Thermoplastic is a common material used in the welding industry. Hot Air Tools® guides you through everything you need to know about this versatile material.
What Are Thermoplastics?
Thermoplastics are a category of polymers that become soft and moldable when heated and return to a solid state once cooled. This is because of their molecular structure, which doesn’t form permanent chemical bonds during heating. The process is reversible and can be repeated many times without significantly altering the material’s properties. This makes thermoplastics highly versatile in construction and manufacturing, where reshaping or recycling materials is commonly required.
You can think of thermoplastics as being similar to candle wax: apply heat, and the material softens or melts; remove the heat, and it solidifies again. No chemical change occurs in the wax. The same principle applies to thermoplastics, which makes them ideal for processes like injection molding, vacuum forming, and 3D printing.
Thermosetting plastics are different, however. They undergo a chemical reaction when heated that creates irreversible cross-links between polymer chains. Once set, these plastics can’t be remelted. Attempting to do so will cause them to char or degrade.
Key Properties of Thermoplastics
Thermoplastics are known for a range of properties that make them perfect for use in a variety of applications across industries. Let’s take a look at a few advantages of thermoplastics.
Recyclability and Reshaping Potential
One of the best advantages of thermoplastics is their ability to be repeatedly reshaped without degradation. As mentioned earlier, when heated, they soften and become moldable, making them ideal for processes like injection molding and extrusion. This feature also supports their recyclability, as they can be melted down and reprocessed into new products.
Lightweight Yet Durable
Despite being lightweight, thermoplastics are durable materials that offer excellent strength-to-weight ratios. This combination of lightness and toughness makes them especially popular in industries where minimizing weight without compromising on performance is top priority, such as in automotive and aerospace applications.
Chemical and Moisture Resistance
Thermoplastics are popular for their resistance to chemicals, oils, and moisture. This makes them a strong choice for environments that may expose materials to harsh substances or extreme weather conditions. They can withstand corrosive elements for greater longevity and reliability in various industrial and consumer applications.
Range of Hardness/Flexibility Depending on Formulation
One of the key benefits of thermoplastics is the wide range of hardness and flexibility they can exhibit, depending on their specific formulation. By adjusting the type of monomers used and the polymerization process, manufacturers can produce thermoplastics with specific degrees of rigidity, from soft, flexible materials like polyethylene to harder, more rigid materials like polycarbonate.
Potential for Transparency or Colorability
Thermoplastics offer high potential for both transparency and colorability. Some thermoplastics, like acrylic or polycarbonate, can be made nearly transparent, while others, such as ABS (see below), can be easily colored during manufacturing. This makes them highly customizable for consumer products, electronics, and even architectural uses where aesthetics are just as important as function.
Common Types of Thermoplastics (With Examples)
Thermoplastics come in various types, each with unique properties that make them ideal for specific applications. Understanding these properties can help you choose the right one for your projects.
Polyethylene (PE)
Polyethylene is a versatile, flexible, and low-cost thermoplastic. It’s resistant to impact and chemicals, with good electrical insulation properties. However, it tends to be somewhat soft and can be prone to stress cracking under certain conditions.
Common Applications:
- Plastic bags
- Bottles and containers
- Toys and household goods
Polypropylene (PP)
Polypropylene is known for its high chemical resistance, stiffness, and ability to withstand heat. It’s lightweight, tough, and has a high melting point, making it suitable for applications that involve higher temperatures.
Common Applications:
- Food containers
- Automotive parts
- Laboratory equipment
Polyvinyl Chloride (PVC)
PVC is a strong, rigid thermoplastic with excellent chemical and moisture resistance. It can be made flexible when plasticizers are added, making it versatile for a range of applications. It’s also resistant to UV light and weathering, though it can become brittle at lower temperatures.
Common Applications:
- Pipes and fittings
- Cable insulation
- Flooring
Polystyrene (PS)
Polystyrene is a lightweight, rigid material that is easy to mold but tends to be brittle. It can be clear or opaque and is often used in its expanded form (EPS), which is lightweight and provides insulation.
Common Applications:
- Disposable cutlery
- Packaging materials
- CD cases
Polycarbonate (PC)
Polycarbonate is a strong, transparent thermoplastic with high impact resistance. It has excellent optical clarity, making it ideal for applications where transparency and strength are needed. It’s also heat-resistant and can withstand significant stress without cracking.
Common Applications:
- Eyewear lenses
- CDs and DVDs
- Bulletproof windows
Acrylonitrile Butadiene Styrene (ABS)
ABS is a tough, rigid plastic that is highly resistant to impact and can withstand moderate heat. It also has good chemical resistance, making it a popular choice for durable and functional products.
Common Applications:
- LEGO bricks
- Electronics housings
- Automotive parts
Polytetrafluoroethylene (PTFE/Teflon)
PTFE, commonly known by its brand name Teflontm, is known for its exceptional chemical resistance, non-stick properties, and ability to perform well at high temperatures. It’s also electrically insulating and has a low coefficient of friction.
Common Applications:
- Non-stick cookware coatings
- Chemical processing tubing
- Gaskets and seals
Advantages and Disadvantages of Thermoplastics
Thermoplastics offer a wide range of benefits, but like any material, they also come with certain drawbacks. Let’s take a look at the advantages and disadvantages of using thermoplastics in various applications.
Advantages of Thermoplastics
As we’ve seen, thermoplastics are favored in manufacturing for their ease of molding and remolding, making them ideal for mass production methods like injection molding and extrusion. They’re also cost-effective for large-scale production and can be produced quickly with minimal waste.
Thermoplastics have excellent impact resistance, which makes them durable in everyday products, from packaging to automotive components. Their recyclability promotes sustainability by reducing environmental impact. These features, along with their versatility in design and material formulation, make thermoplastics a go-to choice in a variety of industries.
Disadvantages of Thermoplastics
Despite their many advantages, thermoplastics have a few limitations. For starters, they can deform under high heat, limiting their use in environments with extreme temperatures. Some thermoplastics are also prone to degradation when exposed to UV light or certain chemicals, making them unsuitable for long-term outdoor use without additives to protect them. While thermoplastics are recyclable, improper disposal remains an environmental concern, as they accumulate in landfills if not properly processed. These factors need to be considered when choosing thermoplastics for specific applications.
Shop Hot Air Tools® For All Your Thermoplastic Needs
Hot Air Tools® has everything welders need for a successful project. From the right types of thermoplastics to high-quality tools, you’ll find the experience and expertise you need with us. And if we don’t have what you need, we’ll point you in the right direction. That’s our commitment to quality welding.
Contact us today to speak with one of our skilled welding professionals.