SYNTACTIC FOAM BUOYANCY MATERIALS 

 FOR SUBNERGED RESEARCH VEHICLE 



by 



Israel Resnick 

 U. S. Naval Applied Science Laboratory 



INTRODUCTION 



Buoyancy materials are needed for deep submergence vehicles to permit 

 them to carry an adequate payload and still remain buoyant. Buoyancy 

 materials are also needed to support ocean platforms and acoustic arrays. 

 This paper describes the development of syntactic foam buoyancy material 

 by the U. S. Naval Applied Science Laboratory, for deep research vehicles 

 and other applications. 



At the inception of the development program on buoyancy materials, the 

 Applied Science Laboratory studied and investigated a large number of low- 

 density materials, both liquids and solids, and considered their poten- 

 tials and limitations. 



LOW DENSITY LIQUIDS AND SOLIDS 



Low Density Liquids 



A comparison of low density liquids is shown in Table 1. Low 

 density liquids have limited usefulness since all these materials require 

 a thin walled shell to contain them (e.g. Trieste) and damage to the shell 

 can be catastrophic. This becomes increasingly significant during han- 

 dling of the vessel and during operation at great depths. 



Low Density Solids 



A comparison of the properties of low density solids is given in 

 Table 2. The low density solids which may be considered for deep sub- 

 mergence buoyancy include low density metals such as lithium, woods, 

 organic polymers such as polyethylene, or polypropylene, expanded plastics, 

 inorganic (metal or ceramic) foams, and syntactic foams. The potential 

 for lithium or wood as a buoyancy material for deep submergence is limited. 

 As described in Table 2, lithium is very reactive and needs a container; 

 woods have low strength and high water absorption. The foamed plastics 



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