Bakelite synthesis PDF

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Description

Synthesis of Bakelite

Theory: 1. Description Phenol-formaldehyde resin is a condensation polymer and it is obtained by condensing phenol with formaldehyde in the presence of an acidic or alkaline catalyst. It was first prepared by the Belgian-American chemist Leo Baekeland in 1907–1909, who gave it the name as Bakelite. It is thermosetting polymer. A thermosetting plastic is a plastic that liquefies and is malleable when heated. Then it becomes permanently hard and rigid when cooled. Thus, it can be used to make a variety of items. 2. Properties and Products of Bakelite Bakelite’s characteristics include having low electrical conductivity and high heat and chemical resistance. It deforms permanently and retains its shape after being heated and molded. It is strong but brittle. Phenol-formaldehyde resins having low degree of polymerization are soft. They possess excellent adhesive properties and are usually used as bonding glue for plywood etc. Phenol-formaldehyde resins having high degree of polymerization are hard, rigid, Scratch-resistant and infusible. They are resistant to non-oxidizing acids, salts and many Organic solvents. They can withstand very high temperatures. They act as excellent electrical insulators also. Owing to its resistance to heat, electricity, and chemical action, Bakelite is used to manufacture: ■ Bases and sockets for light bulbs ■ Vacuum tubes ■ Electrical components ■ Automobile distributor caps and other insulators ■ Insulation of wires, brake pads, and some select automobile parts ■ Jewelry ■ Clocks ■ Radios ■ Toys, and game pieces used in chess, poker and billiards etc. ■ Kitchenware such as canisters, saucepan handles, etc. 3. Industrial Importance Due to above mentioned properties and products Bakelite has a huge demand in market and hence it is a value able product. Therefore it has a great industrial importance. 4. Routes of Manufacture of Product on Industrial scale Phenol-formaldehyde resin is been manufactured, mainly by two process. Depending on the application of resin the required process can be chosen. The two process are explained in brief below,  Manufacture of phenol formaldehyde resin using alkaline catalyst. Phenol-formaldehyde resins are manufactured in batch process. Phenol and formaldehyde are charged into the kettle in specified quantities. The kettle is kept under continuous agitation. An alkaline catalyst is added to initiate the reaction. Heat evolved is controlled and cooking temperature is maintained by circulating cooling water and by cooling oil within the pipe and the outer jacket respectively. After 2 hours of reaction continuous distillation takes place for 6 hours. The whole manufacturing process takes place under vacuum. Once the distillation starts heating oil is circulated in place of cooling oil. After achieving the viscosity/water tolerance, vacuum distillation is stopped and the reactor is cooled to below 40ºC. Then the contents are discharged 2017-CH-52

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Synthesis of Bakelite

into specific containers. The product is kept in a cold room at below 10ºC till the time of dispatch.  Manufacture of phenol formaldehyde resin using acid catalyst: Phenol-formaldehyde resins (in acid medium) are ordinarily manufactured by batch process in a jacketed acid resistant stainless steel kettles equipped with shell and tube vapor condensers and heavy duty turbine blade agitator. In a typical reaction cycle molten phenol at 60-65ºC and warm 37-40% formaldehyde are charged to the kettle from weigh tanks. Agitation is started and is continuous throughout the cycle. The acid catalyst is then added and the batch is tested for ph. Steam heat is applied to raise the temperature this heating is necessary for 3-6 hours.at the end of reflux period the condensate is rerouted to receiver and the water is distilled from the kettle. Vacuum is applied when temperature reaches to 120-150ºC.melting point or solution viscosity is used to test the sample for checking its completion. When the resin is completed, it is discharged.

Procedure: 

Take 50mL of glacial acetic acid in a 500mL beaker.

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Add 25mL of 37% formaldehyde solution in the beaker.

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Now add 20g phenol into above solution. (Continuously keep stirring)

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Finally add 12mL HCl into above solution. (Continuously keep stirring)

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Keep on stirring the solution unless there is a solid mass formed in the beaker with small amount of H2O present.

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Now filter this mixture with the help of funnel & filter paper. The solid sticking mass is Bakelite. Put the product in the oven for about 20-25 minutes at 95 degree C temperature. Weigh the product with the help of electrical weigh balance.

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Precautions: 

Lab Coat, Safety Goggles, Safety Gloves and Safety Mask must be worn.

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The contact of Phenol with skin should be avoided. Stir the solution with great care to avoid splashing. Carefully handle the glass wares. Do not drink or eat anything while performing the experiment in the lab. Keep work station neat and clean. Wash your hands and mouth with a good quality soap before leaving the lab.

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