Polyphenylene-sulfide

Polyphenylene sulfide (PPS) is a relatively inexpensive material made by the reaction of sodium sulfide and dichlorobenzene. It 

In many ways PPS can be regarded at a low-temperature version of PAEK although with perhaps less toughness, greater flow and a greater tendency to flash in moulds. Chemical resistance and many key properties decrease significantly above Tg (90 C). 

There have been several earlier attempts to make polyphenylene sulfide (PPS), but in the late 1960s, workers at Phillips Petroleum developed the first commercial process [36]. Sodium sulfide reacts with p-dicldorobenzene in a polar organic solvent. Common trade names are Ryton (Phillips Petroleum) 

The minimal properties of a stabilizer suitable for electronic applications made from polyphenylene sulfide are the following  

30 days storage time, 1 %, additive, plate-out on Ag (8 pm), closed volume [573] 

The effectiveness of PEEK and PAI ends above 350 °C. PPS, both stabilized and non-stabilized with PAI, shows the same degradation behavior at 370 °C. In order to stabilize over the entire processing range, lithium carbonate should be added, because it becomes effective at approx. 370 °C. In principle, a notable increase in the amount of added polymer could also be used in order to stabilize at 370 °C [573]. 

Left Ryton R-4 with 1 % lithium carbonate, 40%glass fibers, non-tempered with various additives at 200 °C 

Adding PEEK and PAI for electro-technical applications, where gas released from PPS plays a role, the upper service temperature of PPS can be increased by 20 to 50 K. With polymer additives, such as polyvinyl carbazole that exhibit lower heat resistance than PPS, their long-term effect is questionable, because these additives slowly degrade [573]. The active mechanisms for this behavior have not yet been explained. Pure absorption in the form of addition complexes must be excluded because of the effectiveness at high temperatures. More probable is the integration of sulfur compounds in the chain of the additive polymers, possibly with further cyclizations [573]. 

Unreinforced PPS resins are also available for use in slurry coating and electrostatic spraying. Resin coatings are suitable for food-contact applications as well as chemical processing equipment. 

PPS has excellent resistance to a broad range of chemicals, even at high temperatures. In fact, below 200°C (400°F) the resin has no known solvent. PPSs are flame retardant without additives, being rated at UL 94V-0-V5. The oxygen index of the neat resin is 44, with the indexes of the compounds ranging from 47 to 53. Because flame retardance is inherent in it, a regrind will be as flame resistant as a production in the virgin material. 

Polypropylenes (PPs) are in the polyolefin family of plastics. They are semitranslucent and milky white in color, with excellent colorability. They are produced by a stereoselective catalyst that puts order in their molecular configuration so that the basic resin has a predominantly regular, uniform structure. This means that the molecules crystallize into compact bundles, which makes them stronger than other members of the polyolefin family. PPs are an extremely versatile plastic available in many grades as well as copolymers like ethylene propylene. Neat PP has a low density of 0.90, which, combined with its good balance of moderate cost, strength, and stiffness as well as excellent fatigue, chemical resistance, and thermal and electrical properties, makes PP extremely attractive for many indoor and outdoor applications. 

Although PPs retain their strength and stiffness at elevated temperatures, their performance at low temperatures leaves much to be desired. However, copolymers of PP that are available offer as much as two to three times the impact strength of general-purpose PP, even at temperatures as low as -29°C (-20°F). 

PP is widely known for its application in the integral living hinges that are used in all types of applications (see Chapter 11). PP s excellent fatigue resistance is utilized in molding these integral hinges. 

Liquid crystalline polymers such as thermoplastic elastomer copolyesters are being used in lower power, higher speed gears because it allows them to tolerate inaccuracies and reduce noise while providing sufficient dimensional stability and stiffness [7]. 

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Negative mass spectrum from polyphenylene sulfide, 0-250 amu. 

Fig. 11. Effect of polyolefin primers on bond strength of ethyl cyanoacrylate to plastics. All assemblies tested in accordance with ASTM D 4501 (block shear method). ETFE = ethylene tetrafluoroethylene copolymer LDPE = low-density polyethylene PFA = polyper-fluoroalkoxycthylene PBT = polybutylene terephthalate, PMP = polymethylpentene PPS = polyphenylene sulfide PP = polypropylene PS = polystyrene PTFE = polytetrafluoroethylene PU = polyurethane. From ref. [73].

As regards the general behaviour of polymers, it is widely recognised that crystalline plastics offer better environmental resistance than amorphous plastics. This is as a direct result of the different structural morphology of these two classes of material (see Appendix A). Therefore engineering plastics which are also crystalline e.g. Nylon 66 are at an immediate advantage because they can offer an attractive combination of load-bearing capability and an inherent chemical resistance. In this respect the arrival of crystalline plastics such as PEEK and polyphenylene sulfide (PPS) has set new standards in environmental resistance, albeit at a price. At room temperature there is no known solvent for PPS, and PEEK is only attacked by 98% sulphuric acid. 

PP-g-AA - acrylic acid grafted polypropylene PP-g-MAH - maleic anhydride grafted polypropylene PPacr - acrylic acid grafted polypropylene PPmal - maleic anhdride grafted polypropylene PPS - polyphenylene sulfide PS - polystyrene... 

Newer fabrics, not in common use but in development, test, and field trials, are described for higher temperature applications by Reference [50]. Application to 400°F—2100°F are potentially available using ceramic fibers Nextel 312 , laminated membrane of expanded PTFE on a substrate, polyimid fiber P-84, Ryton polyphenylene sulfide, and woven fiberglass. The heat and acid resistance of these new materials... 

Polyphenylene sulfide Melts at 270-315°C (578-599°F) crosslinked polymer stable to 450°C (842°F) in air adhesive and laminating applications. 

Polyphenylene sulfide Toughen brittle resins, +Can impart special properties such... 

Note Glass filler can considerably extend the performance of the above polymers. PEI = polyetherimide PES = polyether sulfone PPS = polyphenylene sulfide PSF = polysulfone PC = polycarbonate. 

POLY IM IDES SILICONES FLUOROPLASTICS POLYAMIDE-IMIDE EPOXY POLYPHENYLENE SULFIDE 500-800 400-600 300-550 520-545 175-500 500... 

Polyphenylene sulfide Melts at 270 to 315°C (578 to 599°F) cross-linked polymer stable... 

Polyphenylene sulfide PPS is able to resist 450°F (232° C), and has good low temperature strength as well. It has low warpage, good dimensional stability, low mold shrinkage. Use includes hair dryers, cooking appliances, and critical under-the-hood automotive and military parts. 

PESA can be blended with various thermoplastics to alter or enhance their basic characteristics. Depending on the nature of thermoplastic, whether it is compatible with the polyamide block or with the soft ether or ester segments, the product is hard, nontacky or sticky, soft, and flexible. A small amount of PESA can be blended to engineering thermoplastics, e.g., polyethylene terepthalate (PET), polybutylene terepthalate (PBT), polypropylene oxide (PPO), polyphenylene sulfide (PPS), or poly-ether amide (PEI) for impact modification of the thermoplastic, whereas small amount of thermoplastic, e.g., nylon or PBT, can increase the hardness and flex modulus of PESA or PEE A [247]. 

The palladium-catalyzed formation of sulfides can generate polyphenylene sulfide from a dithiol and a dibromoarene, or from 4-bromobenzenethiol (Equation (38)).17 In 1984 Asahi Glass obtained patents for the formation of this polymer in the presence of palladium and nickel catalysts.125,126 In addition, Gingras reported palladium-catalyzed couplings of aryl halides and thiols to form discrete phenylene sulfide oligomers.127,128 A number of polyphenylene sulfide wires, ranging from dimeric to pentameric structures, were prepared by the palladium coupling, albeit in modest yields ... 

Graphite/ Thermo- plastic AS4/PPS Phillips Petroleum Phillips Petroleum Polyphenylene sulfide, semicrystalline thermoplastic... 

There is no true correlation between the two methods as we can see in Figure 3.5, which displays the notched versus un-notched impact strength of various grades of polycarbonates, acrylics, polyphenylene sulfide and nylon. 

The UL rating depends on the exact grade and the sample thickness. For the same grade of polyphenylene sulfide, the UL ratings are ... 

Semi-aromatic PAs generally have a weak and slow absorption of water, a high rigidity, and are claimed to be more resistant to weathering and oils. For example, properties of polyphthalamides are intermediate between those of PA 66 and polyphenylene sulfide (PPS). 

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