THE EFFECT OF OXYGEN ON THE POLYMERIZATION OF ACRYLONITRILE

119 Pages·04.394 MB·English

by  SMELTZ, KENNETH C

69-7922
SMELTZ, Kenneth C., 1921-
THE EFFECT OF OXYGEN ON THE POLYMERIZA­
TION OF ACRYLONITRILE. II.
University of Delaware, Ph.D., 1951
Chemistry, polymer
University Microfilms, Inc., Ann Arbor, Michigan
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THE EFFECT OF COOTC-FN ON THE
POUHERIZATION OF ACRXLONITRILE. II
by
Kenneth C. Smeltz
A dissertation submitted to the Faculty of the University of
Delaware in partial fulfillment of the requirements for the degree of
Doctor of Philosophy.
June, 1951
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Pro£<'jpo^ui Charge
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rH£ad of Department
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Dean of the School of Arts and Science
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Dean of the fix&ool of Gnaduate S'tuo.ies
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ACKNOWIHDGMENT
The author wishes to acknowledge his indebtedness to the Office
of Naval Research and to the Department of Chemistry of the University
of Delaware for a fellowship in support of this investigation, and to
express his appreciation to Dr^ E. Dyer for her advice and assistance.
Also, the author wishes to express his thanks to Miss Roberta McCleary
for carrying out the viscosity measurements, to Hiss Janet Hucks and
Dr. Harold C. Beachell for infra-red absorption measurements and inter­
pretations, and to E. I. duPont de Nemours and Company for the generous
samples of dimethylformamide.
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DEDICATION
This work is dedicated to my "wife who, because of her under­
standing, helped make th is work possible.
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TABLE OF CONTENTS
Summary
Introduction...................................................................................................................................1
H istorical S ectio n ......................................................................................................................3
I. Diacyl P eroxides...........................................................................................................3
A. Benzoyl Peroxide and Substituted Benzoyl Peroxides . . . . 3
B. Acetyl Peroxide and Substituted Acetyl Peroxides . . . . . 7
II. Acyl H ydroperoxides..................................................................................................9
III. Dialkyl P e ro x id e s....................................................................................................10
IV. Alkyl and Aryl H ydroperoxides.........................................................................12
Experimental S ectio n ...............................................................................................................19
I. Purification of M a te ria ls ..................................................................................19
II. Procedure for Experiments Using Potassium Persulfate as
In itiato r in Aqueous Solutions ..........................................................................20
III. Study of the Rate of Decomposition of Potassium Persulfate
in Aqueous Solution with A erylonitrile Using an Atmosphere
of O xygen........................................................................................................................21
IV. Determination of Intrinsic V iscosity of Polyacrylonitrile
Formed in Aqueous Solution Experim ents.......................................................22
V. Procedures for Experiments in Non-Aqueous S y ste m s...........................23
A. Closed System Shaken In an Atmosphere of Oxygen at
Constant Pressure ............................... 23
B. Open System with Oxygen Continuously Bubbling Through
Reaction M ixture............................................................................................23
1. Thermally, With and Without an In itia to r.......................23
2. With and Without an In itiato r Using an U ltra-
V iolet Light S o u rc e .....................................................................24
VI. Oxidation P roducts...................................................................................................25
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A. Products from A crvlonitrile and Oxygen in
Aqueous Experim ents......................................................................................25
B. Q uantitative Determinations and Estimations of Some of
the Oxidation Products and Reactants from Persulfate
Initiated Aqueous Experim ents.................... 34
C. Products Obtained from the Reaction of A crvlonitrile
with Oxygen in Non-Aqueous S y stem s.................................................35
1. Initiated by Benzoyl Peroxide in 3 u lk ...............................35
2. Bulk Systems Without an In itia to r........................................44
3. Bulk Systems Using U ltra-V iolet Light and
No I n it ia to r .................................................... ..............................44
4. Bulk Systems Using U ltra-V iolet Light and
Diacetyl as In itiato r ................................................................. 45
Results and Discussion S e c tio n ......................................................................................46
I. Inhibitory Effect of Oxygen on the Polymerization of
A crvlonitrile in Aqueous Solution Using Potassium
Persulfate as In itia to r ................................ 46
II. Inhibitory Effect of Oxygen on the Polymerization of
A erylonitrile in Non-Aqueous Systems ........................................................ 61
A. Solution Polymerization . ...................................................................61
3. Bulk Polymerizations With Benzoyl Peroxide as In itiato r . 62
C. 3u!k Polymerization Without an I n itia to r ....................................64
D. Photopolym erisations.................................................................................64
III. Polymeric Peroxide and Oxidative Degradation Product's.......................65
IV. Possible Mechanisms of Reactions .................................................. . . . 7 8
V. The Polymerization of A crylonitrile in Aqueous Solutions
by 0 eric Io n s ......................................... . . 8 6
Bibliography ............................................................................................................................. 90
Figures (Drawings, Graphs and Infrared Spectra) ................................................. 95
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SUMMARY
In this investigation, the effect of oxygen on the polymeri­
zation of acrylonitrile was studied using aqueous and non-aqueous solu­
tion systems, bulk systems both with and without an in itia to r, and
photosensitized systems with and without a chemical in itia to r. In a ll
cases, normal polymerization was inhibited by the oxygen, and oxygen
was absorbed.
The rate of absorption of the oxygen, using 100'S oxygen atmos­
pheres, was found to vary with the system being used, the concentration
of the in itia to r, the concentration of the monomer, the solvent, and
the temperature.
In the aqueous systems, using potassium persulfate as in itia to r,
the rate of oxygen absorption was firs t order with respect to the in itia l
persulfate concentration and three-halves order with respect to the
in itia l acrylonitrile concentration when the reactions were done for
seven hours. Over much longer periods of time the order of the reaction
with respect to oxygen absorption was a function of the persulfate con­
centration and varied from firs t order for the lowest value of per­
sulfate to three-halves order for the highest value used. At th is
highest value, normal polymerization was barely suppressed.
In non-aqueous solution systems with benzoyl peroxide as
in itia to r, the rate of oxygen absorption was dependent on the 33 lvent
used.
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A highly unstable polymeric peroxide was isolated from the
non-aqueous experiments and evidence for a sim ilar peroxide was obtained
in the aqueous experiments. The products of decomposition that were
isolated or identified include hydrogen cyanide, carbon dioxide, for­
maldehyde, glycol aldehyde cyanohydrin, glycolic acid and water.
Evidence was also obtained for the presence of small anounts of carbon
monoxide, glyoxylic acid and a v o latile peroxide.
Q uantitative data obtained from experiments in aqueous solu­
tion showed that for every six moles of oxygen absorbed, twelve moles
of acrylonitrile were used, and there were produced six moles of hydro­
gen cyanide, two moles of formaldehyde, two moles of carbon dioxide
and three moles of hydrogen ion.
Svidence was obtained for the presence of three different
in itiatin g radicals, namely, sulfate ion free radical, hydroxyl free
radical, and a radical frcsn the acrylonitrile formal by the lass of
the hydrogen atom alpha to the cyanide group. A mechanism was proposed
to account for the formation of a peroxy polymer and for most of the
decomposition products.
It was found that acrylonitrile could be polymerized in
aqueous solution by eerie ions alone. This fact gave more evidence
for the existence of an in itiatin g radical formed from acrylonitrile.
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1
INTRODUCTION
During the past few years, there has been an increasing
interest in the effect oxygen has on various vinyl polymerizations,
71,72
especially that of inhibition with the formation of peroxy p o l y m ^0 * •
L ittle is known as to the effect of oxygen on the polymerization of
acrylonitrile using various types of polymerizing systems.
Bacon^ has shown that oxygen inhibits the aqueous solution
polymerization of acry lo n itrile by causing an induction period which
varied with the oxygen content of the system, the temperature, and the
concentration of in itiato r. Morgan shewed that the induction period
was inversely proportional to the in itia l persulfate concentration.
Baxendale, Evans and P ark ^, who studied the polymerization of acrylo­
n itrile with hydrogen peroxide-ferrous salt systems, stated that oxygen
was absorbed only when a ll three substances—monomer, peroxide, and
ferrous ion were present. The sole report as to the nature of the
products resulting fron the attack of oxygen on acrylonitrile was that
of Kern and Fernow®^, 'who reported that hydrogen cyanide was formed
in the benzoyl peroxide-initiated polymerization, presumably done under
a ir.
In a previous investigation dene in these laboratories5®,
some data were obtained on oxygen absorption of acrylonitrile in aqueous
systems using potassium persulfate as in itiato r with a 100^ oxygen
atmosphere. From these data, it was proved that the induction neriods
found when polymerizations were dene under nitrogen, were due solely
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