Question

This section contains multiple choice questions. Each question has 4 choices (a), (b), (c) and (d), out of which ONLY ONE is correct. Which of the following is an example of phenol-formaldehyde resin? (a) Perlon (b) Nylon-6,6 (c) Bakelite (d) Dacron

Short answer

a) Perlon b) Nylon-6,6 c) Bakelite d) Dacron Answer: c) Bakelite

Step-by-step solution

Understanding Phenol-Formaldehyde Resin

Phenol-formaldehyde resins, also known as phenolic resins, are synthetic polymers formed through the reaction of phenol and formaldehyde. These resins have a wide range of applications, including molded products, adhesives, and coatings. They are generally hard, durable, and have good heat and chemical resistance.

Comparing the Options

Let's briefly analyze each option to determine which one is an example of phenol-formaldehyde resin: (a) Perlon: Perlon is a brand name for a specific type of synthetic polyamide material, commonly known as nylon. This material is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin. (b) Nylon-6,6: Nylon-6,6 is a specific type of polyamide made from the condensation polymerization of hexamethylenediamine and adipic acid. Like Perlon, it is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin. (c) Bakelite: Bakelite is a resin formed by the polymerization of phenol and formaldehyde. Due to its composition, it falls under the category of phenol-formaldehyde resins. Bakelite is a thermosetting plastic, which means it cannot be melted and re-molded once cured. This resin is known for its durability, heat resistance, and insulation properties. (d) Dacron: Dacron is a brand name for a specific type of polyester material, also known as polyethylene terephthalate (PET). It is not formed from the reaction of phenol and formaldehyde, so it is not a phenol-formaldehyde resin.

Identifying the Correct Option

Comparing all the options, we can see that Bakelite (option c) is the only resin formed by the reaction of phenol and formaldehyde. Therefore, the correct answer is (c) Bakelite.

Key concepts

Bakelite

Bakelite is a pioneer in the world of synthetic polymers. It was one of the first plastics to be made from synthetic components, marking a significant shift in the materials available for manufacturing. Developed by Leo Baekeland in 1907, Bakelite is a type of phenol-formaldehyde resin.

Bakeland's innovation came from the chemical reaction between phenol and formaldehyde, resulting in a rigid, strong, and lightweight plastic. Bakelite is known for its excellent heat resistance and electrical insulating properties. This made it ideal for a wide range of applications, such as electrical insulators, radio and telephone casings, and in the automotive industry for components such as distributor caps and other ignition system parts.

Unlike many other plastics, once Bakelite has been molded and set, it cannot be re-melted, making it a thermosetting plastic. This property gives it some of its potential uses, such as in heat-demanding scenarios, where a robust and enduring material is needed.

Thermosetting Plastics

Thermosetting plastics, like Bakelite, are materials that undergo a chemical change and solidify during the curing process. Once they are heated and formed, they cannot be re-melted or reshaped. This is due to the formation of cross-linked bonds during polymerization.

Key characteristics of thermosetting plastics include:

• Heat Resistance: They maintain structural integrity at high temperatures.
• Durability: They are strong and resist deformation under stress.
• Chemical Resistance: They can withstand various chemicals without degrading.

These properties make them suitable for various industrial applications, including electronic components, adhesives, and various everyday items found around the home.

Thermosetting plastics stand in contrast to thermoplastics, which can be remelted and reused multiple times, giving them more versatile uses but generally less thermal stability.

Synthetic Polymers

Synthetic polymers are large molecules created through the process of polymerization, where small molecules called monomers are chemically bonded to create long chains. These polymers are man-made and have been specifically engineered to possess certain desired properties.

Some common categories of synthetic polymers include:

• Polyethylene: Used in plastic bags and bottles.
• Polypropylene: Common in packaging and textiles.
• Polystyrene: Often found in disposable cutlery and CD cases.

Synthetic polymers, like Bakelite, are crucial in modern society due to their versatility and strength. They can be tailored to possess various properties, such as flexibility, durability, and resistance to heat and chemicals.

The development of synthetic polymers has enabled a wide variety of new products and technologies, contributing significantly to advancements in industries ranging from automotive to medicine.