Polymer Phthalate esters

Raw Materials. PVC is inherently a hard and brittle material and very sensitive to heat it thus must be modified with a variety of plasticizers, stabilizers, and other processing aids to form heat-stable flexible or semiflexible products or with lesser amounts of these processing aids for the manufacture of rigid products (see Vinyl polymers, vinyl chloride polymers). Plasticizer levels used to produce the desired softness and flexibihty in a finished product vary between 25 parts per hundred (pph) parts of PVC for flooring products to about 80—100 pph for apparel products (245). Numerous plasticizers (qv) are commercially available for PVC, although dioctyl phthalate (DOP) is by far the most widely used in industrial appHcations due to its excellent properties and low cost. For example, phosphates provide improved flame resistance, adipate esters enhance low temperature flexibihty, polymeric plasticizers such as glycol adipates and azelates improve the migration resistance, and phthalate esters provide compatibiUty and flexibihty (245). 

Plasticizers. Monomeric (mol wt 250—450) plasticizers (qv) are predominantiy phthalate, adipate, sebacate, phosphate, or trimeUitate esters. Organic phthalate esters like dioctyl phthalate (DOP) are by far the most common plasticizers in flexible PVC. Phthalates are good general-purpose plasticizers which impart good physical and low temperature properties but lack permanence in hot or extractive service conditions and are therefore sometimes called migratory plasticizers. Polymeric plasticizers (mol wt up to 5000 or more) offer an improvement in nonmigratory permanence at a sacrifice in cost, low temperature properties, and processibiHty examples are ethylene vinyl acetate or nitrile polymers. 

Plasticizers. Plasticizers are materials that soften and flexibilize inherently rigid, and even britde polymers. Organic esters are widely used as plasticizers in polymers (97,98). These esters include the benzoats, phthalates, terephthalates, and trimeUitates, and aUphatic dibasic acid esters. Eor example, triethylene glycol bis(2-ethylbutyrate) [95-08-9] is a plasticizer for poly(vinyl butyral) [63148-65-2] which is used in laminated safety glass (see Vinyl POLYMERS, poly(vinyl acetals)). Di(2-ethyUiexyl)phthalate [117-81-7] (DOP) is a preeminent plasticizer. Variation of acid and/or alcohol component(s) modifies the efficacy of the resultant ester as a plasticizer. In phthalate plasticizers, molecular sizes of the alcohol moiety can be varied from methyl to tridecyl to control permanence, compatibiUty, and efficiency branched (eg, 2-ethylhexyl, isodecyl) for rapid absorption and fusion linear (C6—Cll) for low temperature flexibiUty and low volatility and aromatic (benzyl) for solvating. Terephthalates are recognized for their migration resistance, and trimeUitates for their low volatility in plasticizer appHcations. 

The activated carbonyl of anhydrides can acylate alcohols or amines at the temperatures necessary for polymer processing. These reactions have been verified by HPLC using the polymer system described in Table 2. An examination of the HPLC chromatograms in Fig. 25 indicates that the phthalic anhydride peak (3.2 min) diminishes with increasing injection-molding temperatures and that two new peaks (4.6 and 6.9 min) increase in intensity. These new peaks corresponded to the half phthalate esters of 1,6-hexanediol and trans-... 

Brandt [200] has extracted tri(nonylphenyl) phosphite (TNPP) from a styrene-butadiene polymer using iso-octane. Brown [211] has reported US extraction of acrylic acid monomer from polyacrylates. Ultrasonication was also shown to be a fast and efficient extraction method for organophosphate ester flame retardants and plasticisers [212]. Greenpeace [213] has recently reported the concentration of phthalate esters in 72 toys (mostly made in China) using shaking and sonication extraction methods. Extraction and analytical procedures were carefully quality controlled. QC procedures and acceptance criteria were based on USEPA method 606 for the analysis of phthalates in water samples [214]. Extraction efficiency was tested by spiking blank matrix and by standard addition to phthalate-containing samples. For removal of fatty acids from the surface of EVA pellets a lmin ultrasonic bath treatment in isopropanol is sufficient [215]. It has been noticed that the experimental ultrasonic extraction conditions are often ill defined and do not allow independent verification. 

RPLC-PDA is frequently used for quality control, such as the determination of free Irganox 1098 in PA4.6 (at 278 nm after dissolution/precipitation), of free Irganox 1010/1076 in PP (at 278 nm after extraction with MTBE, thus avoiding dissolution of polymer waxes), of Luperco 802 in PP (at 218 nm, after extraction with HCC13), and of Tinuvin 122 in HDPE (at 225 nm as diol). The advantages of the use of HSLC over conventional LC in QC of plastics and additives have been demonstrated, e.g. for AOs in PE, mixed phthalate esters and residual terephthalic acid in PET and partially cured epoxy resins [557],... 

More problems are encountered with plasticisers because most extracts from polymer compositions are mixtures and, when separated by TLC, the amount of the individual fractions is often too small for convenient examination by 1H 1-NMR spectroscopy. Moreover, the original plasticisers themselves are often mixtures. For example, tricresyl (tritolyl)phosphate is based on mixed cresols, while most of the higher phthalate esters are based on complex mixtures of alcohols. 

Vinyl polymers [polystyrene, PVC, polyethylene, polypropylene, poly(vinyl acetate), poly(vinyl alcohol), polyacrylonitrile] -1920 Packaging, tubing, household goods, records, carpets, toys, water based paint, adhesives, varnishes Phthalate esters, poly(vinyl alcohol) ... 

Brunelle, D. J. and Serth-Guzzo, J. Titanate-catalyzed ring-opening polymerization of cyclic phthalate ester oligomers, Polym. Prep., 40(1), 566 (1999). 

Phthalate esters are used widely as plasticizers in commercial polymers and plastic endproducts such as PVC. One phthalate classified as a priority pollutant is suspected to be present in three pesticide processes. Dimethyl phthalate is known to be a raw material in two products. 

To determine whether the plasticizer was functioning as solvent, attempts were made to extract the analyte (salicylic acid) with liquid diethyl phthalate. The distribution ratio for this extraction was negligibly small. This finding indicated that the PVC polymer rather than the phthalate ester plasticizer served as the solvent. 

The technique was further improved by employing a polymer coating on the polymeric fibers packed in a fused silica capillary. The coating material was based on GC stationary phases. The polymer-coated fiber-packed capillary was used as the sample loop of the LC injection valve for the extraction of phthalate esters from river water and wastewater.22 The coated-fiber extraction capillaries demonstrated a better extraction efficiency and lower limit of quantification (LOQ) than the uncoated-fiber capillaries. Also, the coated fibers were similarly packed in a PEEK tube, which was used as the injection loop or integrated in the rotor of an LC injection valve employed for the extraction of phthalates. The results clearly showed that an extraction with high selectivity could be established with an appropriate type of polymer coating.23... 

Mori [20] has identified and determined very low levels of phthalate esters in river water using reversed phase high performance liquid chromatography using an ultraviolet detector. Phthalates were extracted with n-hcxanc and the uncleaned or concentrated extracts were injected into three chromatographic systems, these being cross-linked porous beads (Shodex HP-225, Showa Penko Co.), porous polymer beads and polystyrene GPC gel. The eluants were respectively / -hexane (system A) and methanol (system B), and chloroform (system C). 

PCAs (typically medium carbon chain length compounds of 50 - 60 wt% Cl) are also used as secondary plasticizers for polyvinyl chloride (PVC) and in other plastics (polyesters, polyolefins, polystyrene) and rubbers (neoprene). PCAs can partially replace primary plasticizers such as phthalates and phosphate esters [21]. As plasticizers, PCAs lend flame retardancy to the product, unlike phthalate esters [5]. They are added prior to the processing step for the polymer. 

A plasticizer is a material that enhances the processibiIity or flexibility of the polymer with which it is mixed. The plasticizer may be a liquid or solid or another polymer. For example, rigid polyfvinyl chloride) is a hard solid material used to make credit cards, pipe, house siding, and other articles. Mixing with about 50-100 parts by weight of phthalate ester plasticizers converts the polymer into leathery products useful for the manufacture of upholstery, electrical insulation, and other items. Plasticizers in surface coatings enhance the flow and leveling properties of the material during application and reduce the brittleness of the dried film. 

It is often useful to employ so-called secondary plasticizers, which have limited compatibility with the host polymer. Thus, aliphatic diesters are poorly compatible with PVC, but they can be combined with the highly compatible phthalate ester plasticizers to improve low temperature properties of the blend. 

Plasticizers perform this function if a single plasticizer solvates the dissimilar major components of a blend. Phthalate esters help to stabilize mixtures of poly(vinyl chloride) and poly(melhyl methacrylate) for example. These materials are also plasticizers for polystyrene, and stable blends of this polymer with poly(vinyl chloride) can be made by adding dioctyl phthalate to a blend of polystyrene and rigid PVC. 

A number of studies were done to assess thermal stability of aromatic polyesters. Some of these studies describe flash pyrolysis [27-32]. Some studies are dedicated to slow thermal degradation in an inert atmosphere, and others describe the decomposition in specific conditions such as in the presence of humidity or in the presence of catalysts [33]. For example, thermal decomposition of poly(butylene terephthalate) was significantly influenced by the presence of water vapor, and the amount of the residues decrease with increasing the partial pressure of water in the atmosphere [34]. In another study, thermal stability of some small molecule phthalate esters was studied [35]. The results can be used for inferring information on the thermal stability of related polymers. The influence of substitution on the p-carbon atom was evaluated on compounds such as bis(2-aminobutyl) phthalate, bis(2-nitrobutyl) phthalate, bis(2,4-diphenylbutyl) phthalate, and dineopentyl phthalate. Only the phenyl groups were found to improve the heat resistance by the obstruction of the planar configuration necessary for the c/s-elimination and the hindrance of the formation of a six-membered cyclic transition state. 

For propylene polymerization, it has been demonstrated that the chain transfer is dependent not only on regio -but also on stereo -selectivity.412 This is in keeping with the tendency that, with catalyst systems of the type MgC /TiCU/phthalate ester-AlR3-alkoxysilane, the silanes which give the most stereoregular isotactic polymer also give relatively low hydrogen response. 

Most recently, a further family of MgCl2-supported catalysts has been developed in which the internal donor is a succinate rather than a phthalate ester. As is the case with the phthalate-based catalysts, an alkoxysilane is used as external donor. The essential difference between these catalysts is that the succinate-based systems produce polypropylene having much broader molecular weight distribution, discussed below in the section entitled Catalyst/Polymer Relationship. ... 

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