Is Polyethylene a Copolymer?
Is Polyethylene a Copolymer?
Before we go to the summary of whether polyethylene is a copolymer or not we need to understand three terms:
A Polymer: A Polymer is a substance or lets say material that consists of very large molecules or macromolecules that are composed of subunits that are repeating. The polymers are considered very substantial for our daily existence and both natural and synthetic polymers are essential for us. The four types of polymers are thermoplastics, thermosets, elastomers and synthetic fibres. These are all synthetic polymers and are made by man. These synthetic polymers are found in a variety of consumer products.
A Copolymer: This is a polymer which is derived from one species of monomer. Monomers are molecules which react with other molecules which are monomers and form a larger polymer chain or a three dimensional network. The polymerisation of monomers into copolymers is called as copolymerisation. The copolymers which are got from such a copolymerisation process is called biopolymer. There are basically three different type of copolymers – they are block, random and alternate. A block copolymer is made of two homopolymers and is linked to one single polymer chain. Random are those which consist of randomly linked monomers in a polymer chain.
We apply block polymers to thermal plastic elastomers and polymer blends. The use of block polymers is also in technologies like nanotechnology, controlled drug delivery, photonics etc.
Polyethylene:They are also known as polythene. Other names include poly (methylene) and are most common used plastic today. It is a polymer and used for packaging, plastic bags, bottles etc. As of recent statistics, over 100 million tonnes of polyethylene resins are being produced annually.
We may have high density polyethylene which is nothing but a thermoplastic polymer that is produced from the monomer ethylene. It is sometimes called alkathene. They are widely used for HDPE pipes. Polyethylene has a melting point of 110 degree C. Its principal use is in packaging films, trash, and bags, wire and cable insulation, housewares etc.
There are many kinds of polyethylene and they have a chemical formula of (C2H4)n. PE is highly mix of similar polymers of ethylene and the value of n may vary. IT can be low density or high density even. The high density polyethylene uses low pressure and low temperature. The polyethylene is thermoplastic and can be made into some other forms like for example cross linked polyethylene. Vice versa with low density polyethylene.
Is polyethylene a polymer?
Polyethylene is a vinyl polymer and is made up of monomer ethylene. By the process of coploymerization the monomers with an alkyl branched comonomer we get a copolymer which has a short hydrocarbon branch. These copolymers are called low density polyethylene or even LLDPE. We can also say that Polyethylene is made up of radical polymerisation of ethylene where the chemical formula for ethene is C2H4. For example- Acrylic is an example of plastic formed by additional polymerisation and these polymers are thermoplastics in nature. They can heated or even made soft and when they are cooled they hardens. Polyethylene is the simple example of linear polymer.
Properties of Polyethylene:
- Mechanical properties: Polyethylene is of low strength, rigidity and hardness. They can be waxy when you touch and have ductility and low friction.
- Thermal properties : They have low melting point as compared to other thermoplastics. The melting point for an average low density commercial polyethylene is around 105 to 115 degree C. But depending on the type of polyethylene the thermal temperatures may vary.
- Chemical properties: The polyethylene consists of saturated, high molecular hydrocarbons. Its chemical behaviour is similar to paraffin. The macromolecules are not lined. They have symmetrical molecular structure and they tend to crystallize. They are actually partially crystalline. They can become brittle when exposed to dense light. They do not absorb any water and the gas and water vapour is lower in most cases. Oxygen, carbon etc can pass through it easily. Most of the LDPE, HDPE have very good chemical resistance and that means they are not attacked by acids or bases which are strong. They are resistant to gentle oxidants and other agents. They do get dissolved at certain elevated temperatures.
- Optical properties:They can range from clear to milky opaque to opaque. HDPE is the least transparent.
- Electrical properties: They are usually good electric insulator and they become charged electrostatic ally charged.
Polymerisation process: We have ethylene which is a stable molecule and that will polymerise upon contact with catalysts. This is a highly exothermic process. We have most common catalysts such as titanium chloride or philips catalyst. Polyethylene can also be produced through some radical polymerisation but this is only implemented in high pressure apparatus. The ingredient or monomer used is ethylene which is a gaseous hydrocarbon with a formula of C2H4 which is a pair of methylene groups.
Refer: Polymers from Class 12 Chemistry English Medium – Find All the Questions & Answers