Sylvia Stoesser

Five of Stoesser's patents involved the use of acid inhibitors to increase crude oil production in oil wells, a type of well stimulation.[17] The flow of oil wells had been stimulated by the addition of acids as early as 1865, but acids tended to damage well casings and other equipment. Approached in 1932, John Grebe of Dow insisted that any acid used to improve oil well production must include an inhibitor to mitigate corrosion.[11]^{: 237–240}

One of several scientists tasked with developing effective inhibitors, Stoesser is credited as the "key inventor" of second-state inhibitors,[18]^: 157 achieving "the second great milestone in the history of acidizing" due to her work in 1932–1933.[19]^: 5 Her work was "particularly important"[11]^: 240 because she shifted focus from inorganic to organic compounds, seeking something that would produce a protective film on metallic surfaces.[11]^: 240[19] The organic inhibitors (including mercaptans) that she discovered were much more effective than the inorganics previously tried (arsenic acid and copper salts).[11]^: 240[19]

Burgeoning demand for oil well treatment led to the creation of the Dow Well Service, which became the subsidiary Dowell Incorporated in November 1932.[19]^: 7 Stoesser's inhibitor research was essential to the creation and success of Dowell.[11]^: 245

Another problem that affected wells was the buildup of substances that clogged the well and restricted production. Stoesser and L. C. Chamberlain developed an organic solvent mixture that could be used to remove built-up paraffin deposits. Marketed as Dowell Paraffin Solvent, it contained carbon tetrachloride, perchloroethylene, and petroleum naphtha. It was a very successful product for Dowell.[11]^: 245

Stoesser and John Grebe may also have described the first known case of the technique that is now called hydraulic fracturing.[19]^: 8

Another of Stoesser's assignments was to study cleaning solvents such as naphtha. Naphtha posed a combustion risk, and attempts were being made to ban its use.[16][11]^{: 246–248} Stoesser developed an alternative dry cleaning fluid using perchloroethylene that was non-flammable and non-explosive.[11]^: 248[16] She also developed inhibitors that helped to prevent metal corrosion in the dry-cleaning equipment.[11]^: 248

Twelve of Stoesser's patents relate to the development of early plastics in the 1930s.[17] Stoesser was responsible for significant improvements in plastics production. Dow wanted to find ways to use benzene. Benzene reacted with ethylene to form the liquid hydrocarbon ethylbenzene. Ethylbenzene could be hydrogenated to form the flammable liquid monomer styrene. Styrene could be used to make the hydrocarbon polymer polystyrene.[20]

The Dow Physics Laboratory began working with styrene in 1931.[20]^: 92 Styrene was difficult to process. Reactions were highly sensitive to even small differences in temperature, and styrene was capable of reacting with itself and releasing additional heat. Even in very small amounts, some of the compounds that were produced during processing could contaminate the desired end products of the reactions. As a result, polymers made from styrene were not stable: they tended to craze and change color over time.[20]

Stoesser took on the analytical work of testing the quality of the styrene and the polymers that were created.[20]^: 92–93 She also studied the effects of various inhibitors on the processes. After recommending the purchase and use of a special rotary Podbielnick still,[20]^: 92–93 and distilling the styrene six times,[11]^: 258 she was able to successfully produce small quantities of pure styrene for use as a standard.[20]^: 92–93 This demonstrated that it was possible to make a pure form which was stable.[14]

Stoesser's work was essential in identifying points in the process where contamination or uncontrolled heating caused impurities. Impurities due to traces of a sulfur compound were eventually tracked back to production of the original ethylene, from which they were transferred to ethylbenzene and styrene.[11]^: 258

Working with Jim Pierce, Stoesser developed an inhibitor to produce a polystyrene of extremely high quality. This was a key step towards a low-cost commercial process for polymerization of the polystyrene Styron and a related plastic called Styraloy. Styron was crystal-clear and could be colored.[21]

Styrene was important in creating synthetic substitutes for rubber, which were of great strategic importance in World War II. It also had great commercial importance.[20]^: 91 Styron, a polystyrene, was the first of the modern plastics. It became Dow's number one product in both sales volume and earnings, during Dow's first century.[18]^{: 582–583} In 1941, Dow company developed processes for extruding polystyrene to form foam polystyrene, also known as Styrofoam.[22]

Stoesser contributed the brief reminiscence "A stimulating group" to the edited collection A History of the Dow Chemical Physics Lab : the freedom to be creative (1990).[23] She describes the atmosphere created in her group, directed by John Grebe:

In our laboratory no idea was discarded as being too crazy to investigate. In fact, we were encouraged daily to consider the impossible goal. Along with that freedom of thought and encouragement to try the impossible came many failures at the laboratory stage – but there were also many new product and process successes. – Sylvia Stoesser[23]^: 115

Stoesser co-edited Styrene, Its Polymers, Copolymers, and Derivatives (1952) with Ray H. Boundy and Raymond F. Boyer. Stoesser is credited by Boundy as having been the primary writer of the two-volume work.[24]