Silly Putty has been described as a fun toy that could be purchased in eggs and desk drawers throughout America. However, it all started from research conducted in wartime laboratories. The scientists were looking for a solution to the problem of a shortage of rubber, which had become problematic for military needs and industry at that time.
The attempt to find an effective rubber replacement did not end up well, but resulted in a very unusual material that was stretchable, elastic, and even flowing at times. It became one of the most famous novelties in American history.
A rubber shortage due to war gave rise to research
With Japan occupying Southeast Asian countries rich in rubber, natural rubber became scarce for Americans during World War II. According to a report published by Carnegie Mellon University, tires, boots, various machines, medical items, and military supplies suffered from this shortage.
Chemists of the US Synthetic Rubber Program started researching different silicone substances in order to create a good alternative. One team, led by Earl Warrick, attempted to thicken polydimethylsiloxane fluids with the help of boric acid.
The scientists’ aim was rather practical and urgent – they needed a material similar in its properties to natural rubber. However, the result turned out to be quite peculiar. The material was capable of bouncing like a ball, elongating steadily, and suddenly snapping in two after rapid pulling. Thus, the material possessed both liquid-like and solid-like properties.
According to the educational resource created by Carnegie Mellon University, initially, Silly Putty was intended to be used as an alternative to rubber in case of war. However, several years later, its commercial application appeared.
Why the material turned out to be inappropriate to be used as artificial rubber
It did not take long for researchers to figure out that the material would not suit the needs of the wartime industry. As a PDMS-based elastomer with abnormal viscoelastic behavior, Silly Putty would not be able to provide enough strength for any application. The material did not respond to pressure and stress in a predictable way. Slow elongation resulted in deformation. It broke when you pulled on it too quickly.
Later research on borosiloxane systems discovered that it was due to its dynamic molecular bonding structure that created such strange rheological properties. According to a PubMed article, these unique properties were the reason why Silly Putty had that bouncy and stretchable feature.
While those features were undesirable during wartime for engineers who needed reliable materials, they would become their most appealing traits among the public later on.
