1.2
1.0
Rigid PVC
0.8
0.6
0.4
Flexible PVC
0.2
Figure 1. Sorption of benzene by rigid and
0
flexible PVC (Gillham and O'Hannesin
100
10 1
10 2
10 3
10 4
10 5
1990).
Contact Time (min)
mers to the greater density and crystallinity of
ducted a study that compared sorption of organ-
those polymers. Of all the types of polymeric
ic solutes by twenty sampling tubings, including
tubings that have been tested, PTFE (Teflon) was
thirteen rigid tubings and seven flexible tubings,
among the least sorptive (Ho 1983, Barcelona et
of which eight were fluoropolymers (Table 1).
al. 1985, Reynolds and Gillham 1985, Devlin
The tubings were filled with a test solution that
1987, Pearsall and Eckhardt 1987, Gillham and
contained low mg/L concentrations of eight or-
O'Hannesin 1990).
ganic analytes (two nitroaromatic compounds
Recently, we (Parker and Ranney 1996) con-
and six volatile organic compounds). We found
Table 1. Materials used in Parker and Ranney (1996) study.
Cost per ft.a
($)
Flexible polymers b
polypropylene-based material with plasticizer, formulation 1 (PP1)
0.58
polypropylene-based material with plasticizer, formulation 2 (PP2)
2.48
polyvinyl chloride (PVC)
0.89
thermoplastic elastomerc (TPE)
0.96
linear copolymer of vinylidene fluoride and hexafluoropropylene [P(VDF-HFP)]
1.99
polyurethane
0.64
fluoroelastomer
8.70
Rigid polymers d
polyethylene, low density (LDPE)
0.19
polyethylene, cross-linked high density (XLPE)
0.43
polyethylene liner in ethyl vinyl acetate (EVA) shell
0.57
polyethylene liner cross-linked to EVA shell
1.08
co-extruded polyester lining in PVC shell
0.77
polypropylene (PP)
0.27
polyamide (nylon)
0.71
polytetrafluoroethylene (PTFE)
4.27
perfluoroalkoxy (PFA)
5.58
ethylene tetrafluoroethylene (ETFE)
5.50
polyvinylidene fluoride (PVDF)
1.80
fluorinated ethylene polypropylene (FEP)
3.90
FEP-lined polyethylene
3.00
a
1994 prices; cost varies with quantity, dimensions, and supplier.
b
Finger pressure can collapse tubing.
c
Styrene-ethylene-butylene block copolymer modified with silicon oil.
d
Can be stepped on without collapsing the tubing.
2
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