Natural Plastics What is a natural plastic? What is plastic? Identify how it differs from other materials Metals, Ceramics, Polymers, Semiconductors
Natural Plastics Horn – Comes from animals (natural grown)
Natural Plastics Horn – Comes from animals (natural grown) – Products made from horn: Spoons, combs, lantern windows – Lightweight – Flexible – Corrosion Resistant – Decorative
Natural Plastics Horn – Includes all types of bonecrafting Tortoiseshell, Bull Horns, Skulls – Combs Difficult to mass produce Clamping fixtures + cutting Movements require flat piece Bone is not flat.
Natural Plastics Horn – Combs Too slow to make, demand for substitute rises – Buttons Horners made powdered bone into molds Ground cow hooves Pulling meat from bone is still a chore
Natural Plastics Shellac – Polymer from insects, lac – Native to India and Southeast Asia – Hardened secretion – Can dissolve in alcohol, and apply to surfaces as a clear coat. – Moldable using heat and pressure. – Some of the first records for phonographs were made from shellac.
Natural Plastics Shellac – Problems with Shellac Moisture absorption Can absorb up to 20% water and change to a white color. Can pull moisture from high humidity areas Buttons often cracked from moisture absorption Inconsistent color
Natural Plastics Gutta Percha – Made from Palaquium gutta trees Malay Peninsula – First used to make knife handles mid-1800s – Room Temperature – Solid Slightly maleable – can dent, but not break – Heated Can be drawn into long strips
Natural Plastics Gutta Percha – Inert Resists vulcanization Resist Chemical Attack = insulation for wires – First underwater telegraph cable ran across the English Channel – Morse Telegraph Company draws across the Hudson River – Contamination from non-uniform gutta-percha
Early Modified Natural Materials Casein – Made from milk curd – Valued as “artificial horn” – Dried milk curd Ground into powder Plasticized with water Dough was moldable – Problem: Dissolved when wet
Early Modified Natural Materials Galalith – Casein + Formaldehyde – “Gala” = Milk – “Lith” = Stone – Moldable and held shape – One of first group of polymers to originate from nature that become chemically altered
Early Modified Natural Materials Natural Rubber – “Gum Rubber” – Natural latex Emulsion of polymer microparticles in an aqueous solution – Specific latex creates specific product
Early Modified Natural Materials Rubber Tree – Large latex producer – Latex is harvested and processed – Most common for making rubber products
Early Modified Natural Materials Opium Poppy Latex – Contains morphine and codeine – Used to make heroin
Early Modified Natural Materials Chicle Tree – Native tree in Mexico and Central America – Latex used to make chewing gum (chicle)
Early Modified Natural Materials Natural Rubber – Earliest uses Waterproofing clothes – Very little use Sensitive to temperature – Charles Macintosh creates the Mackintosh
Early Modified Natural Materials Charles Goodyear – Mixed various materials to gum rubber to make it stronger
Early Modified Natural Materials Charles Goodyear – Tried kneading sulfur and heating – Discovered Vulcanization – Sulfur content controlled properties
Early Modified Natural Materials Vulcanization – Little sulfur = flexible rubber – Ebonite = up to 50% sulfur Hard
Early Modified Natural Materials Hard and Flexible Rubber – Exhibits showed complete rooms made entirely from rubber – Horners used hard rubber as a substitute for horn Less wasteful Better mechanical and thermal properties Greatest limitation Only comes in black or dark brown – How did vulcanization work?
Early Modified Natural Materials Cotton fiber roughly 90% cellulose Came from one of many chemical changes derived from cellulose. – Cotton nitro-cellulose Nitric acid + sulfuric acid + cotton = High Explosive “Gun Cotton” Low nitrogen content = Mr. Curiel’s Flaming Balls – Pyroxylin Moderate nitrated cellulose Dissolved in organic solvents Used for photosensitive materials
Early Modified Natural Materials John W. Hyatt – Made a solid material from pyroxylin called Celluloid Celluloid – Failed to substitute horn, ivory, and other natural polymers – Famous for use in photographic film
Early Modified Natural Materials Celluloid – Extremely flammable – Film reels, when jammed in a projector, heated to ignition – Hundreds dead from theater fires
Early Modified Natural Materials Celluloid (Later use) – Ping Pong Balls 1920’s onwards – Rise of synthetic polymers
Early Modified Natural Materials Bakelite (Dr. Leo H. Baekeland) – Search for a substitute for shellac and varnish – Phenol + Formaldehyde Both of which come from chemical companies – The General Bakelite Company founded – Series of materials called Phenolics
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