In the realm of engineering and manufacturing, the choice of material can significantly impact the quality, performance, and sustainability of a product. One of the most versatile and widely used materials today is plastic. But with a plethora of plastic types available, each possessing unique characteristics and properties, how do you decide which plastic is best for your specific application?
As the leading plastic fabrication Perth company, JohnDec Engineering Plastics WA understands that the choice of plastic can be crucial in determining the success of a project. Therefore, we have compiled this extensive guide to assist you in understanding the various types of plastics, their specific uses, and factors to consider when choosing a plastic for your application. If you require expert guidance on the type of plastic that would work best for your project, don’t hesitate to get in touch with JohnDec today.
Understanding the basics: the plastic types
There are two primary types of plastic: thermoplastics and thermosetting polymers.
Thermoplastics soften when heated and become more fluid as additional heat is applied. The curing process is completely reversible as no chemical bonding takes place. This characteristic allows thermoplastics to be remoulded and recycled without negatively impacting the material’s physical properties. Examples include polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS).
Thermosetting polymers, on the other hand, form irreversible chemical bonds during the curing process. Once these materials are moulded and heated, they cannot be remoulded or recycled. Examples include polyurethanes, epoxy resins, and polyesters.
Now let’s dive deeper into some specific types of plastic and their specialist uses:
Polyethylene (PE)
Polyethylene, in its high-density form (HDPE), is often used in outdoor furniture due to its weather-resistant nature. Its resistance to most chemicals makes it a common choice for storage containers for household cleaners and industrial chemicals. HDPE’s high strength-to-density ratio makes it ideal for high-performance piping systems and protective gear like hard hats and motorcycle helmets.
Low-density polyethylene (LDPE), on the other hand, is more flexible and is used in applications such as plastic wrap, packaging films, and squeezable bottles. Due to its insulating properties, LDPE is also used to make electrical wire and cable coverings.
Polyvinyl chloride (PVC)
PVC is the world’s third-most widely produced synthetic plastic polymer. It’s known for its durability, affordability, and resistance to environmental degradation. PVC is often used in construction applications, such as pipes and window frames, due to its resilience and low cost. It can also be made more flexible and softer through the addition of plasticisers, making it suitable for uses such as clothing, upholstery, and electrical cable insulation.
Polystyrene (PS)
Polystyrene in its solid state is used in items like plastic cutlery, CD and DVD cases, and smoke detector housings. Because of its clarity, it is also often used in laboratory ware and food packaging. Expanded polystyrene (EPS), also known as Styrofoam, is used for thermal insulation in buildings and refrigeration devices, as well as disposable coffee cups, packing peanuts, and protective packaging for fragile goods.
Polyethylene terephthalate (PET)
PET is primarily used in the textiles industry where it’s known as polyester. It is woven into synthetic fibres for clothing and used in filling for insulated clothing and home furnishings. PET’s strength and lightness make it ideal for carbonated drink bottles. Its resistance to water and UV radiation also makes it ideal for outdoor signage.
Polypropylene (PP)
Polypropylene is commonly used in packaging, automotive, and textiles. Its resistance to chemicals and high melting point make it ideal for dishwasher-safe food containers. It is also used in automotive parts due to its toughness and resistance to various chemical solvents, bases, and acids. In the textiles industry, PP is used in thermal underwear, carpets, and rope.
Polycarbonate (PC)
Polycarbonate’s high impact resistance combined with its transparency makes it suitable for eyewear, optical storage media like DVDs and CDs, and protective visors. It is also commonly used in automotive components, such as headlight lenses and bumpers. In construction, PC is used in roofing panels due to its resistance to weather, UV radiation, and impact.
Acrylonitrile butadiene styrene (ABS)
ABS has a high impact resistance and toughness, making it ideal for automotive parts, protective headgear, and toys (including Lego blocks). ABS is also commonly used in the casings of power tools and similar appliances due to its resilience and ability to withstand high temperatures.
Polyurethane (PU)
Polyurethane is used extensively in furniture and bedding due to its flexible foam characteristics. It is also used in insulation panels, thermal insulation, and refrigerator and freezer units. In the automotive industry, PU is used in seat cushions, suspension bushings, and tires.
Epoxy resins
Epoxy resins are used in a variety of applications, including electronics for circuit boards, in the automotive industry for coatings, and in the aerospace industry for composite materials. Epoxies are also used in adhesives and structural glues due to their strong adhesion and chemical resistance.
Polyesters
Polyesters are used widely in the textiles industry for clothing, home furnishings, and industrial fabrics. They are also used in tire reinforcements, conveyor belts, and safety belts due to their high tensile strength. When combined with fibreglass, polyesters can produce durable, lightweight materials used in boats, cars, and other structures.
In the packaging industry, polyesters are used in films and bottles due to their barrier properties and mechanical characteristics. In the electronics industry, polyesters serve as a base for the production of flexible printed circuit boards and as an insulating material.
Factors to consider when choosing a plastic
When choosing a plastic for a specific application, it’s not a one-size-fits-all process. Several critical factors should be taken into account to ensure the chosen material will meet the demands of its intended use. The following elaborates on the primary considerations:
Mechanical properties
Mechanical properties, including strength, flexibility, hardness, toughness, and elasticity, significantly influence a plastic’s suitability for specific applications.
- Strength: Strength refers to how well a material can resist an applied force without failure. If you’re creating a product that needs to withstand significant stress, such as protective gear or load-bearing parts, high-strength plastics like polycarbonate (PC) or acrylonitrile butadiene styrene (ABS) might be appropriate choices.
- Flexibility: is the ability of a material to bend under stress without breaking. For items that need to be bent, twisted, or compressed without breaking, such as plastic bags or squeeze bottles, flexible plastics like low-density polyethylene (LDPE) or plasticised PVC would be suitable.
- Hardness: refers to a material’s resistance to surface indentation or abrasion. It’s an essential factor for applications that require high wear resistance, like gears or bearings, where materials like PC or polyurethane (PU) could be used.
- Toughness: is the measure of a material’s ability to absorb energy and deform without fracturing. It’s crucial for impact-resistant applications like helmets or car bumpers, where ABS or PC would be ideal choices.
- Elasticity: is the ability of a material to return to its original shape after being stretched or deformed. Rubber-like materials, such as thermoplastic elastomers, are typically highly elastic and are used in applications like seals and gaskets.
Thermal properties
The thermal properties of plastic, including its heat resistance, thermal stability, and thermal conductivity, are crucial depending on the environmental conditions where the product will be used.
- Heat resistance: This refers to a material’s ability to resist damage at high temperatures. If a product is intended for use near heat sources or in hot environments, a plastic with a high melting point, like polypropylene (PP) or polyethylene terephthalate (PET), might be required.
- Thermal stability: is the degree to which a material can maintain its properties over time under a specific temperature. Plastics with high thermal stability, like PP or polyurethane (PU), are less likely to degrade when exposed to high temperatures for extended periods.
- Thermal conductivity: This refers to a material’s ability to conduct heat. In applications where insulation is needed, plastics with low thermal conductivity, like expanded polystyrene (EPS), are often used.
Chemical resistance
Chemical resistance is the degree to which a plastic can resist damage caused by chemicals. This characteristic is vital for products that will be exposed to corrosive substances. For instance, polyvinyl chloride (PVC) and polypropylene (PP) have excellent resistance to many acids, alkalis, and salts, making them suitable for chemical storage and handling applications.
Cost and availability
The cost of the plastic material and its availability can also be deciding factors. Polyethylene (PE) and PVC are among the most widely available and affordable plastics. However, the cost must be balanced with the material’s performance characteristics. For instance, while polycarbonate (PC) may be more expensive than other options, its superior strength and transparency might justify the added cost in certain applications.
Sustainability
As environmental concerns become more prominent, the sustainability of plastic materials is becoming an increasingly important factor in material selection.
- Recyclability: The ability of a material to be recycled into a new product at the end of its life is a key sustainability factor. Some plastics, such as PET and HDPE, are widely recyclable and are commonly accepted by municipal recycling programmes. Others, like PVC and PS, are more challenging to recycle and may not be accepted by all recycling programmes.
- Biodegradability: Some plastics are designed to biodegrade under specific conditions. While these materials can help reduce environmental impact in certain applications, it’s important to understand the specific conditions required for biodegradation. In some cases, biodegradable plastics may only break down in industrial composting facilities and could still persist for many years in a typical landfill.
- Bio-based plastics: These are plastics derived from renewable sources, such as corn or sugarcane, instead of fossil fuels. Bio-based plastics can help reduce the carbon footprint of a product, but it’s important to note that being bio-based does not necessarily make a plastic biodegradable or recyclable.
- Life cycle assessment: This is an analysis of the environmental impacts of a product throughout its life cycle, from raw material extraction to end-of-life disposal. A life cycle assessment can provide a comprehensive view of a material’s environmental impact and can be a valuable tool for comparing different materials.
Conclusion
Navigating the diverse realm of plastics can be challenging. Each type of plastic has specific properties and uses, making the material selection crucial for your unique needs. Whether it’s durability, flexibility, heat resistance, chemical resistance, or sustainability, there’s a suitable plastic for you.
At JohnDec Engineering Plastics WA, we’re committed to guiding you through the selection and custom plastic fabrication process from start to finish. This guide is just the beginning. Our expert team is always ready to provide further insights and address your queries. Reach out to us today, and together, we’ll find the perfect plastic for your project, striking the right balance between performance, cost, and sustainability. Let’s collaborate to bring your extraordinary vision to life!