Bakelite is chemically known as phenolic plastic and was among the first plastics to enter industrial production. Phenolic resins are made by the polycondensation of phenolic and aldehyde compounds under acidic or alkaline catalysis. Phenolic resin is thoroughly mixed with wood flour, talc as a filler, hexamethylenetetramine as a curing agent, stearic acid as a lubricant, pigments and other ingredients, then heated and compounded in a mixer to produce Bakelite powder. Heating and compression-molding the powder in a mold produces thermosetting phenolic plastic products.
Advantages
　　Bakelite has relatively high mechanical strength, good insulation, heat resistance and corrosion resistance. It is therefore commonly used to manufacture electrical products such as switches, lamp holders, headphones, telephone housings and instrument cases. This is the origin of its Chinese name, meaning 'electric wood.'
Disadvantages
　　The disadvantages of phenolic resin include relatively poor mechanical properties and limited resistance to oil and chemical corrosion. To overcome these shortcomings, phenolic resins have been modified. Adding different fillers produces modified phenolic plastics with different functions. For example, adding asbestos and mica to the formulation improves acid, alkali and wear resistance, allowing use in chemical equipment and components for motors and automobiles. Adding glass fibers increases hardness, making the material suitable for machine parts. Modification with nitrile rubber greatly improves oil resistance and impact strength, while modification with polyvinyl chloride improves mechanical strength and acid resistance.
Raw Material Sources
　　With abundant raw materials, a simple synthesis process, low cost and excellent product properties, phenolic plastic remains one of the world's highest-volume thermosetting plastics.
Other Information
　　Bakelite is an artificially synthesized chemical material and a type of plastic. It can be used to make lamp holders, switches, sockets and circuit boards. It does not absorb water or conduct electricity, and it has high-temperature resistance and high strength. Because it is widely used in electrical products, its Chinese name means 'electric wood.' Bakelite is made by mixing powdered phenolic resin with sawdust, asbestos or clay, then molding the mixture at high temperature. Phenolic resin was the world's first synthetic resin. Phenolic plastic (Bakelite) has a hard surface, is brittle and breaks easily, and makes a wooden-board sound when struck. It is generally opaque and dark-colored, usually brown or black, and does not soften in hot water. It is an electrical insulator whose main component is phenolic resin.
The Arrival of Bakelite
　　One day in 1905, the German chemist Baeyer was experimenting with phenol and formaldehyde in a flask when he discovered that a sticky substance had formed. He tried washing it away with water, but it would not come off. He then tried gasoline, alcohol and other organic solvents, again without success. This gave Baeyer a considerable headache. After trying every possible method, he finally removed the troublesome substance. With a sigh of relief, he tossed it into the waste bin. A few days later, while emptying the bin, Baeyer noticed the substance again. Its surface was smooth and shiny, with an attractive luster. Curious, he took it out and heated it over a flame, but it no longer softened. He dropped it on the floor, and it did not break. When he tried cutting it with a saw, it cut cleanly. The perceptive Baeyer immediately realized that it might be an excellent new material. Subsequent experiments confirmed that this formerly troublesome substance was now highly desirable. It was impermeable to water, did not deform when heated, had a certain degree of mechanical strength, was easy to process and provided excellent electrical insulation. It was almost ideal for the emerging electrical industry. It consequently came into widespread use for electrical switches, light switches, lamp holders, telephones and other electrical products, earning it the name Bakelite. To this day, Bakelite remains one of the most important, highest-volume and most widely used plastics.
Bakelite Powder
　　Bakelite molding powder has good insulating properties and is used to make electrical products and everyday industrial goods. It is a phenolic plastic using mainly wood flour as filler and is formed by compression molding.
Physical and Chemical Properties
　　When the formaldehyde-to-phenol molar ratio is less than 1, a thermoplastic product can be obtained, called thermoplastic phenolic resin or linear phenolic resin. It contains no groups capable of further polycondensation and requires the addition of a curing agent and heating to cure. When hexamethylenetetramine is used as the curing agent, for example, the curing temperature is 150°C. Molding powder prepared by mixing it with fillers is commonly known as Bakelite powder. When the formaldehyde-to-phenol molar ratio is greater than 1, an A-stage resin, or thermosetting phenolic resin, is initially obtained under alkaline catalysis. It dissolves in organic solvents and contains hydroxymethyl groups capable of further polycondensation, so it can cure without an added curing agent. Reaction under heat produces a B-stage resin, also called resitol, which is insoluble and infusible but can swell and soften. Further reaction produces an insoluble, infusible C-stage resin with a three-dimensional network structure, also called resite. A-stage resin can also cure spontaneously during prolonged storage. Thermosetting phenolic resins cure in two ways: at room temperature or under heat. Room-temperature curing can use the non-toxic room-temperature curing agent NL, or benzenesulfonyl chloride or petroleum sulfonic acid, although the latter two materials are more toxic and irritating.