What is PPS Plastic?

Polyphenylene sulfide (PPS) is a high-performance thermoplastic with outstanding chemical resistance, which is soluble in almost no solvent at all temperatures up to 200 ° C. It has low moisture absorption and gives high mechanical strength and thermal stability and is hence suitable for precision machined parts. Go to high temperature plastic matreial page to know more related materials.

This material is semi-crystalline in nature and has a melting point of up to 225°F and thermal degradation of up to 425°F. It has a low coefficient of thermal expansion and has been stress-relieved during manufacturing thus making it ideal for parts that need close tolerances. In extreme conditions, PPS shows excellent performance and can be used as a cheaper substitute for PEEK at lower temperatures. Due to very low levels of ionic impurities, the material is suitable for applications requiring high purity.

You can go to PEEK injection molding page to know more about PEEK material.

Many different PPS grades are produced and they are available in glass-fiber reinforced, mineral, and internally lubricated variants. They can afford such advantages such as a low coefficient of friction, increased wear resistance, and high impact strength.

Introduction To PPs Plastic

Polyphenylene sulfide (PPS) is a high-performance thermoplastic which is known for its excellent chemical resistance, this material is resistant to all solvents at temperatures up to 392°F (200°C). The low moisture absorption rate coupled with mechanical strength and thermal stability makes it suitable for applications where precision engineering components are required.

Thermal Properties of Polyphenylene Sulfide (PPS)

PPS is very well known to have high thermal stability and it can work at high and low temperatures without changing its properties. The following specifications are derived from the tests conducted on Techtron® 1000 PPS which is an unfilled grade.

Heat Deflection Temperature (HDT)

The heat deflection temperature describes the amount of heat that a certain type of plastic can endure before it begins to give in to deformation under a certain weight. For PPS, this is at 115°C (250°F) when it is loaded with 1. 8 MPa (264 PSI) and according to ISO 75-1/2 and ASTM D648 standards.

Maximum Service Temperature

The continuous service temperature of PPS can reach up to 220 °C, the material can be used for a very long time, around 20,000 hours in air and its physical characteristics will not be affected.

PPS Plastic Melting Point

The glass transition temperature of PPS is found to be 280°C according to the I1357-1/-3 while it is 540°F according to the ASTM D3418 test standards.

Thermal Conductivity

Thermal conductivity is defined as how well the material in question will conduct heat. Thermal conductivity: As you can see PPS has better thermal conductivity than PEEK but less than PE and PTFE. At room temperature (23°C or 73°F), the thermal conductivity values for PPS are:

ISO: 0.3 W/(K·m)

ASTM: 2 BTU in. /(hr·ft²·°F)

Flammability and Fire Resistance

The flame resistance of PPS is reasonably good with a UL 94 V-0 rating and no additional fillers or additives are needed. It has an oxygen index of 44% according to the results of the tests conducted according to ISO 4589-1/2, which also speaks about the fire resistance of the material.

Coefficient of Linear Thermal Expansion (CLTE)

The coefficient of linear thermal expansion or CLTE shows how much a material expands when the temperatures rise. PPS has a CLTE of less than 40 compared to most other engineering plastics such as PET and POM making it even more cost-effective than PEEK and PAI. This low expansion rate is beneficial for applications where close tolerance is required in moderate to high-temperature environments.

Mechanical Properties of Polyphenylene Sulfide (PPS)

PPS is well known for its balance of low expansion coefficient and high mechanical strength and thus it is suitable for both load-bearing applications and for components that demand complex machining. The following specifications are based on the tests that were conducted on Techtron® 1000 PPS which is an unfilled grade.

Key Mechanical Properties

Property	Value (ISO)	Value (ASTM)
Density	1.35 g/cm³ (unfilled)	1.66 g/cm³ (40% glass-fiber reinforced)
Tensile Strength	102 MPa	13,500 PSI
Tensile Strain at Yield	12%	3.6%
Tensile Strain at Break	12%	20%
Tensile Modulus of Elasticity	4,000 MPa	500 KSI
Compressive Strength	–	21,500 PSI (ASTM D695)
Rockwell M Hardness	100	95
Rockwell R Hardness	–	125
Charpy Impact (Unnotched)	–	No break
Charpy Impact (Notched)	2.0 kJ/m²	–
Izod Impact (Notched)	–	0.60 ft·lb/in
Flexural Strength	155 MPa	21,000 PSI
Flexural Modulus of Elasticity	–	575 KSI

Density

Unfilled PPS has a density of about one. 35 g/cm³. If reinforced for instance with 40% of glass fibers, the density rises to about 1.66 g/cm³.

Tensile Strength

This tensile strength is much higher than other engineering plastics that are available in the similar price range of PPS. The tensile properties of Techtron® 1000 PPS consist of tensile strength of 102 MPa (13,500 PSI), yield strain of 12%, and break strain of 12%.

Compressive Strength

Another mechanical property that deserves mention is the compressive strength of PPS which is estimated to be about 21,500 PSI according to the ASTM D695 test.

Hardness and Impact Resistance

PPS demonstrates excellent hardness and impact resistance: PPS demonstrates excellent hardness and impact resistance:

 

Rockwell M Hardness: 100 (ISO), 95 (ASTM).

Rockwell R Hardness: 125, (ASTM)

Charpy Impact Strength: Unnotched samples do not have any cracks, whereas notched samples have a strength of about 2. 0 kJ/m².

Izod Impact (Notched): 0.60 ft·lb/in.

Flexural Properties

PPS polymer has a high strength and flexural modulus that can enable it to be used in structural applications. It has a flexural strength of 155 MPa (21,000 PSI) and a flexural modulus of 575 KSI, these are indicative of its stiffness and load-bearing capability.

It can be stated that PPS possesses rather high mechanical characteristics, which allows it to be used in those industries where high-strength and accurate parts are required.

Electrical Properties of Polyphenylene Sulfide (PPS)

Among all the polymer materials, polyphenylene sulfide (PPS) is particularly suitable for high-voltage electrical insulation. Its semi-crystalline and non-polar molecular structure makes it have a very low electron mobility and therefore a high electrical resistivity which makes it a poor conductor of electricity.

 

The following electrical specifications are based on tests done on Techtron® 1000 PPS, an unfilled grade.

Table: Key Electrical Properties

Property	Value
Dielectric Strength	18 kV/mm (IEC 60243-1)
	540 V/mil (ASTM D149)
Surface Resistivity	10^12 Ohm/sq (ANSI/ESD STM 11.11)
Volume Resistivity	10^13 Ohm/cm (IEC 62631-2-1)

Dielectric Strength

Dielectric strength refers to the electric strength of a material when stressed. For unfilled PPS this value is approximately 18 kV/mm according to IEC 60243-1 or 540V per mil as per ASTM D149 standard. This property is of significance in assessing the competency of PPS as an electrical insulator.

Electrical Resistivity

Electrical resistivity on the other hand is the measure of the ability of a material to offer resistance to the flow of electric current. PPS has very low electrical conductivity thus its electrical resistivity is low compared to many other common engineering plastics and this makes it ideal for use in insulation services. Unfilled PPS has shown surface resistivity to be 10^12 Ohm/sq (ANSI/ESD STM 11. 11) and the volume resistivity of 10^13 Ohm/cm (IEC 62631-2-1).

Chemical Compatibility of Polyphenylene Sulfide (PPS)

One of the most important properties of PPS is its very good chemical resistance which ranks it among the most chemically resistant engineering thermoplasts on the market today especially when one considers its cost. It absorbs even less moisture which makes it even more tolerant in various difficult uses. PPS is an excellent choice for environments involving:

• Strong Acids and Bases: It can also be exposed to some substances such as sulfuric acid, hydrochloric acid, sodium hydroxide, and potassium hydroxide.
• Organic Solvents: PPS exhibits acceptable solvents resistance to several organic solvents including alcohols, ketones, esters, and aromatic hydrocarbons.
• Oxidizing Agents: It is possible to use this material with oxidizers for example hydrogen peroxide and chlorine.
• Hydrocarbons: They can also be used with fuels, oils, and any type of lubrication that can be used in the automobile.

 

• Halogens: It is good for applications that involve sterilization and disinfection like using bleach and cleaning in place/sterilizing in place.
• Moisture and Humidity: Due to its low moisture absorption it is ideal for places with high humidity.

All in all, PPS material is ideal for use in applications that come into contact with a broad spectrum of chemicals and will offer long-lasting service in harsh environments.

Applications of Polyphenylene Sulfide (PPS)

Polyphenylene sulfide (PPS) is a high-performance thermoplastic material that has many special characteristics. Due to its relatively low cost and the ability to produce items from it, it is well-suited for several industries especially those involving high temperatures.

Here’s a breakdown of its primary applications:

Automotive Industry

PPS also finds its application in the automotive industry because of its capability to substitute metals and other materials in harsh application areas. It is particularly effective for components exposed to: It is particularly effective for components exposed to:

• High Temperatures: Best suited for use in areas where it is difficult to install fixed equipment such as under the car hood.
• Automotive Fluids: Not easily corroded by different types of fluids.
• Mechanical Stress: It offers much-needed endurance during stressful moments.

Key automotive applications include:

• Fuel injection systems
• Coolant systems
• Water pump impellers
• Thermostat housings
• Electric brake components
• Switches and bulb casings

In some cases, where interior or exterior trim parts are concerned, PPS is not frequently used; however, it is highly suitable for functional automotive applications.

Electrical and Electronics

PPS is a preferred material in the electrical and electronics (E&E) sector due to its:

• High Thermal Resistance: Best used in parts that are exposed to heat.
• Excellent Toughness and Dimensional Stability: Guarantees dependability in accuracy-sensitive applications.
• Low Shrinkage: Enables better shaping of complex connectors and sockets in the right manner.

PPS is also known for the UL94 V-0 flammability rating without the use of further flame retardants. It is commonly used in:

• Connectors and sockets
• Bobbins for electrical coils
• Electronic housings
• Hard disk drive components
• Switches and relays

The transition to PPS in E&E applications is therefore necessitated by the fact that there is a need to substitute polymers that are less resistant to low temperatures.

Home Appliances

Because of its minimal shrinkage and swelling, and non-corrosive and non-hydrolyzing properties on exposure to heat, PPS is used in different home appliances. Common applications include:

• Heating and air conditioning components
• Frying panhandles
• Hair dryer grills
• Steam iron valves
• Toaster switches
• Microwave oven turntables

Industrial Uses

The tendency is observed for PPS to replace metals and thermosetting plastics in the fields of mechanical engineering where chemically aggressive environments are present. Its properties make it ideal for:

Applications are not normally considered standard reinforced injection molding, but rather more heavily industrialized.

Fiber Extrusion Processes and Nonstick Coatings.

• Pressure-formed components for equipment and fine mechanics, including pump, valve, and pipe.
• Centrifugal pump components that are used in oil fields as well as the rod guides for the same.
• Such elements of equipment as HVAC systems, compressor components, blower housings, and thermostat parts.

Medical and Healthcare

In the medical industry, PPS with glass reinforcement is utilized for the construction of surgical tools and other elements of equipment that have to be both strong and refractory to high temperatures. Moreover, PPS fibers find their use in medical membranes and other uses as well.

Diverse Material Options

PPS is obtainable in various forms including filled with glass, filled with minerals, and internally lubricated. These options may include such benefits as reduced friction, enhanced wear resistance, and increased impact strength.

Types of PPS Based on Synthesis Methods

Polyphenylene sulfide (PPS) can be classified into three primary types based on its synthesis process. Each type offers distinct characteristics and benefits, making them suitable for various applications.

Overview of PPS Types

PPS Type	Description
Linear PPS	This version features a molecular weight that is nearly double that of standard PPS. It offers enhanced tenacity, elongation, and impact strength due to its longer molecular chains.
Cured PPS	Produced by heating regular PPS in the presence of oxygen (O2). This curing process extends the molecular chains and creates some branching, resulting in higher molecular weight and thermoset-like properties.
Branched PPS	This type has a greater molecular weight compared to regular PPS. Its molecular structure includes branched chains, which improve mechanical properties, tenacity, and ductility.

Detailed Characteristics

• Linear PPS: Linear PPS has high mechanical strength and therefore it is used where tensile strength and flexibility of the product is desired. It also solidifies rapidly when exposed to heat above the glass transition temperature which is about 85 0 C and is therefore useful in various processes of production.
• Cured PPS: The curing process also induces an increase in molecular weight of the thermoset material and its properties hence making it ideal for high temperature use. These changes are beneficial in that they provide increased strength and stability of the structures, which is especially important under conditions of high stress.
• Branched PPS: The branched PPS has a branching structure which is useful to provide high toughness and impact resistance for the application. Because of its higher ductility, it is suitable for parts that may be subjected to dynamic loads or impact.

From the understanding of these types of PPS, a manufacturer will be in a position to select the appropriate type of material for his application to improve performance and longevity.

Improving PPS plastic Material Properties with Additives

PPS is available in different types and because of its inherent chemical resistance, it is possible to compound with various additives to improve its properties. These improve the mechanical properties, thermal characteristics, and other relevant characteristics.

PPS is typically modified using fillers and fibers or copolymerized with other thermoplastics to enhance its properties. Popular reinforcements include:

• Glass Fiber
• Carbon Fiber
• PTFE (Polytetrafluoroethylene)

Several grades of PPS are offered, including:

• Unfilled Natural
• 30% Glass-Filled
• 40% Glass-Filled
• Mineral-Filled
• Glass-Mineral-Filled
• Conductive and Anti-Static Variants
• Internally Lubricated Bearing Grades

Among these, PPS-GF40 and PPS-GF MD 65 have emerged as the market standard as they perform, thus they occupy a considerable market share.

Comparing Properties between Different Grades of PPS

The following table summarizes the typical properties of unfilled and filled grades of PPS:

Property Comparison of PPS Grades

The following table summarizes the typical properties of unfilled and filled grades of PPS:

Property (Unit)	Test Method	Unfilled	Glass Reinforced	Glass-Mineral Filled
Filler Content (%)	–	–	40	65
Density (kg/l)	ISO 1183	1.35	1.66	1.90 – 2.05
Tensile Strength (MPa)	ISO 527	65 – 85	190	110 – 130
Elongation at Break (%)	ISO 527	6 – 8	1.9	1.0 – 1.3
Flexural Modulus (MPa)	ISO 178	3800	14000	16000 – 19000
Flexural Strength (MPa)	ISO 178	100 – 130	290	180 – 220
Izod Notched Impact Strength (kJ/m²)	ISO 180/1A	–	11	5 – 6
HDT/A @ 1.8 MPa (°C)	ISO 75	110	270	270

Processing Techniques for Polyphenylene Sulfide (PPS)

PPS resins are employed in various processes such as blow molding, injection molding, and extrusion and normally at a temperature of 300-350 ℃. However, due to the high melting point, it is not very easy to process especially filled grades where there are chances of overheating the equipment.

Pre-Drying Requirements

The molding process is critical in transforming the shape of the molded products and preventing drooling. It is recommended to dry PPS at: It is recommended to dry PPS at:

• At 150-160°C for 2-3 hours or at 170-180°C for 1-2 hours or at 200-220°C for 30 min-1 hr.
• 120°C for 5 hours

This step is especially crucial for carbon fiber-filled grades as they are known to swell and absorb moisture that is inimical to the final product.

Injection Molding Parameters

It’s important to point out that PPS can be processed using injection molding. To improve the productivity of the molding process, the mold temperature should be at 50 degrees Celsius while the post-crystallization temperature should be at 200 degrees Celsius. However, this method cannot be applied to the application where a high value of dimensional stability is required. Since PPS has low viscosity to fill, there is a need to focus on mold closure.

Typical parameters include:

• Cylinder Temperature: 300-320°C
• Mold Temperature: 120-160°C to enable the fabric to crystallize in its proper manner and not to warp.
• Injection Pressure: 40-70 MPa
• Screw Speed: 40-100 RPM

Extrusion Process

PPS also can be extruded and this process is applied in the production of fibers, monofilaments, tubes, rods, and slabs. Recommended processing conditions include:

• Drying Temperature: 121 °C for 3 h
• Mold Temperature: 300-310°C
• Melt Temperature: 290-325°C

Sustainability of PPS

However when PPS is sourced responsibly and when manufacturing it then it is considered to be one among the sustainable polymers. Its sustainability hinges on the following factors: On this basis, its sustainability depends on the following factors:

Raw Material Sourcing:

Selecting renewable materials in the manufacture of PPS can also help in decreasing greenhouse gas emissions as well as improve efficiency.

Durability:

PPS does not wear out in heat and chemicals and therefore, it lasts longer since it does not wear out most of the time, replacement is rare.

 

Recycling Options: Polyphenylene sulfide is recyclable in the following ways:

• Mechanical Recycling: Processes such as milling or chopping.
• Chemical Recycling: Such steps like depolymerization or other similar steps are taken.

While the melting point of PPS is high and is chemically inert creating a hurdle in recycling, there has been a constant development in the recycling industry for post-consumer plastics that have invested in facilities for recycling PPS and other similar thermosetting polymers which means it supports a circular economy.

Lightweight Features

The most typical or favored use of PPS is in replacement of metals as it is lightweight and serves as a non-corrosive to salts and automotive fluids. It can assemble several segments of high complexity correctly to accommodate several functions.

Certifications and Safety Considerations

PPS products that are made out of materials that have been recycled and/or produced from biomass and which are ISCC+ certified are deemed sustainable. They are not very hazardous to human beings and the environment but precaution should be exercised to minimize the risks associated with them.

Benefits of Injection Molding with PPS

The use of injection molding with polyphenylene sulfide (PPS) has many advantages so it is preferred for manufacturing high-performance parts.

Superior Mechanical Strength

PPS has several excellent characteristics as a material in terms of its mechanical properties including tensile strength, flexural strength, and impact strength. These characteristics enable PPS components to afford severe conditions where material strength is of paramount importance.

Outstanding Thermal Stability

One of the key characteristics of PPS is its heat resistance: this plastic does not disintegrate, lose its strength and elasticity, or warp if it is exposed to high temperatures for a long period. Due to its thermal stability, it is well fitted for use in areas where there is production of heat.

Excellent Chemical Resistance

PPS appears to be highly immune to several chemicals including acids, bases, solvents, and hydrocarbons. This property makes it suitable for use in difficult chemical applications.

Consistent Dimensional Stability

PPS parts can also not be affected by changes in shape and size by changes in temperature and therefore can be suitable for use in applications that require tight tolerances.

Lightweight Composition

PPS has a relatively lower density than metals and at the same time has good mechanical strength and therefore is more suitable for applications where weight is a compromising factor.

Drawbacks of PPS Plastic Injection Molding

However, it is important to take into account the following limitations of PPS in the injection molding process. These factors have to be assessed to better understand whether they are suitable for your particular use.

Higher Cost

PPS resins are comparatively expensive compared to many other thermoplastics and this is a factor that may make the overall cost of using PPS high in large-scale production or on projects that are sensitive to cost.

Abrasive Qualities

The high extent of filler incorporation that is utilized to improve the mechanical characteristics of PPS affects the wear of injection molding equipment. This can in turn cause wear and tear on screws, barrels, and molds before their useful life is due.

Limited Color Choices

Properly prepared PPS is generally in black or dark brown thus limiting the possibilities of bright or lighter shades in finished products.

Inherent Brittleness

Although PPS may be somewhat brittle, this is not an enormously huge problem and can be balanced with the help of fibers and reinforcements. However, these additives may also change the properties of the material which will affect the strength, the surface finish, the dimensional stability and the cost of the product.

Conclusion

In conclusion, it can be noted that injection molding with PPS offers several benefits, especially when it comes to high-performance parts with high mechanical load, heat, and chemical resistance. However, one has to take into account the higher cost and some of the inherent limitations of the approach depending on the specifics of the projects. Thus, by comparing these factors, manufacturers can make correct decisions about the utilization of inS in their applications, for maximum performance and cost.