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Polyethylene Boon or Bane
Team Chemical Market
22 Feb 2024
Introduction
In the realm of modern industry, one substance stands resolute, steadfast in its ubiquity and versatility: Polyethylene. Born from the crucible of human innovation, it has emerged as a stalwart among polymers, weaving its intricate strands into the fabric of contemporary life. It still has a profound effect on modern existence. Gone are the days of fragile glass bottles and cumbersome metal containers. Instead, we have a legion of plastic counterparts, from humble milk jugs to elegant shampoo bottles. We therefore find ourselves inexorably tethered to polyethylene, unable to sever ties, owing to the unparalleled convenience it affords. It is also referred to as polythene in some countries, particularly in the UK and the Commonwealth. In this article, we dwell on the applications of polyethylene and all its other major aspects.
Types and Uses
The most common types of Polyethylene are HDPE, LDPE, and LLDPE.
HDPE (High-density polyethylene)
- Synthesized using the process of polymerization of Ethylene under high temperature and pressure. Specialized catalysts are used to form the long linear chains of HPDE.The productsolidifies upon cooling and is pelletized.
- Possesses a robust molecular structure, imparting excellent strength and durability
- Resistant to chemicals, moisture, and termites.
- Utilized in pipes, bottles, and containers.
- Its impermeable nature makes it attractive for the manufacture of Geo membranes. This is useful for Civil and Environmental Engineering applications such as landfills and pond liners.
- Can serve as a sustainable alternative to wood for children’s playground equipment and outdoor furniture.
LDPE (Low-density polyethylene)
- Mainly derived from ethylene monomer obtained from natural gas or petroleum feedstock. The process is similar to the production of HDPE, but octene and hexene co-monomers are used. This results in more branched and lower product density.
- Exhibits higher flexibility and resilience compared to HDPE.
- Used in squeeze bottles, shrink wraps, packaging films, bubble wraps, etc.
- Coatings for paper cups and cartons, and electrical insulation for wires and cable are some additional applications.
LLDPE( Linear low - density polyethylene)
- Produced by combining ethylene monomer and alpha-olefin comonomers such as butene, hexene, etc, through gas-phase and solution-phase polymerization. This results in a high-efficiency process, where the molecular weight, branching, and energy consumption are controlled.
- Combines the properties of HDPE and LDPE offering enhanced flexibility, toughness, puncture resistance, and stretchability.
- Extensively used in single-use packaging like packaging films, trash bags, etc.
- Also used in rotational moulding applications like tanks, toys, and containers.
Each type of polyethylene has unique properties. Applications of Polyethylene are numerous from rigid containers to industrial and consumer products.
Advantages and Disadvantages
Advantages :
- Versatility:- Can be manufactured into a wide range of products from carry bags and bottles to more specialized items like pipes, films, and medical devices.
- Lightweight:- Reduced weight compared to many other materials for the same functional requirements. Leads to cost - savings in transportation.
- Durability:- Possibly the single most important advantage. They exhibit resilience against moisture, chemicals and other assorted environmental elements.
- Cost Effective:- Economically viable due to its relatively low cost.
- Recyclability:- Can be recycled, reducing the need for new raw materials and minimizing waste.
Disadvantages:
- Limited Heat resistance:- Lower heat resistance compared to other materials, restricting its use in high-temperature applications.
- Non - biodegradable:- Can persist in the environment for hundreds of years if improperly managed. Contributes to long-term environmental degradation and impacts wildlife.
- Environmental impact:- Despite recyclability, improper disposal can lead to significant pollution of oceans and landfills.
- Health concerns:- Some chemicals used in the production may pose health risks if they leach into food or water.
- UV (Ultraviolet) radiation:- Susceptible to degradation from sunlight, making it brittle. This can be mitigated to some extent by the addition of UV stabilizers.
Bio-degradable polymers :
Environmental concerns have spurred the development of bio-degradable polymers. They decompose naturally when exposed to moisture, heat, or microbial action. Given below are a few examples:
- Mater- Bi:- Manufactured by Navomont, it is made out of vegetable oils and corn starch. Used for making bags, packaging, and food service items.
- Polylactic acid (PLA):- Made out of corn starch or sugarcane, for use in disposable containers and packaging materials.
- Polyhydroxyalkanoates (PHA):- Produced by microorganisms through a fermentation process. The raw materials are plant oils or sugars. The properties are similar to conventional plastics.
Some of the biodegradable polymers may require industrial composting facilities to decompose efficiently.
Re- cycling
One of the biggest Advantages of Polyethylene is re-cycling. However, it presents its challenges. Below we delineate several facets that merit description:
- Contamination:- Polyethylene can get contaminated by food residues and dirt when recycling bottles, bags, and films.
- Sorting and separation:- For effective recycling, this aspect is very important as each of the types requires a different process.
- Collection Infrastructure:- An effective mechanism for collection, transport, and recycling, and coordination between the activities is vital.
- Downcycling:- The recycling process in most cases results in downcycling. Here the recycled material is of a lower quality than the original material. Recycled materials are often used for lower-grade applications. As an example, food-grade polyethylene is not produced from recycled material.
Much has been written and said about the Environmental impact of polyethylene. If the products are not recycled, they are disposed of in landfills or incinerated. In the first case, it leads to leeching and results in soil and water degradation. In the second, harmful emissions pollute the atmosphere.
Conclusion
From its humble origins from the laboratories of scientific inquiry to its ubiquitous presence in the farthest reaches of civilization, polythene has woven itself into the very fabric of our existence. Despite our profound aversion to its role in environmental degradation, we find ourselves inexorably tethered to Polyethylene. Thus we find ourselves ensnared in a complex relationship one characterized by a simultaneous love and loathing, unable to extricate ourselves from its grasp. As we stand at the precipice of tomorrow, we are filled with a sense of wonder and anticipation, eager to discover the next saga of this remarkable material.
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