Migration of plasticizers

When plasticized polymers are in contact with the mother polymers, plasticizers are likely to migrate to mother polymers and the extent of their migration depends on a number of factors such as polymer-plasticizer system, polarity of polymer and plasticizer, crosslink density of polymer, molecular weight of plasticizer etc. 

It is reported in the literature that small migration does not change the properties of a polymer significantly but extensive migration severely affects their properties. 

Some of the well-known plasticizers used in the field of explosives or propellants are given in Table 4.7a,b. 

Triacetin ( ) Diethyl phthalate (DEP) Function as plasticizers and also desensitizer for nitroglycerine (NG) used as an explosive plasticizer for DB and CMDB propellants. 

Dioctyl azelate (trade name - Emolein) Dioctyl adipate (DOA) Bring down viscosity of HTPB and consequently, increase solids loading which improve performance of propellants and PBXs. 

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Solvation—Desolvation Equilibrium. From the observation of migration of plasticizer from plasticized polymers it is clear that plasticizer molecules, or at least some of them, are not bound permanently to the polymer as iu an internally plasticized resia, but rather an exchange—equiHbrium mechanism is present. This implies that there is no stoichiometric relationship between polymer and plasticizer levels, although some quasi-stoichiometric relationships appear to exist (3,4). This idea is extended later ia the discussion of specific iateractions. 

Bishop CS, Dye A. 1982. Microwave heating enhances the migration of plasticizers out of plastics. J Environ Health 44 231-235. 

DIN 53 405 Bestimmung der Wanderung von Weichmachern. ISO 177-1988 Plastics -Determination of migration of plasticizers. 

Castle L, Gilbert J, Eklund T (1990) Migration of plasticizer from poly(vinyl chloride) milk tubing. Food Addit Contam 7 591-596... 

Approximately 11.8 million pounds of hexabromobiphenyl were used in commercial and consumer products in the United States, mostly in the production of plastic products. Since the cessation of production of hexabromobiphenyl, all of these products, such as TV cabinet and business machine housings, with a usable life of 5 10 years must have been disposed of by landfilling or incineration (Neufeld et al. 1977). Disposal of these plastic materials in waste disposal sites is an important source of PBBs in soil. The migration of plastic-incorporated PBBs to soil would be very low since PBBs would be tightly bound into the plastic (Neufeld et al. 1977). 

Castle L, Mayo A, Gilbert J. 1989. Migration of plasticizers from printing inks into food. Food Addit Contam 6 437-443. 

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