Effect of nanoZnO over conventional ZnO on preservation of concentrated natural rubber latex

An attempt was made to replace conventional ZnO with nanoZnO in low ammonia, tetramethylthiuramdisulphide (TMTD)/Zinc oxide (ZnO) natural rubber latex preservative system (LATZ). Different percentages of TMTD and nanoZnO dispersions containing equal portions were prepared and used to preserve the latex. Centrifuged natural rubber latex (CNRL) thus prepared were tested for VFA (volatile fatty acid) number and MST (mechanical stability time) periodically over a period of 75 days. Mechanical properties of vulcanized latex thin films made out of CNRL preserved were measured. Development of VFA number in CNRL samples preserved with nanoZnO was lower than the sample prepared with the conventional ZnO (control). Both the VFA number results and surface plots of the matured CNRL samples showed that preservative action of the modified preservative system was mainly governed by the amount of nanoZnO in the system. MST values of CNRL preserved with nanoZnO substituted systems were significantly high when compared to the control. Tensile and tear properties of the vulcanized films prepared using CNRL preserved with nanoZnO were almost comparable with those of the vulcanized films prepared using control system. The statistical analysis indicated that CNRL preserved with modified preservative system of 10% and 15% of TMTD/nanoZnO could be stored up to 55 and 75 days respectively, without exceeding VFA value above 0.02.