The Influence Of HGM Surface Modification On Solid Buoyancy Material

As the development of society and technology,the exploit of land resources can no longer meet the needs of human beings. Thus deep ocean with rich resources reserves has received much more attention. The exploration and development of deep ocean cannot be successful without the equipments where solid buoyancy material is one of the most important general materials. The buoyancy material with low density, high strength and low water absorption is the key technology in deep ocean area. Main components of solid buoyancy material are epoxy resin and hollow glass microsphere (HGM). The performance of material is influenced not only by epoxy resin and HGM themselves, but also by the interface of them. Research about the two former has already been comprehensive, hence this paper has carried out the research about interface between epoxy and HGM, that is the surface modification of HGM.Two modification methods of HGM were adopted, which were treatment with silane coupling agent and polymer grafting. Successful modification of the two methods was demonstrated through FTIR, SEM, EDS and TGA. The water absorption, comprehensive strength, tensile strength and flexural strength of buoyancy material were tested. The optimum modification method of HGM was selected.Silane coupling agents (KH550, KH560, KH570, KH591) with different end groups were investigated, among which KH591 showed the best modification performance. The buoyancy material made with KH591 modified HGM showed low water absorption (only 0.35%), which was lower than the equilibrium water content (EWC) of pure resin. In addition, the comprehensive strength of the above mentioned buoyancy material was 62.15 MPa, which promoted 47.6 % compared to the buoyancy material without modification;tensile strength of it was 40.15 MPa, which increased 60% approximately; flexural strength of it was 53 MPa, which increased 40 %.We also studied silane coupling agents (KH553, KH593, KH602, KH792) with different main chain structures. Results showed that KH553 with no pendant groups on the backbone,of which the inorganic group was silanol bond, gained the best modification effect. The water absorption of the buoyancy material which was made with KH553 modified HGM was lower than the EWC of pure resin; the comprehensive strength of it was 64.15 MPa, tensile strength of it was 35.47 MPa and the flexural strength of it was 53.99 MPa, therefore KH553 also showed a better modification effect.The influence of KH560 and KH553 quantity on the properties of buoyancy material was investigated. As for KH560, when the dose of KH560 in the HGM was 4%, results showed the best performance with a lower grafting ratio (1.4087 %). The EWC of buoyancy material made with the above mentioned KH560 was 0.4%. What's more, the comprehensive strength of it promoted 50% compared to the buoyancy material without modification; tensile strength of it increased 13%; flexural strength of it increased 67%. For KH553, when the dose of KH553 in the HGM was 6%,and 12%,results showed the best performances, which meant that when the grafting ratio was 3.2%, modification effects were better.Another modification method, i.e. polymer grafting, was studied. We investigated the influence of different kinds and quantities of isocyanate which acted as the intermediate reactant. Results showed that the modification effect of aromatic isocyanate was better than that of aliphatic. Thus the buoyancy material made by HGM which was modified with diphenyl-methane-diisocyanate (MDI) performed a better water absorption and mechanical strength. The EWC of the above mentioned material was 0.41 %, while the comprehensive strength of it was 64.98 MPa, tensile strength of it was 37.78 MPa, flexural strength of it was 46.53 MPa. Studies about the quantity of MDI turned out that optimum quantity of MDI was 20%.We investigated different filling amounts of HGM in the epoxy resin,and studied the effect of filling amount on the viscosity, density, water absorption and compressive strength,etc. Results indicated that when there was a increase in the filling amount of HGM,the viscosity of buoyancy material made with HGM increased, the density of it decreased, water absorption was higher and the compressive strength of it decreased. Even though, the HGM modification still made a certain improvement on the above properties.