The use of plastic material is getting rapidly common in our daily life. Different types of plastics are available commercially to overcome our daily needs.
Plastics have been utilized for years in almost every sector, including packaging, industrial machinery, textile, construction & buildings, electronics, and daily consumer-based products.
In recent years, a very drastic growth has been seen in the research and development of plastic materials, their derivatives, and their applications. Every year many articles & research addressing plastics are published, which are even more in numbers than the number of articles for any other material.
Currently, the researchers are focusing on Self-Healing Polymers, Shape Memory Polymers, and Light Responsive Polymers for research and development to address the innovative, efficient, and advantageous properties of polymers or plastics.
However, the commercialization of these classic plastics is under consideration, and better results will be out soon.
Types of Commercial Plastics
Modified polymers and engineering plastics are difficult to commercialize. However, many commodity or commercial plastics are considered the most efficient for particular characteristics and properties.
These commercial plastics are available easily. The most common plastics usually include polypropylene, polyethylene terephthalate, polyethylene, polyvinyl chloride, Polystyrene, etc.
These polymers are considered for manufacturing different types of plastic products for construction, energy, furniture, aerospace, packaging, electronics, automobiles, marine, health, and safety tools.
1. Polyethylene Terephthalate (PET)
Polyethylene terephthalate (PET) is a widely used polyester-based plastic used as a commodity thermoplastic polymer. The glass transition temperature of PET is 66oC to 80oC, and it melts near the temperature of 260oC.
Polyethylene terephthalate is a strong, transparent, lighter plastic material used typically for beverages and food packaging applications. The PET is synthesized using ethylene glycol and terephthalic acid following the polymerization reaction.
PET offers high modulus, strength, and stiffness. It has high tremendous anti-electric properties. The chemical resistance of PET is very impressive, even in the case of water as well, and that is the reason PET is highly used in beverage industries for containing or carrying food-grade liquids.
Furthermore, its stable structure shows strong barrier characteristics towards moisture, oxygen, and carbon dioxide, which are not present in different commercially used plastics, i.e., Polystyrene, Polyamide.
Due to its exceptional optical properties, PET is considered to be used under micro radiations and for recycling. Mostly, PET is processed using injection molding machines.
But it is not a biodegradable material, which continuously increases the annual waste production rate globally.
2. High-Density Polyethylene (HDPE)
High-density polyethylene (HDPE) is a petroleum-sourced plastic material. This plastic material is a versatile polymer with various commodity applications, including piping, bottles, liquid jugs, and packaging.
HDPE possesses high melting point and impact strength because of tremendous tensile modules, high density, and lightweight.
Malleability or mold-ability is one of the best properties of this plastic material because of its inherent stiff chemical structure. As it has a high melting point, it does not soften earlier, but as the melting point approaches, it rapidly melts itself and may be molded in different shapes or products as per requirements.
Linear structure with low branching helps HDPE improve its backbone intermolecular forces and tensile strength. HDPE offers high corrosion and weather resistance with high durability and dimensional stability.
HDPE may be easily recycled. Its recyclability can reduce up to 50% of the production of commercial plastics. Moreover, HPDE is a highly adaptable material by larger industries as a replacement or alternative to heavy metals or other materials.
Conclusively, HDPE offers high mechanical properties at a low cost without any environmental hazards.
3. Low-Density Polyethylene (LDPE)
Low-Density Polyethylene (LDPE) is a transparent, commercial thermoplastic polymer. It is very popular in manufacturing garbage boxes, liquid containers, and packaging applications.
The corrosion resistance, flexibility, toughness, low energy consumption, higher efficiency, and less waste make it appealing to utilize in several important applications. LPDE may be recycled fully.
Low-Density Polyethylene is synthesized using free radical polymerization, offering presentable toughness, flexibility, and corrosion resistance. It offers greater strength with less weight making it a suitable material for low-weight applications.
The thermal stability of LDPE is also very interesting. It shows higher strength even at very low temperatures. Some polymers are found brittle generally because of a lowering in the surrounding temperature.
But LDPE can stand at a lower temperature without any dominant structure changes. Keeping apart its advantages, it is a highly flammable organic material. The gas permeability values of LDPE are also not up to the mark.
They are not resistant to UV radiation and are highly susceptible to stress cracking because of this poor resistance. They have less strength and density than High-Density Polyethylene because of a more amorphous region and irregular main chain structure.
4. Polyvinyl Chloride (PVC)
Polyvinyl Chloride (PVC) is a highly versatile, flexible, and strong thermoplastic material. PVC is widely used for applications involving pipes, ducts, medical devices, insulations, etc. PVC is considered the number three most manufactured or synthesized plastic material.
PVC is a white granular or powdered solid material with brittle nature. As an economical plastic option, it is commonly used in construction industries to make doors and windows profiles.
Moreover, it is also used for wastewater piping, heavy-duty wire insulations, and several medical equipments. Recent research has approved the utilization of PVC in building materials and construction applications as suitable replacements for metal, wood, ceramics, concrete, and rubber.
This effective prolonged utilization or usage of PVC is due to its easy processability, low cost, good mechanical properties, and lightweight. PVC resin synthesized through polymerization reaction is mostly found unstable.
This instability of PVC is due to its temperature-sensitive behavior and very high melt viscosity. So, to overcome this instability issue, suitable additives are added to the PVC to make them able to be processed as per the required parameters and ultimate properties.
5. Polypropylene (PP)
Polypropylene (PP) is considered one of the highly processed and used commercial plastics. It is also a thermoplastic polymer with textiles, fiber, machinery, small parts, and packaging applications.
It was first synthesized through polymerization in 1951 and is now utilized in common daily and industrial uses. The growth and demand for polypropylene are increasing exponentially day by day globally. Its per-year global demand is recorded at around 45 metric tons.
Due to its glossy and tactile surface, polypropylene is utilized in many applications, including plastic furniture, gearboxes, and in-vehicle machinery.
This tremendous thermoplastic polymer is highly considered because of its adaptability towards new processes and parameters, lighter density, ability to withstand, and optimized flexible properties. It presents excellent electrical resistance and resilience, leading to ultimate durability and toughness.
The insulation properties of polypropylene are impressive, showing its application space in the fields of cable coating and electrical appliances. The fibrous form of polypropylene is highly adaptable because of its improved strength for carpets, tapes, and roping applications.
The use of polypropylene is also growing rapidly in the field of the automotive vehicle industry. In the automotive industry, polypropylene is typically used to manufacture instrumental panels, bumpers, holders, battery casings, and door trims.
6. Polystyrene (PS)
Polystyrene is a hard, cheaper, and highly flexible plastic material. It is a vinyl polymer that is more common than any other commercial polymers used in our daily needs.
In model cars, several parts have been manufactured using Polystyrene. These are done for packaging and insulation purposes. Several applications of Polystyrene have been found easily in our daily life, including molded car parts, toys, kitchen appliances, and housing for construction and other purposes.
Polystyrene is a class of vinyl polymers; Its structure is made up of a long hydrocarbon chain containing a phenyl group which is found to be attached to every single atom of carbon present in the backbone chain.
Polystyrene is made or formed using free radical vinyl polymerization. There are several rubbers applications where polypropylene is used in rubber class SBS and its derivative thermoplastic. The rubbery polystyrene state is also known as poly(styrene-butadiene-styrene).
The injection molding of PS is done using its common grades General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS). General-purpose Polystyrene is a brittle material showing less flexibility and modules.
7. Polycarbonate (PC)
Polycarbonate is a transparent thermoplastic polymer with carbonate as a functional group. Its strong and stable structure allows greater strength, hardness, impact strength, and resistance to being broken.
The optical properties of Polycarbonate are tremendously well, which is why they are used as a replacement for glass in several applications. They are preferred over glass because of their weight as well.
Polycarbonate processing is very attractive and well adaptable, with its eco-friendly nature. The recyclability of Polycarbonate is also preferred as it offers energy-efficient and high-precision recycled products.
Moreover, the dominant properties of Polycarbonate may involve greater toughness, transparency, and a strong amorphous structure. This strong structure is because of the very strong bonding between the functional groups of carbonate groups.
Polycarbonate is the only type of commercial plastic used as transparent engineering thermoplastic with unique properties, including excellent electrical insulation, greater impact, and dimensional stability.
However, the properties of Polycarbonate are similar to that of Polymethyl methacrylate (PMMA). Still, polycarbonate costs are higher than PMMA because of its high strength and usability across a wide range of temperature values.
The melting point of Polymethyl methacrylate (PMMA) is 155oC while Polycarbonate melts at 155oC.
8. Acrylic – Polymethyl Methacrylate (PMMA)
Acrylic or Polymethyl methacrylate (PMMA) is classified as one of the alternative thermoplastic materials used as an alternative for. PMMA is used at illuminated signs, shattered windows, skylights, and aircraft canopies.
Generally, acrylic is considered an important class of resin produced or synthesized through the polymerization of methyl methacrylate. PMMA is used in sheets because of its high usability as a replacement or alternative to glass.
PMMA is also considered engineering plastic and is used to cast resins, coatings, and inks.
Acrylic is classified into two types, i.e., cast acrylic and extruded acrylic. Cast acrylic is expensive as it offers high strength, heat capacity, and optical properties than extruded acrylic.
Cast acrylic can be mixed with multiple additives for excellent chemical resistance and long-term durability.
However, extruded acrylic offers competitiveness, low price, and high strength to be used as an alternative for the applications of glass panes.
9. Nylon
Nylon is one of the most important and useful synthetically built materials, which offers a vast range of applications from our daily life to the industrial level. Nylon is a type of thermoplastic that may easily be transformed into a fibrous form.
It may also be melted and remolded in precisely shaped products. Nylon is a series of synthetic polymers. These are synthesized from polyamides which are long chains of amide functional groups. Due to the versatile structure of nylon, it may easily be processed into films, fibers, and various mold shapes.
The blend of nylon with additives can produce high-quality products with the required characteristics. A small variation in the formulation may form a unique set of properties for nylon showing its versatility.
Nylon is considered commercial plastic, which is significantly used in many fiber applications, including flooring, textile, apparel, elastomer reinforcements, electrical equipment, and vehicle components.
Nylon offers durable properties and good wear characteristics, which is highly required in applications of textiles or fabrics.
However, due to the hygroscopic nature of nylon, it loses its structural strength upon interaction with water for a long period. It also has low UV light resistance, making it weak and deteriorating.
10. Poly Lactic Acid (PLA)
Poly Lactic Acid (PLA) is a thermoplastic biopolymer. The sources of polylactic acid are starch, corn, and sugar cane. This commercial plastic is derived from biomass and is called bioplastic.
PLA is the only bioplastic used widely in many applications among all ten commercial plastics. Poly Lactic Acid (PLA) is a biodegradable polymer with similar characteristics to polypropylene and polyethylene.
Furthermore, PLA is marked as the second highest by volume among plastics which mainly contributes to producing biopolymers or bioplastics.
Commercially, several applications involve polylactic acid, including biodegradable films, cups, glasses, and bottles. PLA has a wider scope of applications in the field of medical devices as well.
