Preparation And Properties Of Water Swelling Rubber Modified By Organic Montmorillonite

Water swelling rubber (WSR) is a kind of a new special rubber with excellent elasticity and absorptivity. It can be used widely as caulking, sealing of gap and water-prove materials. However, the mechanical properties and water swelling properties of WSR will markedly decrease after long-term use, and H2S gas which was detected several times in the underground engineerings in recent years may cause WSR seal failure in the short term due to its strong corrosiveness. Consequently, it is of great importance to improve the durability and H2S resistance of WSR.In this paper, the Na-montmorillonite was organically modified, and organic montmorillonite (OMMT) modified WSR which contained different contents of OMMT were prepared by melt intercalation. The microstructure of OMMT modified WSR were characterized via X-ray diffraction (XRD), and their mechanical properties, water swelling properties, gas barrier properties, H2S corrosion resistance and durability was investigated. The following conclusions can be drawn in the paper.(1) XRD results indicated that OMMT layers were stripped off and formed exfoliated nanocomposites with rubber matrix when the OMMT content was within 10phr.(2) The addition of OMMT can improve the tensile strength, volume expansion ratio and water retention of WSR effectively, but only cause a slight decrease of the elongation at break.(3) The gas permeability coefficient of OMMT modified WSR was smaller than common WSR. When the OMMT content increased to 10phr, the lower rate was up to 34.5%.(4) The H2S corrosion resistance of WSR was improved by addition of OMMT and the improvement was gradually heightened with the increase of OMMT content. The retentions of tensile strength, elongation at break and expansion rate in volume of WSR modified by 10phr OMMT increased by 10% in comparison with unmodified WSR. After corroded in H2S solution (0.04%) for 20 days, the retention of mechanical properties enhances by 20% for OMMT modified WSR.(5) Compared with common WSR, OMMT modified WSR showed better durability. The retentions of tensile strength, elongation at break and expansion rate in volume of OMMT modified WSR (10phr) increased by 10.1%,6.2% and 12% than unmodified WSR after 20 cycles of alternate immersion in water, while those increased by 10.8%,7.5% and 11% after the samples aged at 70℃for 28 days.(6) Accelerated thermal aging experiment and Arrhenius'equation figure was used to predict the life of WSR. The results showed that the static service life of WSR was prolonged by introducing OMMT. When the OMMT content was 10phr, the static service life of WSR was increased 58.5% in room temperature.(7) The improvement of OMMT on WSR performance can be attributed to the formation of exfoliated structure between OMMT and rubber matrix, which enhances the mechanical properties and barrier ability of WSR.