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Extraction and analysis of monomer in film during radiation grafting.

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Die Angewndte Makrornolekdare Chemie 13 (1970) 199-202 (Nr. 213)
From the Department of Chemistry, University of Salford,
Salford M5 4WT, Lanceahire, England
Kunmitteilung
Extraction and Analysis of Monomer
in Film During Radiation Grafting
By J. T.GUTHRIE,M.B. HUGLIN
and G. 0. PHILLIPS
(Eingegangenam 19. Juni 1970)
SUMMARY:
A rapid and reproducible method is described for extrmting and estimating the
concentration of styrene in ceklulose film which is swollen in a typical radiationgrafting medium.
Introduction
Current investigations in this laboratory are concerned with the kinetics of
grafting styrene to regenerated, and partially carbanilated, cellulose film by the
mutual (gamma) irradiation technique. An important variable is the local
concentration of monomer within the swollen film, which is not necessarily the
same as that in the bulk medium owing to the adsorption characteristics of
cellulose. Since both styrene and the polystyrene produced in the attendant
homopolymerisation are soluble in dioxan, this liquid was selected as solvent
medium and a low concentration of water incorporated as a swelling agent to
enhance diffusion to the radical sites. The concentration of styrene either
initially or a t any stage of grafting is best expressed as moles of styrene per unit
volume of swollen film. It is necessary, therefore, to be able to extract and
estimate the monomer from the film with a high degree of accuracy. In this note
some established methods of estimating styrene are reviewed briefly and details
are then given of the procedure adopted. The composition of all liquids is expressed in terms of percentage by volume.
Methods based on refractive index1 or depression of freezing point2 are
difficult to interpret for multicomponent systems. Titrimetry, e. g. volumetric2
or amperornetrifi94 analysis, is generally considered to be too insensitive. An
exception involving methoxymercurations can be modified to determine low
concentrations of styrene by means of PAL IT'S^ procedure. Such modifications
are, however, tedious and unsuited to routine analysis. Gravimetry involving
styrene as the nitrosite7 or phenylhydrazine complex8 is time-consuming and
somewhat insensitive. Recent developments indicate that polarography may
199
J. T. GUTHRIE,
M. B. H U ~ L Iand
N G. 0. PHILLIPS
prove useful, but its applicability in this context is limited by the degree of
instrumental sophistication requireds-14. Gas phase chromatography (G. P. C.)
has been utilised successfully by several workers 15-18. CROMPTON~~
and
BRIGHT^^ compared this technique with ultraviolet (U. V.) spectroscopy for
styrene analysis and concluded that G. P. C. is preferable in most respects.
However, in view of its sensitivity, simplicity and speed we have selected
U. V. analysis162 18-21.
Experimental
a) Reagents
Styrene :Commercial styrene was purified by standard methods2 and stored at low
temperature in the dark.
Dioxan : Rigorous purification as described by BAXENDALE~~
was found to be
essential for subsequent use in U. V. analysis. Peroxidation of the purified product
was minimised by storage over sodium in the dark at low temperature.
Cellulose: Strips (2" x 0.5" x 0.002") of regenerated cellulose film were extracted
with methanol in a Soxhlet apparatus to remove plasticiser and dried to constant
weight in vacuo at 4OoC ( 5 mm Hg).
Water: Deionised water was used throughout.
b) Calibration Procedure
Calibration was effected by measuring the optical densities, read directly on a
Perkin Elmer 137 U. V. spectrophotometer,of solutions of known concentration of
styrene in dioxan/water. The composition of water was fixed at 2% and the compositions of the other two componentsvaried. The U. V. spectrum of styrene exhibits
two bands a t 282 and 291 nm. Use of both absorption bands affords a check on the
sensitivity of the analysis. Using a 1 cm cell and a slow scan speed, optical densities
within the convenient range 0.1-0.6 were obtained for solutions in which the concentration of styrene was varied from ca. 1.7 x 10-4 - 7.0 x 10-4 mole/litre of solution. BEER'SLaw was obeyed accurately and the derived molar extinction
coefficients found to be 8.32 and 6.48 1 mole-1 cm-1 for A = 282 nm and A = 291
nm, respectively.
c) Extraction and Analysis of Styrene in Swollen Film
A film was swollen at 30°C in a solution of composition typical of that used in
radiation grafting (e. g. styrene : water : dioxan = 10 : 2 : 88). The time taken to
attain equilibrium @wellingat this temperature had been established previously as
1 hour. The swollen film waa then removed, surface dried between filter papers,
transferred to a tared air-tight bottle and weighed to yield the degree of overall
swelling. 8 ml of solvent (dioxan : water = 98 : 2) were addedand the bottle shaken
periodically over two hours. The removed solution and washings were made up to
10 ml and the styrene concentration determined by U. V. analysis. The presence
of water in the extracting mixed solvent was found to be essential for complete
removal of styrene.
Results
The mass of styrene taken up by the f
ilm is easily obtained from the styrene
concentration in the extract. This is converted to concentration of styrene in
200
Extraction and Analy.68 of Monomer
the swollen film, utilising the densities of the three Liquid constituents a t 30 "C
and the density of cellulose at this temperature, which was found to be 1.470
g/ml by the flotation technique using a mixture of benzene and carbon tetrachloride. Results from extractions following swelling in different media are
shown in Table 1.
Table 1. Determination of Styrene.
concentration of
styrene in bulk medium
(Yo vlv)
102 x concentration of styrene in
cellulose film (moles 1-1 of swollen
film)
5
2.02
10
6.88
20
11.0
30
15.1
40
21.6
To test the reproducibility of the extraction, experiments were conducted in
which the original film weight was varied, but the concentration of monomer
in the bulk swelling medium maintained constant a t 20%. Typical results are
shown in Table 2.
Table 9. Reproducibility of the Extraction.
weight of initial
cellulose film (g)
concentration of
styrene in extracted
solution (moles 1-1)
104 x
Yo sytrene based on
initial weight of
0.0426
0.0541
4.20
5.45
1.00
1.00
0.0577
5.95
0.0587
6.20
1.03
0.95
The quantity of styrene absorbed and hence extracted is seen to increase
with the weight of the film but, when allowance is made for this in the third
column of Table 2, the reproducibility is seen to be good. The efficiency of
the extraction is demonstrated by the fact that no more styrene was obtained
after repeated extractions. An absence of styrene absorption bands in the
spectrum of the film itself after the initial extraction also supports this view.
Discussion
The following additional points are noteworthy :
(i) The composition of the mixed solvent used in the extraction is the same
asthat used in the calibration, but may well differ from the ratio of dioxan/water
201
J. T. GUTHRIE,M. B. HUGLINand G. 0. PHILLIPS
present in a swollen film.However, the effect of this is wholly insignificant,
since the total volume of liquid absorbed by the film only constitutes a maximum of ca. 0.1% of the volume (10 ml) analysed.
(ii) The techniques for extraction and analysis are easily applicable t o a
variety of polymer/monomer systems, provided that characteristic absorption
bands exist for the monomer.
(iii) Examples have been quoted here from un-irradiated systems. After
irradiation polystyrene is also present in the swollen (grafted) film but, as it
exhibits a negligible background absorption a t the wavelengths considered,
no interference with the styrene analysis is encountered.
We thank TRANSPARENT
PAPERLTD.,Bury, Lancs., England for assistance
and for kindly donating the cellulose film. The provision of a SCIENCERESEARCH COUNCILC. A. P. S. award (to J. T. G.) is’gratefully acknowledged.
1
2
3
4
Dow CHEMICALCOMPANY,“Analytical Techniques for Styrene Monomer“, Mid land, Michigan, 1946.
S. POLSTEIN
in “Monomers“ (Edited by E. R. Blout, W. P. Hohenstein and
H. Mark), Interscience, New York, 1949.
I. M. KOLTHOFF
and F. A. BOVEY,Analytic. Chem. 19 (1947) 498.
D. B. GURVICH,
V. A. BALANDINA
and L. M. PARKINA,
Zavodsk. Lab. 30 (1964)
278.
5
6
7
8
9
10
11
12
13
M. N. DAS,Analytic. Chem. 26 (1954) 1086.
S. R. PALIT,
Ind. Engng. Chem., analyt. Ed. 18 (1946) 246.
G. R. BOND,JR.,Ind. Engng. Chem., analyt. Ed. 19 (1947) 390.
G. COSOVEANU,
Farmacia (Bucharest) 11 (1963) 419.
H. A. LAITINEN
and S. WAWZONEK,
J. Amer. chem. SOC.,64 (19L2) 1765.
A. G. STROMBERG
and A. G. POZDEEVA,
Zh. Analit. Khim. 5 (1950) 101.
A. G. STROMBERG
and A. G. POZDEEVA,
J. Gen. Chem. U. S. S. R. 20 (1950) 57.
(Also, C. A. 44 (1950) 8267).
A. G. POZDEEVA
and A. G. VOLKOV,
Zh. Prikhd. Khim. 26 (1953) 1067. (Also,
C. A. 48 (1954) 14162).
V. D. BEZUGLYI,
Yu. P. PONOMAREV
and V. N. DIMITRIEVA,
Zh. Analit. Khim.
19 (1964) 881.
l4
15
16
17
18
J. H. PASIAK,Chem. Analit. (Wartmw) 3 (1960) 477.
T. R. CROMPTON,L. W. MYERS and D. BLAIR,Brit. Plastics 38 (1965) 740.
T. R. CROMPTONand L. W. MYERS,Europ. Polymer J. 4 (1968) 355.
P. SHARPAS
and G. C. CLEAVER,
Analytic. Chem. 36 (1964) 2282.
K. BRIGHT,B. J. FARMER,
B. W. MALPASSand P. SNELL,Chem. Ind. (London)
14 (1965) 610.
19
20
21
22
J. J. MCGOVERN,
J. M. GRIMand W. C. TEACH,
Analytic. Chem. 20 (1948) 312.
J. F. NEWALL,
Analytic. Chem. 23 (1951) 445.
N. I. KAZNINA,
Gig. Sanit. 33 (1968) 65. (Also, C. A. 69 (1968) 29956).
J. H. BAXENDALE
and M. A. RODGERS,
Trans. Faraday SOC.63 (1967) 2004.
202
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