Syntactic foam is a high strength, light weight material that is created by using hollow spheres, typically made of glass, that are bound together with a thermoset polymer. The use of the word foam can be misleading as many people when they think of foam think of something that is weak and flexible. Here the word foam related to the cellular structure of the material, but SynFoam is a material that has incredibly high strength and modulus that makes it useful for many composite applications.
SynFoam syntactic foam, with its unique properties of high strength and low density, is widely used in the subsea buoyancy industry. They provide weight reduction and buoyancy for various underwater applications and resist hydrostatic pressure and long term water exposure up to the depth at which the syntactic foam is rated.
To determine how much SynFoam is needed for an application to make it neutrally buoyant, you simply calculate the amount of material needed to displace the weight in water of the material. For example if you wanted to use SynFoam HP-28 (a 28 pcf density foam) to make a vehicle that weighs 1,000 lbs in sea water neutrally buoyant you would perform the following calculation:
Volume of foam = (Weight in Sea Water) / (Density of Sea Water – Density of SynFoam)
In this example you would need about 27.8 cubic feet of SynFoam HP-28 to allow the 1,000 lb vehicle to float in water. Because SynFoam HP-28 is rated to 3,780 meters that would mean that using HP-28 for the vehicle would give it the ability to reach a depth of 3,780 meters and remain neutrally buoyant.
While the subsea industry is the area where syntactic foam is associated with the most, SynFoam has a wide range of uses. Syntactic foam has been used in the production of radomes due to its light weight nature and outstanding dielectric properties. These dielectric properties also make it useful for the embedding of electronics where it has been used to house animal and aquatic life tags and cameras. SynFoam syntactic foam is an excellent structural material that can be used civil engineering and aerospace applications, providing weight reduction with far more support than a typical honeycomb structure. SynFoam has outstanding acoustic properties that make it useful for sound proofing and insulation. The high temperature properties and fine cell structure make it highly desirable for tooling applications.
Syntactic foam generally comes in two forms- either a precast block or a two component pourable mixture. Precast blocks range in size from 4 x 12 x 12 inch to 6 x 12 x 24 inch. The blocks can then be easily machined much in the way that you would machine wood or soft metals. If large structures are needed materials can be bonded together with a syntactic adhesive to make large structures.
Our precast SynFoam blocks range in density from 6 pounds per cubic foot to 44 pounds per cubic foot. The HP, SW, DW, and MW grades are all rated for water use while the UL, AI, and HT are tailored more towards electronics and aerospace applications.
Our pourable systems come in two forms. The higher density materials are simple mix and pour systems. You mix and A and a B side and pour them into a cavity and they will cure to the final shape. The lower density materials (SynFoam SG, LG, FP, and ELG) are unique foams that will expand after pouring to the final density and then cure in place. These expandable syntactic foams are used for underwater and other applications. They compare favorably with more traditional urethane and vinyl cell foams used for similar applications, providing more strength and stiffness and typically better underwater performance at a similar density. In all cases the pourable foam will exotherm during cure so care needs to be taken when casting the material.