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Encyclopedia of Physical Science and Technology en012c-586 July 26, 2001 10:34
Plasticizers
B. L. Wadey
BASF Corporation
I. Historical
II. Classification of Plasticizers
III. Theory of Plasticization
IV. Process of Plasticization
V. Raw Materials and Chemical Reactions
VI. PVC Plasticization
VII. Plasticization of Other Resins
VIII. Health and Safety Factors
GLOSSARY to dissolve the resin at normal temperatures but be-
comes a solvent for the resin when heated.
Compatibility Ability of two or more substances to mix Polyvinyl chloride Resin made by polymerization of
without objectionable separation. vinyl chloride. The pure polymer is hard, brittle, and
Dry blend Dry free-flowing mixture of resin with plas- difficult to process but can be made flexible by addition
ticizer and other additives, prepared by blending of plasticizers.
the components at temperatures below the fusion Solvation Process of swelling, gelling, or fusion of a resin
temperature. by a plasticizer as a result of mutual attraction. Plasti-
Fusion Condition attained in the course of heating a mix- cizers are modifiers used with polymeric substances to
ture of resin, plasticizer, and other additives when all alter processing or end-property characteristics by im-
the resin particles have dissolved in the plasticizer, so proving workability, flexibility, or extensibility of the
that on cooling a homogeneous solid results. system. Plasticizers can be either external or internal
Gel Condition attained in the course of heating a mix- in classification. External plasticization based on or-
ture of resin, plasticizer, and other additives when the ganic esters is the more widely used of the two and
plasticizer has been absorbed by the resin to an extent is the subject of this article. A plasticizer lowers the
resulting in a dry but weak and crumbly mass. glass transition temperature, melt viscosity, and mod-
Low-temperature flexibility Denotes a temperature at ulus of elasticity without altering the chemical charac-
which the composition attains a specified apparent ter of the plasticized polymer. A plasticizer is bound
modulus of elasticity as measured by a torsional test. physically to the polymer by dipole forces. Examples
Plastisol Suspension of a finely divided polyvinyl chlo- of plasticization are evident from earliest times where
ride in a liquid plasticizer that has little or no tendency clay was modified with water to make pottery to the
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