Plastic 101
What is Plastic?
Plastic, a synthetic polymer derived most commonly from petroleum, has transformed the modern world with its versatility and affordability.
The story of plastic began in the late 19th century. Early forms like celluloid and Bakelite paved the way for the development of modern plastics and plastic products.
In the early 20th century, chemists began experimenting with different materials and processes, leading to the creation of versatile polymers like polyethylene and polyvinyl chloride (PVC). These breakthroughs and mass manufacturing of plastic pellets marked the beginning of the plastic revolution.
Since its invention, plastic has experienced exponential growth and has become an integral part of our daily lives. Annual plastic production has increased to approximately 400 million tons per year.
Nowadays, plastic pellets are building blocks that go into the production of countless plastic end-user products.
However, massive production and widespread improper disposal have led to an environmental crisis, fully unfolding now in the 21st century.
Key Properties that Make Plastic Appealing
Typically rigid at its service temperature, an important characteristic of plastic as a polymer is its low elasticity. If stretched, a plastic object is most commonly deformed and keeps its new shape; it does not return to its original shape.
This contrasts, for example, with another type of polymer such as rubber, which is highly elastic.
Plastic as a material is highly desirable - and likely to only increase in use - due to its unique properties:
Chemical resistance: will not react with a lot of common chemicals; can use in food
Lightweight: good for water, liquids, containers for almost anything
Electrical insulation: casing of wires, circuit boards
Water repellant: therefore is used for boats, kayaks
Ease of melting (only thermoplastics): advantage over metal which requires much greater heat to melt and mold; lower melt temperature thus leads to lower cost and lower complexity of processing.
It is therefore not surprising that modern civilization has become so heavily reliant on plastic as a material used in all sorts of tools and everyday objects.
Types of Plastic
Plastics are broadly categorized based on their chemical composition and properties, each being assigned a resin identification code. These are:
Polyethylene terephthalate (PET or PETE)
High-density polyethylene (HDPE)
Polyvinyl chloride (PVC)
Low-density polyethylene (LDPE)
Polypropylene (PP)
Polystyrene (PS), and
Others.
Each type of plastic possesses unique characteristics that make them suitable for specific applications.
Importantly, their chemical properties affect their functional properties. Plastic processing practices typically involve rigorous quality testing before being mass-produced.
To determine the suitability of polymers for certain processes and applications, companies in the plastic production industry test how plastic behaves during heating, deforming (molding, wear/tear), dissolving or reacting, chemical exposure, electrical contact, or radiation.
Plastic Products
The ubiquity of plastic in everyday life is undeniable. For example, plastic pellets can be melted and shaped into PET, commonly used in beverage bottles and food containers, providing lightweight, durable, and hygienic packaging.
HDPE finds applications in milk jugs, shampoo containers, and household products due to its strength and resistance to chemicals.
PVC is employed in plumbing pipes, window frames, and electrical insulation.
LDPE is utilized for plastic bags and wraps, while PP is found in food packaging, automotive parts, and consumer goods.
Polystyrene, often seen in disposable cups and packaging materials, offers insulation and impact resistance and does not generate toxic additives.
Specialized Industries
Beyond everyday applications, plastic plays a crucial role in numerous industries. The medical field relies on sterile plastic instruments, transparent or intravenous tubing, and implantable devices. Automotive manufacturers utilize lightweight plastics to improve fuel efficiency.
Companies in the electronics industry employ plastics in casings, circuit boards, and cables, often in sizes that can be measured in millimeters. Aerospace companies develop plastic composites to reduce aircraft weight, which helps in transportation. These examples demonstrate the importance of plastic in specialized sectors.
Once produced, plastic pellets can be turned into objects of different shapes and sizes. Plastic processing techniques vary greatly and include extrusion, fiber spinning, thermoforming, rotational molding, film casting, blow molding, or injection molding, just to name a few.
Like blowing bubble gum, for example, melted plastic can fit a mold and take the desired shape and color. Countless plastic objects are produced every day, as manufacturing companies melt and mold plastic into different shaped and sized objects.
The Plastic Waste Challenge
Despite the undeniable utility of items made of plastic pellets, plastics create a major challenge for the environment in their afterlife. Plastic waste, once discarded, could become plastic pollution and poses a severe environmental threat due to its non-biodegradable nature.
The alarming truth is that only a fraction of plastic is recycled, with the majority ending up in landfills, water bodies, and ecosystems. Improper disposal and inadequate waste management systems have resulted in pollution, affecting ocean wildlife, waterways, marine ecosystems, and even human health.
Tiny bits of plastic pellets cause problems around the globe as they do not filter and through ingestion, they end up in the bodies of marine animals. The food web is absorbing more than a handful of microplastics as tiny plastic pellets are mistaken due to their size and color at sea. Microplastic pollution is swept by ocean currents and can either wash up on a beach or be ingested by wildlife. The marine food web is an important part of our planet and impacting it ins this way poses great risk for the environment.
The Urgent Need for Change
At this stage, to tackle the plastic waste crisis and to make sure we limit the amount of plastic spilled in waterways and on beaches, it is crucial to adopt a comprehensive approach. Strategies to reduce plastic pollution include reducing plastic consumption through alternatives, promoting recycling infrastructure, implementing extended producer responsibility, and raising awareness among individuals and communities. Innovations like biodegradable plastics and advanced recycling technologies also show promise in addressing the issue.
The journey of plastic from a revolutionary material to a global waste crisis highlights the need for responsible consumption, proper waste management practices, and sustainable alternatives.
It requires a fundamental change in the way we interact with it. If humans continue to view it as waste, allowing it to be released in the environment, sometimes not even hours after using it, we cannot prevent it from negatively affecting our future. Microplastics can end up in drinkable water, or wash up on beaches. It is easier to prevent a problem of this magnitude rather than address it after.
There is no device yet that can easily remove microplastics from a beach or from the sea. Once a tiny plastic pellet spills into the water, it can be easily carried away and becomes much harder to collect.
While plastic has undeniably transformed our lives, its indiscriminate disposal has wreaked havoc on the environment. By recognizing the value of plastic as a resource and adopting a circular economy approach, we can mitigate its negative impact and pave the way for a better, more sustainable future.
Sources:
Fundamentals of Plastics and Polymers - Udemy.com course by Ololade Olatunji, University Lecturer and Chemical Engineer; Author of Natural Polymers, Industry Technique and Applications - Springer 2016.