Stabilizers for polymers

Tetraorganotins Used in manufacture of R nX compounds from SnCI4 catalysts for olefin polymers stabilizers for transformer oils corrosion inhibitor in lubricating oils (CEC 1978 WHO 1980 Davies and Smith 1982)... 

Polymer stabilization is another area in which the peroxide-decomposing and chain-breaking antioxidant properties of diorganotellurides has found utUity. Alone or in combination with phenol and phosphate antioxidants, electron-rich dialkylamino-substirnted diaryltellurides and alkylaryltellurides provided greatly enhanced polymer stability for a thermoplastic elastomer and for polypropylene. The effects were unique to the tellurides, with selenides not providing similar protective effects. ... 

Each sample was evaluated by thermogravimetry to determine if the thermal stability could be enhanced by removing some residual cobalt chloride. The BTDA-ODA polyimide film thermal stability is reduced about 50 C due to the cobalt chloride dopant. Soa)cing or extraction with water has no positive effect on the thermal stability whereas soxhlett extraction with DMAc severely degrades the polymer stability. For the BDSDA-ODA polyimide films the incorporation of cobalt chloride also reduces the bul)c polymer thermal stability. Soa)cing this film in water for 24 hours, however, increased the bul)c thermal stability slightly from 512 to 532 C. 

The pace of development is accelerating in supercritical chemistry. Increasing numbers of chemists are being attracted to the field and new reactions and applications are being reported all the time. Two particularly exciting developments have been in the control of reactions and in the development of new polymer stabilizers for CO2. 

Use Intermediate for various polymers, stabilizer for chlorinated solvents. 

PolygeL [3-V Sigma Prodotd Qumici] ( toxyvinyl polymers stabilizers for plastic additives, detergents, car waxes and polishes, scouting creams. 

Diarylarnines are of the greatest industrial importance as stabilizers and antioxidants (qv) for polymers, stabilizers for explosives, polymerization inhibitors, and in dyes. Today, the use of these materials as antioxidants is essentially limited to derivatives of diphenylamine since AJ-phen5i-2-naphth5iamine is no longer used. 

Precursors, Reducing Agents, and Polymer Stabilizers for Ag Cluster Synthesis... 

Gerald Scott is Professor Emeritus in Chemistry at Aston University, Birmingham, Professor Scott left industry in 1967, after 15 years in polymer research, to accept the Chair of Chemistry at Aston. During his years there, he developed an internationally renowned research group concerned with the oxidative deterioration and stabilization of polymers. More recently, a major research interest has been the disposal of polymeric materials by recycling and induced biodegradation. Professor Scott has published some 300 scientific papers, mainly in the field of polymer stabilization, for which he was awarded a DSc, of Oxford University in 1983, His expertise in the area of polymer degradation has also resulted in a number of international patents for his work. 

Polymer stabilizers for the plastics, mbber and polymer industries, supplier product guide. RT. Vanderbilt Company, Inc. 2007. 

Uses Antioxidant for PE, PR ABS, NR, synthetics, latexes, adhesives, oils for fiber finishes, food-grade polymers stabilizer for syn. polymers, resins, inks stabilizer, antigellant for drying oils antioxidant, stabilizer for paper coatings, photographic coatings, thermal fax paper food pkg. adhesives, coatings, mbber articles... 

Whilst a great deal of research has been carried out to study the interactions of particles featuring adsorbed polymer chains, especially with respect to the chemistry and conformation of the polymer chains, the dependence of these interactions on the size of the involved particles is an aspect that has not so much been in the focus of research activities. Whereas the particle interaction is relatively independent of the particle size for larger colloids, for particles smaller than 100 mn in size, this is no longer true [29]. The thickness of the adlayer formed by common polymer stabilizers for such particles starts to become considerable... 

Formaldehyde homopolymer is composed exclusively of repeating oxymethylene units and is described by the term poly oxymethylene (POM) [9002-81-7]. Commercially significant copolymers, for example [95327-43-8] have a minor fraction (typically less than 5 mol %) of alkyUdene or other units, derived from cycHc ethers or cycHc formals, distributed along the polymer chain. The occasional break in the oxymethylene sequences has significant ramifications for polymer stabilization. 

Acryhc acid and esters are stabilized with minimum amounts of inhibitors consistent with stabihty and safety. The acryhc monomers must be stable and there should be no polymer formation for prolonged periods with normal storage and shipping (4,106). The monomethyl ether of hydroquinone (MEHQ) is frequentiy used as inhibitor and low inhibitor grades of the acrylate monomers are available for bulk handling. MEHQ at 10—15 ppm is generally... 

Chemical Stabilization Processes. This method is more versatile and thus has been used successfully for more materials than the physical stabilization process. Chemical stabilization is more adaptable for condensation polymers than for vinyl polymers because of the fast yet controUable curing reactions and the absence of atmospheric inhibition. 

The discussion centers on heat stabilizers for PVC because this polymer is the most important class of halogenated polymers requiring these chemical additives. PVC of ideal chemical stmcture (1) should be a relatively stable compound as predicted from model studies using 2,4,6-trichloroheptane [13049-21-3] (2) (1). 

Additioaal uses for higher olefias iaclude the productioa of epoxides for subsequeat coaversioa iato surface-active ageats, alkylatioa of benzene to produce drag-flow reducers, alkylation of phenol to produce antioxidants, oligomeriza tion to produce synthetic waxes (qv), and the production of linear mercaptans for use in agricultural chemicals and polymer stabilizers. Aluminum alkyls can be produced from a-olefias either by direct hydroalumination or by transalkylation. In addition, a number of heavy olefin streams and olefin or paraffin streams have been sulfated or sulfonated and used in the leather (qv) iadustry. 

Sesamex [51-14-9] (Sesoxane) (30) is a synergist oflow toxicity, acute oral LD q (rat) = 2000 2270 mg/kg, for pyrethrins and allethrin. 6,7-Dihydroxy 4-methylcoumarin has been offered as an antioxidant for phenoHcs and polymers, and as an anthelmintic. 2,4,5-Trihydroxybutyrophenone has been available as an antioxidant and light stabilizer for polyolefins, waxes, and foods. Isoflavones, eg (31), have been patented as components of antioxidant compositions for foods and cosmetics (qv) (97). 

Although examples in the Kureha patent Hterature indicate latitude in selecting hold times for the low and high temperature polymerization periods, the highest molecular weight polymers seem to be obtained for long polymerization times. The addition of water to PPS polymerizations has been reported to effect polymer stabilization (49), to improve molecular weight (50,51), to cause or enhance the formation of a second Hquid phase in the reaction mixture (52), and to help reprecipitate PPS from NMP solution (51). It has also been reported that water can be added under pressure in the form of steam (53). 

Diazo Coupling Reactions. Alkylphenols undergo a coupling reaction with dia2onium salts which is the basis for the preparation of a class of uv light stabilizers for polymers. The interaction of orxv i -nitrobenzenediazonium chloride with 2,4-di-/ r2 -butylphenol results in an azo-coupled product (30). Reduction of the nitro group followed by m situ cyclization affords the benzottiazole (31) (19). 

Many antioxidants ia these classes are volatile to some extent at elevated temperatures and almost all antioxidants are readily extracted from their vulcanizates by the proper solvent. These disadvantages have become more pronounced as performance requirements for mbber products have been iacreased. Higher operating temperatures and the need for improved oxidation resistance under conditions of repeated extraction have accelerated the search for new techniques for polymer stabilization. Carpet backiag, seals, gaskets, and hose are some examples where high temperatures and/or solvent extraction can combine to deplete a mbber product of its antioxidant and thus lead to its oxidative deterioration faster (38,40). 

Minor and potential new uses include flue-gas desulfurization (44,45), silver-cleaning formulations (46), thermal-energy storage (47), cyanide antidote (48), cement additive (49), aluminum-etching solutions (50), removal of nitrogen dioxide from flue gas (51), concrete-set accelerator (52), stabilizer for acrylamide polymers (53), extreme pressure additives for lubricants (54), multiple-use heating pads (55), in soap and shampoo compositions (56), and as a flame retardant in polycarbonate compositions (57). Moreover, precious metals can be recovered from difficult ores using thiosulfates (58). Use of thiosulfates avoids the environmentally hazardous cyanides. 

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