Often, people use plastics and polymers interchangeably, considering the former is an example of the latter. Polymers refer to a wide range of substances that occur naturally or are synthesized artificially. They are formed by what we refer to as polymerization, a process where smaller molecules react, leading to these long-chain macromolecules called polymers.
This article will explore the basics – discussing the building blocks of all polymers – monomers. We also discussed polymers and plastics extensively, providing detailed distinctions between both substances. Let’s get right into it.
What Are Monomers?
Monomers are molecules capable of chemically binding to other molecules – usually identical molecules – to form a long chain called a polymer. The polymer tends to contain an unspecified number of the basic unit – monomers. Examples of monomers include simple molecules like glucose, ethene, vinyl chloride, etc.
Basically, monomers are the building blocks for more complex organic molecules – polymers. An ideal polymer comprises at least 100 repeating monomers bonded by covalent bonds.
What Are the Characteristics of Monomers?
As mentioned earlier, monomers are small molecules that aggregate and polymerize to form larger molecules called polymers. Below are typical characteristics of monomers.
- Small Molecular Size: Monomers tend to have a low molecular weight. This is why they can interact and polymerize to form larger macromolecules.
- Solubility: Monomers are generally soluble in suitable organic solvents.
- Polymerization: Under suitable conditions, such as condensation polymerization, hundreds or thousands of monomers can aggregate and polymerize to form larger molecules – polymers.
- Stability: Monomers are generally reactive. Therefore, handling the organic molecules requires care. In fact, it is during such reactions that result in polymerization.
- Monomers are generally organic molecules, with each having specific physical and chemical properties relating to itself.
What Are the Applications of Monomers?
Monomers have an extensive range of applications, especially in the manufacturing sector. They include the following.
- Plastics: Monomers are the building blocks for manufacturing different plastics. They are the basics for polymers like polythene, polystyrene, PVC and other industrial-grade plastics.
- Medical Products and Devices: Monomers such as ethylene oxides are used as sterilants for various medical products. Also, medical-grade plastics used in manufacturing implants, catheters, hand gloves and other medical gadgets are products of monomer polymerization.
- Fuel Additives: The common additives added to fuel and oil filters consist of monomers like butene and ethylene, which help enhance the performance of auto engines and other gas-powered machines.
- Paints, Adhesives and Coatings: The constituents of these substances are monomers like ethylene oxide, styrene, etc. Adhesives, paints and coatings have vast applications in various industries, including aerospace, automotive and other engineering sectors.
Again, remember that monomers are the building blocks for polymers. And considering that all natural polymers are also formed from the reaction and aggregation of monomers. These small molecules possess immense applications beyond the few we listed above.
What Are Polymers?
Polymers are large molecules (or macromolecules) comprising – hundreds or thousands – of repeating similar subunits covalently bonded together. These large structures exist naturally as biological molecules, such as carbohydrates, cotton, wood, cellulose, wool, proteins, etc. They could also be semi-organic or synthetic, which is produced artificially.
Semisynthetic polymers are formed from the modification of natural polymers. Typical examples include cellulose nitrate and cellulose acetate. Synthetic polymers, that is, artificial ones, are synthesized in industries. The commonest of such polymers is plastic, which has a vast application.
What Are the Characteristics of Polymers?
Since polymers are an aggregation of several smaller molecules to form large macromolecules, they usually present unique characteristics different from the constituting molecules. Let’s examine some of these features.
- Molecular Size: They are large macromolecules formed from the aggregation and polymerization of several units of monomers. Their molecular mass is usually about 20,000 to millions.
- Resistance to Chemicals: Polymer usually possesses considerable resistance to different chemicals. This increases their durability since they tend to be long-lasting.
- Thermal Stability: Besides the chemical resistance, most polymers have high resistance to high temperatures and harsh environmental conditions.
- Vast Structural Diversity: Polymers exist in different forms, each having distinct physical and chemical properties.
- Strength: Polymers are large macromolecules formed by bonding and linking many monomers. They are relatively strong and highly durable. This feature enhances their functionality for several industrial applications.
- Flexibility: Most polymers are flexible and versatile. They can be easily reshaped, molded and processed through various manufacturing processes like machining, blow molding, extrusion, and injection molding. This increases their application, especially in the manufacturing sector.
What Are the Applications of Polymers?
The industrial applications of polymers are extensive, considering different materials are created through the polymerization process. Moreover, they include natural substances like rubber, cellulose, silk, bitumen, etc. However, the most common polymer used for industrial applications is synthetic plastics.
Essentially, polymers are raw materials for various industrial uses, including the following.
- Molded and formed products
- Car tires
- Adhesives
- Coatings, inks, paints, etc.
- Fibers and yarns for clothing industries
- Lighting fixtures
- Automotive and engineering parts
- Elastomers, etc.
What Are Plastics?
Plastics are a group of synthetic or semisynthetic materials consisting of an aggregation of polymers, for example, polyethylene, nylon, polyvinyl chloride, etc. Most plastics are from the condensation of petroleum chemicals. All plastics possess similar physical characteristics and are highly versatile, making them suitable for various applications, including domestic and industrial use.
Depending on their physical properties, plastics can be grouped into two broad categories – thermoplastics and thermosets.
Thermoplastics
These plastics can be deformed upon heating and reshaped without fundamental alteration at the molecular level. When heated, thermoplastics will melt, yielding liquefied plastic suitable for further fabrication. Subjecting the molten plastic to a suitable manufacturing process, such as injection molding, will allow you to reshape it into the desired shape. Examples of such plastics include nylon, polyethylene, PVC, etc.
Thermoplastics can occur in two different forms based on molecular structure.
- Amorphous Thermoplastics: These polymer chains of plastics are not arranged in an organized fashion. The chains interconnect disorderly, which makes them have a low thermal resistance. However, they are rigid and tough under low-temperature conditions. Since they lack a real structure, these plastics are clear and transparent, making them suitable for light fixtures and plastic window components.
- Semi-crystalline Thermoplastics: The polymers that make the plastics interconnect and join in a particular arrangement. Though, it could also contain some amorphous areas, seeing that it isn’t completely crystalline. Therefore, the ratio of the crystalline component to the amorphous component plays a significant role in the characteristics of the plastic. In addition, the higher the crystalline components, the more the opacity of the plastics. However, they tend to be tougher, showing improved resistance to heat and chemicals than amorphous thermoplastics.
Thermosets
Unlike thermoplastics, these plastics cannot be softened after initial shaping and molding. Upon exposure to high temperatures, these plastics will burn and not melt. However, they have high thermal resistance, making them suitable for several applications. They are mainly used in high-precision fabrication, knowing they will not change shape or shrink upon exposure to high temperatures. Typical examples include polyurethane, silicone, Bakelite, melamine etc.
What Are the Characteristics of Plastics?
The properties of plastics include the following:
- Lightweight, Strength and Durability: Plastics possess lightweight yet considerable strength, making them suitable for various purposes.
- Plastics are Poor Conductors: They are poor conductors of heat and electricity. Instead, they possess excellent insulating properties that make them suitable for creating plastic coverings for electrical wires, handles of screwdrivers etc.
- Plastics are Cheap: They are generally cheaper than metals, making them a suitable alternative for various industrial fabrications and household products.
- Unreactivity: Unlike metals, plastics are relatively inert. Upon exposure to moisture and air, they do not rust. In addition, they are resistant to corrosion. This makes them suitable for storing different substances, including chemicals.
- Appearance: Plastics can be made into any color or texture variation to suit a specific application. In addition, these plastics, like polyethylene, can appear clear and transparent like glass.
- Weather Resistance: Plastics are non-biodegradable. Therefore, unlike natural polymers like rubber and wood, they maintain their characteristics even upon exposure to harsh weather conditions.
- Toughness: Compared to other nonmetals, plastics show considerable toughness and tensile strength, allowing them to withstand a lot of weight and are suitable for vast fabrication.
What Are the Applications of Plastics?
Besides metals, plastics are one of the commonest components in manufacturing industries. Their characteristics and cost-effectiveness make them suitable as substitutes for metals in various fabrications. However, the applications of plastics vary depending on the type of plastics. For example, thermoplastics are compatible with injection molding, while thermosets are not. That said, we will group the application of the plastics based on the plastic type.
Because of their high resistance to high temperatures, thermosets are used for the various applications
- Electrical switches, insulators and other electronic components
- Car parts and covers
- Lighting fixtures
- Household equipment
- Energy equipment
- Heat shields
- Tiles manufacturing, etc.
On the other hand, thermoplastics are more versatile with a wider industrial application, which include the following.
- Car lighting, dashboards and other automotive components
- Medical devices and equipment
- Plastic injection molding and blow molding
- Packaging materials
- Various engineering and mechanical parts
- Storage containers
- Substitutes for metals in various fabrication
Difference Between Plastics vs Polymers
Plastics and polymers share a close relationship. However, they do not necessarily mean the same. While polymers refer to large macromolecules consisting of several units of monomers, plastic is a specific kind of polymer that has undergone processing. Therefore we can infer that all plastics are polymers, but not all polymers are plastics.
Let’s take a quick look at other distinctions between the two under the following headings.
● Physical and Chemical Properties
Since plastics are a specific type of polymers, most plastics share the same characteristics. They are often categorized based on their reaction upon exposure to high temperatures into thermoplastics and thermosets, with each group sharing more closed relationships. On the other hand, polymers are a vast group of large compounds, each having a unique characteristic to its group. For example, wool and carbohydrates are two distinct polymers. The properties of the polymer are often related to the monomers and the process of polymerization that forms it.
● Molecular Weight
Depending on the size of the polymer, its molecular weight can be as high as millions. However, plastics usually have a molecular weight of just a few thousand. In addition, polymers are often a product of aggregation or condensation of uniform molecules of small-sized monomers. On the other hand, plastics are a product of the cross-linking of long-chain molecules.
● Applications
Considering plastic itself is a polymer. Therefore its application also falls under those of polymers. Therefore, polymers have a more extensive application than plastics. Polymers are used in more diverse industries than plastics. In addition, some polymers are even edible, providing nutrition to humans and animals. Typical examples include carbohydrates and proteins, starch, etc.
● Source or Origin
We have established that polymers may be natural or synthetic, with plastics being a typical example of the latter. That said, plastics are of synthetic origin; they are strictly a product of the laboratory. For example, natural rubber is obtained from the latex tree; we can’t say the same for any plastic.
Kemal: Plastic Injection Molding Services
It is not enough to understand the differences between plastics and polymers, including their characteristics and applications. When looking to use plastics for your fabrication, it is best to work with an experienced partner that will guarantee your project a resounding success.
Kemal is an expert at offering plastic injection molding services. Our facilities boast of highly skilled machinists and engineers who are knowledgeable in the latest technologies needed for your fabrication.
Besides injection molding, we also offer services in CNC machining, 3D printing, rapid prototyping, blow molding and all related technologies, with suitable finishing operations. We just require you to upload your CAD files. Then, we will provide you with an instant quotation. So, when injection molding other manufacturing solutions, do not hesitate to contact us – Kemal.
Conclusion
Plastics and polymers are essential materials used in manufacturing. Generally, plastics are often a suitable replacement for metals when possible, considering they are cheaper and lighter. In addition, they are more flexible and pliable, which enables them to fit easily into fabrications, including structures where metals are unfit.
