Chlorobutyl Rubber Research Paper

It has been proved that chlorobutyl rubber (CIIR) can be vulcanized with the accelerated sulphur system because of the small amount of cis-1, 4-polyisoprene units present in the backbone of CIIR. However, such vulcanizates generally exhibit poor cross-linking density owing to the low level of unsaturation. Therefore, the sulphur cured CIIR shows inferior compression set at elevated temperature. In addition to this, the vulcanization of CIIR with accelerated sulphur is limited at higher temperature due to reversion. To solve these problems, 4, 4 '-bis (maleimido) diphenyl methane (BMDM) was applied as a novel crosslinking additive along with the accelerated sulphur system. The detailed curing studies based on oscillating disc rheometer have

The bismaleimide [(4, 4 '-bis (maleimido) diphenylmethane] with a purity of 99.2% procured from New Century Holding Group Co., Ltd., China was used as a novel crosslinking additive along with accelerated sulphur for the vulcanization of CIIR. The chemical structure of the bismaleimide is shown in Figure 1. Other ingredients such as sulphur, mercaptobenzthiazole disulphide (MBTS), stearic acid and zinc oxide (ZnO) were purchased from

Dumbbell shaped specimens were prepared from the molded sheets of the samples and tested at a cross-head speed of 500 mm/min at room temperature. Six samples have been taken for each compound and their averages with standard deviations are reported.
(b) Hardness testing: Round shaped samples having 6mm thickness and 10mm diameter with smooth and uniform surface were used to measure the indentation hardness of the cured samples using a Shore A hardness tester (Asker, Kobunishi Keiki Co. Ltd) as per ASTM D2240 specification. By applying a constant force without any disturbances for a specific time, indentations were made in the various positions. Ten readings were taken from different areas of the testing samples and the average value was estimated.
(c) Compression set: The compression set of the vulcanized compounds were determined using cylindrical specimens (12.5 mm height and 29 mm diameter) by applying a 25% compression. The samples were kept in an air oven at the testing temperature (100°C) for 72 hours according to ASTM D 395. At the end of the test, the samples were taken out and allowed to cool at room temperature for 30 min and the final height was measured. The compression set (CS) was then calculated using the