Preparation And Application Of Pressure-resistance Sealing Gel

With the development of urbanization,the cable needs to be buried.The sealing has considerable effect on the safety and reliability of the cable.The commonly used sealing devices have many disadvantages,such as short service life and high reparing cost.However,the high-performance air sealing devices have long service life and can be repared easily,which will be used largly in cable sealing.At present,high-performance air sealing devices and its raw materials are mainly imported from Germany(Raychem).As a result,the price is high and the large-scale application is limited.In this paper,we investigate pressure resistant sealing gel,which is one of the key materials for preparing high-performance air sealing devices.The main contents are as follows:1)Additional silicone gel was prepared by using vinyl silicone oil as the matrix.The effects of viscosity of vinyl silicone oil,cross-linking agent amount,type and amount of reinforcement materials on sealing and mechanical properties of gel were investigated.The optimal prescription of additional silicone gel was as follows:viscosity of vinyl silicone oil was 1200mPa·s,hydrosilicone oil content was 1.8%,and MQ resin content was 4.0%.But the sealing property of additional silicone gel was poor.2)Condensed silicone gel was prepared by using hydroxyl silicone oil as the matrix.The effects of viscosity of hydroxyl silicone oil,cross-linking agent content,type and content of reinforcement materials on sealing and mechanical properties of gel were investigated.The strength of condensed silicones gel was increased with increasing MQ resin content.The tensile strength reached to 0.62MPa,and fully squeezed time was 320h in the seal test.The optimal prescription to prepare condensed silicone gel was as follows:the viscosity of hydroxyl silicone oil was 10000mPa·s,cross-linking agent content was 0.2%,and MQ resin content was 4.0%.Compared with additional silicone gel,the seal property of condensed silicone gel was improved,but they were still unsatisfied with the requirement.3)Ethylene-propylene-diene copolymer(EPDM)gel was prepared using EPDM as the matrix.The effects of EPDM and paraffin oil mass ratio,cross-linking agent type and content,and assistant crosslinker on gel properties were investigated.The strength of EPDM gel was increased with increasing dicumyl peroxide(DCP)and divinylbenzene(DVB)content.Seal property was excellent and squeezed amount was less 1.6%after 180 d in the seal test.The optimal prescription to prepare EPDM gel was as follows:EPDM/paraffinum liquidum was 15/85(W/W),DCP content was 1.2%,and DVB content was 0.3%.Compared with additional silicone gel and condensed silicone gel,the seal property of EPDM gel was improved greatly,and EPDM gel can meet the requirements.The EPDM gel could be applyed in wide temperature range by guessing from the results of dynamic thermomechanical ananlysis.