Types of Plastics in Chemistry and Their Properties

Plastic is defined as a material that contains an organic substance of greater molecular weight as an important ingredient. It is also characterized as polymers with long chains of carbon. All plastics are said to be polymers. There are two different types of plastic-

1. Thermoplastic

2. Thermosetting

In this article, we will study different types of plastic and their uses in detail.

Thermoplastic and Thermosetting Plastic

Thermoplastic: 

Plastics that are easy to bend when heated. Thermoplastics include linear polymers and a mixture of linear and cross-linked polymers. For instance, PVC, nylon, polythene, etc.

Types of Plastic Materials

There are 7 types of plastic. They are as follows-

1. Polyethylene Terephthalate

PET is often known as a fabric that is wrinkle-free. It's different from the plastic bag we usually see at the grocery store. Due to its good ability to avoid oxygen from getting in and spoiling the substance inside, PET is often used for food and drink packaging purposes. It also helps keep carbon dioxide from getting out of carbonated drinks.

2. Polyvinyl Chloride

A synthetic polymer whose monomer is vinyl chloride (a chemical compound with the formula CH₂=CHCl or C₂H₃Cl) is polyvinyl chloride (often abbreviated to PVC). More than 40 million tons of this plastic are manufactured around the globe every year. Rigid PVC (or RPVC) and flexible PVC are the two basic types of PVC. Rigid PVC is mainly used for plumbing, windows, and doors in the building industry. In the development of bank cards, packaging, bottles, and food-covering sheets, this type of PVC is often used. It is understood that flexible PVC has applications in electrical cable insulation, flooring, plumbing, and imitation leather. The melting point ranges from 100 to 200 degrees celsius.

3. Polyethylene

Polyethylene is a very popular plastic, or simply polythene, whose monomer is ethylene (a chemical compound with the formula C₂H₄). You can write the generalized chemical formula of this plastic as (C₂H₄)n. Polyethylene density can vary between 0.88 grams per cubic centimetre and 0.96 grams per cubic centimetre. This plastic has a relatively low melting point, ranging from 115 degrees Celsius to 135 degrees Celsius. There are four different polyethylene densities-

Low-density polyethylene - It is used for the production of plastic bags, shopping bags, and disposable products.

• Medium-density polyethylene-  It is used in gas pipes, carrier bags, etc.

• High-density polyethylene- As they are more rigid than the above two they are used in plastic bottles, snowboards

• Ultra-high molecular weight polyethylene- They are highly resistant. Used in is in military body armour, hydraulic seals and bearings, biomaterial for hip, knee, and spine implants, and artificial ice skating rinks.  

4. Polypropylene

Polypropylene is a non-polar, partly crystalline polymer whose monomer is propylene (sometimes referred to as polypropene and abbreviated to PP) a chemical compound with the formula C₃H₆. The generalized polypropylene chemical formula may be written as (C3H6)n. It is important to note that when heated to certain temperatures, polypropylene becomes moldable so it is a thermoplastic polymer. The melting point usually ranges from 130 degrees Celsius to 171 degrees Celsius. It is estimated that the density of amorphous polypropylene is 0.855 grams per cubic centimetre, whereas that of the crystalline variant is approximately 0.95 grams per cubic centimetre.

To make laboratory equipment, vehicle parts, medical devices, and food containers, polypropylene sheets are used.

5. Polystyrene

Acrylonitrile butadiene styrene (often abbreviated to ABS) is a thermoplastic synthetic polymer that is made up of three different monomers.

Acrylonitrile - they are represented by the formula

Styrene- It is a derivative of benzene with the chemical formula C8h8

1,3 butadiene- organic compound with the formula c4h6

The density typically varies from 1.06 to 1.08 grams per cubic centimetre of this engineering plastic. In drain-waste-vent pipe systems or DWV pipe systems, one of the most important applications of ABS is In certain musical instruments, inhalers, automobile bumper bars, and the heads of golf clubs, this plastic is often used.

6. Nylon

Nylon 6 - they have very high tensile strength and, to some degree, are also lustrous and elastic. It is known that nylon 6 fibres are highly resistant to chemical products (such as alkalis and acids). They are immune to abrasion or wrinkling, too. In addition, nylon 6 is proven to be wrinkle-proof. Nylon 6 plastic is commonly used in many sectors, such as the aircraft industry, the automobile industry, the electronics industry, and the textile industry, because of its many attractive properties.

7. Others

Others refer to all plastics other than those referred to in numbers 1-6 and also to plastics that may be layered or mixed with other plastics, such as bioplastics. The most popular plastic in this group is polycarbonate (PC), which has not been used as much in recent years because of its association with bisphenol A. (BPA). PCs are known by different names as well: Lexan, Makrolon, and Makroclear. Ironically, for baby bottles, sippy cups, water bottles, water gallons, metal food can liners, ketchup containers, and dental sealants, PC is usually used. Owing to its toxicity, the use of PCs for baby bottles and infant formula packaging has been banned in many countries.

Thermosetting: 

Plastics that, once molded, can not be softened again by heating. Heavily cross-linked polymers fall into the thermosetting plastics group. There are primary bonds between molecular chains in thermosetting plastics and strong cross-links hold them together. Bakelite, melamine, etc. Example: Bakelite is used to make electrical switches, while floor tiles use melamine.

Types of Plastic Materials

1. Melamine formaldehyde- Heat-resistant plastic. Hardest of all the plastics.

2. Bakelite- Used in bottle caps, plastic automobile parts, etc.

3. Polyesters- Used for reinforced plastics

4. Epoxies - Used as adhesives

Did You Know?

Plastic recycling is very significant. If they are not recycled at the right time, they are mixed with other chemicals or products, making them harder to recycle and a source of pollution. They are non-biodegradable, and the microbial effect does not decompose them. It is important to use biopolymers or biodegradable polymers to prevent this.