In the CNC machining industry, we use various types of plastic materials, each with its own characteristics. Presumably, some of the plastic parts you need must have excellent heat resistance, so that they can be used in a variety of extreme environments. And what plastic materials have high heat-resistance? Read this article with your questions!
What is Heat Resistant Plastic?
First, you should know the definition of heat-resistant plastic. Heat-resistant plastics can maintain their plastic structure, mechanical properties and functionality at high temperature. These plastics have been processed in a special way so that they can be used in an extreme environment of more than 100 °C(212 °F) or even 300 °C(572 °F) in the worst case. Because of their heat-resistant property, heat-resistant plastics are also used in aerospace, automotive, industrial manufacturing and other industries.
Thermal Properties of Heat-Resistant Plastics
In order to learn more about heat-resistant plastics, you also have to know why it can stay a good performance in high temperature, and that are the thermal properties. Below, we will explore thermal properties in detail.
1. Heat Deflection Temperature(HDT)
This is one important measure of how good a plastic is at the high-temperature mechanical stress. HDT is the temperature at which a material deforms under a high temperature condition.
2. Glass Transition Temperature（TG）
TG index refers to the temperature at which the material melts from solid to liquid. The TG value of a material indicates if it has the ability to retain its dimensional stability at elevated temperatures. Generally, the TG value of high heat-resistance plastic is very high.
3. Melting Point(Tm)
The melting point is the temperature at which a crystal solid begins to melt. The heat resistant plastics have a very high melting temperature in the range of 300-400°C, or even more.
4. Thermal Conductivity
The definition of thermal conductivity is the ability of a material to transfer heat. A plastic with low thermal conductivity is well-suited as a thermal insulation material and can be used at high temperatures. The thermal conductivity of heat-resistant materials is very low, about 0.1 – 0.4 W/m·K.
5. Coefficient of Thermal Expansion(CTE)
Material size changes when the temperature changes, referred to as CTE. Heat-resistant plastics generally have a low CTE (for example, PI has a CTE of about 20-30 X 106°C, PEEK has a CTE of 47 X 106°C).
6. Thermal Stability
The ability of materials not to decompose and not degrade in high-temperature environments is called thermal stability. This indicator will determine the service life of plastics under long-term high temperature exposure.
7. Flame Resistance
Flame retardance is also a key performance for high temperature resistant material, which refers to the combustion behavior of material at high temperature or under the open flame.Flame-resistance materials can ensure safety in high-temperature environments and reduce the risk of fire.
Top 5 Heat-Resistant Plastics
Next, I will tell you about the five heat-resistant plastics in more detail. Knowing the properties of these materials allows you to make better material decisions when designing parts at a later time.
1. PEEK
PEEK material is a semi-crystalline structure, its crystal region provides heat resistance and chemical stability. And It also contains aromatic rings and ketone bonds, thereby increasing the TG value and thermal decomposition temperature of the material, which is approximately 143°C. At the same time, the melting point of peek is also very high, about 343°C, so it can maintain excellent mechanical properties in high temperature environments. As for thermal conductivity, it is about 0.25 W/m·K. In addition, PEEK also has high strength and corrosion resistance, so it is widely used in the aerospace, medical and electronic industries.
2. PSU
PSU is an amorphous high-performance thermoplastic that can maintain high modulus and low creep at high temperatures. Its TG value is 185°C. Moreover, the rigid main chain of PSU is quite stable, which can improve the material’s thermal oxygen and thermal deformation resistance. On the other hand, PSU’s HDT is about 175–190°C, and CTE is about 55–65×10^-6/K (23–150°C). The material is resistant to hydrolysis and has high transparency, so it is used to make medical equipment, electrical insulation parts, etc.
3. PI
PI is a representative of high-temperature resistant plastics. It is a type of high-performance heat-resistant polymer with an imide ring as its characteristic structure. PI has very high TG and TG value (approximately 500–600°C), it can be used for a long time in an environment of 200℃, and can also withstand high temperature of 400℃ in the short time. Its thermal conductivity is about 0.2–0.4 W/m·K. The material has good mechanical and electrical insulation properties, so PI is often applied in aerospace components, high-temperature coatings, etc.
4. PET
PET is a semi-crystalline thermoplastic polyester. It maintains structural stability in high-temperature environments and can withstand temperatures up to 120°C. In fact, among the many forms of PET, only crystalline injection-grade PET, GF-reinforced PET, and reflow-resistant PET fall into the heat-resistant category. As for the common UL RTI, it is basically between 100-130°C. In addition, the cost of this materials is very low, and it has good chemical resistance and mechanical properties. Therefore, the material is also used in the automotive industry, food packaging and other industries.
5. PC
PC（Polycarbonate）is an amorphous engineering plastic. Its TG value is 145–150°C and the HDT is 120–135°C. PC can be used continuously in a temperature environment of 110–125°C. Meanwhile, because of its excellent mechanical properties and high temperature resistance, this material is often used to produce electronic equipment casings, automobile parts, etc. In addition, PC is also tough and easy to process. Through Polycarbonate machining, this material can be made into many types of high-performance components
Summary
Well, by reading the entire article, I believe you have an understanding of the best 5 high heat resistant materials. As a machining manufacturer, DSR has partnered with excellent material suppliers, so we can produce excellent high-temperature resistant components for you. If you have a need for this, please come and communicate with us, we can give you a satisfactory service!
FAQ
Q1: Is PVC plastic heat-resistant?
A: PVC plastic has limited high temperature resistance, its HDT is about 60°C – 80°C, and its decomposition temperature is about 140°C – 160°C. Therefore, PVC is not a high temperature resistant material.
Q2: What plastic can withstand 300 degrees?
A: Plastics that can withstand 300°C include PI, PEEK, LCP, PTFE, etc.
Q3: What plastic can withstand 400 degrees?
A: There are few plastics that can withstand 400°C, there are PFA and PI.
Q4: Is heat-resistant plastic safe?
A: High temperature plastics in general are safe. These plastics have a very stable structure, and they do not emit toxic products.
Q5: What plastic is heat-resistant food safe?
A: High temperature resistant materials suitable for the food industry include PTFE, PEEK, PES, PP and PC, etc. These materials have beenhave been certified by the FDA, so you can use them with confidence.
Q6: What is the cheapest type of heat-resistant plastic?
A: According to my understanding of the market conditions, the cheapest high-temperature resistant plastic currently is polypropylene (PP).
Q7: Is PLA or PETG more heat-resistant?
A: The heat resistance of PETG is generally better than PLA. The TG of PETG is about 55-65°C and the TG of PETG is about 75-85°C.
Q8: Can PLA withstand 100c?
A: No. PLA has been deformed at 100 degrees Celsius.
Q9: What type of plastic does not melt?
A: Non-melting plastics are usually thermoset plastics, including epoxy resins, phenolic resins, polyurethanes, unsaturated polyester resins, melamine resins, silicone resins, and imide resins.
Q10: Is PP plastic heat resistant?
A : PP plastic has certain heat resistance, and its melting point is usually 160-170°C. The material can be used for a long time in an environment of 100-120°C without deformation.
