How is Plastic Made?
There are mainly two types of plastics – 1) Synthetic 2) Bio-based. Synthetic plastics are extracted from petrol products like crude oil, natural gas, or coal. On the other side, bio-based plastics are derived from renewable products like vegetable fats and oils, starch, corn, carbohydrates, bacteria, etc.
Synthetic plastics dominate the plastic processing industry because of their ease of processability. However, the shortage of oil reserves worldwide has led to the slow but steady adoption of bio-plastics extracted from animal wastage and waste biomass.
Plastics are made utilizing a total of four steps. Here are they:
- Extracting the raw materials
- Refining Process
#1 Extraction of Raw Materials –
It all begins with extracting raw materials from crude oil, natural gas, and sometimes coal. The overall mixture needs to be processed under particular conditions. Handling the mixture is a complex task as it contains thousands of compounds.
#2 Refining Process –
The transformation of crude oil and natural gases into various petroleum products is called the refining process. The derived petroleum products are converted into useful chemicals, including “monomers.”
Crude oil is heated in a furnace and sent to the distillation unit. Here the filtration will occur, leading to the separation of crude into lighter and smaller compounds called “fractions.”
Out of the extracted compounds, a range of hydrocarbon distillates is favored by the plastic industry collectively called Naptha. It can make large amounts of plastic, but other means like gas can also be utilized.
#3 Polymerization –
Most plastics are produced using two methods – Polymerization (Chain Growth Method) and step-growth method.
Polymerization begins with olefin gas converting into higher molecular weight hydrocarbons(Polymers). To make that possible, monomers must be bonded into chains. There are two variations of polymerization – Addition Polymerization and Condensation Polymerization.
Going by its name, addition polymerization means one monomer connecting to another(dimer), connecting to another(trimer), and so on. To achieve this perfectly, a catalyst named Peroxide should be used.
It means combining multiple monomers by removing small molecules like water. A catalyst is also necessary to make a reaction between adjacent monomers. Adding an existing chain to another is quite common to get desired results.
Common examples are polyester and nylon.
#4 Compounding –
Compounding means the mixing of various blends within a certain temperature to get formulations of plastics. The mixing is carried out using some extruder followed by fastening the mixture.
After that, the pallets are brought to the shop floor, where they are processed in injection molding or any other processing method to transform them into finished or semi-finished products.
The processing nature is completely dependent on the end application. It can vary in terms of size, shape, color, and properties.
Identification of Plastics –
We just learned how plastic is made. Now, let’s take a look at the classification of plastics. The classification depends on many factors like the reaction to chemicals, melting point, applications, and properties.
- Thermoplastics and Thermosets
- Amorphous and semi-crystalline
- Homopolymers and Copolymers
|It can be heated multiple times without significant degradation, which can be injected, molded easily, and later recycled.||
It can only once be heated once during the processing cycle as heating changes its chemical nature into 2 part epoxy. Continuous heating will burn the material.
|The overall usage in the plastic processing industry is more than thermosets.||
Overall usage is less because of its chemical nature and is utilized in particular applications.
|The molecular structure involves a series of repeat units combined linearly.||
The molecular structure involves two-three dimensional structure as opposed to one-linear in thermoplastics.
|Great candidates for recycling||
Poor candidates for recycling
|Common examples are poltypropylene(PP), acrylonitrile-butadlene-styrene, Polyoxymethylene(POM)||
Common examples are Polyurethane(PUR), phenolic, epoxy, silicone, etc.
The classification between amorphous and semi-crystalline materials is totally dependent on their molecular structure.
|Amorphous materisl lacks long-range symmetry like semi-crystalline materisl and thus become soft when additional heat is applied.||
Semi-crystalline materials have a more defined structure and exhibit a smooth transition from solid to liquid using a small temperature range.
|Applications – Tyres, hoses, gaskets, seals, etc||
Applications – Bearings, gears, structural loads, etc
|Examples – acrylonitrile-butadlene-styrene(ABS), Polystyrene(PS), Polycarbonate(PC), polysulfone||
Examples – Polyethylene(PE), polyethylene terephthalate (PET), Polypropylene(PP)
Talking about homopolymer and copolymer, their classification is based on the final material’s monomer make-up. A monomer is a molecule that combines with other molecules to become a larger molecule(polymer).
|If the final plastic is made up of a single type of monomer, it is called a homopolymer.||
If plastic is made from two or more different types of monomers, then it is called copolymers.
|Homopolymers have greater room temperature impact strength.||
Copolymers have better dimensional stability and tensile strength.
|Homopolymers have greater room temperature and impact strength.||
Copolymer possesses better chemical resistance.e
|Examples – polypropylene, Polymethyl-methacrylate, etc.||
Examples – polyethylene-vinyl acetate (PEVA), acrylonitrile butadiene styrene (ABS), etc.,
Bonus:- Let’s get into more details about how to make plastic?
What are Hydrocarbons?
A hydrocarbon is simply an organic compound consisting of carbon and hydrogen. Carmon having a valency of 4 meaning, it has 4 electrons in the outermost cells. It has the ability to pair up with four electrons of any element from the periodic table to create chemical bonds.
Hydrogen, on the other side, has only 1 electron in the valency shell. When the single hydrogen atom is paired up with 4 carbon atoms, a single bond is formed with the chemical name CH4 molecule called methane.
Methane is the elementary hydrocarbon and the first member of the alkane family.
Alkane Family – Methane (CH4), ethane (CH3-CH3 or C2H6), pentane (CH3-CH2-CH2- CH2-CH3), propane (CH3-CH2-CH3), butane (CH3-CH2-CH2-CH3), octane, nonane, hexane, heptane, etc.
This kind of carbon and hydrogen bond is called Saturated Bond (also called sigma bond). There can be another kind of bond named unsaturated bond (Pi bond ) with sigma bond crating Carbon-Carbon double bonds(alkenes) or two Pi bonds with sigma bond Carbon-Carbon triple bond(alkynes).
Alkene Family – Ethylene (CH2=CH2 or C2H4), propylene (CH2=CH-CH2), 1-butylene (CH2=CH-CH2-CH3), 2-butylene (CH3-CH=CH-CH3), etc.
Alkyne Family – Ethyne (CH ≡ CH or C2H2), propyne (CH≡C-CH3), 1-butyne (CH≡C-CH2-CH3), 2-butyne (CH3-CH≡CH-CH3), etc.
What is the Difference Between Plastic and Polymer?
Note that all plastics are polymers, but not all polymers are plastics.
Plastics are essentially high molecular weight organic polymers consisting of elements like carbon, hydrogen, nitrogen, sulfur, chlorine, and oxygen. Plastics can be made utilizing silicon atoms and carbon mixing. The main ingredients of plastics are polymeric resins and additives.
“Plasticity” is a term often used by plastic manufactures for describing the properties, key features, and attributes of all plastic materials that can deform unalterably without breaking or cracking. Plasticity is crucial for determining that the plastic will survive the heat and temperature during the molding process.
With the development in chemistry and increased R&D activities around plastic manufacturing, fine-tuning polymer properties depending on the requirement is doable.
Many different re-arrangements can be done with monomers to get the polymer’s desired shape, properties/attributes.
Interesting Read – What is a Plastic Pallet? | The Defintive Guide
How is Plastic Made From Naphtha?
Naphtha is a range of distillate hydrocarbons responsible for the creation of plastics. It is a combination of C5 to C10 Hydrocarbons.
Naphtha is kept in a steam cracker in hot water and decomposed at temperature (~800 °C), divided into two major hydrocarbons known as major intermediaries.
These small molecules are joined together, making a long chain called a polymer. When making their way to the shop floor, these polymers are shaped like granules (sometimes powder when processing in rotational molding ).
Before they take the shape of our everyday, beautiful-looking plastic products, go through the intense heating, melting, and cooling processes within different processing methods (Injection Molding, Extrusion, Blow molding, etc.)
The Future of Plastics –
Shoutout – Grandviewresearch.com
According to serval research conducted by Grand View Research, the global plastics market is valued at USD 568.9 billion in 2019 and will register a CAGR of 3.2% for 2020-2027. Packaging, construction, electronics, and electrical are the largest plastic consumers in business verticals.
Consumer Goods, medical, and Agriculture are also growing rapidly and can hold a significant chunk of the market share for plastic consumption in the future.
Global Plastic Market Share, By industry (2019)
However, the recent outbreak of Covid-19 has hindered the growth of plastics and overall manufacturing, construction, and other verticals because of nationwide lockdowns, supply chain constraints, and no economic activity whatsoever.
As of working this piece, a vaccine rollout is on the cards, and with government stimulus spending worldwide, things can get better in no time. So the long-term growth outlook is positive.
1. Who made the first plastic?
Ans. One of the earliest examples of the invention of plastics was in 1855 by Alexender Parkes, and he nomenclature his invention Parkesine, which we today know as celluloid. After that, a breakthrough came with creating Polyvinyl chloride somewhere between the years 1838-1872.
A quantum leap in the plastic invention story came in 1907 when Belgian-American scientist Leo Baekeland invented Bakelite, the first synthetic mass-produced plastic (still being used but meagrely).
2. What are the 7 types of plastics?
Ans. Below are the seven most common types of plastics:
1) Polyethylene Terephthalate (PET or PETE)
2) High-Density Polyethylene (HDPE)
3) Polyvinyl Chloride (PVC or Vinyl)
4) Low-Density Polyethylene (LDPE)
5) Polypropylene (PP)
6) Polystyrene (PS or Styrofoam)
3. Which is the safest plastic to drink from?
Ans. There are multiple plastic materials used in consumer applications. However, according to my knowledge and experience, the best plastics to drink or consume anything from is HDPE. Most detergent and juice bottles, milk jugs, toiletries containers, butter tubs, and even a good amount of water bottles (Although the most utilized plastic for making water bottles is PET with more than 70% market share) are also made from HDPE.
4. What are the steps of the plastic recycling process?
Ans. There are six main steps in the plastic recycling process. Here are they:
1. Collection of waste plastic
2. Organizing plastics into categories
3. Washing to remove impurities
4. Stressing and resizing
5. Identification and uncoupling of plastics
5. What are the most common plastic processing methods?
Ans. The most common plastic processing techniques are Injection molding, Extrusion, rotational molding, blow molding, thermoforming, and compression molding.
Suggested Read –
Final Words –
I have tried to keep this piece short (I don’t want to waste much of your time). So that was my take on how plastics are made. The plastic creation process si complicated and takes much time and investment to even start. However, innovating has been made to make the process more transparent and inexpensive and make it less harmful for the environment. So keep researching this ans stay updated for the best knowledge.
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