The research and development in the fields of polymer chemistry and material science was significant in the mid of twenty century. The plastics and polymers were created as a result of this research and development. These materials had the capability to withstand higher temperatures. Polyphenylene sulfide and Polytetrafluoroethylene were initially created which proved to face and withstand higher temperatures as compared to traditional plastics. The aerospace industry raised significant demand and requirement of high temperature polymers or plastics in the 1970s.The efforts which were exerted because of the requirement of lightweight materials, bearing outstanding mechanical and thermal characteristics then resulted in the creation of the polymers like numerous types of polyamides and polyetheretherketone.

Ultimately metal parts of air craft engines and its structural components were replaced by these light weight and high temperature resistance plastics. The conventional plastics tends to get soften at high temperatures and then start to degrade at these elevated temperatures. While on the other hand high temperature plastics keep their properties intact at elevated temperatures and are considered suitable to be used in industries where extreme operating conditions exist. These properties include chemical resistance, dimensional stability and mechanical properties which are vital to performance of high temperature plastics. These high temperature plastics which are engineered to face and withstand high temperatures in extreme environments are also called engineering thermoplastics or high performance thermoplastics.

Defining the High Temperature Plastic Material

High temperature plastic matreial is the material which is specially designed to be operated at high temperatures and withstand these elevated temperatures. The basic feature which is of importance is that high temperature plastics maintain their structural integrity and their mechanical properties at high temperatures. These high performance engineering plastics keep their original shape and do not deform while operating at elevated temperatures.

Depending upon the category of the plastics, they maintain their characteristics between the temperature ranges from 150°C to above 300°C.These high temperature plastics find their utilization in high temperature applications where normal plastics would degrade and deform and cannot sustain that high temperature. It is pertinent to mention that metals bear high weight and metals are also susceptible to corrosion. Keeping that in view high temperature plastic materials replace meals in such applications being light weight and corrosion resistant.

High temperature polymers and high temperature plastics (Differentiation)

The variation in composition and structure differentiate plastics and polymers. High temperature polymers are a vast category while high temperature plastics are subset of this broader category. High temperature polymers are comprised of both thermoset and thermoplastics. Advanced polymerization methods are applied to synthesize these polymers. Most of the times specific reinforcements or additives are utilized to increase their performance against high temperatures.

However, high temperature plastics are only comprised of thermoplastics. These plastics are designed to face and sustain elevated temperatures without deforming. These plastics offers very little or no degradation at high temperatures. These plastics are specifically engineered to keep their chemical resistance, mechanical properties and dimensional stability high temperature environment.

What Are the Materials of High Temperature Plastics (characteristics and Applications)?

Followings are the materials which fall in the category of high temperature plastics.

1. Polytetrafluoroethylene (PTFE)

This material which is also termed as PTFE is excellent electrical insulator and is extensively utilized in applications where electrical insulation is required. This material is also used for non stick coating especially in cookware and in seals and bearings. This utilization is based on some prominent properties of this material as follows.

• High temperature stability
• Low friction coefficient
• Good chemical resistance

2. Polyphenylene Sulfide (PPS)

This PPS material is a thermoplastic which has semi crystalline structure and exhibits following important characteristics.

• Flame retardency (inherent)
• High temperature resistance
• Chemical resistance
• Dimensional stability

These characteristics made this material suitable to be utilized in industrial applications. This material is also utilized in electrical and electronics sector in production of housings and connectors. Moreover in automotive industry this material is used to manufacture under the hood components. Go to PPS injection molding to know more about this material.

3. Liquid crystal polymer (LCP)

This material which is also referred as LCP finds its applications in the following areas.

• Telecommunication sector
• Electronics industry (switches and connectors manufacturing)
• Automotive industry (production of under the hood components)

This material bears the following significant properties which enable these materials to be utilized in above mentioned applications.

• Excellent chemical resistance
• High mechanical strength
• Good dimensional stability
• Excellent stiffness

4. Polyetheretherketone (PEEK)

This material is also thermoplastic having semi crystalline structure and is also termed as PEEK. This material exhibits following characteristics.

• High strength to weight ratio
• Good mechanical properties
• Excellent chemical resistance
• Stability at elevated temperatures up to 250°C

Keeping in consideration of above mentioned properties of PEEK, it is extensively utilized in the following applications for manufacturing f the components which demands resistance to extreme environmental conditions and good mechanical strength. Go to peek plastic injection molding to know more.

• Semiconductor industry
• Automotive sector
• Aerospace industry
• Medical sector

5. Polyetherimide (PEI)

This material which is also called PEI provides followings important properties.

• Flame resistance
• Good mechanical strength
• High thermal resistance
• Excellent dimensional stability
• Good electrical properties

Major applications of this material cover the following sectors.

• Medical sector (manufacturing of sterilizable surgical instruments)
• Automotive industry
• Electronics industry
• Aerospace sector

6. Polyimides (PI)

Ployimides material which is also termed as PI offers following characteristics.

• Good mechanical properties
• Excellent thermal stability up to 400°C
• Good chemical resistance
• Low thermal expansion

This material is extensively utilized in the electronic industry, aerospace sector and automotive industry for following applications.

• Electrical insulation
• Thermal shields
• Engine parts and spares
• Circuit boards

7.  Fluoropolymers (FPE)

The high temperature plastic materials which fall in this broader category are as follows.

• Fluorinatedethylenepropylene
• Polytetrafluoroethylene
• Perfluoroalkoxy

These polymers tend to show certain qualities described as follows.

• Elevated temperature stability
• Excellent chemical resistance (against acids, bases and many solvents)
• Low friction coefficient

These materials find their applications mainly in the following applications.

• Wire coatings
• Semiconductor processing
• Tubing
• Seals
• Linings
• Chemical processing equipment

  8.Polyphenylsulfone (PPSU)

PPSU is a thermoplastic, high-temperature engineering plastic part that was discovered in the 1960s. Their density is 1.24 g/cm2, water absorption is 0.22%, shrinkage rate is 1.007 (0.7%), melting temperature is 190 °C, heat distortion temperature is 1.82 MPa at 174 °C, and long-term use temperature ranges from -100 °C to +150 °C. This is one of the highest-quality plastic materials among them.

Simple molding process for PPSU plastic material

Pre-drying: PPSU needs to be pre-dried before processing to remove moisture in the material and prevent hydrolysis reactions at high temperatures. The drying temperature is 90℃–110℃, at least 3–4 hours of drying time.

Preheating: PPSU needs to be preheated before injection molding to improve the fluidity of the material. The preheating temperature is usually between 80 and 120 °C.

Injection: injecting PPSU into the mold. Injection pressure and speed need to be determined according to the type and injection molding wall thickness.

Cooling: This is pretty much the same as other injection molding parts, but PPSU needs a higher mold temperature than ABS or PC material, so normally the cooling time will be a little longer, but this depends on the wall thickness of the molding part.

Ejection: Once the PPSU injection molding parts have completely cooled in the mold cavity, the mold opens, and the ejector system ejects the molded part out of the mold.

Post-processing: some parts may need some post-manufacturing, such as machining, CNC turning, cleaning, etc., depending on the customer’s requirements.

Application of PPUS molding parts,

PPUS is very expensive and is normally used in electrical appliances, electronics, medical industries, baby bottles, instruments, and aerospace departments for heat-resistant, corrosion-resistant, high-strength parts and insulation parts, industrial films, etc.

Below table are some of high temperature materials for your reference, if need high temperature plastic molding parts, you are welcome to contact us.

What Are The Processing Methods Of High Temperature Plastics?

Special techniques are used for processing of high temperature plastics. Moreover, during the processing it is make sure that characteristics of high temperature plastics including mechanical strength and heat resistance remain intact during the whole manufacturing operation.

The most common and extensively used processing methods for high temperature plastics are as follows.

1. Compression Molding

In this process an open mold cavity is prepared. This mold cavity is then heated and a calculated amount of plastic is placed inside it. After that this mold is closed and an adequate pressure is applied onto the material. Application of this pressure compresses the material and the material is transformed into the required shape. The parts which are of large size and have complex geometries are molded by this method. These parts are difficult to be molded by other molding processes. The materials which are processed by compression molding method include polyetheretherketone, polyimides and thermoset high temperature plastics. Following parameters need to be controlled for producing uniform and defects free final product.

• Temperature
• Pressure
• Molding time

2. Injection Molding

In this processing method a mold cavity of desired shape is prepared first. After that the plastic material in molten form is injected into that mold cavity. This injection is carried out under high temperature and pressure. High temperature plastics are most commonly processed through injection molding. This processing method is feasible for high volume items and intricate shapes. The materials which are processed through injection molding consist of fluoropolymers, polyphenylene sulfide, polyetheretherketone and polyetherimide. The parameters which are required to be controlled to avoid warping and to achieve dimensional stability are as follows:

• Cooling rates
• Temperature
• Mold material resistance to corrosive environment
• Mold material resistance to high temperature

3. Extrusion

This method utilizes extrusion process to produce desired product or item. In this processing technique a permanent die of desired shape is utilized. The plastic material in molten form is forced into the die by using compressive force. As a result of this product of uniform cross section bearing continuous profile is produced. In order to avoid thermal degradation the control of extrusion temperature is critical.

In extrusion processing of high temperature plastics the quality of the extruded product and smooth flow of the material varies from material to material. So, die geometry and design of screws are adjusted to achieve the desired quality. The most common high temperature plastics which are commonly processed through extrusion method include thermoplastic composites, fluoropolymers, polyphenylene sulfide and polyetheretherketone. Following products are produced commonly through this processing method.

• Tubes
• Sheets
• Rods
• Profiles of high temperature plastics

4.  Machining

This processing technique involves utilization of various machines and tools to shape the high temperature plastics. In this method most commonly used machines are CNC machines, milling machines and lathe machines. This kind of processing is applied on the products or items which have complicated geometries and are of low volume. This method demands special tooling and specialized techniques because of the resistance and toughness of the material. Check PEEK CNC machining to know more.

But still all kinds of high temperature plastics can be machined by using this technique. During the machining process of high temperature plastics a considerable amount of heat is generated. This heat is crucial to destabilize the dimensional accuracy of the item and also propagate the degradation of the material. In order to eliminate the adverse effects of this heat lubrication is carried out during the machining process.

5. Additive Manufacturing

This processing method is very unique as compared to other processing methods. In this technique high temperature plastics are utilized in the form of filaments or powders. This powder is used to produce the parts layer by layer. This is carried out by adopting additive manufacturing techniques. Mainly there are two additive manufacturing techniques which are as follows.

• Fused deposition modeling
• Selective laser sintering

This process is feasible for producing prototypes. However, parts having complex geometries are also produced. This processing method offers minimal wastage of the material. There are numerous high temperature plastics which are compatible with additive manufacturing method. These materials include polyetheretherketone and polyetherimide. This method requires very accurate control of the process parameters in order to achieve demanded dimensional accuracy and mechanical properties. Moreover, special equipment is required for this processing method which can handle high temperature plastic materials.

Conclusion

Material science is touching new horizon and showing advancement because of high temperature plastics. These materials provide very unique and special properties including mechanical strength, elevated temperature stability and resistance to chemicals such as acids, basis and solvents. High temperature plastics materials have enabled the manufacturing of top notch performing spares and products which are strong, lighter and durable. Subsequently, all prominent sectors and industries have experienced revolution including electronics, automotive, medical and aerospace.

The conventional plastic materials cannot withstand high temperatures and experience degradation. However, high temperature plastics are very suitable for those applications because they have the prominent property to face elevated temperatures. Moreover, high temperature plastics show resistance to corrosion and mechanical stresses. These materials provides extended lifespan to products and spares because of their unique characteristics such as resistance to fatigue, keep dimensional stability and electrical insulation under extreme operating conditions.

High temperature plastics are being more important day by day because industrial sector is demanding high performance of components and spares. Advance research and development in the fields of material science and processing methods is depicting that these materials can be utilized for higher requirements. This will result in increased efficiency, sustainability along with safety in numerous sectors.Top of Form