Low Temperature Vulcanisation  Technique for CR BIIR Blend for Encapsulation of Oceanic Sensors

P. N. Mohanadas; T. Mukundan; T. Santhanakrishnan

doi:10.14429/dsj.70.14321

P. N. Mohanadas DRDO-Naval Physical and Oceanographic Laboratory, Kochi - 682 021
T. Mukundan DRDO-Naval Physical and Oceanographic Laboratory, Kochi - 682 021
T. Santhanakrishnan Naval Physical and Oceanographic Laboratory, Thrikkakara, Kochi, India

DOI: https://doi.org/10.14429/dsj.70.14321

Keywords: Chloroprene rubber, Bromobutyl rubber, Sonar sensor, Low temperature vulcanisation

Abstract

Blend of chloroprene rubber (CR) and bromobutyl rubber (BIIR) is used for encapsulation of piezo sensors used in sea water. Conventional encapsulation method of these sensors involving high temperature vulcanisation (HTV) often leads to deterioration of piezo properties due to thermal degradation. This paper reports a low temperature vulcanisation (LTV) technique carried out at 90 °C for CR-BIIR blend using chlorinated polyethylene (CPE) as compatibiliser and LTV system consisting of modified di-o-tolyl guanidine and thiocarbanilide as accelerators and ZnO as curing agent. The conventionally used scavenger MgO was eliminated and only ZnO was used to boost the cure reaction. Properties specific to sonar sensors, namely, acoustic transparency, electrical resistivity, water absorption and physico‑mechanical properties were evaluated besides evaluation of morphology. The results are found to compare better than the conventional blend. Accelerated thermal ageing at 70 °C for 7 days yielded 97 % retention of tensile strength. The technique was implemented in a PZT hydrophone sensor and was successfully underwater tested.

Author Biographies

P. N. Mohanadas, DRDO-Naval Physical and Oceanographic Laboratory, Kochi - 682 021

Mr P.N. Mohanadas obtained his MTech (Polymer Technology) from Cochin University of Science and Technology, Kochi, Kerala. He also secured DPRI of Plastics and Rubber Institute, UK. He is presently working as Scientist ‘E’ in the Materials Science Division of DRDO-Naval Physical & Oceanographic Laboratory, Kochi. His area of interests is low temperature vulcanisation of rubbers, rubber blends and development of processes and products for underwater applications. He has been granted an Indian patent for low temperature vulcanisation of rubber.

T. Mukundan, DRDO-Naval Physical and Oceanographic Laboratory, Kochi - 682 021

Dr T. Mukundan obtained his MSc in Chemistry from the Calicut University, Calicut and PhD from the Indian institute of Science, Bangalore. He is presently working as Associate Director (Materials Science & Materials Engineering) at DRDO-Naval Physical & Oceanographic Laboratory, Kochi. His areas of interest are encapsulants, adhesives, acoustic materials, electronic materials, transduction materials and application of nanotechnology to underwater materials technologies. He has about 60 research papers in journals and 1 US Patent and 4 Indian patents to his credit. He is a recipient of the DRDO Laboratory Scientist of the Year Award and DALMIA - HEMSI Award of the High Energy Materials Society of India.