Ester Plasticisers

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 extensively employed in industrial corrosion-resistant surface coatings, for which purpose it is marketed by ICI under the trade name Alloprene. Although thermoplastic moulding compositions have been made by plasticising with the common ester plasticisers such as tritolyl phosphate they are of no commercial importance. 

Copper alloys are particularly prone to attack by long-chain fatty acids which are often present in sealing compositions, temporary protectives and as trace additives in many plastics under acid conditions ester plasticisers may saponify in the presence of copper giving rapid corrosion of the copper and accelerating degradation of the polymer. 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

SPE has been applied to phthalate esters (plasticisers in PVC), polar pesticides (agricultural usage) and for other continuous pollution monitoring problems and environmental analyses [272]. For these applications SPE has largely displaced LLE as the preferred technique for the preparation of liquid samples, e.g. EPA method 506 is concerned with the determination of phthalates and adipate esters in drinking water. 

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]. 

Brown D, Croudance CP, Williams NJ, Shearing JM, Johnson PA (1998) The effect of phthalate ester plasticisers tested as surfactant stabilized dispersions on the reproduction of the Daphnia Magna. Chemosphere 36 1367-1379... 

Organic compounds derived by replacing the hydrogen of an acid by an organic radical or group. Examples of ester plasticisers are tritolyl phosphate, dioctyl phthalate and dioctyl sebacate. ETAD... 

Triethylene glycol dicaprylate/caprate, ester plasticiser. 

The low temperature properties of nitriles can be improved by the use of suitable plasticisers, e.g., ester plasticisers. 

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. 

PVC-U formulations have low flammability due to the chlorine content. The addition of plasticiser in PVC-P formulations necessitates the use of flame retardant and smoke suppressant additives. These additives are known as functional fillers and a correct balance is necessary to achieve all the end-use specification requirements. They are predominately used in cable, conveyer belting and roofing membrane formulations to give resistance to fire initiation and propagation. It is also important to reduce dripping in a fire situation and that as little smoke as possible is generated. Antimony trioxide has been used extensively, usually in combination with phosphate ester plasticisers, giving excellent fire performance and mechanical properties. 

Zinc borate is also an effective SS in combination with phosphate ester plasticiser (130). The combination of ammonium octamolybdate and zinc stannate is also beneficial (435). It has been shown that ATH and MDH functional fillers coated with zinc hydroxystannate give significantly increased combustion resistance and lower levels of smoke evolution (386). Copper (I) complexes have been suggested as smoke suppressants (241). Copper oxides have also been investigated with positive results (60). 

The results are reported of studies on PVC formulations, which show that lead-free, heat stable, flexible PVC compounds can be prepared through the proper selection of calcium/zinc stabilisers combined with selected costabilisers, fillers and other additives. The preparation of PVC insulation and sheathing compounds having oxygen index values greater than 30% using a combination of Firebrake ZB zinc borate and a phosphate ester plasticiser is also demonstrated. 6 refs. 

The influence of dicarboxylic acid ester plasticisers on the thermal degradation of PVC significantly depends on the physical state of the PVC-plasticiser system. If PVC retains the structure formed in the stage of suspension polymerisation, the additive produces inhibition of the process of thermal dehydrochlorination. In the case of true diluted PVC solutions in ester plasticisers, the polymer exhibits accelerated degradation, in accordance with a high value of the solvent basicity. 7 refs. 

On the other hand, there are also studies showing the effects of UV irradiation on the change of migration characteristics of the matrix polymer, (i.e., effect on the migration of phthalate ester plasticisers from clear PET water bottles [87]), and some data are provided on the effects of ionising irradiation on polymer additives, monomers and polymers themselves in general [88]. 

The use of Rheofos 90, a phosphate ester plasticiser, as part of the formulation improves the flame retardancy even more. Firebrake ZB can replace antimony trioxide in flexible PVC formulations to improve smoke performance while maintaining good Are performance and good heat stability characteristics. 

Many ordinary ester plasticisers reduce the flame resistance of PVC, but the aryl phosphates are helpful, being flame retardant. 

PVC applications of polymeric ester plasticisers include food wrap, calendered sheet, electrical tape, industrial gloves, protective clothing and roofing materials. Polymeric ester plasticisers are biodegradable, and short life products can be made that degrade in around four weeks under the right conditions. 

---