Why Polyphenylene Sulfide (PPS) The Most Cost-Effective Specialty Engineering Plastics

September 05, 2024

Why Polyphenylene Sulfide ( PPS ) is the most cost-effective specialty engineering plastics

Polyphenylene sulfide (PPS) resins, also known as polyphenylene ether and polyphenylene sulfide, are macromolecular linear rigid structures consisting of a benzene ring attached in the para-position to a sulfur atom.PPS is a semi-crystalline engineering thermoplastic that bridges the gap between standard and advanced polymers in terms of price and performance.

PPS is a semi-crystalline engineering thermoplastic that bridges the gap between standard polymers and advanced polymers in terms of price and performance.PPS plastics are notable for their excellent dimensional stability and chemical resistance, making them an affordable material with advanced properties.

PPS sheets, rods and tubes have high dimensional stability during processing and use, making them ideal for complex parts with precise tolerances. In addition, PPS plastics have excellent mechanical properties, inherent electrical insulation, high heat and flame resistance.

Often used as a low-cost alternative to PEEK in applications where machining is too complex and the use of metal is too bulky, PPS plastics excel in applications that require excellent load-bearing capacity and abrasion resistance, as well as exposure to corrosive chemicals and high temperatures.

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PPS is by far the world's most cost-effective specialty engineering plastic. It has become the number one specialty engineering plastic. In the ranking of general-purpose engineering plastics, PPS ranks after polycarbonate, polyester, polyformaldehyde, nylon and polyphenylene ether, with the production volume in the 6th place.

01 The most cost-effective specialty engineering plastics

PPS resin is usually white or nearly white beads or powder products, due to its structure for the benzene ring and sulfur alternately connected, the molecular chain has a great deal of rigidity and regularity, so the PPS is a crystalline polymer, with high strength, modulus and good dimensional stability of the product, creep is small, there is a very high fatigue, good flame retardant, moisture absorption is small, in high temperature and high humidity conditions do not deform and can maintain excellent Electrical insulation, good solvent and chemical resistance, almost insoluble in any solvent below 200 ℃, and radiation resistance.

In engineering plastics and special engineering plastics, PA, POM, PET and other general engineering plastics performance may not meet the technical requirements, and the use of Polyimide ( PI ), polyether ether ether ketone (PEEK), polysulfone (PSU) and polyamide-imide (PAI) is too high when the price is too high, the PPS has become a more ideal application of the materials.

02 Physical and mechanical properties

As the molecular weight of PPS resin produced in the early stage is not high enough, the resin needs to be treated with thermo-oxygen cross-linking before it can be extruded and pelletized to make plastics, therefore, for a long time, PPS is brittle, which is one of its major points. But since the emergence of high molecular weight PPS resin, especially the Japanese Wu Yu Chemical Industry Company launched Foruon pps - the second generation of linear high molecular weight PPS resin, PPS brittleness has been fundamentally improved, and its elongation and impact strength are greatly improved to become toughness of PPS. at the same time, compared with the thermo-oxygen crosslinked resins, high molecular weight PPS resin, the thermal and other mechanical properties have also been further improved. have been further improved.

The tensile strength and flexural strength of unmodified PPS are only medium level, and the elongation and impact strength are also low. Therefore, PPS is often modified with glass fibers and other inorganic mineral fillers to enhance the end-filling modification, so that it can further improve the physical and mechanical properties while maintaining the heat resistance, flame retardancy and media resistance.

03 Thermal Properties

The heat resistance of polymers is specifically reflected in the molecular size, mechanical properties and its own weight stability at high temperature, therefore, you can determine the mechanical properties of polymers at high temperature and its weight loss to determine its heat resistance. pps in all thermoplastic engineering plastics shows excellent heat resistance.

PPS melting point as high as 280 ~ 290 ℃, in the air 430 ~ 460 ℃ above the beginning of decomposition, thermal stability far beyond the PA, PBT, POM and PTFE and other engineering plastics reinforced with glass fiber composite, PPS heat distortion temperature of up to 260 ℃, long-term use of the temperature of the thermoplastics can reach a maximum of 220 ~ 240 ℃, the bending strength of 200 ℃ is still higher than room temperature ABS so it is a thermoplastic engineering plastics. Higher than room temperature ABS so it is an excellent high-temperature structural materials.

PPS solder heat resistance is also much higher than other engineering plastics, making it suitable for the production of electronic and electrical components. Such thermal performance, even in thermosetting plastics is rare. In addition, PPS itself has good thermal insulation, but by adding the appropriate filler, can also produce good thermal conductivity of PPS composite materials.

04 Chemical resistance

PPS chemical resistance and the so-called “king of plastics” Polytetrafluoroethylene (PTFE) similar, PPS in addition to strong oxidizing acids (such as concentrated sulfuric acid, nitric acid and aqua regia, etc.), not subject to most other acids, alkalis, salts, in 200 ℃ insoluble in any chemical reagent. In addition to strong oxidizing acid and fuming nitric acid, chlorosulfonic acid, fluorine acid, almost not eroded by all inorganic media. Above 250℃, it is only soluble in biphenyl, biphenyl ether and their halogenated substitutes. At high temperature even the best solvent chlorinated biphenyl can only dissolve 10%. In boiling concentrated hydrochloric acid, PPS does not undergo any change. The good processability of PPS is far superior to PTFE, making PPS more widely used in petroleum, chemical and automotive industries and sectors that require oil and corrosion resistance.

05 Electrical properties

PPS and other engineering plastics, compared with the dielectric constant is small, dielectric loss is quite low, and in the larger frequency range does not change much, its conductivity is generally between 10-18 ~ 10-15S/cm, in a high vacuum (1.33x10-3Pa) conditions and even as low as 10-20S/cm, so the PPS resin is used as an insulating material of excellent performance and widely used.

PPS can still maintain good electrical properties at high temperature and high humidity. Whether modified or not, PPS electrical properties with the temperature and humidity changes are very small, and in a wide range of temperatures and frequencies have a certain dielectric properties, and some even in the water impregnated with 11 months after the temperature of 120 ~ 150 ℃ is still very stable.

Usually, thermoplastic arc resistance is lower than thermosetting plastics, but PPS arc resistance is excellent, unmodified PPS arc resistance of 34s, inorganic materials modified PPS arc resistance up to 200s or so, to become a thermoplastic in the electrical material may replace thermosetting plastics.

PPS in the case of high temperature, high humidity volume resistance coefficient change is very small, its dielectric constant with the temperature and frequency change is very small, coupled with ionic impurity content is very low, can withstand 10s in 260 ℃ solder bath impregnation, and thus enough to withstand the thermal shock of the surface soldering of electronic components for products with extremely stringent requirements for electrical properties, is an excellent electrical insulating material.

06 Flame retardant

In order to improve the flame retardancy of most polymer materials, it is usually necessary to add a certain amount of flame retardant, and the presence of flame retardant often affects the electrical properties of the products; in the molding process will also cause a certain degree of corrosion of the equipment, molds; once the combustion occurs, the flame retardant will also release corrosive toxic gases, resulting in safety problems.

PPS due to the molecular structure with sulfur atoms, so that its flame retardancy is very prominent, its oxygen index of 44% ~ 53%, can reach UL94 V-0/5V level, for the highest level of combustion safety, without the need to add flame retardant in the resin that can meet the requirements of flame retardant, so PPS can be in the mechanical, electrical components, such as safety shields to obtain a wide range of applications in line with international requirements for polymer materials in the safety, non-toxicity and other aspects. Therefore, PPS can be widely used in mechanical and electrical parts such as safety guards, which is in line with the international requirements for polymer materials in terms of safety, non-toxicity and its development trend.

07 Adhesion

PPS on glass, aluminum, ceramics, steel, silver, chrome, nickel-plated products have good adhesive properties, the adhesive shear strength of steel for 20.58 ~ 22.54MPa, the adhesion of glass and even more than the cohesive force of glass. Due to its good corrosion resistance and adhesive properties, it is very suitable for the preparation of chemical equipment lining.

08 Dimensional stability

PPS has excellent dimensional stability, molding shrinkage and linear expansion coefficient is small, molding shrinkage of 0.15% to 0.3%, the lowest up to 0.01%. In addition, PPS water and oil absorption is small, and good chemical resistance, in the humid, oil and corrosive gas environment, PPS products still have excellent dimensional stability.

In addition, for most of the engineering plastics, often due to water absorption, in the molding process Xia Xia on the material for a long time pre-drying, otherwise the products will be due to water evaporation and produce pores, or in the molding process due to the decomposition of water and cause aging. However, due to the very low water absorption of PPS, pre-drying time before molding can be greatly reduced, and in the process, will not produce due to moisture absorption caused by aging and electrical properties such as degradation of undesirable phenomena.

In addition, although PPS melt temperature is high, but the melt viscosity is low, good fluidity, suitable for processing into thin-walled or precision size products.

09 Radiation Resistance

PPS is stable to UV and 60Co rays, especially thermally and chemically crosslinked PPS is resistant to 107Gy dose of radiation.

10 Other Properties

PPS is a physiologically inert substance, non-toxic, has passed the U.S. FDA safety certification, can be used in contact with food, and its non-stick coating mixed with PTFE is widely used in the production of non-stick pans. valves, tubes, etc. produced by PPS are also used in the delivery of potable water system.

Author:

Ms. Tina

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sales@honyplastic.com

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