Basic Properties of Specialty Engineering Plastics

August 25, 2024

Definition of special engineering plastics

Specialty engineering plastics is a class of engineering plastics with high comprehensive performance, long-term use of temperature above 150 ℃, such as Polyphenylene Sulfide

( PPS ), Polyimide ( PI ), polyether ether ketone (PEEK), liquid crystal polymer (LCP) and polysulfone (PSF). These plastics have rigid backbones, high melting points and well-organized molecular chains, and exhibit excellent stability in high-temperature environments. Specialty engineering plastics are mainly used in electrical, electronic and specialty industrial applications to meet the special performance needs of high temperature, corrosion and wear resistance, and are used to manufacture electronic components, insulating materials, chemical equipment and automotive engine parts.

The classification of special engineering plastics

The main classification criteria of special engineering plastics industry include material type, performance characteristics and application areas. According to the type of material, special engineering plastics can be divided into polyphenylene sulfide (PPS), polyimide (PI), polyether ether ketone (PEEK), liquid crystal polymers (LCP), and polysulfone (PSF).

The introduction of special engineering plastics

The background of the research and development of special engineering plastics was driven by the international arms race at that time. At that time, major companies in Europe and the United States have invested a lot of financial resources, manpower competing for development. From the early 1960s to the 1980s, the basic stereotypes, the following are introduced to the following kinds of special engineering plastics:

1. Polyimide (PI)

Polyimide (PI), first developed by the U.S. DuPont success, the trade name of Kapton, belongs to the amorphous polymer, Tg at 400 ℃ or more.

Polyimide is an aromatic heterocyclic polymer compound containing an imide ring (-CO-NH-CO-) in the main chain of the molecule, with good electrical insulation properties, mechanical properties, chemical stability, aging resistance, radiation resistance, low dielectric loss and other excellent properties, and these properties in the temperature range of -269-400 ℃ will not have a significant change in the temperature range, has been classified as “” the most promising engineering plastics in the 21st century. One of the most promising engineering plastics in the 21st century”.

2. Polyamide-imide ( PAI )

Polyamideimide (PAI), first developed under the trade name Torlon by Toray Co., Ltd. of Japan, is an amorphous, non-thermoplastic polymer with a Tg=285°C. It is recognized as a high-performance melt-processable polymer.

Polyamideimide is recognized as a high-performance melt-processable polymer. Chemically, it belongs to the family of imide resins. Among the ultra-high performance polymers, PAI has particularly good loading strength at high temperatures. It maintains its stiffness even near the glass transition temperature (Tg) or softening point of 537°F (280°C) and resists deformation under static loading for long periods of time with its excellent compressive strength and creep resistance. Polyamide-imide's abrasion resistance, broad chemical resistance and resistance to high-energy radiation add to its outstanding performance, making it ideally suited for applications in the harshest service environments.

3. Polyetherimide ( PEI )

Polyetherimide (PEI), developed by GE in the 1970s under the trade name Ultem, is an amorphous polymer with a Tg = 217°C. It is a thermoplastic polyimide that can be extruded and injection molded using thermoplastic processes. Unlike its predecessors, it is a thermoplastic polyimide and can be extruded and injection molded using thermoplastic processing.

Polyetherimide (PEI) is a member of the polyimide family of high performance materials, which also includes polyamideimide (PAI). PEI is an amorphous thermoplastic whose polymer structure includes an ether (E) linkage to the polyimide (PI) molecular structure. This modification allows PEI to be melt processed by injection molding and extrusion, which is a limitation of traditional polyimide materials such as PI. The basic form of polyetherimide is a transparent amber color. Its properties are characterized by a high strength-to-weight ratio, strength retention up to 390°F (200°C), long-term resistance to thermal oxidation, good electrical properties, and inherent chemical resistance and flame retardancy.PEI's ability to retain its properties after prolonged exposure to steam and hot water is also a major advantage in food processing equipment and medical applications requiring aggressive cleaning or sterilization.

4. Polysulfone (PSU)

Polysulfone (PSU or PSF), is the late 1960s by the United States UCC company developed and commercialized successfully, trade name UDEL, is an amorphous polymer, Tg = 192 ℃.

Polysulfone contains a benzene ring in the main chain, and the sulfur atom of the -SO2 - group is in the highest oxidation state, thus the antioxidant properties, mechanical properties and thermal stability is better, and the presence of ether bonds provides a certain toughness. In addition, polysulfone also has the advantages of non-toxic, self-extinguishing, corrosion resistance, etc., in aerospace, automotive, tableware, medical equipment and other fields are applied.

Currently commercialized and more mature polysulfone resin has three categories: bisphenol A type polysulfone (PSU), Polyphenylsulfone (PPSU) and polyethersulfone (PES).

5. Polyethersulfone (PES)

Polyethersulfone (PES), developed and commercialized in the 1970s by the British ICI company, under the trade name of PES, is an amorphous polymer, Tg = 225 ° C. The molecular structure of polyethersulfone (PES) contains neither aliphatic hydrocarbon links nor rigid biphenyl links.

Polyethersulfone (PES) molecular structure contains neither the poor thermal stability of aliphatic hydrocarbon links, nor the rigidity of the biphenyl chain, but mainly by the sulfone group, ether group and sub-phenyl composition. The sulfone group gives heat resistance, the ether group makes the polymer chain links in the molten state has good fluidity, easy molding and processing, in the p-phenylene support structure alternately connected to the sulfone group and the ether group can be obtained non-crystalline polymers.

PES is known as a combination of high heat distortion temperature, high impact strength and excellent moldability of engineering plastics.

6. Polyarylate (PAR)

This is a family of aromatic polyester products in general, one of the earliest successful development and commercialization of a company by the Japanese UNITIKA in the early 1970s to complete the development of the trade name: U-polymer, is an amorphous polymer, of which U-100 Tg = 193 ℃.

Polyarylate (PAR), is the main chain of the molecule with a benzene ring and ester group of special engineering plastics, the main chain of a ring of high density, improve heat resistance, heat deflection temperature 175 ℃ ℃; the main chain contains para- and meso-benzene ring links, hindering the polymer molecule crystallization, for the amorphous transparent polymers. Transparency and PC , PMMA compared to no less than 90% light transmittance; good bending resilience in a wide range of temperatures, excellent creep resistance; excellent weathering performance, can prevent the passage of ultraviolet rays below 350nm, long-term outdoor conditions, the mechanical properties of the basic unchanged; with self-extinguishing, low smoke emission when burning, non-toxic.

Polyarylate (PAR) can be processed by injection, extrusion, blow molding and other heating and melting methods. It can be used for high temperature resistant components and parts in the electrical, electronic and automotive industries, and is also commonly used as medical devices.

7. Polyphenylene sulfide (PPS)

Polyphenylene sulfide (PPS), first developed and commercialized by Philips in the 1970s under the trade name Ryton, is a crystalline polymer with Tg = 88°C and Tm = 277°C. PPS is composed of benzene rings and sulfur atoms arranged alternately, giving it a regular structure with a high degree of crystallinity of 75%.

Polyphenylene sulfide (PPS) consists of benzene ring and sulfur atoms arranged alternately, so that the structure of PPS regular, with a high degree of crystallinity, the degree of crystallinity of up to 75%, the melting point of up to 285 ° C. At the same time, the benzene ring for PPS to provide a good quality, and the melting point of PPS. At the same time, the benzene ring provides PPS with good rigidity and heat resistance, while the sulfur ether bond gives PPS a certain degree of flexibility. Polyphenylene sulfide (PPS) has excellent heat resistance, flame retardancy, insulation and corrosion resistance, its thermal stability, mechanical strength, electrical properties and other comprehensive performance, long-term heat resistance up to 220 ℃. Therefore, PPS is known as the “world's sixth largest engineering plastics” after polycarbonate (PC), polyester ( PET ), polyoxymethylene ( POM ), nylon (PA), polyphenylene ether (PPO).

8. Poly(ether ether ketone) (PEEK)

Polyaryletherketone (PAEK) is a crystalline polymer produced from a phenylidene ring connected by an oxygen bridge and a carbonyl group (ketone). Due to the different structure, polyarylether ketone varieties, mainly polyether ketone (PEK), polyether ether ketone (PEEKK), polyether ketone ether ketone (PEKEKK), polyether ether ketone (PEEK), polyether ether ketone ketone (PEKK), and several other varieties.

Among them, polyether ether ketone (PEEK), was first developed and commercialized in the 1980s by the British ICI company, trade name PEEK, is a crystalline polymer, Tg = 143 ℃, Tm = 334 ℃.

Poly(ether ether ketone) (PEEK) is a polymer consisting of repeating units containing one ketone bond and two ether bonds in the main chain structure. Polyarylene ether ketone molecular structure contains a rigid benzene ring, so it has excellent high temperature performance, mechanical properties, electrical insulation, radiation resistance and chemical resistance and other characteristics. Polyaryletherketone molecular structure of the ether bond and make it flexible, so you can use thermoplastic engineering plastics processing methods for molding. Polyaryletherketone products are generally wear-resistant, dimensionally stable, self-lubricating, and have a low dielectric constant, so they are suitable for use as parts under severe working conditions. In addition, its oxygen index is high, not easy to burn, belongs to the self-extinguishing material, good flame retardant. Since polyaryletherketone contains only C, H, O three elements, so the gas after combustion is non-toxic, is a better flame retardant material.

PEEK melting point (Tm) up to 340 ℃, high melting point so that PEEK has excellent high temperature resistance. Fiber reinforcement grade PEEK heat distortion temperature can be as high as 315 ℃, and the long-term continuous use temperature

The heat distortion temperature of fiber reinforced PEEK can be as high as 315°C, and the long-term continuous use temperature (UL 946B) can reach 260°C, and the short-term heat-resistant temperature is as high as 300°C. Even if it is used for 5000 hours at 260°C, the strength is almost the same as the initial state, and the thermal stability is excellent. As a result, PEEK has a long service life in harsh environments.

Author:

Ms. Tina

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sales@honyplastic.com

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