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Neoprene, often known as polychloroprene, is a class of synthetic rubbers made from chloroprene polymerization. Medicine, automotive, building and construction, aquatics, and electronics are just a few of the industries that use it. In this article, we will discuss the polymer neoprene, its properties, preparation and uses in-depth.
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Keyterms: Neoprene, Polychloroprene, Synthetic rubbers, Chloroprene, Polymerization, Medicine, Automotive, Building and construction, Aquatics, Electronics, Polymers
Read Also: Condensation Polymerization
What is a Polymer?
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Polymer is derived from two Greek words: ‘poly’ which means ‘many’ and ‘mer’ which means unit or portion. Polymers are characterised as big molecules with a high molecular mass (103 -107u).
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Polymerization
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Polymers are made up of repeated structural units. These structural units are made up of monomers, which are simple and reactive molecules that are joined together by covalent bonds. Polymerisation is the process of forming polymers from individual monomers.
Neoprene
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Neoprene, often known as polychloroprene, is a class of synthetic rubbers made from chloroprene polymerization. It is chemically stable and resistant to a wide variety of temperatures. The great tensile strength, oil and flame resistance, and oxygen and ozone degradation resistance of neoprene make it a valuable general-purpose rubber. Nevertheless, its expensive cost limits its employment to applications requiring particular qualities.
Neoprene comes in a variety of shapes and sizes, depending on the application. Here are a few examples:
Sheets made of neoprene: Sheets are useful for making safety gear like wet suits and gloves, but they can also be utilized as landfill liners or protective equipment covers.
Neoprene that has been extruded: Extrusions of neoprene can be used as tubing or window seals, or split into gaskets, seals, or washers.
Foam made of neoprene: Because foam neoprene is thick and spongy, it can be utilised for cushion athletic equipment (such as elbow and knee pads). It is also used to insulate industrial machinery and as a weather-stripping material.
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Preparation of Neoprene
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Previously, it was made by treating acetylene with cuprous chloride, which was then treated with hydrochloric acid to produce chloroprene. Chloroprene free-radical polymerization produces neoprene.
During commercial processing, this polymer is made by free-radical emulsion polymerization.
- Polymerization is started with potassium persulfate. Bifunctional nucleophiles, metal oxides (e.g. zinc oxide), and thioureas are employed to crosslink individual polymer chains.
- Chloroprene is emulsified in water and subsequently polymerized by the action of free-radical initiators to produce rubber.
- In the resultant polymer chain, the chloroprene repeating unit can take on a number of configurations, trans-polychloroprene being the most frequent. The use of various substances results in elasticity and colour.
- The entire mixture is combined to form a dough. After that, it receives heat and is converted into sheets.
Read Also: Polythene
Properties of Neoprene
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- Neoprene is good all-around rubber. It has a high tensile strength, which makes it ideal for use in industrial settings and other places with a lot of movement.
- Neoprene is resistant to chemicals, water, heat, fires, oxygen, and ozone are all resistant to neoprene. When compared to natural rubber, it is more resistant to water, chemicals, and heat.
- Neoprene is resistant to weather and sunlight, so it lasts long and does not need to be replaced frequently. Neoprene has a low oxidation rate and is UV and ozone resistant.
- Despite its chemical inertness, neoprene is prized for its ability to tolerate petroleum-based mixtures including solvents, oils, and greases, Alkalies, mineral acids, and some salt solutions, as well as methyl and ethyl alcohols.
- Neoprene can be mechanically bonded to cotton and a variety of metals, such as stainless steel, aluminium, brass, and copper. The procedure is aided with a basic bonding agent. Adhesion between neoprene and materials such as glass and acrylic can be induced with certain additions.
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Uses of Neoprene
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Neoprene can be used in a variety of sectors due to its many useful qualities. It is primarily used for the following purposes.
General Uses: Neoprene is more resistant to degradation than natural or synthetic rubber. Because of its relative inertness, it is ideal for high-stress applications including gaskets, hoses, and corrosion-resistant coatings. It can be used as a basis for adhesives, noise isolation in power transformer installations, and cushioning in external metal enclosures to protect contents while allowing a tight fit.
Electrical and Electronic Applications: Neoprene is frequently used as an insulator in power transformers, light bulbs, cables, and other electrical applications due to its fire and static resistance. It's also used as a shield for devices like laptops for the same reason.
Safety Equipment Uses: Because of its ability to work in a wide variety of temperatures while offering heat resistance and remaining flexible, neoprene fabric is appropriate for gloves and other protective gear. The resistance of neoprene against oil, chemicals, and water adds to the defence.
Marine Uses: Neoprene is also used in wetsuits and diving suits because of its water and temperature resistance. Nitrogen is added to boost insulation, which raises overall buoyancy, thus the suits must be weighted to avoid floating or dragging the diver back to the surface.
Automotive Uses: Neoprene may be used to make vehicle parts since it is abrasion, tear, solvent, oil, and weather-resistant, as well as heat and fireproof. It can be found in window and door seals, hose covers, belts, vibration mounts, and shock absorber seals.
Medical Uses: Neoprene is used to manufacture supports and braces, such as hand, knee, and elbow braces, because of its flexibility and wearability.
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Things to Remember
- Neoprene rubber, often known as polychloroprene, is a synthetic substance made out of polymerized chloroprene. Carbon, hydrogen, and chlorine polymers make up the majority of it,
- Polymerisation is the process of combining molecules to form long chains known as polymers, which is how neoprene is made. It is made by chlorinating butadiene or isoprene in current manufacture. To make rubber, chloroprene is emulsified in water and then polymerized using free-radical initiators.
- Chloroprene free-radical polymerization produces neoprene.
- Vibration dampening, weather resistance, heat resistance, waterproofness, chemical resistance, and durability are just a few of the many qualities of neoprene.
- Because of its qualities, neoprene has a wide range of uses in everyday life, including electrical appliances, naval applications, and medicinal applications.
Read Also: Measurement of Mass and Weight
Sample Questions
Ques. Arrange the following polymers in increasing order of their intermolecular forces. [3 marks]
(i) Nylon 6,6, Buna-S, Polythene
(ii) Nylon 6, Neoprene, Polyvinyl Chloride
Ans: Based on intermolecular forces, polymers
are classified as elastomers, fibres and plastics. The increasing order of intermolecular polymerization forces is Elastomer < Plastic < fibre.
Thus, we have
- Buna-S < Polythene < Nylon 6,6
- Neoprene < Polyvinyl chloride < Nylon 6.
Ques. Write the partial structure of Neoprene. [2 marks]
Ans: The partial structure of Neoprene is:
Ques. What is the use of neoprene? Mention any three. [3 marks]
Ans.
- Neoprene is used to make wetsuits and fly fishing waders because it helps provide insulation against the cold. Wetsuits made from closed cell foam neoprene can provide insulation against cold water by trapping heat in the suit.
- Due to its fire- and static-resistance properties, neoprene can be used as an insulator in power transformers, light bulbs and other electrical applications. Neoprene is also used in sealing gaskets for electricity to provide waterproof sealing, heat and static resistance and keep dust and contaminants out.
- Neoprene’s cushioning abilities make it ideal for laptop sleeves and protection for other electronics. It is also used for exercise equipment as a soft coating for hand weights
Ques. What are the monomers of neoprene? [2 marks]
Ans. The monomer for neoprene is 2-chloro-1,3-butadiene and the polymer is prepared by emulsion polymerization.
Ques. What type of polymer is neoprene? [2 marks]
Ans. Neoprene is produced by the free-radical polymerization of chloroprene. In commercial production, this polymer is prepared by free-radical emulsion polymerization.
Ques. Is neoprene a natural rubber? [2 marks]
Ans. Neoprene, also known as polychloroprene, is a specific type of synthetic rubber, made up of carbon, hydrogen, and chlorine polymers. These polymers cross-link during the vulcanization process, giving neoprene its temperature, oil, water, and solvent resistance, as well as chemical inertness.
Ques. What is the formula of neoprene? [2 marks]
Ans. Neoprene is a type of polymer (a large molecule composed of repeating structural units) known as polychloroprene that is produced by the polymerization (chemical reaction) of chloroprene
Formula: CH2=CCl-CH=CH2
Ques. What are the physical properties of neoprene? [3 marks]
Ans. The following are some of the outstanding characteristics of the neoprene polymer when properly compounded.
- Tear resistance.
- Vibration dampening.
- Water resistance.
- Weather resistance.
- Compression set resistance, stress relaxation, compression recovery.
- Chemical resistance.
- Flame resistance.
- Heat resistance.
Ques. What are polymers? [2 marks]
Ans. Polymers are high molecular mass substances (103 — 107u) consisting of a very large number of simple repeating structural units joined together through covalent bonds in a linear fashion. They are also called macromolecules. Ex: polythene, nylon 6,6, bakelite, rubber, etc.
Ques. How are polymers classified on the basis of structure? [5 marks]
Ans. On the basis of structure, polymers are classified into three types. These are linear chain polymers, branched-chain polymers and cross-linked polymers.
- Linear chain polymers: In this case, the monomer units are linked to one another to form long linear chains. These linear chains are placed one above the other and are closely packed in space. The close packing results in high densities, tensile strength and also high melting and boiling points. High-density polyethene is a very common example of this type. Nylon, polyesters and PVC are also linear chain polymers.
- Branched-chain polymers: In this type of polymers, the monomer units are linked to form long chains which also have side chains or branched chains of different Lengths attached to them. As a result of branching, these polymers are not closely packed in space. They have low densities, low tensile strength as well as low melting and boiling points. Some common examples of such polymers are low-density polyethene, amylopectin, starch, glycogen etc.
- Cross-linked polymers: In these polymers, also called network polymers, the monomer units are linked together to form three dimensionaL networks as shown in the figure. These are expected to be quite hard, rigid and brittle. Examples of cross-linked polymers are bakelite, glyptal, melamine-formaldehyde polymer etc.
Ques. What are natural and synthetic polymers? Give two examples of each. [3 marks]
Ans.
- Natural polymers: The polymers which occur in nature mostly in plants and animals are called natural polymers. A few common examples are starch, cellulose, proteins, rubber nucleic acids, etc. Among them, starch and cellulose are the polymers of glucose molecules. Proteins are formed from amino acids which may be linked in different ways. These have been discussed in detail in unit 15 on biomolecules. Natural rubber is yet another useful polymer that is obtained from the latex of the rubber tree. The monomer units are of the unsaturated hydrocarbon 2-methyl-i, 3-butadiene, also called isoprene.
Examples of natural polymers: Natural rubber, cellulose, nucleic acids, proteins etc.
- Synthetic polymers: The polymers which are prepared in the laboratory are called synthetic polymers. These are also called man-made polymers and have been developed in the present century to meet the ever-increasing demand of modern civilization.
Examples of synthetic polymers: Dacron (or terylene), Bakelite, PVC, Nylon-66, Nylon-6 etc.
Ques. How do you explain the functionality of a monomer? [2 marks]
Ans. The functionality of a monomer implies the number of bonding sites present in it. For example, monomers like propene, styrene, acrylonitrile have the functionality of one which means that they have one bonding site.
Monomers such as ethylene glycol, hexamethylenediamine, adipic acid have the functionality of two which means that they have two bonding sites.
Ques. What are Elastomers? [2 marks]
Ans. In Elastomers polymers, the intermolecular forces are the weakest. As a result, they can be readily stretched by applying small stress and regain their original shape when the stress is removed. The elasticity can be further increased by introducing some cross-links in the polymer chains. Natural rubber is the most popular example of elastomers. A few more examples are buna-S, buna-N and neoprene.
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