Polystyrene and polyethylene are two polymers reputed for their array of uses in the field of manufacturing. They display excellent properties and are available in different forms. They are common plastics used to produce day-to-day products as well as for engineering purposes.
Polystyrene and polyethylene have their unique characteristics and differences. It is important to have a good understanding of the applications and uses of these polymers.
In this guide, we discuss polystyrene and polyethylene in detail, outlining their benefits and purposes to help you select the right material for your requirements.
What is Polystyrene?
Polystyrene (PS) is a commonly used polymer plastic to manufacture commercial and consumer products today. It is made by combining styrene, which is a clear and colorless liquid.
Polystyrene is very transparent in solid form, and the transparency offers excellent optical clarity and can also be dyed using different colorants.
Polystyrene is a thermoplastic. It melts at high temperatures, particularly above 210℃. So, it can be remolded and used for another purpose. It is also amorphous and easy to process into a variety of shapes and objects.
Polystyrene is available in both low-impact and high-impact strength. Its mechanical and aesthetic properties can be enhanced with the addition of colorants, additives, and polymers.
What is Polyethylene?
Polyethylene (PE) is also another thermoplastic polymer that is found in a wide range of products in the market today. It is made by combining the monomer ethylene and is a very versatile material in manufacturing.
It can be melted and reused many times without degradation. Polyethylene has good transparency, but it can be opaque or translucent depending on the grade, thickness of the film, and inclusion of additives.
The properties of polyethylene may vary based on the density.
However, the polymer is generally renowned to be very durable and tough. It shows impressive resistance to chemicals, abrasion, weather, and tensile stress.
However, when exposed to sunlight for a prolonged period of time, it can become brittle. With low thermal conductivity, polyethylene is also used for insulation purposes in different industries.
Polystyrene VS Polyethylene: Which Polymer is Best for Your Application
Polystyrene: Benefits and Uses
What Are the Benefits of Polystyrene?
- As a thermoplastic, polystyrene can be reshaped into different structures multiple times without losing much of its mechanical properties.
- The thermoforming ability makes it easy to be processed into different structures.
- Low thermal conductivity
- Lightweight and stackable
- Impressive resistance to chemical reactions.
- It is a very cost-effective and widely available thermoplastic used in production.
- It is a strong and tough material.
- Polystyrene in the form of styrofoam and peanuts is used to cushion goods that are ready to be shipped.
- Compared to polypropylene, polystyrene is less prone to shrinkage, and therefore, the precision of the final output is higher.
What Are the Applications of Polystyrene?
- Expanded polystyrene is popularly used to create food packaging materials for residential and commercial uses. As it provides good insulation, it keeps the food fresh for a longer period of time.
- The optical clarity of the polymer is useful for an array of applications in the medical field, including equipment like test tubes and gloves to medical devices like implants.
- In automotive, high-impact polystyrene is used for door knobs, panels, airbags, and many other components in vehicles.
- In construction, it is used for both decorative and functional purposes, such as roofing and flooring.
- It is also used to manufacture protective casings like trays, CD cases, and even door panels.
- Polystyrene is also used for a variety of electronics, toys, household appliances, and many more.
Polyethylene: Benefits and Uses
What Are the Benefits of Polyethylene?
- One of the most affordable polymers available
- It is easy to process
- Renowned for its impact resistance and ductility, which will cause the material to stretch rather than break.
- It is more durable and robust than polystyrene, with good resistance to punctures and tears
- Corrosion-resistance
- Flexible and very light in weight. Even high-strength products made from polyethylene are comparatively low in weight.
- As it can be melted and remolded, polyethylene is easily recyclable.
- Good heat and water resistance
- Low coefficient of friction
- Good electric and thermal insulation
- Polyethylene can be recycled and reused multiple times, unlike polystyrene products designed for single use.
What Are the Applications of Polyethylene?
- The high impact resistance makes polyethylene a better packaging alternative to polystyrene. It is a dominant material in the packaging industry. Examples are water bottles, shampoo bottles, juice bottles, plastic bags, trays, containers, and cans. LDPE is also more transparent, making it ideal for decorative packaging.
- It is also excellent at cushioning to keep the goods safe during transportation.
- A wide range of consumer goods like toys, tumblers, furniture, reusable water bottles, luggage, and household appliances.
- Fabrics and textiles, including carpets, furniture fabric, fishing nets, and ropes, are made from high-density polyethylene.
- Pipelines, valves, and fittings for sewage, industrial, and other purposes.
- Insulations for cables, wires, walls, and pipelines
- Medical devices, implants, and prosthetics
- Floating equipment
- Different types of flooring and roofing purposes
- For the production of automotive parts
Differences Between Polyethylene and Polystyrene
1. Composition
Polystyrene is made from the monomer called styrene and has a chemical formula of (C8H8)n. Styrene, also known as vinylbenzene, is a colorless liquid hydrocarbon that’s extracted from petroleum products by reacting ethylene with benzene.
Polymerization of styrene gives birth to polystyrene, which can also be copolymerized with other polymers to enhance its features.
Polyethylene is made from the monomer called ethylene and has a chemical formula of (C2H4)n. Ethylene is derived by heating petroleum and purifying ethylene, and adding a catalyst will give birth to polyethylene.
It can also be derived from renewable resources. The polymerization can happen in both long or branched forms. This polymer can be in different structures and densities.
2. Properties
While both are thermoplastics, low-density polyethylene has a lower melting point (110°C) than polystyrene. For this reason, polystyrene is preferred for food packaging and other heat-resistant purposes.
However, both can be recycled as they can be melted, reshaped and reused several times without degrading the materials. The issue, however, is that polystyrene is designed mostly for single-use purposes and is difficult to reuse. In this sense, reusable products from polyethylene are somewhat recyclable.
Polyethylene also wins over polystyrene when it comes to impact resistance and durability. It is a stronger polymer that’s preferred for sturdy products. It also shows better resistance to chemicals and acids than polystyrene.
Both these polymers are available in different forms, but polyethylene comes in different densities and characteristics, allowing users to select the best choice for their purpose.
3. Advantages
Polystyrene and polyethylene are both cost-effective and versatile plastic polymers you can use to manufacture a variety of items. However, the correct choice depends on the purpose you require them for.
Polystyrene’s transparency combined with thermal insulation is highly preferred in the disposable packaging industry. It is also easy to process and is preferred for a variety of engineering purposes.
However, it’s noteworthy that polystyrene is not entirely waterproof or vapor proof.
High-density polyethylene boasts remarkable features. While it is robust and resistant to pressure, it is also light in weight than other alternatives. Polyethylene is highly resistant to water and vapor absorption too.
4. Types
Polystyrene is available in many types, such as:
- Solid plastic form: The unrefined form of polystyrene is rigid, brittle, reasonably strong, and easily moldable. It is primarily used to make items that require excellent transparency. It is available as General Purpose Polystyrene(GPPS) and High Impact Polystyrene(HIPS)
- Foam: It is the extended form of polystyrene available as Expanded Polystyrene(EPS) or Extruded Polystyrene(XPS). It is lightweight, durable, and easy to use. The popular trademarked styrofoam comes under this.
- Film: Available in varying thicknesses, polystyrene film is lightweight, tear-resistant, and flexible. As it is transparent, it can be vacuum formed and used in food packaging applications.
Polyethylene can be categorized based on different densities.
- Polyethylene Terephthalate (PET): PET is strong and resistant to impact, heat, moisture, and chemicals. As it’s also light in weight, products made from PET are also easy to transport. PET is referred to as polyester when it’s in the fiber form.
- Low-density polyethylene (LDPE): LDPE is a very flexible, soft, and transparent material used to produce low-strength products like plastic bags. It is easy to fabricate and form different items using it.
- Linear Low-Density Polyethylene (LLDPE): LLDPE is also very flexible and elongates under stress. With a higher tensile strength and impact resistance than LDPE, it can be used for a variety of purposes, like flooring and plastic films.
- High-Density Polyethylene (HDPE): HDPE is used for products that demand high strength and rigidity. It is translucent in nature and is flexible. HDPE is available in different grades to be useful for applications such as cooking, medicine, and outdoor use.
- Ultra High Molecular Weight Polyethylene (UHMW): UHMW is the toughest type of polyethylene, and is extremely abrasion resistant. It is ideal for heavy-duty products as it can withstand fatigue and frequent usage.
5. Uses
Common products made from polystyrene are:
- Solid: Test tubes, Petri dishes, gloves, optics, medical implants, disposable utensils and cups, CD cases, housings on smoke detectors, bowls, trays, containers, and toys.
- Foam: Packaging purposes, low-quality disposable cutlery, automotive parts, protective casings for devices, walls of storage facilities, and insulation of appliances like refrigerators, microwaves, and vacuum cleaners.
- Film: Food packaging, decorative wrapping purposes, and protective coverings for electronics.
Common products made from polyethylene are:
- PET: All types of bottles, food containers, polyester fabrics, components in automotive, vending machines, and decorative items.
- LDPE: Grocery bags, hot and cold drink cups, food containers, squeeze bottles, juice, and milk boxes, and plastic components for electronics.
- LLDPE: Shopping bags, toys, buckets, bins, containers, bottles, caps, cling film wrap, flexible tubes, and pipelines.
- HDPE: Durable pipes, milk jugs, toys, food storage containers, and boxes, cutting boards, recycling bins, and grocery shopping bags
- UHME: Sliding plates, bulletproof vests, cabinetry, docks, packaging for machinery parts, and medical devices.
6. Cost
Both are budget-friendly plastics available for manufacturing purposes. Polystyrene can cost around $1000-1500 per metric ton. Polyethylene also costs a similar amount per metric ton, but the price can vary depending on the density of the polymer you require.
Choose Kemal for Your Molding Needs
Both polystyrene and polyethylene are favorable for injection molding purposes. If you are looking for high-precision molding solutions to fulfill your manufacturing requirements, you have come to the right place.
Our high-quality, ISO-certified molds ensure you receive the best output. All the materials and other raw materials we use in production also comply with industry-recognized standards.
With our decades of expertise and advanced machinery, we can meet your tight tolerance requirements and deliver products with optimum mechanical and aesthetic value.
Take a look at our wide range of rapid prototyping and on-demand manufacturing solutions we offer for our global client base! Get in touch with us to fulfill your needs from the best!
Conclusion
We hope our detailed comparison guide on the uses and differences between polystyrene and polyethylene helps you make a sound decision.
They are both very useful in the modern world and have become indispensable materials in both residential and industrial spaces.
You can also contact us and talk to one of our experts for further recommendations. They are highly experienced in the field and will offer valuable suggestions to select the best material for your requirement.
