days' contact (Table 11). Clearly there is a com-
LITERATURE CITED
bined effect with these two organic solutes!
ASTM (1988) ASTM standard test method D 2583-
87 for indentation hardness of rigid plastics by
means of a Barcol Impressor. American Society
CONCLUSIONS
for Testing and Materials, Philadelphia, Pennsyl-
These data show that when the relative solu-
vania, p. 337339.
bility of a single organic solute is less than 0.1,
Berens, A.R. (1985) Prediction of organic chemi-
there will not be any measurable effect on PVC,
cal permeation through PVC pipe. Journal of the
either weight gain or hardness readings. For solu-
American Water Works Association, p. 5765.
tions that contain several organic solvents, we
Dean, J.I. (Ed.) (1985) Lange's Handbook of Chemis-
have found the sum of the relative solubilities of
try, Thirteenth Edition. New York: McGraw-Hill
the organic solutes in the test solution to be a
Publishers.
useful, if not rudimentary, indicator of the ability
Holsen, T.M. (1988) The effect of soils on the
of an aqueous solution to degrade PVC. If the
permeation of plastic pipes by organic chemicals.
sum of the relative solubilites of the organic sol-
Ph.D. Thesis, University of California-Berkeley.
utes in solution is less than 0.1, there does not
University Microfilms International Dissertation
appear to be any measurable effect on rigid PVC.
Information Service order number 8902122.
This relative solubility corresponds to an activity
Jenkins, D., R.E. Selleck, L. Bontoux, and D.
level (0.1) where diffusion is slowest and Fickian.
Soong (1986) Permeation of plastic pipes: Litera-
At slightly higher relative solubilities (0.2, 0.4),
ture review and research needs. Sanitary Engi-
there are slight changes in the hardness readings,
neering and Environmental Health Research Labo-
although in the time frame of our studies (18
ratory, College of Engineering, School of Public
months and less) PVC does not become pliable or
H e a l t h , University of California-Berkeley,
rubbery.
SEEHRL Report 86-12.
We do not have any parameters that can be
Leggett, D.C. and L.V. Parker (1994) Modeling
used to predict the ability of aqueous solutions
the equilibrium partitioning of organic contami-
that also contain PVC solvents and swelling agents
nants between PTFE, PVC, and groundwater. Envi-
that are completely miscible in water to soften
ronmental Science and Technology, 28(7): 12291233.
PVC. The relative solubility cannot be used to
Montgommery, J.H. (1991) Groundwater Chemi-
predict the ability of the solution to soften PVC
cals Desk Reference. Volume 2. Chelsea, Michigan:
because this involves dividing the concentration
Lewis Publishers, Inc.
of the analyte by an infinitely large number. It is
Montgommery, J.H. and L.M. Welkom (1990)
interesting that a 1% solution of acetone had no
Groundwater Chemicals Desk Reference. Chelsea,
effect on the hardness readings after 18 months'
Michigan: Lewis Publishers, Inc.
exposure, while a solution containing methylene
Parker, L.V. and T.A. Ranney (1994) Softening of
chloride with a relative solubility of 0.4 (0.76%)
rigid PVC by aqueous solutions of organic sol-
and 0.5% acetone softened PVC after only a few
vents. USA Cold Regions Research and Engineer-
days' contact. Clearly, further study is needed to
ing Laboratory, Special Report 94-27.
delineate the influence miscible PVC solvents and
Parker, L.V. and T.A. Ranney (1995) Additional
swelling agents have on the softening ability of
studies on the softening of rigid PVC by aqueous
aqueous organic solutions.
solutions of organic solvents. USA Cold Regions
Previously Leggett and Parker (1994) used a
Research and Engineering Laboratory, Special Re-
model based on multiparameter linear solvation
port 95-8.
energy relationships to describe equilibrium par-
Parker, L.V., T.A. Ranney, and S. Taylor (1992)
titioning between PVC and water for several or-
Softening of rigid polyvinyl chloride by high con-
ganic compounds. Partitioning of these solutes
centrations of aqueous solutions of methylene
was related to the molecule's acidity, polarity/
chloride. USA Cold Regions Research and Engi-
polarizability, basicity, and molecular volume. A
neering Laboratory, Special Report 92-12.
similar approach might prove useful here for pre-
Ranney, T.A. and L.V. Parker (1995) Susceptibil-
dicting in a more meaningful way the ability of
ity of ABS, FEP, FRE, FRP, PTFE, and PVC well
aqueous organic solutions to soften PVC.
casings to degradation by chemicals. USA Cold
19
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