Presentation on theme: "By: Valentina Caval And Wajeeha Jafferalli. Silly String was invented by Leonard A. Fish and Robert P. Cox A patent was issued in 1972 for foamable resinous."— Presentation transcript:
By: Valentina Caval And Wajeeha Jafferalli
Silly String was invented by Leonard A. Fish and Robert P. Cox A patent was issued in 1972 for foamable resinous composition Originally it was named as :“squibbly.”
A resin forms the plastic structure of the strand. The original formula used polyisobutyl methacrylate— an acrylic resin. A surfactant—or surface-active agent—helps the resin foam and modifies the stickiness of the strands. Propellant: 75% liquid in the can : forces the other ingredients out of the aerosol can, and causes them to foam and helps form the skin. The propellant described in the patent is Freon-12. The Silly String manufactured today uses other propellants –Freon-12 is an ozone depleting substance that is no longer manufactured.
Dibutyl phthalate makes it sticky to the touch. Silicone fluids such as dimethyl siloxane make the finished streamers easier to peel away from most targets. A bit of solvent such as dichloromethane keeps everything as a one-phase mixture.
dimethyl siloxanedichloromethane Dibutyl phthalate Chemical Structures
At normal air pressure the propellant in Silly String would be a gas. The high pressure inside the can keeps it in its liquid state. When you press the nozzle, a valve opens inside the can, giving the highly compressed liquid a chance to escape. Liquid rapidly moves up the tube inside the can, and travels from the high-pressure environment inside to the lower-pressure environment outside. Outside of the can, the liquid propellant becomes a gas, causing the remaining ingredients to foam.
It was used by American and British forces to detect tripwires for explosive booby traps. The soldier would stand in the doorway and spray the material over the suspect area. If the string fell to the ground there were no tripwires. However, if there was a tripwire, the string would be suspended in the air without pulling the wire They can not use silly string in the current war because you cant ship aerosol over seas
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Its large proportion of propellant can also give Silly String two seemingly opposite safety hazards: Some propellants are flammable, and others become so cold when leaving the container that they can freeze a person's skin.
Silly string can clog storm drains and take up space in landfills. Silly String is banned in Hollywood on Halloween night : If you are caught with silly string you could be faced with a $1,000 fine!