Plastics Vs. Polymers | What are the Differences?
Polymers and plastics are often mistaken for being the same thing. Both the terms are often used synonymously, but they are very different from each other. Polymer-plastic is used extinsively in our day-to-day lives, more than we realize, and they’ve acquired a non-replaceable part in our routine.
The major difference between polymer and plastic is that polymers exist organically or are created synthetically and comprise joined chains of individual molecules or monomers. On the other hand, plastics comprise long chains of polymers composed of tiny, uniform molecules.
In laymen’s terms, all plastics are polymers, but not all polymers are plastics. Let start with a detailed guide on the major differences between polymer vs. plastic to understand their structure, properties, and applications.
What are Polymers?
A polymer is a chemical compound comprising huge molecules or macromolecules composed of repeating subunits made up of endless series of interconnected links. There are two types of polymers – natural and synthetic. Both of them boast a huge set of properties used in many of our day-to-day, mundane activities we don’t even bother to notice.
Natural Polymers or biopolymers range from wool, cotton, wool, DNA, proteins, etc.
Synthetic polymers are classified into four types – thermoplastics, thermosets, elastomers, and synthetic fibers.
- Thermoplastics: The main characteristic of any thermoplastic is that it can retain its properties even after prolonged exposure to heat. When heated to their melting point, thermoplastics melt rather than burning them, perfect for shaping and molding.
- Thermosets: A thermoset, also known as a thermosetting polymer, becomes set in its physical and chemical properties after an initial treatment of heat, and that makes them unaffected to the additional heat exposure.
- Elastomers: Elastomers are elastic materials with low strength molecular bonds and high flexibility. They are amorphous and lightly cross-linked with a glass transition temperature well below room temprature. The most popular examples are Thermoplastics elastomers, Acrylic Rubber, and Acrylic Ethylene Rubber.
The classification of a synthetic polymer is determined by its fundamental structure, physical properties, and applications. There are thousands of polymers out there, so it crucial to understand the attributes and uses of a polymer to make sure that they are being used in suitable applications.
The molecular structure of a polymer can be described at various length scales, from the sub-nm length scale up to the macroscopic one. To synchronize everything properly, as a matter of fact, there is a hierarchy of structures in which each stage provides the foundation for the next one. The starting tip of the structure of a polymer is the identity of its component monomer.
After that, the microstructure essentially represents the monomer sorting and arrangement within the polymer at a reach of a single chain. The microstructure plays a key role in figuring out the possibility of a polymer to configure phases with different arrangements.
The molecular structure of a polymer decides the fundamental propertoes of the material. The following are the points crucial in classifying a particular polymer material.
Molecular bonds: The polymer structure is heavily dependent on how the monomers are linked to each other or if there are no cross-branching bonds between polymer chains.
Monomer configuration: For better classification of material, knowing which monomer make up the polymer chain, how many of each, and the nature of those monomers will play a vital role.
Chain attributes: The average length and weight of the chains in a polymer help figure out the degree of polymerization and the molecular configuration of the polymer.
Polymerization method: The methods used to join the monomers into polymers decides the structure of the polymer, regardless of it being natural or synthetic polymerization, through using heat, condensation, or chemicals.
- Polymers don’t melt; they change state from crystalline to semi-crystalline.
- As the chain length and cross-linking increase, the tensile strength of the polymer also increases.
- Polymer is enabled with hydrogen bonding and ionic bonding resulting in superior cross-linked strength.
- Polymers with Van der Waals forces linking chains are weak, but they give a polymer a low melting point.
Polymers are created by polymerization, and there are a variety of polymers that can be created through polymerization. That makes polymers useful in a wide array of applications.
- Thin Films and Sheets
- Formed and molded products
- Coatings, paints, and inks
- Yarns and other fibers
Engaging Read – UHMW Vs. Delrin: Which one is the Best?
What are Plastics?
Plastics are synthetic polymers extracted from petroleum through the use of polymerization or polycondensation process. Although polymers occur naturally, plastics are completely man-made.
Plastics are all one kind of polymers with similar physical properties and versatility, making them useful in a wide array of applications. They are classified into two main types – thermoplastics and thermosets.
Thermoplastics become liquid after being heated to their melting point, making them perfect for molding and shaping purposes. What makes them so useful is their ability to retain their properties even after consecutive heating sessions. Consistent reheating and reshaping doesn’t affect thermoplastic’s molecular makeup.
They are available in two forms – Amorphous and semi-crystalline.
Amorphous Thermoplastics: Amorphous thermoplastics are comprised of polymer chains that are not arranged in a particular fashion. They are muddled up together in a very uneven and unorganized manner. Amorphous thermoplastics have low heat resistance but are tough and rigid and low temperatures. They tend to be clear and transparent, thanks to their lack of structure.
Semi-crystalline thermoplastics: Semicrystalline thermoplastics are compromised of polymer chains in a sophisticated and ordered manner or a crystalline structure mixed with amorphous areas. The amount of crystalline or amorphous structure decides the physical characteristics of plastic. The greater the crystalline structure, the opaque the material becomes. Semi-crystalline thermoplastics show impressive strength, heat resistance, stability, and chemical resistance than their amorphous equivalents.
Below are the most common thermoplastic materials:
- Acrylonitrile butadiene styrene (ABS)
- Polyvinyl chloride (PVC)
- Thermoplastic olefins
Thermoplastic owing to their impressive physical properties are used in a wide array of applications. Here are some:
- Packaging materials
- Consumer goods
- Pipes & Fittings
- Electrical & Electronics
- Medical Equipment
- Industrial Applications
The easily formable attributes of thermoplastic make them ideal for machining in processing techniques like Injection Molding, Blow molding, compression molding, thermoforming, ultrasonic welding, casting, sintering, and rotational molding.
Thermoset plastics are obtained by irreversibly curing a soft solid or resin. They are hardened by applying heat to a permanent design. Once shaped, thermosets remain in solid form even after being exposed to heat again. The high resistance to heat and corrosion makes thermosets useful in particular applications like precision components that will not change shape in extreme temperatures.
The most common thermosets include:
- Certain polyesters
Due to temperature withstanding nature, thermosets are sued in applications such as:
- Electronic components
- Household appliances
- Lighting components
- Energy equipment
- Heat shields
- Motor parts and covers
Interesting Read – What is Condensation Polymerization? | The Definitive Guide
1. What are the 7 types of plastic?
1) Polyethylene Terephthalate (PETE)
2) High-Density Polyethylene (HDPE)
3) Polyvinyl Chloride (PVC – U)
4. Low-density polyethylene (LDPE)
5) Polypropylene (PP)
(6) Polystyrene or Styrofoam (PS)
2. What are the advantages of polymers?
Ans. The advantages are as follows:
- Chemical resistant than metals.
- No requirement for post-treatment finishing efforts
- 10 times lighter than typical material
- Fantastic thermal and electrical insulation properties
3. What are the disadvantages of polymers?
Ans. The disadvantages are as follows:
- It cannot be easily machined
- Low structural rigidity
- The strength to size ratio is less compared to metals.
- Meager heat withstanding capacity
4. Which country uses the most plastic?
Ans. The US and UK use more plastic and generate more plastic water than any other country in the world.
The Conclusion –
That’s all I wanted to say about plastic vs. polymers. I have done my best to mention all the necessary information regarding the topic.
I show my gratitude to everyone who is reading. Kindly share your thoughts and views on the article in the comment box.
Have a fantastic day 🙂