Heat stabilizers antioxidants

The stabilizers chosen for evaluation include different types of heat and light stabilizers selected to represent different mechanisms of action as well as chemical compositions (ArJi). Types of stabilizers evaluated include benzotriazole and benzophenone light stabilizers [ultraviolet (UV) light absorbers], hindered amine light stabilizers (HALS, catalytic radical scavengers), hindered phenol heat stabilizers (antioxidant radical scavengers), and thioester heat stabilizers (antioxidant hydroperoxide decomposers). 

In the polymer engineering we call compounds those intimate solid mixtures in which the technical polymer material for a specific application contains all the necessary additives -e.g. plasticizers, lubricants, impact modifiers, heat stabilizers, antioxidants, flame retardants, colorants, etc. — making the material suitable for the given task. A typical PVC compound e g. for a window profile, consists of 8 - 10 components [4],... 

Irgafos . [Ciba-Geigy/Additives] Phosphite heat stabilizer, antioxidant for polyolefins. 

The combination of poly(arylene ether) (PAE) resins with PAs into com-patibilized blends results in improved overall properties, such as chemical resistance and high strength. The properties of these blends can be further enhanced by the addition of various additives, such as impact modifiers, flame retardants, light stabilizers, processing stabilizers, heat stabilizers, antioxidants and fillers. 

Synonyms Phenyididecyl phosphite Empirical C26H47O3P Formula C6H50P(OCioH2i)2 Properties Nearly water-wh. liq. alcoholic odor m.w. 438.64 dens. 0.940 (25/15.5 C) m.p. 0 C flash pt. (COC) 218 C ref. index 1.4785 Precaution Combustible Uses Heat stabilizer, antioxidant for resin systems, esp. PVC chemical intermediate lubricant, processing aid for PVC Manuf./Distrib. Akcros Am. http //www.akcros.com, GE Spec. http //www.ge.com/specialtychemicals Trade Name Synonyms Mark DDMPP t[Crompton/Witco Vinyl Addit.] Stavinor DDPP [Ceca SA http //www.ceca.fr]... 

TPO materials are defined as compounds (mixtures) of various polyolefin polymers, semicrystalline thermoplastics, and amorphous elastomers. Most TPOs are composed of polypropylene and a copolymer of ethylene and propylene called ethylene—propylene rubber (EPR) [2]. A common rubber of this type is called ethylene propylene diene monomer rubber (EPDM), which has a small amount of a third monomer, a diene (two carbon-carbon double bonds in it). The diene monomer leaves a small amount of unsaturation in the polymer chain that can be used for sulfur cross-linking. Like most TPEs, TPO products are composed of hard and soft segments. TPO compounds include fillers, reinforcements, lubricants, heat stabilizers, antioxidants, UV stabilizers, colorants, and processing aids. They are characterized by high impact strength, low density, and good chemical resistance they are used when durability and reliability are primary concerns. 

Formulation of cellulose esters is required to reduce charring and thermal discoloration, and typically includes the addition of heat stabilizers, antioxidants, plasticizers, UV stabilizers, and coloring agents Cellulose molecules are rigid due to the strong intermo-... 

Plastics are compounds made up of resins (polymers) and additives. Additives, which are used to obtain specific effects in the plastic material during fabrication or use, expedite processing, heighten certain properties, provide color, and furnish the needed protection during fabrication and use. Some of the key additives used in thermoplastic piping are heat stabilizers, antioxidants, ultraviolet saeens, lubricants, pigments, property modifiers, and fillers. Table 2.1 lists some of the main additives used in plastic piping materials and their purpose. 

Cost bilizers. In most cases the alkyl tin stabilizets ate particularly efficient heat stabilizers for PVC without the addition of costabilizers. Many of the traditional coadditives, such as antioxidants, epoxy compounds, and phosphites, used with the mixed metal stabilizer systems, afford only minimal benefits when used with the alkyl tin mercaptides. Mercaptans are quite effective costabilizets for some of the alkyl tin mercaptides, particularly those based on mercaptoethyl ester technology (23). Combinations of mercaptan and alkyl tin mercaptide ate currendy the most efficient stabilizers for PVC extmsion processes. The level of tin metal in the stabilizer composition can be reduced by up to 50% while maintaining equivalent performance. Figure 2 shows the two-roU mill performance of some methyl tin stabilizers in a PVC pipe formulation as a function of the tin content and the mercaptide groups at 200°C. 

The metal coordination complexes of both sahcylaldehyde phenyhiydrazone (91) and sahcylaldoxime provide antioxidant (92) protection and uv stabihty to polyolefins (see Antioxidants). In addition, the imines resulting from the reaction of sahcylaldehyde and aromatic amines, eg, p- am in oph en o1 or a-naphthylamine, can be used at very low levels as heat stabiLizers (qv) in polyolefins (93). 

The phosphonate esters, HP(=0(OR)2, of alkylated phenols are used extensively as lubricating-oil additives to control bearing corrosion and oxidation, and to impart antimst properties as stabilizers, as antioxidants (qv) and flame retardants in plastics, as specialty solvents, and as intermediates (see Corrosion AND corrosion control Heat stabilizers). 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Polymers. In combination with various metal salts, sorbitol is used as a stabilizer against heat and light in poly(vinyl chloride) (qv) resins and, with a phenohc antioxidant, as a stabilizer in uncured styrene—butadiene mbber (qv) compositions and in polyolefins (see Heat stabilizers Olefin POLYMERS Rubbercompounding). Heat-sealable films are prepared from a dispersion of sorbitol and starch in water (255). Incorporation of sorbitol in coUagen films gready restricts their permeabiUty to carbon dioxide (256). 

Irg 1076, AO-3 (CB), are used in combination with metal dithiolates, e.g., NiDEC, AO-30 (PD), due to the sensitized photoxidation of dithiolates by the oxidation products of phenols, particularly stilbenequinones (SQ, see reaction 9C) (Table 3). Hindered piperidines exhibit a complex behavior when present in combination with other antioxidants and stabilizers they have to be oxidized initially to the corresponding nitroxyl radical before becoming effective. Consequently, both CB-D and PD antioxidants, which remove alkyl peroxyl radicals and hydroperoxides, respectively, antagonise the UV stabilizing action of this class of compounds (e.g.. Table 3, NiDEC 4- Tin 770). However, since the hindered piperidines themselves are neither melt- nor heat-stabilizers for polymers, they have to be used with conventional antioxidants and stabilizers. 

Many additives are used with PVC polymers such as plasticizers, antioxidants, and impact modifiers. Heat stabilizers, which are particularly important with PVC resins, extend the useful life of the finished product. Plastic additives have been reviewed by Ainsworth. 

Acid-treated clay catalyst Engelhard F-24 was found to be very effective for the alkylation of diphenylamine (DPA) with an olefin such as a-methyl styrene (AMS) to obtain a mixture of mono and dialkylated diphenylamines (Chitnis and Sharma, 1995). For example, alkylation of DPA with AMS produced a mixture of 4-(a,a-dimethyl benzyl) diphenylamine, i.e. monocumyl-diphenylamine (MCDPA) and 4,4 -bis(a,a-dimethylbenzyl) diphenylamine, i.e. dicumyldiphenylamine (DCDPA) (Eqn.(l 1)). The dialkylated diphenylamine, i.e. DCDPA, is indu.strially important as an antioxidant and heat stabilizer. DCDPA is reported to be an ideal antioxidant for many materials like polyethylene, polypropylene, polyether polyol, polyacetals, nylon 6, synthetic lubricants, hot melt adhesives, etc. 

The plasticizer-range alcohols are largely used as feedstock for production of high molecular weight diesters of phthalic, adipic, azelaic, and sulftiric acids. All these are used primarily in plasticizers for polyvinyl chloride (PVC) and other plastics. The plastics industry also uses them as additives for heat stabilization, to control the viscosity of PVC plastisols, ultraviolet absorbers, flame retardants, and antioxidants. They are also found in synthetic, lubricants, agricultural chemicals, and defoamers. 

The effects of release additives on bulk properties must also be carefully considered, particularly with integral additives to plastics. For example, partial solubility usually confers some plasticizing effect. This may improve impact strength but could reduce the heat distortion temperature. Some release additives such as metallic soaps have secondary antioxidant and heat-stabilizer benefits. Such effects are exploited in multipurpose formulations. 

Other contaminants that can originate from plastic containers are the additives necessary to turn the raw polymer into adequate containers. While PE may be used without any additive, the other plastics are virtually useless alone but are converted into highly serviceable products by combining them with other substances or materials. The additives most commonly found in plastics used for pharmaceutical products are antioxidants, heat stabilizers, lubricants, plasticizers, fillers, and colorants. These additives can be in liquid, solid, or fine particle forms and are used in amounts varying from less than 1% to more than 50% of the plastic mass. The additives necessary for each of the selected types of polymers are described in Table 23. 

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