Poly sulfide applications

Significant progress has been achieved in the identification of poly sulfides in non-aqueous solvents, mainly by application of Raman spectroscopy. However, there are... 

Table 11.18 shows the effect of increasing the poly sulfide-epoxy ratio on impact properties the effect at concentrations of polysulfide polymer greater than 1 1 is especially significant. The combination of increased flexibility, tensile strength, and elongation is very desirable in certain adhesive applications. 

Poly(thioether)s should not be confused with poly(sulfide)s, in that the term poly refers directly to the sulfide linkage, i.e., —Sn—, but at the same time to a polymer. These types of polymers are used in a completely different field of application, e.g., additives for elastomers, antioxidants for lubricating oils, intermediates for the production of organic chemicals, insecticides, germicides, and as an additive to diesel fuels to improve the octane number and ignition qualities of these fuels. These polymeric types are not dealt with in this chapter. 

Applications of epoxy-polysulfide adhesives primarily include structural assemblies requiring some degree of resilience. Epoxy-poly sulfides are used in bonding concrete for floors, airport runways, bridges and other concrete structures, metals, glass and ceramics, wood, rubber, and some plastics. They are particularly durable in outdoor applications where temperature extremes (freeze-thaw cycles) will be encountered. Epoxy-poly sulfides can be heavily filled without adversely affecting their properties. 

Many of the sealants have been prepared using Thiokol LP -2, LP -32 or LP -31 as the base poly sulfide liquid polymer the chemistry, cure mechanisms, reinforcement, and applications will thus be restricted to these polymers. The chemistry and applications of polysulfide polymers, crudes, water dispersions, and various liquid polymers are covered completely in extensive bibliographies by Berenbaum and Pa-nek. 

With the development of synthetic elastomers during World War II, new types of adhesives appeared for application to a broader range of substrates and for use at higher temperatures. Styrene-butadiene and butadiene-acrylonitrile copolymers found application in new adhesives. There were also significant concurrent developments in adhesives based on chlorinated rubber, polychloroprene (neoprene), and poly sulfide rubber. Development of carboxylic elastomers, silicone rubbers, and polyurethanes followed. 

Polysulfide Sealants. Liquid poly sulfide polymers are the base of poly sulfide sealants, the workhorse elastomeric sealants used in construction, glazing, marine, and aircraft applications for over 35 years. 

More recently, in the nineteenth century, there was a great increase in the application of foreign chemicals to agriculture. Discovered or, more precisely, rediscovered was the usefulness of sulfur, lime sulfur (calcium poly sulfides), and Bordeaux mixture (basic copper sulfates). With the exception of formaldehyde, inorganic chemicals provided farmers with their major weapons. 

Polyarylates can be blended with a wide range of commercially available thermoplastics, including polyamides, polycarbonates, polyetherketones, polyesters, and poly(phenylene sulfide), thus broadening their application domain. 

Zinc sulfide, with its wide band gap of 3.66 eV, has been considered as an excellent electroluminescent (EL) material. The electroluminescence of ZnS has been used as a probe for unraveling the energetics at the ZnS/electrolyte interface and for possible application to display devices. Fan and Bard [127] examined the effect of temperature on EL of Al-doped self-activated ZnS single crystals in a persulfate-butyronitrile solution, as well as the time-resolved photoluminescence (PL) of the compound. Further [128], they investigated the PL and EL from single-crystal Mn-doped ZnS (ZnS Mn) centered at 580 nm. The PL was quenched by surface modification with U-treated poly(vinylferrocene). The effect of pH and temperature on the EL of ZnS Mn in aqueous and butyronitrile solutions upon reduction of per-oxydisulfate ion was also studied. EL of polycrystalline chemical vapor deposited (CVD) ZnS doped with Al, Cu-Al, and Mn was also observed with peaks at 430, 475, and 565 nm, respectively. High EL efficiency, comparable to that of singlecrystal ZnS, was found for the doped CVD polycrystalline ZnS. In all cases, the EL efficiency was about 0.2-0.3%. 

PP-g-MA) silicate nanocomposites and intercalated thermoset silicate nanocomposites for flame-retardant applications were characterised by XRD and TEM [333], XRD, TEM and FTIR were also used in the study of ID CdS nanoparticle-poly(vinyl acetate) nanorod composites prepared by hydrothermal polymerisation and simultaneous sulfidation [334], The CdS nanoparticles were well dispersed in the polymer nanorods. The intercalation of polyaniline (PANI)-DDBSA (dodecylbenzene-sulfonate) into the galleries of organo-montmorillonite (MMT) was confirmed by XRD, and significantly large 4-spacing expansions (13.3-29.6A) were observed for the nanocomposites [335],... 

The cadmium chalcogenide semiconductors (qv) have found numerous applications ranging from rectifiers to photoconductive detectors in smoke alarms. Many Cd compounds, eg, sulfide, tungstate, selenide, telluride, and oxide, are used as phosphors in luminescent screens and scintillation counters. Glass colored with cadmium sulfoselenides is used as a color filter in spectroscopy and has recendy attracted attention as a third-order, nonlinear optical switching material (see NONLINEAR OPTICAL MATERIALS). Dialkylcadmium compounds are polymerization catalysts for production of poly (vinyl chloride) (PVC), poly(vinyl acetate) (PVA), and poly(methyl methacrylate) (PMMA). Mixed with TiCl4, they catalyze the polymerization of ethylene and propylene. 

Acrylic ester polymers Acrylonitrile polymers Cellulose esters). Engineering plastics (qv) such as acetal resins (qv), polyamides (qv), polycarbonate (qv), polyesters (qv), and poly(phenylene sulfide), and advanced materials such as liquid crystal polymers, polysulfone, and polyetheretherketone are used in high performance applications they are processed at higher temperatures than their commodity counterparts (see Polymers containing sulfur). 

In automotive and aerospace end uses, the applications are also often electrical. Polysulfones do not have as good solvent resistance as poly(phenylene sulfide). They perform well in hydrocarbons like gasoline and oil, or in antifreeze, but are attacked by the alcohol-blend fuel mixtures. This may limit their under-the-hood applications. 

The PEEK resin is marketed as neat or filled pellets for injection molding, as powder for coatings, or as preimpregnated fiber sheet and tapes. Applications include parts that are exposed to high temperature, radiation, or aggressive chemical environments. Aerospace and military uses are prominent. At present, polyamideimide (PAI) resin and poly(arylene sulfides) are the main competitors for applications requiring service temperatures of 280°C. At lower temperatures, polyethersulfones, amorphous nylons, and polyetherimides (PEI) can be considered. 

Over the past 20 years a considerable chemical research effort was devoted to developing new high temperature polymers. It is interesting to note that some of these materials are now finding new applications and solutions to old problems of processing through blending. A commercial series of products trade-named Tribolon XT has been announced which are based on an aromatic polymide (Upjohn s 2080) with Phillips poly(phenylene sulfide), trade-named Ryton. A recent publication (88) describes some of the unique characteristics of this new family of materials. 

Arylated and alkylated poly(p-phenylene sulfide) derivatives have been synthesized by the method shown in Eq. (33). Sulfonium ion polymers, such as 217, have potential applications as electronic components and lithographic materials [122]. 

Applications for the Stabaxol stabilizers include thermoplastic polyester urethanes, polyesteramide thermoplastic elastomers, castable polyester urethanes, polyester polyols, monofilament PET fibers, polycarbonates, polycarbonate/PETblends, EVA copolymers and poly(caprolactones). The thermal stabilization of poly(ethylene sulfide) is also accomplished with 4 % hexamethylenebis(t-butyl)carbodiimide and 2 % diphenylacetylene. Also, alternating carbon monoxide/ethylene copolymers are stabilized using aromatic carbodiimides. ... 

Organic photoreceptors can be prepared in either a flexible web or drum format. Webs are usually prepared on polymer substrates, polyethylene tere-phthalate being the most common. The substrates are between 100 to 200 pm in thickness and coated with a conducting surface layer. The substrates often contain layers on the reverse side for reduced curl, static discharge prevention, and control of frictional characteristics. The web configuration is also widely used for laboratory studies. For drums, the substrate is a metal cylinder, usually Al. Recently, however, drums of a poly(phenylene sulfide) resin doped with conductive C black have been developed (Kawata and Hikima, 1996). Drums are widely used in low- and mid-volume applications. Drums, however, are not well suited for research purposes. Thus, the preparation and characterization of drum photoreceptors is usually related to a specific application. 

Some organotin thiolates and sulfides have found industrial application as stabilisers for poly (vinyl chloride). Much of the work on organotin compounds of sulfur has been directed towards this end, and much of it has been published only in the patent literature. 

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