Identification and assessment of alternatives to selected phthalates

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ates distance between the freely organised polymer chain parts, and shields the
attraction forces between polar parts of the chain, and thereby weakens the
attraction between the chain parts. This allows for more free movement
amongst the weakly bound chain parts, which means that the material becomes
flexible.
The properties of the plasticiser have immense influence of how well it plasticises
the polymer, and on the performance characteristics of the plasticised
material. It is however important to understand that the plasticiser (with a few
exceptions) does not form specific chemical bonds with the polymer, and
there is therefore in principle a flexibility in which type and configuration of
plasticisers that actually can be used to obtain the desired plasticising performance
characteristics.
External plasticisers may be separated from the PVC matrix due to extraction
by solvents, oils, water, surface rubbing, volatility, migration into adjacent
media, or degradation mechanisms.
Structure of some plasticiser families
As mentioned, many families of plasticisers are available. Most of them have
however certain chemical functionalities in common with the phthalates family.
This can be seen in Figure 3.1, which shows representatives of some different
plasticiser families. They are typically branched, quite "voluminous"
molecules, with many oxygen bonds (= carbonyl groups). Many have benzyl
rings or the hydrogenated counterpart, cyclohexane.
Even so, many similar plasticisers have distinctly different impacts on health
and environment, and are therefore relevant alternatives to phthalates. This is
probably primarily due to the fact that many types of interactions with biological
systems are substance specific, and even shape-specific (structurally
specific), meaning that substances with identical chemical composition may
work differently, if just a part of the molecule has shifted position from one
place to another.
Phthalate (DEHP, DOP; di
2-ethylhexylphthalat)
Terephthalate, (DEHT,
DOT DOTP; di 2-ethylhexyl
terephthalate)
Trimellitates (TOTM; tri
(2-ethylhexyl) trimellitate)