Silly Putty is a toy containing silicone polymers that have unusual physical properties. It can flow like a liquid, bounce and can be stretched or broken depending on the amount of physical stress to which it is subjected. It contains viscoelastic liquid silicones, a type of non-Newtonian fluid, which makes it act as a viscous liquid over a long period of time but as an elastic solid over a short time period. It was originally created during research into a potential rubber substitutes for use by the United States in World War II. [1] [2] [3]
The name Silly Putty is a trademark of Crayola LLC. [4] Other names are used to market similar substances from other manufacturers.
As a bouncing putty, Silly Putty is noted for its unusual characteristics. It bounces when dropped from a height, but breaks when struck or stretched sharply; it can also float in a liquid and will form a puddle given enough time. Silly Putty and most other retail putty products have viscoelastic agents added to reduce the flow and enable the putty to hold its shape. [5]
The original coral-colored Silly Putty is composed of 65% dimethylsiloxane (hydroxy-terminated polymers with boric acid), 17% silica (crystalline quartz), 9% Thixatrol ST (castor oil derivative), 4% polydimethylsiloxane, 1% decamethyl cyclopentasiloxane, 1% glycerine, and 1% titanium dioxide. [6]
Silly Putty's unusual flow characteristics are due to the ingredient polydimethylsiloxane (PDMS), a viscoelastic substance. Viscoelasticity is a type of non-Newtonian flow, characterizing a material that acts as a viscous liquid over a long time period but as an elastic solid over a short time period. [7] Because its apparent viscosity increases directly with respect to the amount of force applied, Silly Putty can be characterized as a dilatant fluid. [5]
Silly Putty is also a fairly good adhesive. When newspaper ink was petroleum based, Silly Putty could be used to transfer newspaper images to other surfaces, providing amusement by distorting the transferred image afterwards. Newer papers with soy-based inks are more resistant to this process. [8]
Generally, Silly Putty is difficult to remove from textured items such as dirt and clothing. Hand sanitizers containing alcohol are often helpful. Silly Putty will dissolve when in contact with an alcohol; after the alcohol evaporates, the material will not exhibit its original properties. [9]
If Silly Putty is submerged in warm or hot water, it will become softer and thus "melt" much faster. It also becomes harder to remove small amounts of it from surfaces. After a long period of time, it will return to its original viscosity. [6]
Silly Putty is sold as a 13 g (0.46 oz) piece of clay inside an egg-shaped plastic container. The Silly Putty brand is owned by Crayola LLC (formerly the Binney & Smith company). As of July 2009 [update] , twenty thousand eggs of Silly Putty are sold daily. Since 1950, more than 300 million eggs of Silly Putty (approximately 4,500 short tons or 4,100 tonnes) have been sold. [10] It is available in various colors, including glow-in-the-dark and metallic. Other brands offer similar materials, sometimes in larger-sized containers, and in a similarly wide variety of colors or with different properties, such as magnetism and iridescence.
During World War II, Japan invaded rubber-producing countries as it expanded its sphere of influence in the Pacific Rim. Rubber was vital for the production of rafts, tires, vehicle and aircraft parts, gas masks, and boots. In the US, all rubber products were rationed; citizens were encouraged to make their rubber products last until the end of the war and to donate spare tires, boots, and coats. Meanwhile, the government funded research into synthetic rubber compounds to attempt to solve this shortage. [11]
Credit for the invention of Silly Putty is disputed [12] and has been attributed variously to Earl Warrick [3] of the then newly formed Dow Corning; Harvey Chin; and James Wright, a Scottish-born inventor working for General Electric in New Haven, Connecticut. [13] Throughout his life, Warrick insisted that he and his colleague, Rob Roy McGregor, received the patent for Silly Putty before Wright did; [14] but Crayola's history of Silly Putty states that Wright first invented it in 1943. [11] [15] [16] Both researchers independently discovered that reacting boric acid with silicone oil would produce a gooey, bouncy material with several unique properties. The non-toxic putty would bounce when dropped, could stretch farther than regular rubber, would not go moldy, and had a very high melting temperature. However, the substance did not have all the properties needed to replace rubber. [1]
In 1949, toy store owner Ruth Fallgatter came across the putty. She contacted marketing consultant Peter C. L. Hodgson (1912–1976). [17] The two decided to market the bouncing putty by selling it in a clear case. Although it sold well, Fallgatter did not pursue it further. However, Hodgson saw its potential. [1] [5]
Already US$12,000 in debt, Hodgson borrowed $147 to buy a batch of the putty to pack 1 oz (28 g) portions into plastic eggs for $1, calling it Silly Putty. Initial sales were poor, but after a New Yorker article mentioned it, Hodgson sold over 250,000 eggs of silly putty in three days. [5] However, Hodgson was almost put out of business in 1951 by the Korean War. Silicone, the main ingredient in silly putty, was put on ration, harming his business. A year later, the restriction on silicone was lifted and the production of Silly Putty resumed. [10] [18] Initially, it was primarily targeted towards adults. However, by 1955, the majority of its customers were aged six to twelve. In 1957, Hodgson produced the first televised commercial for Silly Putty, which aired during the Howdy Doody Show . [19]
In 1961, Silly Putty went worldwide, becoming a hit in the Soviet Union and Europe. In 1968, it was taken into lunar orbit by the Apollo 8 astronauts. [18]
Peter Hodgson died in 1976. A year later, Binney & Smith, the makers of Crayola products, acquired the rights to Silly Putty. As of 2005 [update] , annual Silly Putty sales exceeded six million eggs. [20]
Silly Putty was inducted into the National Toy Hall of Fame on May 28, 2001. [21]
In addition to its success as a toy, other uses for the putty have been found. In the home, it can be used to remove substances such as dirt, lint, pet hair, or ink from various surfaces. The material's unique properties have found niche use in medical and scientific applications. Occupational therapists use it for rehabilitative therapy of hand injuries. [22] A number of other brands (such as Power Putty and TheraPutty) alter the material's properties, offering different levels of resistance. The material is also used as a tool to help reduce stress, and exists in various viscosities based on the user's preference.
Because of its adhesive characteristics, it was used by Apollo astronauts to secure their tools in zero gravity. [23] Scale model building hobbyists use the putty as a masking medium when spray-painting model assemblies. [24] [25] The Steward Observatory uses a Silly-Putty backed lap to polish astronomical telescope mirrors. [26] [27]
Researchers from Trinity College Dublin School of Physics (Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and Advanced Materials and Bioengineering Research (AMBER) Research Centers) have discovered nano composite mixtures of graphene and Silly Putty behave as sensitive pressure sensors, claiming the ability to measure the footsteps of a spider crawling on it. [28]
A polymer is a substance or material consisting of very large molecules linked together into chains of repeating subunits. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals.
Rheology is the study of the flow of matter, primarily in a fluid state but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. Rheology is the branch of physics that deals with the deformation and flow of materials, both solids and liquids.
In organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane. They are typically colorless oils or rubber-like substances. Silicones are used in sealants, adhesives, lubricants, medicine, cooking utensils, thermal insulation, and electrical insulation. Some common forms include silicone oil, grease, rubber, resin, and caulk.
Crayola LLC, formerly the Binney & Smith Company, is an American manufacturing and retail company specializing in art supplies. It is known for its brand Crayola and best known for its crayons. The company is headquartered in Forks Township, Pennsylvania in the Lehigh Valley region of the state. Since 1984, Crayola has been a wholly owned subsidiary of Hallmark Cards.
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist both shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and immediately return to their original state once the stress is removed.
An elastomer is a polymer with viscoelasticity and with weak intermolecular forces, generally low Young's modulus (E) and high failure strain compared with other materials. The term, a portmanteau of elastic polymer, is often used interchangeably with rubber, although the latter is preferred when referring to vulcanisates. Each of the monomers which link to form the polymer is usually a compound of several elements among carbon, hydrogen, oxygen and silicon. Elastomers are amorphous polymers maintained above their glass transition temperature, so that considerable molecular reconformation is feasible without breaking of covalent bonds. At ambient temperatures, such rubbers are thus relatively compliant and deformable. Their primary uses are for seals, adhesives, and molded flexible parts.
Polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone, is a silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication and passive daytime radiative cooling.
James Gilbert E. Wright was a Scottish-born inventor, researcher and chemical engineer at General Electric who invented Silly Putty in 1943 while looking for a replacement for rubber.
Silicone rubber is an elastomer composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers are often one- or two-part polymers, and may contain fillers to improve properties or reduce cost. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures from −55 to 300 °C while still maintaining its useful properties. Due to these properties and its ease of manufacturing and shaping, silicone rubber can be found in a wide variety of products, including voltage line insulators; automotive applications; cooking, baking, and food storage products; apparel such as undergarments, sportswear, and footwear; electronics; medical devices and implants; and in home repair and hardware, in products such as silicone sealants.
Sorbothane is the brand name of a synthetic viscoelastic urethane polymer used as a shock absorber and vibration damper. It is manufactured by Sorbothane, Inc., based in Kent, Ohio.
Pressure-sensitive adhesive is a type of nonreactive adhesive which forms a bond when pressure is applied to bond the adhesive with a surface. No solvent, water, or heat is needed to activate the adhesive. It is used in pressure-sensitive tapes, labels, glue dots, stickers, sticky note pads, automobile trim, and a wide variety of other products.
Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction sealant is sometimes synonymous with caulk and also serve the purposes of blocking dust, sound and heat transmission. Sealants may be weak or strong, flexible or rigid, permanent or temporary. Sealants are not adhesives but some have adhesive qualities and are called adhesive-sealants or structural sealants.
Curing is a chemical process employed in polymer chemistry and process engineering that produces the toughening or hardening of a polymer material by cross-linking of polymer chains. Even if it is strongly associated with the production of thermosetting polymers, the term "curing" can be used for all the processes where a solid product is obtained from a liquid solution, such as with PVC plastisols.
A silicone oil is any liquid polymerized siloxane with organic side chains. The most important member is polydimethylsiloxane. These polymers are of commercial interest because of their relatively high thermal stability and their lubricating properties.
Polymer engineering is generally an engineering field that designs, analyses, and modifies polymer materials. Polymer engineering covers aspects of the petrochemical industry, polymerization, structure and characterization of polymers, properties of polymers, compounding and processing of polymers and description of major polymers, structure property relations and applications.
Resin casting is a method of plastic casting where a mold is filled with a liquid synthetic resin, which then hardens. It is primarily used for small-scale production like industrial prototypes and dentistry. It can be done by amateur hobbyists with little initial investment, and is used in the production of collectible toys, models and figures, as well as small-scale jewellery production.
Earl Leathen Warrick was an American industrial chemist at Dow Corning who is noted for his claim to being the inventor of Silly Putty.
Constant viscosity elastic liquids, also known as Boger fluids are elastic fluids with constant viscosity. This creates an effect in the fluid where it flows like a liquid, yet behaves like an elastic solid when stretched out. Most elastic fluids exhibit shear thinning, because they are solutions containing polymers. But Boger fluids are exceptions since they are highly dilute solutions, so dilute that shear thinning caused by the polymers can be ignored. Boger fluids are made primarily by adding a small amount of polymer to a Newtonian fluid with a high viscosity, a typical solution being polyacrylamide mixed with corn syrup. It is a simple compound to synthesize but important to the study of rheology because elastic effects and shear effects can be clearly distinguished in experiments using Boger fluids. Without Boger fluids, it was difficult to determine if a non-Newtonian effect was caused by elasticity, shear thinning, or both; non-Newtonian flow caused by elasticity was rarely identifiable. Since Boger fluids can have constant viscosity, an experiment can be done where the results of the flow rates of a Boger liquid and a Newtonian liquid with the same viscosity can be compared, and the difference in the flow rates would show the change caused by the elasticity of the Boger liquid.
Recoil is a rheological phenomenon observed only in non-Newtonian fluids that is characterized by a moving fluid's ability to snap back to a previous position when external forces are removed. Recoil is a result of the fluid's elasticity and memory where the speed and acceleration by which the fluid moves depends on the molecular structure and the location to which it returns depends on the conformational entropy. This effect is observed in numerous non-Newtonian liquids to a small degree, but is prominent in some materials such as molten polymers.
Rheological weldability (RW) of thermoplastics considers the materials flow characteristics in determining the weldability of the given material. The process of welding thermal plastics requires three general steps, first is surface preparation. The second step is the application of heat and pressure to create intimate contact between the components being joined and initiate inter-molecular diffusion across the joint and the third step is cooling. RW can be used to determine the effectiveness of the second step of the process for given materials.
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