Plasticisation, chemical

N. A. J. Plat2er, Plasticicyation and Plasticiser Processes, American Chemical Society, Washington, D.C., 1965. 

Nitration of cellulose followed by plasticisation of the product with camphor has the effect of reducing the orderly close packing of the cellulose molecules. Hence whereas cellulose is insoluble in solvents, except in certain cases where there is chemical reaction, celluloid is soluble in solvents such as acetone and amyl acetate. In addition the camphor present may be dissolved out by chloroform and similar solvents which do not dissolve the cellulose nitrate. 

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

Compared with the phenolics and polyesters the resins have better heat resistance, better chemical resistance, particularly to alkalis, greater hardness and better water resistance. In these respects they are similar to, and often slightly superior to, the epoxide resins. Unlike the epoxides they have a poor adhesion to wood and metal, this being somewhat improved by incorporating plasticisers such as poly(vinyl acetate) and poly(vinyl formal) but with a consequent reduction in chemical resistance. The cured resins are black in colour. 

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. 

It is essential to appreciate that such plasticisers will considerably modify the chemical properties of the plastics material since the plasticiser may be readily extracted by certain chemicals and chemically attacked by others whilst the base polymer may be unaffected. 

Physico chemical factors Chemical attack, physical changes such as plasticiser bleed... 

The European consumption of plasticisers (as the main modifier) is gradually increasing, as shown in Table 1.7, with an expected growth of 2.7% for 2001-2006. The total European market for flame-retardant chemicals (percent of revenues by product type - forecast for the year 2003) is as follows ... 

Chemical analysis of rubber (specific gravity extract, filler, CB, polymer and sulfur analysis antidegradant and plasticiser analysis)... 

The main features of PC are low cost, need for small sample amount, high level of resolution, ease of detection and quantitation, simplicity of apparatus and use, difficult reproducibility (because of variation in fibres) and susceptibility to chemical attack. Identification of the separated components is facilitated by the reproducible Rj values. Detection methods in PC have been reviewed [368]. Fluorescence has been used for many years as a means of locating the components of a mixture separated by PC or TLC. However, also ATR-IR and SERS are useful. Preparative PC is unsuitable for trace analysis because filter paper inevitably contains contaminants (e.g. phthalate esters, plasticisers) [369]. For that purpose an acceptable substitute is glass-fibre paper [28]. 

The TLC process is an off-line process. A number of samples are chromatographed simultaneously, side-by-side. HPTLC is fast (5 min), allows simultaneous separation and can be carried out with the same carrier materials as HPLC. Silica gel and chemically bonded silica gel sorbents are used predominantly in HPTLC other stationary phases are cellulose-based [393]. Separation mechanisms are either NPC (normal-phase chromatography), RPC (reversed-phase chromatography) or IEC (ion-exchange chromatography). RPC on hydrophobic layers is not as widely used in TLC as it is in column chromatography. The resolution capabilities of TLC using silica gel absorbent as compared to C S reversed-phase absorbent have been compared for 18 commercially available plasticisers, and 52 amine and 36 phenolic AOs [394]. 

IMS can be used for chemical analysis of vapours from electronics packaging [287]. IMS-QMS has been used to analyse headspace vapours in sealed electronic packages [275,288] and to follow outgassing of polymers [287]. Various types of photoresist solvents, phtha-late plasticisers and other polymer additives, such as BHT, were detected. Other applications of IMS in semiconductor technology involve failure analysis control of the efficiency of cleaning and etching steps characterisation of process media and surveillance of the atmosphere of clean rooms. 

Whereas the use of conventional fast atom bombardment (FAB) in the analysis of polymer/additive extracts has been reported (see Section 6.2.4), the need for a glycerol (or other polar) matrix might render FAB-MS analysis of a dissolved polymer/additive system rather unattractive (high chemical background, high level of matrix-, solvent- and polymer-related ions, complicated spectra). Yet, in selected cases the method has proved quite successful. Lay and Miller [53] have developed an alternative method to the use of sample extraction, cleanup, followed by GC in the quantitative analysis of PVC/DEHP with plasticiser levels as typically found in consumer products (ca. 30 %). The method relied on addition of the internal standard didecylphthalate (DDP) to a THF solution of the PVC sample with FAB-MS quantitation based on the relative signal levels of the [MH]+ ions of DEHP and DDP obtained from full-scan spectra, and on the use of a calibration curve (intensity ratio m/z 391/447 vs. mg DEHP/mg DDP). No FAB-matrix was added. No ions associated with the bulk of the PVC polymer were observed. It was... 

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. 

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. 

The rapid movement in the global phthalates market away from using plasticisers 2-ethylhexanol (2-EH) and diethylhexyl phthalate (DEHP) in favour of alternative products was underscored recently when BASF revealed plans to close its 2-EH and DEHP plants in Germany. The restructuring in Europe will have no effect on BASF s plasticiser portfolio in Nafta and Asia, however, where the company will continue to offer 2-EH and DEHP. About 70% of the plasticiser maiket volume is phthalates, and plasticisers make up about 60% of the plastic additives maiket. PVC accounts for 80-90% of global plasticiser consumption. In October 2003, California added DEHP to the state s list of more than 750 chemicals known to cause birth defects or reproductive harm. Previous studies had shown that the chemical can leach from plastic bags that contain intravenous fluids, blood, tube feedings or other medical treatment, and thereby enter the bodies of patients. 

A decision by the European Parliament to put restrictions on the use of six phthalate plasticisers ignores scientific risk assessments and threatens the basis for Reach, the impending European legislation on chemical strategy. The Strasbourg parliament has voted to ban DEHP, DBP and BBP in children s toys and childcare items. DINP, DIDP and DNOP will be banned from use if the toys or items can be put in the mouth by children. An EU scientific risk assessment said children were not at risk from DINP in toys. A similar study in the US by the Consumer Product Safety Commission reached the same conclusion. European Commission... 

For some time now plasticisers, especially phthalates, have been under pressure from environmentalists and regulatory bodies. In the regulatory arena there is the RCRAand CERCL A requirements of the EPA, Proposition 65 in California and the EU labelling requirements of chemicals. Taking this into account, as well as customer demand for alternative plasticisers, BASF has undertaken a project to develop a plasticiser suitable in a wide range of applications and which would meet the following... 

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