Compounding and testing of three modified elastomers as parenteral stopper

ABSTRACT

Tetramethylthiouram disulphide TMTD is known as vulcanizing agent alone or with mercaptobenzothiazole [MBT] in the presence of small quantity of sulfur. Different concentrations of TMTD were added to natural crepe and to bromobutyl rubber mixes in 0.5-3% w/w of rubber at different curing temperatures [140-160C]. It was found that the addition of 2% TMTD for each one of the two elastomers at 150C yielded products with good physicomechanical and swelling properties. When the vulcanizing system of 2% TMTD and 0.1% MBT was used, a delay in the cure time [Tc90] and an increase in the scorch time [TS2] were observed, the effect of blending the natural and bromobutyl rubber mixes in different% showed that increasing the natural rubber [NR] in the blends up to 40% arose the cure time and improved the physicomechanical and swelling properties. The optimal percentage was found to be 30% NR and 70% BR. Three formulations of natural [no 13], bromobutyl [no 14] and their blend [30NR-70BR] [no 18] were subjected to the suitability tests as parenteral stoppers. The results of aging indicated that the three elastomers possess good heat and oxidation resistance characteristics and are also suitable for sterilization. The suitability tests according to the international standards proved that the three elastomers have a suitable limits of physicomechanical and chemical properties