Table 3. Properties of the organic solvents used in the mixed-solvent study.
χ value
Density†
Solubility
PVC softening agent or solvent*
(g/mL)
(mg/L)
Berens (1985) Vonk (1985)
Cyclohexanonec
0.94782
23,0002
Methylene chloridea,b,c
1.32661
19,0001
< 0.53
0.55
Methyl isobutyl ketonec
0.79781
17,0001
Bromochloromethanec
1.93441
16,6911
1,2-dichloroethanea,b,c
1.23511
8,6901
< 0.55
0.56
Chloroformb,c
1.48321
8,0001
0.64
cis-1,2-dichloroethylened
1.28183
7,7003
trans-1,2-dichloroethylened
1.25651
6,3001
Bromodichloromethaned
1.98001
4,5001
1,1,2-trichloroethanea,b,c
1.43971
4,5001
< 0.56
0.58
1,2-dibromoethaned
2.18021
4,3001
Dibromochloromethaned
2.45101
4,0001
Bromoformd
2.88991
3,0101
Benzonitriled
1.00063
2,0003
0.54
2-nitrotoluened
1.16292
6002
3-nitrotoluened
1.15712
5002
Chlorobenzenea,c
1.10581
5001
0.66
* These compounds were determined to be either solvents or good softening agents of PVC
based on information from the following sources:
a Vonk (1985)
b Berens (1985)
c Cole-Parmer (1992) and verified by tests in our laboratory
d Determined in our laboratory
† Densities
and solubility sources:
1 Montgomery
Ground Water Chemical Desk Reference
2 Montgomery Ground Water Chemical Desk Reference, vol. 2
3 Dean Lange's Handbook of Chemistry, 13th Edition
per was then inserted (leaving almost no head-
Model 935 Barcol Impressor was used to mea-
space) and the top of the flask was wrapped tightly
sure the hardness of the PVC. A description of the
with parafilm to reduce vapor loss. The solution
use of the Barcol Impressor on rigid plastics can be
was mixed for approximately three days on a
found in ASTM Standard Test Method D2583-87
magnetic stirring plate. When the solution was
(ASTM 1988). However, the impressor employed
mixed, preweighed PVC pieces were added to
in this study is made for indenting softer plastics
empty vials, the vials were filled with the mixed-
and is not the model described in the ASTM test
solvent solution to capacity so there was no
method. This model was selected so that mea-
headspace and then capped.
surements could be taken during the softening pro-
cess. Observations were also made of any curvature
in the PVC pieces, and the flexibility was tested
General
In all the studies the pieces of PVC were handled
by holding the pieces with forceps and noting the
using stainless steel forceps. The ratio of surface
amount of force necessary to bend the sample.
area of PVC to solution volume was 0.074 cm2/mL,
In all these studies, analysis of variance and
and the ratio of solution volume to volume of PVC
Duncan's New Multiple Range tests were per-
was approximately 386:1. PVC pieces added to
formed on the Barcol readings for each time and
for each analyte in the miscible solvent studies.
deionized water served as controls. All the pre-
pared solutions were checked with a magnifying
glass to ensure that there were no undissolved
droplets of solvent visible. The test samples were
RESULTS AND DISCUSSION
stored in the dark at room temperature.
On the sampling day the pieces of PVC were
Short-term
removed from the solution, placed on paper tow-
miscible solvent study
els, blotted and allowed to air dry for 1 minute
In this study we exposed pieces of PVC to aque-
before weighing. Immediately after weighing, a
ous solutions of five PVC solvents or good swelling
6
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