the addition of sulphur only. Scorch time (Ts1) and optimum vulcanization time (T90) decreased as TMTD was added to the formulations. TMTD only contributed to the crosslink density when low amounts of sulphur were used. Higher values of tensile strength were observed for sulphur, ZDEC and TMTD amounts, but it was close to the centre point experiments. SEV and EV vulcanization systems did not necessarily produce crosslinks that require higher energy to brake when compared to CONV system.