Guide to Selection and Testing

Most people are familiar with plastic's propensity for melting. For example, cooking food in the microwave in a plastic container for too long or leaving a plastic spatula on the stove next to a hot burner will show this. Yet thermoplastics and many other heat-resistant plastic materials can handle very high temperatures. These are known as heat-resistant plastics.

Heat-resistant plastics can handle high working temperatures without softening, breaking down, losing stability, or melting. Often, traditional plastic materials are made more heat-resistant by adding something to them to increase their resistance to high temperatures. Here is a closer look at some of the more popular heat-resistant plastics, their properties, and the common applications where they work well.

Popular High-Temperature Plastics

Temperature ratings can range from 50 degrees Celsius (122 degrees Fahrenheit) to 240 degrees Celsius (464 degrees Fahrenheit), depending on the plastic material. High-temperature labels are typically reserved for plastics with a maximum operating temperature of 300 degrees Fahrenheit or higher. Some popular plastic products that fit this range include:

• Polytetrafluoroethylene (PTFE) – Better known as Teflon, this plastic has a working temperature of 280 degrees Celsius (500 degrees Fahrenheit). Because of this high-temperature rating, it is often added to other plastics to improve their heat stability.
• Polyetheretherketone (PEEK) – PEEK can handle temperatures of up to 250 degrees Celsius (482 degrees Fahrenheit) and sometimes higher, and it also resists radiation and chemical abrasion.
• Polyphenylene Sulfide (PPS) – With a working temperature of 220 degrees Celsius (428 degrees Fahrenheit), this thermoplastic has excellent mechanical strength and works well in injection fabrication applications.
• Polyetherimide (PEI) – PEI has a rating of 171 degrees Celsius (340 degrees Fahrenheit), and it is a great choice for applications that need rigid strength from a heat-resistant material.

Key Factors That Affect the Performance in High-Temperature Environments

Four main factors affect plastic materials’ performance when exposed to high temperatures. These are as follows:

• Chemical makeup of the plastic
• Material thickness of the plastic
• Expansion rate at high temperatures
• Thermal conductivity

These factors work together to determine how well the material will withstand heat exposure for a long period.

Common Applications That Require High-Temperature Plastic Materials

In the manufacturing world, numerous applications require the benefit of high-temperature plastic. The repetitive movement of many factory machines can generate significant heat via friction, and the fabrication of items requires high temperatures to melt or mold the material into a desired shape.

The medical industry also requires high-temperature plastics. These materials can withstand the strenuous sanitation methods necessary for medical equipment. Similarly, the food packaging industry benefits from these materials due to their ability to withstand cooking temperatures and their ability to handle sanitation processes.

In the aerospace engineering, high temperatures are common not only from engines and exhaust but also from the atmosphere. Again, this is a place where you need high-temperature plastic materials. Similarly, transportation technology and engine components for land-based vehicles need to be able to withstand high temperatures.

The world of tech and telecommunications often generates high temperatures, and electronics and semiconductors must be made from high-temperature plastics or coated in them. Because plastic doesn’t conduct electricity easily, it is a common material to insulate electronic components inside computers and other pieces of tech.

Tips for Testing Plastic Materials in High-Temperature Environments

While the team at Piedmont Plastics will help guide you toward plastics that fit your temperature requirements, it is always a good idea to test the stability of the plastic before using it in a high-cost situation. The main factors to test include:

• Vicat Softening Temperature – This is the temperature at which an indentation tool can penetrate 1 mm into the surface of the plastic.
• Heat Distortion Temperature – This is the temperature at which the plastic will deform under pressure.
• Ball Pressure Test - Determines what temperature will cause deformation when the plastic is under a specific, constant load.

Each of these tests will give you a clear picture of the temperature range of the plastic material. Rather than testing the material on your own, reach out to the team at Piedmont Plastics to learn these values for the product you are considering for your particular high-heat application. With the right plastic, you can have reliable products or parts that withstand high temperature ranges well without softening or losing their shape.