Stability of poly

Table 5. Relative Outdoor Stability of Poly(methyl methacrylate) ...

The presence of catalyst residues, such as alkali hydroxide or alkali acetate, a by-product of the hydrolysis reaction, is known to decrease the thermal stability of poly(vinyl alcohol). Transforming these compounds into mote inert compounds and removal through washing are both methods that have been pursued. The use of mineral acids such as sulfuric acid (258), phosphoric acid (259), and OfXv o-phosphotic acid (260) has been reported as means for achieving increased thermal stability of the resulting poly(vinyl alcohol). 

Photostabilizers, regardless of their mechanism of action, have been added as low molecular weight materials at some point in processing. Subsequently, these stabilizers are often lost in further processing due to their volatility or else later migrate to the surface and evaporate. One method which avoids this modifies the polymer to include the quencher as an additional monomer in the polymerization. This paper will describe some recent efforts in our laboratory to pursue this latter approach in the stabilization of poly(ethylene terephthalate). 

The thermal stability of poly(benzimidazole) is further improved by the introduction of hexafluoroisopropylidene units in the main chain. The DTi0 is 520°C in air and greater than 520°C in nitrogen for the polymer from... 

For example, by using 90 parts of vinyl chloride and 10 parts of vinyl acetate, the random copolymer formed has the toughness of poly (vinyl chloride), thermal stability of poly (vinyl acetate) and solubility akin to poly (vinyl acetate). These combination of properties makes it useful as a paint. 

ISO 305, Plastics - Determination of thermal stability of poly(vinyl chloride), related chlorine-containing homopolymers and copolymers and their compounds - Discoloration method, 1990. 

Capan Y, Woo BH, Gebrekidan S, et al. Stability of poly(L-lysine)-complexed plasmid DNA during mechanical stress and DNase I treatment. Pharm Dev Technol 1999 4(4) 491-498. 

Dixon DD, Ford ME, Mantell GJ (1980) Thermal stabilization of poly(alkylene carbonate)s. J Polym Sci, Part C Polym Lett 18 131-134... 

Liu B, Chen L, Zhang M, Yu A (2002) Degradation and stabilization of poly(propylene carbonate). Macromol Rapid Commun 23 881-884... 

Steric stabilization of poly-l-lysine/DNA complexes by the covalent attachment of semitelechelic poly [A-(2-hydroxypropyl)methacrylamide]. Bioconjugate Chem., 11, 492-501. 

Cherng, J.Y., Talsma, H., Crommelin, D.J.A., Hennink, W.E., (1999). Long term stability of poly((2-dimethylAm.ino)ethyl methacrylate)-based gene delivery systems. Pharm. Res., 16, 1417-1423. 

Cobalt complexes find various applications as additives for polymers. Thus cobalt phthalocyanine acts as a smoke retardant for styrene polymers,31 and the same effect in poly(vinyl chloride) is achieved with Co(acac)2, Co(acac)3, Co203 and CoC03.5 Co(acac)2 in presence of triphenyl phosphite or tri(4-methyl-6- f-butylphenyl) phosphite has been found to act as an antioxidant for polyenes.29 Both cobalt acetate and cobalt naphthenate stabilize polyesters against degradation,73 and the cobalt complex of the benzoic acid derivative (12) (see Section 66.4) acts as an antioxidant for butadiene polymers.46 Stabilization of poly(vinyl chloride)-polybutadiene rubber blends against UV light is provided by cobalt dicyclohexyldithiophosphinate (19).74 Here again, the precise structure does not appear to be known. 

CdO is used in connection with the stabilization of poly(vinyl chloride). This is discussed below in more detail. It also finds application in modifying the thermal properties of teflon and some rubbers. CdS is used in some smoke detectors, in lasers and in phosphors. The cadmium(II) halides are important as catalysts and are also used in pyrotechnics. Cadmium borates of the general type (Cd0)x(B203), are also used as phosphors. CdS04 is employed in the Weston cell, which is important as a voltage standard.137... 

Thermal Stabilization of Poly(vinyl chloride) through Graft Copolymerization of cw-1,4-Polybutadiene... 

The thermal stability of poly(vinyl chloride) is improved greatly by the in situ polymerization of butadiene or by reaction with preformed cis-1,4-polybutadiene using a diethyl-aluminum chloride-cobalt compound catalyst system. The improved thermal stability at 3-10% add-on is manifested by greatly reduced discoloration when the modified poly-(vinyl chloride) is compression molded at 200°C in air in the absence of a stabilizer, hydrogen chloride evolution at 180°C is retarded, and the temperature for the onset of HCl evolution and the peak decomposition temperature (DTA) increase, i.e. 260°-280°C and 290°-325° C, respectively, compared with 240°-260°C and 260°-280°C for the unmodified homopolymer, in the absence of stabilizer. The grafting reaction may be carried out on suspension, emulsion, or bulk polymerized poly(vinyl chloride) with little or no change in the glass transition temperature. 

Chevassus, F., DeBroutelles, R., The Stabilization of Poly (vinyl chlo-... 

Steric stabilization of poly(2-ethyl hexyl acrylate) (PEHA) emulsions in C02 was studied with static and dynamic light scattering (DLS) (O Neill et al., 1997 Yates et al., 1997). These emulsions were stabilized with PFOA-based surfactants. Figure 8.9 shows the average droplet size (hydrodynamic radius) measured by DLS for a liquid PEHA emulsion in C02 stabilized... 

Kwoh DY, Coffin CC, Lollo CP et al (1999) Stabilization of poly-L-lysine/DNA polyplexes for in vivo gene delivery to the liver. Biochim Biophys Acta 1444(2) 171-190... 

Fluorinated carbocations play an important role as intermediates in electrophilic reactions of fluoroolefins and other unsaturated compounds. For example, F-allyl cation 1 was proposed as a reactive intermediate in reactions of HFP with fluoroolefins catalyzed by Lewis acids [7]. The difference in stability of the corresponding allylic cations was suggested as the explanation for regio-specific electrophilic conjugated addition to CF2=CC1CF=CF2 [11]. Allylic polyfluorinated carbocations were proposed as intermediates in the reactions of terminal allenes with HF [53] and BF3 [54], ring-opening reactions of cyclopropanes [55], Carbocations are also an important part of the classic mechanism of electrophilic addition to olefins (see Eq. 2). This section deals with the questions of existence and stability of poly- and perfluorinated carbocations. 

Auschra C, Stadler R (1993) Thermal-stability of poly(styrene-b-methyl methacrylate) and poly(styrene-b-ethylene-co-l-butene-b-methyl methacrylate) - a gel-permation. Polym Bull 30 305-311... 

The stability of poly(ethylene oxide)-functionalized SAMs under different storage conditions such as in air, under nitrogen, water, phosphate-buffered saline, and... 

Cyclic voltammetry is also an ideal analytical tool for assessing the electrochemical stability of the polymer films. This is a fundamental requirement for any conducting polymer to be considered for long-term use in electrochemical devices. The use of ionic liquids for the electrochemical cycling of poly(aniline) has been reported to enhance lifetimes to over a million cycles [12], and significant improvements in the cycling stability of poly(pyrrole) have also been reported [32]. 

It should be noted that PCMU based on cross-linked macroligands possess a relatively high chemical and thermal stability. The stability of poly(enol-ketonate) chelates obtained by oxidation of thin polyvinylacetate films increases in the series of mono-, di- and trivalent ions [122], the oxidation promoting the penetration of the metal ions into the deep film layers. The weight loss of Co and Mn polychelates based on the condensation products of stoichiometric amounts of 5,5 -methylene-bis-salicylaldehyde and 4,4 -diaminophenyl ether at 300, 500, and 600 °C is 2.1, and 0.5 8.0 and 9.8 25.0 and 27.5%, respectively [14b]. The stability, in the range between 275 and 640 °C, of chelates formed by the transition metals and condensation products of p-hydroxybenzoic acid, urea and formaldehyde follow the series [123] Fe(III)>Co(II)>Cu(II)>Ni(II)>V02(II)> Zn(II) Mn(II) > CML. 

Journal of Applied Polymer Science 19, No.11, 14th March 2001, p.2029-37 SYNERGETIC EFFECT OF DIMERIZED PENTAERYTHRITOL ESTERS WITH SYNERGETIC METAL SOAP ON THE STABILIZATION OF POLY(VINYL CHLORIDE) Ikeda H Goto H Higaki Y Sunami M NakanO K Nakamura Y Iida T... 

Philadelphia, Pa., llth-12th Oct.2000, p.97-103 MECHANISM OF ORGANOTIN STABILIZATION OF POLY(VINYL CHLORIDE) 5. MECHANISM OF PVC STABILIZATION BY STANNIC COMPOUNDS Fisch M H Bacaloglu R Dooley T Diaconescu C Crompton Corp. 

TABLE 1. Physical and oxidative stability of poly(silarylene-siloxane-acetylene) elastomers after isothermal curing. 

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. ... 

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