Laboratory Synthesis of Bakelite - A K12 Chemistry Project
Laboratory Synthesis of Bakelite
Chemistry Projects at the K11 and K12 level have to be meaningful. They must support if not reiterate the theoretical aspects of rote classroom learning. Preparation of polymers, namely Bakelite is a simple laboratory procedure. This project requires some amount of precaution but the outcome is rewarding.A polymer is a macromolecule composed of repeating structural units connected by covalent bonds. The extraordinary range of properties accessible in polymeric materials, has led to polymers playing a useful and indispensible role in our lives. From synthetic plastics and elastomers on the one hand to natural biopolymers such as DNA and proteins that are essential for life, all polymers are formed from monomers.The small organic molecules which polymerize to form the polymer are called monomers. Polymerisation is the process of converting small organic molecules into high molecular weight molecules either by addition or by the condensation reaction. The first synthetic polymer, a phenol-formaldehyde polymer, was introduced under the name “Bakelite Bakelite was originally used to make billiard balls.
Bakelite is a thermosetting phenol formaldehyde resin, developed in 1907–1909 by Belgian chemist Dr. Leo Baekeland. It is known for its electrically non-conductive and heat-resistant properties in radio and telephone casings and electrical insulators, and was used in diverse products such as kitchenware, jewellery, pipe stems, and children's toys. In our lab, the Phenol-formaldehyde reaction mixture was prepared by mixing 25 g 36-40% formaldehyde + 20 g phenol + 55 mL glacial acetic acid under a fume hood. 25 mL of the phenol-formaldehyde reaction mixture was transferred quantitatively into a 150-mL beaker. The beaker was placed on a white paper towel. About 10 -12 mL of concentrated hydrochloric acid, was added dropwise, with constant stirring. As the point of polymerization approached a white precipitate was formed which is insoluble in the concentrated acid. On stirring vigorously and continuously the plastic forms and becomes pink in color. It is washed before handling.
40-35 *C - No observable changes
50-45 *C - Turbidity started appearing
60-55 *C - Roughly Polymerization started
75-60C - Semi Solid appeared at the bottom of the beaker. The reaction is extremely fast and the heat of reaction is high. On heating, the polymerization begins rapidly.
Important Precautions - Be sure to wear safety goggles and a lab coat at all times in the laboratory.Formalin is an irritant to the skin, eyes, and mucous membranes.Phenol is toxic via skin contact. It is listed as a carcinogen.Glacial acetic acid is an irritant and can cause burns on contact.Work under a fumehood and wear gloves and protective clothing.
Bakelite is a thermosetting plastic. It sets on heating and cannot be re-softened. The polymer chains are linked by strong chemical bonds viz covalent bonds. They are insoluble in organic solvents. Their expansion is only marginal due to heat. They are formed by condensation polymerization They are processed by compression moulding. The scrap cannot be reused. Bakelite or Phenol-formaldehyde is used for making TV cabinets, housing laminates, telephone components, decorative articles, bearings, electrical goods, etc. It is also used as an excellent adhesive
The experimental work for this project was successfully carried out by Viraj Damani and Nirav Shah of Matushri Kashiben Vrajlal Valia International Vidyalaya Borivali(West).
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