Q: Does "Linear PPS" make a superior injection molding compound?
A: We use uncured linear PPS as well as cured PPS in our various Ryton® PPS products, depending on the desired properties of the product. For the most part, we prefer to use cured PPS polymers for injection molding compounds because they provide more of the benefits generally desired from PPS compounds. PPS curing is a process of heating the PPS polymer in air to increase its molecular weight through thermal-oxidative chain extension and cross-linking reactions. Uncured linear PPS will typically have more ductility than cured PPS of similar molecular weight, however cured PPS exhibits better dimensional stability and creep resistance. Furthermore, since any uncured linear PPS polymer will undergo curing when heated in air, cured PPS tends to exhibit less pronounced changes due to thermal aging. Certain compounds made using cured PPS, such as Ryton® R-4-200or Ryton® R-4XT, provide mechanical properties comparable to any compounds based exclusively on uncured linear PPS. For more information see our TSM on Defining and Comparing PPS Types or contact your nearest Technical Service Center.
A: CPChem refers to branched PPS as PPS produced with a branched backbone from the reactor. Some other PPS producers refer to branched PPS as PPS that has been post polymerization treated (PPT) by curing. The two resultant structures are different with different performance. CPChem practices both techniques – whichever is best for meeting the requirements.
A: The MW and it’s structure affect both processing and finished product characteristics, so you cannot say one is “generally” better than the other. A specific part design and processing technique along with finished part requirements should be defined before statements are made about one being more appropriate than another.
Q: Is CPChem the largest PPS producer in the World?
A:
CPChem (previously Phillips Petroleum Ryton) has been the largest PPS producer in the World since PPS was first commercially introduced by Phillips in 1972. That position was temporarily lost for 2008. When CPChem’s new plant comes onstream in 2009, it will be the largest PPS plant in the World and CPChem’s Engineering Polymer’s business will again be the largest PPS supplier in the World with coverage in all regions of the World.
Q: What does the new production facility in 2009 bring to CPChem?
A: More capacity (the largest capacity in the World) and a wider variety of post polymerization treatment (PPT) to produce a broader slate of products than any other PPS producer. CPChem has many years of knowledge and now is adding more equipment to commercialize that knowledge as well as add capacity.
A: Many of our products are already considered the best in the industry in their product/application fit. We use various combinations of MW, structure, PPT and compounding technology to fit the processing and end part requirements of different applications. The new capacity broadens our ability to improve on our overall product performance in many areas.
Q: Which areas will improve the most from the new 2009 facility?
A: The new capacity will significantly add to our product line offerings in the extrusion areas like fibers and profile extrusion. We will also offer additional injection molding products. The ultimate selection of the appropriate product will still depend on the individual requirements. Please consult with CPChem in regards to all the application requirements to select the best product for a specific application.
Q: Will the new capacity have the ability to make lower Cl level products to meet electronics industry desires?
A: Cl levels in PPS are dependent on MW and PPT, and so they vary greatly; We anticipate offering lower Cl level PPS and we expect some of them to meet the currently discussed levels of <900ppm.
Q: Will any new injection molding grades have lower offgassing properties?
A: Offgassing is a result of MW, PPT and compounding and is usually balanced against other variables; but we will be adding some lower offgassing grades. Please consult with CPChem in regards to all the application requirements to select the best product for a specific application.
A: Most of our products are available in either "natural" or black color, but some are available only in black. The "natural" color of most 40% glass fiber reinforced grades varies from dark brown to off white, whereas the natural color of most glass and mineral filled grades is a tan color.
Q: How much color variation can I expect to encounter with natural color Ryton® PPS compounds?
A: The color of Ryton® PPS compounds depends on several factors, including types of fillers and reinforcements, the amounts of these fillers and reinforcements, and the heat history the material sees during processing. Purely glass-reinforced compounds (like Ryton® R-4) are a fairly dark brown color, while glass-and-mineral-filled compounds (like Ryton®R-7) are a lighter brown to dark tan color. These colors can vary somewhat depending on how the compounds are processed. More heat history typically produces a darker molding; however, annealing amorphous (cold molded) parts will result in a lightening of color. Even though there is no color specification for the natural compounds, they are fairly consistent in color, with only slight variations due to the above factors. Variation in color is no indication of diminished mechanical properties.
Q: Is it possible to pigment Ryton® PPS to make it a different color?
A: The dark brown color of the 40% glass fiber reinforced grades is not amenable to pigmenting any color other than black. Some of the lighter color glass and mineral filled grades may be pigmented a variety of colors using commercially available color concentrates blended in at the injection molding machine. However, it is important to understand that the parts will not be color stable if exposed to elevated temperatures, UV light, or outdoor conditions. So, pigmenting Ryton® PPS may be useful in some situations for part identification, but pigmenting Ryton® PPS is not recommended for cosmetic or decorative purposes. Although Ryton® R-7-120NA has a UL "All Color" listing when used in conjunction with certain color concentrates, the addition of pigments may void the UL certification of other Ryton® PPS compounds. In general, if color stability and consistency is required, black color Ryton® PPS compounds should be used. Natural color Xtel® PPS-based alloys (Xtel® XK2040and Xtel® XK2240) may also be pigmented using commercially available color concentrates, but the same limitations apply. For more information see our TSM-326 Blending Color Concentrates with Ryton® PPS or contact your nearest Technical Service Center for more assistance with this matter.
Q: Can you tell me if Ryton® PPS is compatible with a certain chemical?
A: Information on the compatibility of Ryton® PPS with a wide variety of chemicals is available in our Chemical Resistance Guide. If you can not find the information you need, please contact us. Our chemists can provide opinions about the suitability of Ryton® PPS for particular chemical environments, based on our knowledge of the chemistry of PPS and our compounds. However, testing under conditions as similar as possible to actual service conditions is always recommended as the best way to determine chemical compatibility for a particular application.
Q: Will a crystalline part or an amorphous part have better properties?
A: Ryton® PPS in the crystalline state provides better performance in the areas for which PPS is usually chosen. Although amorphous PPS moldings may have somewhat better mechanical strength, crystalline PPS moldings will have higher modulus (stiffness), better creep resistance, and better high temperature dimensional stability. Furthermore, amorphous PPS parts may deform when exposed to temperatures above about 88°C (190°F). Consult the for more information on this issue.
Q: Is there some way to determine whether a Ryton® PPS part is crystalline or amorphous?
A: Yes. The crystalline or amorphous state of the PPS polymer may be determined by Differential Scanning Calorimetry (DSC). Contact your local technical service center for assistance.
Q: Does Ryton® PPS contain any halogenated flame retardants?
A: No. Since polyphenylene sulfide is inherently flame retardant, Ryton® PPS compounds can achieve UL94 V-0 and V-0/5VA flammability ratings without any flame retardant additives.
Q: Do any of your products meet this "ASTM D4067" requirement?
A: See ASTM D4067 Callouts for an explanation of the ASTM D4067 PPS material callout system and how to select a Ryton® PPS compound to meet the requirements of a specific callout. If you have further questions about the ASTM D4067 callout system, please contact our Quality Assurance or Technical Service staffs.
Q: Do your products contain any of the substances governed by the European Union 2000/53/EC End-Of-Life Vehicles (ELV), 2002/95/EC Restrictions on Hazardous Substances (RoHS), or 2002/96/EC Waste Electrical and Electronic Equipment (WEEE) Directives?
A: See End-Of-Life and Environmental Issues for information about the additives and trace impurities that may be present in Ryton® PPS and Xtel® products and the relevance to these directives.
Q: Do you have any "FDA approved" grades of Ryton® PPS?
A: There are no "U.S. FDA approved" Ryton® PPS injection molding compounds. Polyphenylene sulfide resins are specifically permitted under 21 CFR 177.2490 as coatings or components of coatings of articles intended for repeated food contact use, subject to certain limitations. This permission does not extend to articles injection molded from Ryton® PPS injection molding compounds. But, ordinary houseware articles, such as dishes, flatware, beverage glasses, mugs, cooking utensils, cutlery, and electrical appliances, are not subject to U.S. FDA regulation as "food additives." Therefore Ryton® PPS injection molding compounds may be suitable for use in such articles classified as housewares, but such use is subject to the general safety provisions of the U.S. Food, Drug and Cosmetic Act, meaning their use cannot in any way adulterate the food contacted. It is the responsibility of the manufacturer of the final article to determine the safety and suitability of Ryton® PPS for such applications. Several Ryton® PPS injection molding compounds have been certified to comply with the requirements of various Potable Water and Food Contact Standards.
Q: Is Ryton® PPS suitable for use in applications where it is exposed to ultraviolet (UV) light?
A: Although exposure of Ryton® PPS to UV light may cause some surface degradation, the properties of the bulk material will be relatively unaffected. Several Ryton® PPS compounds (R-4, R-4 02, R-4XT, R-4 02XT, R-7 02, R-10 5002C, and R-10 7006A) have been rated suitable for outdoor use with respect to UV light exposure, water exposure and water immersion, in accordance with UL746C.
Q: Does Ryton® PPS meet the fungus resistance requirements of military specification (MIL-STD-45-4)?
A: Yes, two Ryton® PPS products, R-4 and R-4 02XT have been evaluated by an independent laboratory (Truesdail Laboratories, Inc.) in accordance to MIL-STD-810D test method 508.3 and found not to allow fungus growth. The study was conducted over the prescribed twenty-eight days with the five fungi required by the test method. Observations were taken every seven days. No fungus growth was observed on the Ryton® PPS test specimens.
Q: Do you have a chart cross-referencing the different Ryton® PPS compounds with other manufacturers' PPS compounds?
A: We have no literature that cross-references our products with those of other suppliers. If you would like to substitute some other supplier's product with a Ryton® PPS compound, but are unsure which Ryton®PPS compound to use, please contact us.
Q: Is it really necessary to use a mold temperature of 275°F (135°C)? We are able to reach temperatures of 200°F to 250°F (93°C to 121°C) using hot water. Is this sufficient?
A: We generally recommend using a mold surface temperature of 275°F to 300°F (135°C to 149°C) to achieve a near maximum degree of crystallinity for optimum long-term thermal stability, dimensional stability, and consistent part performance. Consult the for more information on this issue.
Q: In our injection molding facility, we have several methods to heat our molds: circulating water or oil, and electric cartridges. Do you recommend one of these methods in particular for molding Ryton® PPS?
A: Yes, we recommend using oil to heat and cool molds when molding Ryton® PPS thermoplastic compounds. Remember, we typically suggest you mold Ryton® PPS in a mold with surface temperatures of 275-300°F (135-149°C). Because this is well above the boiling point of water, using water to heat and cool the mold to 275°F (135°C) results in very high line pressures and a potential safety hazard. On the other hand, the typical line pressure for oil heating/cooling systems is about 30 psig (2.1 bar). Electric cartridges do not offer the temperature control provided by oil systems. Oil systems are capable of both heating and cooling the mold, resulting in more consistent mold temperatures and improved shot-to-shot consistency.
Q: Can Ryton® PPS still be used after it has been in a dryer longer than the recommended period of time?
A: We have conducted tests on drying Ryton® R-4 at 300°F (149°C) and found that the initial melt flow of 28.7 g/10 min varied from a low of 26.0 g/10 min to a high of 30.0 g/10 min, up to 96 hrs. If, however, your drying temperature was too high (400°F, 204°C), the melt flow would decrease from 28.7 g/10 min to 13.9 g/10 min. Therefore, if your dryer is set at 300°F (149°C) or lower, you should have no problem using that material.
Q: What is the recommended moisture content level for Ryton® PPS compounds?
A: Although we have no recommended moisture level, Ryton® PPS compounds will be more readily processed if dried thoroughly. Less than 0.02% moisture should be sufficient, and following our standard drying recommendations (300-350°F, 149-177°C for 2 to 3 hours) should accomplish this. Longer drying times are not harmful, but temperatures above 400° F (204°C) may reduce melt flow. The resin itself is not hygroscopic, but some mineral fillers may be, so drying is particularly important for mineral filled compounds.
Q: If I need to briefly interrupt production, should I purge the Ryton® PPS from the barrel of my machine?
A: At normal processing temperatures (600-650°F, 315-343°C melt temperature), Ryton® PPS compounds may be allowed to remain in the barrel for up to two hours without suffering any detrimental effects.
Q: I need to recover some molded-in inserts from some reject parts. Is there a solvent I can use to dissolve away the PPS
A: Unfortunately, recovery of molded-in inserts from Ryton® PPS parts is not practical. There is no known solvent for PPS at temperatures below 200°C (392°F), and acids that will degrade the PPS polymer will also likely damage inserts. It is possible to burn away the PPS (with a torch or using a muffle furnace, for example) if the inserts can withstand the temperatures required (over 815°C, 1500°F). If possible, a metal insert may be heated to melt the surrounding PPS (about 316°C, 600°F) to facilitate its removal, but there will still be residual PPS to be removed. Molten PPS can usually be removed using a wire brush or scouring pad. Like chipping or breaking the PPS away from the inserts, these operations generally can not be accomplished without damaging the inserts.
Q: Do you have the properties required for a finite element stress analysis?
A: Yes. Stress-strain curves and elevated temperature data are available for the most commonly used products. Please contact one of our Technical Service Centers to request the data you need.
Q: Do you have the material parameters required for conducting a flow simulation?
A: Yes, the material parameters have been developed for the most commonly used products. This includes PVT data which is needed for warpage analysis. Please contact one of our Technical Service Centers to request the data you need.
Q: What types of adhesives are best for bonding Ryton® PPS?
A: Despite the chemically non-reactive nature of PPS, there are adhesives that will bond PPS providing the surface is properly prepared. Acrylic, cyanoacrylate, and two-part epoxy type adhesives have generally been found to work best with PPS, however surface treatments are often required to attain adequate bond strengths. For more information on this issue see Adhesive Bonding. We also suggest contacting adhesive manufacturers regarding their latest recommendations for adhesives that are effective at bonding PPS.
Q: What is the recommended gap for venting around an ejector pin?
A: Molds for Ryton® PPS compounds may be vented by a 0.0005 inch (0.0125 mm) gap around the radius of the pin (0.001 in, 0.025 mm reduction in diameter). Venting also may be accomplished by flattening pins 0.0007 inches (0.0175 mm) on one to four sides
Q: I'm analyzing a plastic housing that is attached to an aluminum part. I was told that the coefficient of linear thermal expansion (CLTE) for Ryton® PPS was close to that of aluminum. Is that correct?
A: The CLTEs of different Ryton® PPS compounds vary, but in general they are close to that of aluminum in the flow direction. Transverse to flow the CLTEs are higher than aluminum. If large temperature variations are expected, the assembly should be analyzed to determine if problems exist.
Q: I was considering PPS for an injection molded part, but I've heard the material doesn't flow very well. Is this true?
A: Absolutely not! In fact, Ryton® PPS compounds have some of the best flow characteristics of all high temperature engineering thermoplastics. They are used extensively in the connector industry, where part thicknesses of 0.50 mm to 0.75 mm (0.020 to 0.030 inch) are commonplace.
Q: What is your normal lead time and how do I place an order?
A: Standard lead times are twenty business days. It is helpful for new customers who have large volume requirements to provide estimates of annual volume in order to ensure uninterrupted supply. To place an order, please see New Customer Setup or contact one of our worldwide Customer Service Centers.
Q: Do you sell direct or through distributors? Do you have a distributor in my area?
A: We accept customer orders of any volume (in 25 Kg increments) and ship them directly from our warehouse locations, but we also have many distributors worldwide. See New Customer Setup or contact one of our worldwide Customer Service Centers to place an order directly with us. Look in our Contact Us section for direct contacts and distributor information.
Q: Where can I obtain Ryton® PPS stock shapes for machining some prototype parts?
A: Large stock shapes made from Ryton® PPS injection molding compounds are not available because the injection molding compounds are not suitable for producing thick forms. Some Compression Molders (see Processors) supply PPS rod, sheet, and tube stock, but it is important to understand that parts machined from compression molded PPS rods, sheets, or hollow forms will likely not perform the same as parts injection molded from Ryton® PPS injection molding compounds. For more information see Rod, Plate and Tube Stock Availability.
