[Part 2 of a 3-part series on the origins of syntactic foam]
As Lou mentioned in his earlier recollections, syntactic foam was a novel material development following World War II. While polymer systems, including epoxy and polyester resins came a long way very quickly, it was the introduction of hollow glass spheres that proved to be a game-changer in the industry. Looking at the available literature, it appears that the big bang moment arrived sometime in 1953 when Standard Oil Co. applied for their first patent related to hollow spheres called, “Process of Producing Hollow Particles and Resulting Product” ( US Patent 2797201 A, Franklin Veatch and Ralph Burhans). They followed that in 1957 with another patent titled, “Method of Producing Hollow Glass Spheres”, (US2978339 A, Veatch, Alford and Croft) and the floodgates opened. Other important discoveries followed. Standard Oil stayed very active in the area with numerous follow-on and derivative patents. Other companies became players in the early days with their own developments such as Exxon Research Engineering, Corning Glass and Potters Industries. A significant breakthrough came in 1963 when 3M patented a glass bubble method under US patent 3365315A, “Glass Bubbles Prepared by Reheating Solid Glass Particles”. In later years (1970’s, 80’s and 90’s) organizations such as WR Grace, PQ Corp and Saint Gobain Vitrage all produced hollow glass spheres.. 3M became the dominant manufacturer of glass bubbles and remains so today.
As the hollow glass bubble industry began to percolate and form, so too did the variety of areas where the bubble could be used. Scientists and engineers found lots of opportunities to mix this new material into their formulations to enhance the properties. Most saw the potential to reduce weight and cost by replacing some of their matrix material with hollow glass. Others saw the potential to improve their products or processes by reducing shrinkage, improving dimensional stability, or reducing exotherm without significantly diminishing the physical properties of the original products. Hollow glass spheres began to show up in concrete, plaster, paint, wall panels, and even bowling balls. Quietly, the Navy and a few clever engineers and scientists began to experiment with these new hollow spheres. Their interest was in exploiting the low density, high strength and stiffness that could be attained to produce buoyant materials. It was here that syntactics as we now know them really began to take off.
The Navy’s primary interest was buoyancy for subsea vehicles. In 1958, the bathyscaphe Trieste was purchased by the Navy for deep water research under the Office of Naval Research. In 1960, Treiste dove to the bottom of the Mariana Trench (10,910 meters) utilizing huge volumes of gasoline for buoyancy. The use of this incompressible liquid with a lower density than seawater was certainly successful, but it was a less-than-elegant solution. The Navy also had several other Deep Submergence Vehicles (DSV) on the drawing board or in early production that could use a buoyant material capable of survival in the deep. This was the challenge that drove a flurry of activity and new developments. In 1962, the US Bureau of Ships began to investigate alternative buoyancy solutions related to these vessels.
Most of the Navy’s work with syntactics in the early 1960’s appears to have come from the US Naval Applied Science Laboratory (ASL) out of Brooklyn, NY and Electric Boat (EB) in Groton, CT (EB). One name that comes up quite frequently is Israel Resnick from ASL who appears to have spearheaded much of the development. Some of the work was presented in government-sponsored sessions, one of the earliest being, “Syntactic Foam for DeepSea Engineering Applications” presented in 1965 at the Second US Navy Symposium on Military Oceanography. In cooperation with industry, Resnick and his colleagues utilized the glass bubbles and resin systems available at the time to manufacture their syntactics. They also pioneered the earliest development of tests and standards for this new material, including a new ASTM committee on syntactic foam. Substantial testing was conducted to characterize the long term and cyclic hydrostatic performance as well as mechanical properties. E.C. Hobaica from Electric Boat published “Buoyancy Systems for Deep Submergence Structures” in the Naval Engineers Journal in October of 1964. Allen Winer from the Bureau of Ships published a paper in the Journal of Cellular Plastics in May of 1966 titled, “Syntactic Flotation Material for Deep Submergence Vehicles”.
While these teams worked on some of the Navy’s interests in this new material, there was another group working on a completely different project that would greatly change the oil and gas industry. In 1961, the first phase of Project Mohole was executed off the coast of Mexico. The ultimate goal of this ambitious project was to drill into the earth’s mantle to better understand the planet’s history and formation. While the project was not successful in its ultimate mission, it yielded several new critical technologies that would later form the basis for the offshore drilling and oceanographic industries. It was the first use of dynamic positioning which became a critical component for drill ships. It was also the first use of syntactic foam subsea buoys for these positioning systems, introducing this new material to a group of engineers and scientists who would change the oceanographic and offshore oil worlds.