Aromatic Plasticisers

TG-MS couplings are increasingly used by the rubber industry, especially since aromatic plasticisers are toxicologically suspect. Kaisersberger et al. [411] have reported detection of nitrosamine... 

Comparison of Table 5.4 and 5.7 allows the prediction that aromatic oils will be plasticisers for natural rubber, that dibutyl phthalate will plasticise poly(methyl methacrylate), that tritolyl phosphate will plasticise nitrile rubbers, that dibenzyl ether will plasticise poly(vinylidene chloride) and that dimethyl phthalate will plasticise cellulose diacetate. These predictions are found to be correct. What is not predictable is that camphor should be an effective plasticiser for cellulose nitrate. It would seem that this crystalline material, which has to be dispersed into the polymer with the aid of liquids such as ethyl alcohol, is only compatible with the polymer because of some specific interaction between the carbonyl group present in the camphor with some group in the cellulose nitrate. 

Because of the in-chain ring the Tg is as high as -i-35°C and the polymer is therefore not rubbery at usual ambient temperatures. If, however, the polymer is blended with an aromatic oil or certain ester plasticisers a rubbery material is obtained. Because of the ability of the polymer to take up large quantities of oil the Tg of a polymer-oil blend can be as low as -60°C. Such polymer-oil blends can also incorporate very large amounts of filler. 

Chlorinated rubber is soluble in aromatic solvents, and paints made from it dry by solvent evaporation alone. In contrast to the vinyls, there is less difficulty in formulating systems that are suitable for brush application. It has excellent resistance to a wide range of chemicals and to water, but as it is extremely brittle it needs to be plasticised. To preserve chemical resistance it is necessary to use inert plasticisers such as chlorinated paraffin wax. Due to the presence of ozone depleting solvents, chlorinated rubber coatings are being phased out and largely replaced by vinyl acrylic coatings which have very similar performance and can be formulated from lower aromatic or aliphatic solvents. 

Plasticiser/oil in rubber is usually determined by solvent extraction (ISO 1407) and FTIR identification [57] TGA can usually provide good quantifications of plasticiser contents. Antidegradants in rubber compounds may be determined by HS-GC-MS for volatile species (e.g. BHT, IPPD), but usually solvent extraction is required, followed by GC-MS, HPLC, UV or DP-MS analysis. Since cross-linked rubbers are insoluble, more complex extraction procedures must be carried out. The determination of antioxidants in rubbers by means of HPLC and TLC has been reviewed [58], The TLC technique for antidegradants in rubbers is described in ASTM D 3156 and ISO 4645.2 (1984). Direct probe EIMS was also used to analyse antioxidants (hindered phenols and aromatic amines) in rubber extracts [59]. ISO 11089 (1997) deals with the determination of /V-phenyl-/9-naphthylamine and poly-2,2,4-trimethyl-1,2-dihydroquinoline (TMDQ) as well as other generic types of antiozonants such as IV-alkyl-AL-phenyl-p-phenylenediamines (e.g. IPPD and 6PPD) and A-aryl-AL-aryl-p-phenylenediamines (e.g. DPPD), by means of HPLC. 

Aromatic amines formed from the reduction of azo colorants in toy products were analysed by means of HPLC-PDA [703], Drews et al. [704] have applied HPLC/ELSD and UV/VIS detection for quantifying SFE and ASE extracts of butyl stearate finish on various commercial yarns. From the calibrated ELSD response the total extract (finish and polyester trimer) is obtained and from the UV/VIS response the trimer only. Representative SFE-ELSD/UV finish analysis data compare satisfactorily to their corresponding SFE gravimetric weight recovery results. GC, HPLC and SEC are also used for characterisation of low-MW compounds (e.g. curing agents, plasticisers, by-products of curing reactions) in epoxy resin adhesives. 

As the majority of stabilisers has the structure of aromatics, which are UV-active and show a distinct UV spectrum, UV spectrophotometry is a very efficient analytical method for qualitative and quantitative analysis of stabilisers and similar substances in polymers. For UV absorbers, UV detection (before and after chromatographic separation) is an appropriate analytical tool. Haslam et al. [30] have used UV spectroscopy for the quantitative determination of UVAs (methyl salicylate, phenyl salicylate, DHB, stilbene and resorcinol monobenzoate) and plasticisers (DBP) in PMMA and methyl methacrylate-ethyl acrylate copolymers. From the intensity ratio... 

FD-MS is also an effective analytical method for direct analysis of many rubber and plastic additives. Lattimer and Welch [113,114] showed that FD-MS gives excellent molecular ion spectra for a variety of polymer additives, including rubber accelerators (dithiocar-bamates, guanidines, benzothiazyl, and thiuram derivatives), antioxidants (hindered phenols, aromatic amines), p-phcnylenediamine-based antiozonants, processing oils and phthalate plasticisers. Alkylphenol ethoxylate surfactants have been characterised by FD-MS [115]. Jack-son et al. [116] analysed some plastic additives (hindered phenol AOs and benzotriazole UVA) by FD-MS. Reaction products of a p-phenylenediaminc antiozonant and d.v-9-lricoscnc (a model olefin) were assessed by FD-MS [117],... 

Applications Albert et al. [455] have shown continuous-flow SFC-NMR spectra of five plasticisers (DEP, DNPP, DPP, BBP, DNBP). On-flow and stopped-flow pSFC-NMR of synthetic mixtures of phthalates were reported [457]. The feasibility of SFC-NMR coupling has been demonstrated with real-life applications [458]. Figure 7.20 shows a reconstruction of an extraction profile from a PVC tube [152]. The profiles of the integral aromatic proton signals between 7.2 and 8.2 ppm and the ester protons at 4.42 ppm display the relative concentration of the extracted phthalate as a function of the proceeding extraction. The structure of the extracted phthalate could be assigned to DEHP (Figure 7.21). 

Successful combination of a chromatographic procedure for separating and isolating additive components with an on-line method for obtaining the IR spectrum enables detailed compositional and structural information to be obtained in a relatively short time frame, as shown in the case of additives in PP [501], and of a plasticiser (DEHP) and an aromatic phenyl phosphate flame retardant in a PVC fabric [502], RPLC-TSP-FTIR with diffuse reflectance detection has been used for dye analysis [512], The HPLC-separated components were deposited as a series of concentrated spots on a moving tape. HPLC-TSP-FTIR has analysed polystyrene samples [513,514], The LC Transform has also been employed for the identification of a stain in carpet yarn [515] and a contaminant in a multiwire cable [516], HPLC-FTIR can be used to maintain consistency of raw materials or to characterise a performance difference. 

Typically used for the coating of polyester and polyamide substrates with plasticised PVC. Chemically one-component bonding agents (e.g. aromatic polyiso-cyanurate) and two-component bonding agents (e.g. aliphatic polyisocyanate) liquids. 

Assist the widely dissimilar ingredients used in a rubber compound to coalesce and mix into a homogeneous uniform processable mass. Homogenisers are low-MW polymeric resin blends. The homogenising resin blend contains portions that are compatible with aliphatic, naphthenic and aromatic parts of the elastomers in a blend and higher-MW homologues of the plasticisers. They have a wetting effect. Fatty acid derivatives and phenolic resins are used. 

Facilitate pre-vulcanisation processing, increase softness, extensibility and flexibility of the vulcanised end-product. The rubber processing industry consumes large quantities of materials which have a plasticising function complex mixtures (paraffinic, naphthenic, aromatic) of mineral hydrocarbon additives, used with the large tonnage natural and synthetic hydrocarbon rubbers, are termed process oils. Because of the complexity of these products, precise chemical definition is usually not attempted. If the inclusion of an oil results in cost reduction it is functioning as an extender. The term plasticiser is commonly reserved for synthetic liquids used with the polar synthetic rubber. 

Extending oils for compounds crosslinked with peroxides have to be carefully selected. Synthetic ester plasticisers such as phthalates, sebacates and oleates may be used in combination with crosslinking peroxides without affecting the crosslinking reaction. Some derivatives of alkylated benzenes are also known for their very low consumption of free radicals, which is clearly desirable. Mineral oil with double bonds, tertiary carbon atoms or containing heterocyclic aromatic structure may react with radicals paraffinic mineral oils are more effective than naphthenic types, which usually require extra treatment in order to guarantee optimum results when used in peroxide crosslinked blends. 

Little petroleum oil is used in plasticisation of NBR compounds, but generally the aromatic grades are the most compatible. 

The carcinogenicity of polycyclic aromatic compound-rich tyre extender oils has lead to the proposal of a legislative ban on their use in Europe. The suitability of naphthenic oils as non-toxic plasticisers in tyre treads is discussed and results are presented of experimental studies of the use of these plasticisers in SBR, EPDM, sulphur-cured EPDM and peroxide-cured EPDM. Despite their low aromatic content, the naphthenic plasticisers are shown to give good results in SBR, probably as a result of the contribution to solvent characteristics of the naphthenic molecular structure. The use of naphthenic oils is expected to increase worldwide as they are said to be one of the best alternatives to aromatic extracts with regard to solvent properties, compatibility, performance and availability. 

Non-drying oil resins are soluble only in Aromatic hydrocarbons. They are used with amino resins for stoving finishes for appliances. Medium resins are used as plasticisers for cellulose nitrate. Along with natural oils several natural occurring and synthetic acid like resin (abiotic acid) pelargonic acid and isooctanoic acid are added to modify alkye resins. The alkyd resins are obtained by two processes, i.e., (1) Fatty Acid Process and (2) Alcoholysis process. 

Quantitative risk assessments have been performed on a variety of flame-retardants used both in upholstered furniture fabric and foam. The National Research Council performed a quantitative risk assessment on 16 chemicals (or chemical classes) identified by the U.S. Consumer Product Safety Commission (CPSC). The results were published in 2000.88 The 16 flame-retardants included in this NRC study were HBCD, deca-BDE, alumina trihydrate, magnesium hydroxide, zinc borate, calcium and zinc molybdates, antimony trioxide, antimony pentoxide and sodium antimonate, ammonium polyphosphates, phosphonic acid, (3- [hydroxymethyl]amino -3-oxopropyl)-dimethylester, organic phosphonates, tris (monochloropropyl) phosphate, tris (l,3-dichloropropyl-2) phosphate, aromatic phosphate plasticisers, tetrakis (hydroxymethyl) hydronium salts, and chlorinated paraffins. The conclusions of the assessment was that the following flame-retardants can be used on residential furniture with minimal risk, even under worst-case assumptions ... 

The synthesis, physicochemical properties, and characteristics are presented of PVC plasticisers based on pyromellitic tetraesters with a symmetrical and mixed structure respectively. The two alcohols studied were a special aromatic alcohol with a complex structure, such as 2-phenoxy-ethanol and a long branched aliphatic alcohol such as isotridecanol. All showed good thermal resistance, versatile viscosity, and the esters with a mixed structure are shown to have adequate plasticising properties for PVC technology. 21 refs. 

ESTER-TYPE PLASTICISERS FOR PVC, BASED ON SOME AROMATIC CONTENT ALCOHOLS. IX. FUNDAMENTAL PARAMETERS IN DEFINING THE ESSENTIAL PLASTICISER PROPERTIES Mirci L E... 

These additives are essentially high boiling point liquids and so the most appropriate technique to use is liquid chromatography (LC-MS). A range of synthetic plasticisers such as phthalates, adipates, mellitates and sebacates can be detected using the atmospheric pressure chemical ionisation (APCl) mode. Process oils are hydrocarbon mineral oils and require either the atmospheric pressure photoionisation (APPl) head (which can ionise nonpolar species) or, where the oil contains sufficient aromatic character, the use of in-line UV or fluorescence detectors. A fluorescence detector is particularly sensitive in the detection of polyaromatic hydrocarbon (PAH) compounds in such oils. 

Cycloaliphatic and polycyloaliphatic polyamines are finding increasing use as non-toxic replacements. Polycycloaliphatics have shown outstanding mechanical properties, high acid and solvent resistance and similar adhesion compared with standard plasticised aromatic amines (Hunt and Ashcroft, 1994). 

This is similar to PVC, but made from the monomer 1,1-dichloroethylene (CH, = CC I j. It has a specific gravity of 1.67-1.71 and a degree of polymerisation of over 200. The molecular weight of commercial polymers is about 20 0(X). It is often used in the form of a copolymer with vinyl chloride or ethyl acrylate to improve its properties. Coating formulations are plasticised with highly chlorinated aromatics, as common plasticisers are ineffective. 

Coatings, especially PVC, contain plasticisers to render the film coating flexible over a range of utility temperatures. There are a wide variety of plasticisers available in the form of aliphatic and aromatic phthalates, sebacates, ricinoleates, adipates, phosphates, oleates, stearates, pahnitates, lactates andglycollates. Dioctyl phthalate is typically known for its use in PVC coatings. 

Process oils Lightly refined base oils or highly aromatic by-product extracts from oil manufacture are used in various industrial products, e.g. plasticisers in automotive tyres, in printing inks and in mould release oils. 

PA is commercialised in large quantities (especially for use in plasticisers, such as dioctylphthalate and unsaturated polyesters), in high purity form. The aromatic polyester polyols based on PA, due to the purity of the raw materials, are colourless liquids and the process of fabrication, is very reproducible (good consistency). The polyester polyols based on PA and DEG are synthesised in two steps ... 

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