Structure Formation Reaction and Properties of Bakelite
It is the 21st century and we literally live in the world of plastics. It is hard for us to imagine our life without plastic. The plastic furniture at homes, offices and schools, the electric sockets, plugs, devices, buckets- everything has become an essential part of human life. It was between 1907-1909 that the Belgian chemist Leo Baekeland successfully developed the first commercialized synthetic molding plastic, Bakelite. The two major classifications of plastics are- Thermoplastics and Thermosets. Thermoplastics can be softened by heat and can be molded. E.g., PVC. Thermosets or thermosetting plastics on the other hand become hard and rigid on cooling and retain their shape. Bakelite falls under this category of plastics. This thermosetting plastic created a revolution in the world of product design.
What is Bakelite?
Bakelite, which is also known as a 'material of a thousand uses' is chemically called polyoxybenzyl methylene glycol anhydride. It is a thermosetting phenol-formaldehyde resin formed by the condensation reaction of phenol with formaldehyde. So, we can, in general, say that Bakelite is a condensation polymer or a phenolic resin.
History of Bakelite
It is the 21st century and we live in a world of plastic. Now plastic is very common in our daily lives. It was between 1908-1910 when pharmacist from Belgium, Leo Baekeland successfully Introduced in the market the first commercially produced plastic bag, the Bakelite. The two plastic parts are…
Thermoplastics
Thermosets.
Structure of Bakelite
Bakelite is a Polymer composed of monomers, phenol and formaldehyde. The phenol-formaldehyde resin is a Polymer thermosetting. We are surrounded by materials, many of which, in one way or another, have a Polymer associated with them. The ease of forming Polymers into different shapes and their low production costs have been major factors in their widespread use. Therefore, Bakelite is one of the manufactured Polymers that we certify in our daily lives. Bakelite is the brand name for a Polymer made from phenol and formaldehyde Polymerization. These are some of the oldest man-made Polymers synthesized. Phenol is made to react with formaldehyde. The condensation reaction of two reactants in a controlled acidic medium or medium causes the formation of ortho and para hydroxymethyl phenols and their release.
Bakelite Uses
Bakelite has emerged as a huge commercial success and its uses know no boundaries. Based on the above-mentioned properties of the Bakelite, here are some of its uses-
Being a good insulator, it is used in non-conducting parts of radios and other electrical devices like sockets, switches, automobile distribution caps, insulation of wires, brake pads etc.
The ability to be molded makes it a part of the commodities being used in modern life. It is used to make buttons, clocks, washing machine impellers, toys, kitchenware and much more.
Since Bakelite can be made into different colors, Bakelite jewelry was once very much in use. The colorful bangles, earrings and bracelets were widely used. Artificial jewelry made of metals or some other alloys may sometimes result in allergies or skin irritation, but carefully manufactured Bakelite jewelry are cent percent safe to wear which gives it an added advantage in the market.
Bakelite has emerged as a major commercial success and its use is unlimited. By following the above-mentioned structures Bakelite
To be good protection, it is used in parts that do not use radios and other electrical equipment such as bases, switches, hoods, wiring harnesses, brakes etc.
Structural forces make it a part of modern life.
Use of Bakelite various items such as buttons, toys, washing machine impellers, clocks, kitchenware, etc is very common.
As Bakelite can be made in a variety of colors, Bakelite jewellery is widely used. Synthetic jewelry made of metal or other alloys can sometimes cause physical friction or skin irritation, but carefully crafted Bakelite jewelry is safe to wear at a percentage that offers another market opportunity.
Bakelite use may be reduced today compared to years ago, but it is still effective. There are many potential replacements for cheap Bakelite to be used in the market. Bakelite was founded in the early twentieth century but is an important subject for study in the 21st century as well. Bakelite features are researched with information about its commercial use. Bakelite's physical, chemical, electrical, and thermal properties make Polymers commercially available.
Bakelite was definitely a remarkable invention that paved the way to the 'Age of Plastics'. The use of Bakelite might have been reduced today when compared to the earlier years, but it is still in use. Many cheaper substitutes for Bakelite have been investigated which are replacing its use in the market. We may not realize but we live in a world of Polymers, and everything and anything connected to us or our surroundings is Chemistry. Bakelite was invented in the early twentieth century but it is an important topic of study even in this 21st century. The properties of Bakelite are studied to get information regarding its commercial usage. The physical, chemical, electrical and thermal properties of Bakelite make it a widely used commercial Polymers. It is always fascinating to study about Polymers and its Chemistry as they offer a wide range of possibilities to be put into our everyday life. Proper understanding of the structure and properties of synthetic Polymers like Bakelite is, thus, important in Polymer Chemistry.
Before we move on to the preparation of Bakelite, it is important to know how a polymer is prepared. Polymers are formed by combining 'monomer' or single units using a range of reaction mechanisms.
So, what is the monomer of Bakelite?
Bakelite requires two monomers- phenol and formaldehyde. Different substitutes of phenol and formaldehyde can also be used depending on the application.
The reaction involved is condensation reaction in the presence of either a basic or acidic catalyst. The reaction that takes place is highly exothermic, the loss of water molecule result in the cooling process. Also, the reaction should be conducted under pressure, otherwise the product formed will be brittle and a low density material.
The Bakelite preparation can be demonstrated in the following steps of reactions-
Combination of phenol and formaldehyde to form ortho and para hydroxy benzyl alcohols.
Formation of Novalac from ortho hydroxy benzyl alcohol. Water molecule is removed in the process.
Formation of Bakelite from Novolac.
Bakelite Structure
The structure for the cross-linked polymer, known by the commercial name of Bakelite is given below.
Structure of Bakelite
As we now know the Bakelite preparation method as well as its structure, let us now have a look at the properties of Bakelite.
What are the Desirable Properties of Bakelite?
It is due to a number of important properties of the first synthetic plastic, Bakelite that it has been aptly named as 'material of a thousand uses'. We see that a number of things like the plastic handle of utensils, telephones, bangles, automobile parts etc., are made of Bakelite. Studying the properties of Bakelite will give us a wider idea as to why it is used for a wide range of applications.
Bakelite is the commercial name for phenol formaldehyde resin.
It is usually brown/amber but can be made in a variety of bright colors.
It is liquefiable and malleable when heated and becomes permanently hard and rigid on cooling. Hence, it is a thermosetting plastic.
It can be easily molded and hence is used in the making of various products.
It shows high resistance towards heat, electricity and chemical action. This is why they are used to make a number of electronic gadgets, switches and automobile parts.
The dielectric constant of Bakelite falls in the range of 4.4 to 5.4.
Fillers are used to increase the strength and enhance the properties of the Bakelite so that it can be used for various applications. Asbestos, wood flour, cotton flock, cotton pulp, gypsum, mica etc., are a few reinforcing fillers that are added in molding resins like Bakelite. Following are a few properties that are enhanced by the addition of fillers:
Enhanced toughness and strength
Better moldability
Greater thermal, electrical and chemical resistance
Change in color
The addition of an inert filler also reduces the cost of molding. Along with fillers, catalysts are used to accelerate the curing process (the process that results in the hardening and toughening of polymers by forming cross-linked polymer chains).
When phenol is taken in excess and the reaction medium becomes acidic, the resulting condensation reaction is acidic. Although, if the amount of formaldehyde taken is higher than that of phenol in the reaction mixture, and the reaction occurs in the base, the thickening product is known as Resol. The resulting reaction is exothermic in nature.
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Steps for Bakelite Preparation:
1Phenol and formaldehyde are combined to make ortho and para hydroxy benzyl alcohols.
Novolac formation occurs in hydroxy benzyl alcohol and the water molecule is removed from this process.
Bakelite is made from novolac.
In the preparation of Bakelite, phenol and formaldehyde are heated in the presence of catalyst ZnCl2, HCL or NH3.
Bakelite is an important aspect of Chemistry
Structure Study Chemical Formula Of Bakelite
Its chemical formula is labeled (C6H6O-CH2OH)n.
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What are the Desirable Features of Bakelite?
Some important bakelite properties are listed below.
It can be formed quickly.
A smoother texture can be obtained from this Polymer.
Bakelite composition is heat resistant and resistant to scratching.
They are also resistant to a number of destructive solvents.
Due to the lack of electricity, bakelite resists electricity.
Bakelite was definitely a remarkable invention that paved the way to the 'Age of Plastics'. The use of Bakelite might have been reduced today when compared to the earlier years, but it is still in use. Many cheaper substitutes for Bakelite have been investigated which are replacing its use in the market. We may not realize but we live in a world of polymers, and everything and anything connected to us or our surroundings is chemistry. Bakelite was invented in the early twentieth century but it is an important topic of study even in this 21st century. The properties of Bakelite are studied to get information regarding its commercial usage. The physical, chemical, electrical and thermal properties of Bakelite make it a widely used commercial polymers. It is always fascinating to study about polymers and its chemistry as they offer a wide range of possibilities to be put into our everyday life. Proper understanding of the structure and properties of synthetic polymers like Bakelite is, thus, important in polymer chemistry.
FAQs on Bakelite Structure in Polymer Chemistry
1. What is the structure of Bakelite?
The structure of Bakelite is a highly cross-linked three-dimensional network polymer formed from phenol and formaldehyde. In Bakelite structure:
- Phenol units (C6H5OH) are linked through –CH2– (methylene) bridges.
- Cross-linking occurs mainly at the ortho and para positions
- The extensive cross-linking forms a rigid thermosetting polymer.
2. How is Bakelite formed from phenol and formaldehyde?
Bakelite is formed by the condensation polymerization of phenol (C6H5OH) with formaldehyde (HCHO). The process involves:
- Reaction under acidic or basic conditions.
- Formation of hydroxymethyl phenols as intermediates.
- Condensation with elimination of H2O.
nC6H5OH + nHCHO → cross-linked Bakelite + nH2O
The final product is a cross-linked phenol-formaldehyde resin.
3. Why is Bakelite considered a thermosetting polymer?
Bakelite is a thermosetting polymer because it forms a permanent three-dimensional cross-linked network on heating. Once set:
- It cannot be melted or reshaped.
- Heating further causes decomposition instead of softening.
- The strong covalent cross-links prevent chain movement.
4. What type of polymer is Bakelite?
Bakelite is a condensation polymer and a cross-linked thermosetting resin. It is classified as:
- A phenol-formaldehyde polymer
- A network polymer
- A synthetic resin
5. What are the monomers used in Bakelite?
The monomers used in Bakelite are phenol (C6H5OH) and formaldehyde (HCHO). In the polymerization process:
- Phenol provides the aromatic ring structure.
- Formaldehyde forms methylene bridges (–CH2–) between phenol units.
6. What are methylene bridges in Bakelite structure?
In Bakelite, methylene bridges (–CH2–) are the linking groups that connect phenol rings. These bridges:
- Form between the ortho and para positions of phenol.
- Create cross-links between polymer chains.
- Provide mechanical strength and rigidity.
7. What is the difference between novolac and Bakelite?
The main difference is that novolac is a linear phenol-formaldehyde resin, while Bakelite is a cross-linked thermosetting polymer. Key differences:
- Novolac: Formed with excess phenol, linear structure, requires curing agent.
- Bakelite: Formed with excess formaldehyde, highly cross-linked, rigid network.
- Novolac can be converted into Bakelite by further heating with formaldehyde.
8. Why is Bakelite hard and brittle?
Bakelite is hard and brittle due to its extensive cross-linked three-dimensional structure. Because of this:
- Polymer chains cannot slide past each other.
- Strong covalent bonds restrict flexibility.
- It resists deformation under stress.
9. What are the properties of Bakelite related to its structure?
The properties of Bakelite arise from its cross-linked network structure. These include:
- High thermal stability
- Electrical insulation
- High mechanical strength
- Resistance to chemicals
10. What are the uses of Bakelite based on its structure?
Bakelite is used in electrical and heat-resistant applications because of its thermosetting, cross-linked structure. Common uses include:
- Electrical switches and plugs
- Cookware handles
- Telephone casings
- Insulating components
