High-temperature free-radical polymerization of n-butyl acrylate

110 Pages·2005·0.91 MB·English

High-Temperature Free-Radical Polymerization of n-Butyl Acrylate
A Thesis
Submitted to the Faculty
of
Drexel University
by
Congling Quan
in partial fulfillment of the
requirements for the degree
of
Doctor of Philosophy
December 2002
(cid:13)c Copyright 2005
Congling Quan. All Rights Reserved.
ii
Dedications
To the loving memory of my father
iii
Acknowledgments
Many people have contributed to my graduate study through their guidance
and support. I am deeply indebted to my thesis advisor, Prof. Masoud Soroush,
who patiently guided and encouraged my scientific endeavors. I am also grateful
to my co-advisor, Dr. Michael C. Grady , who coordinated and supported the
experimental investigation. I acknowledge the members of my doctoral committee,
Dr. John P. Congalidis, Dr. Joan E. Hansen, Prof. Raj Mutharasan, Dr. John R.
Richards, and Prof. Charles B. Weinberger, for their support, constructive criticism,
and valuable input. A special thanks is due to all staff and workers at DuPont’s
Marshall Laboratory, especially Dr. William J. Simonsick, who helped in analyzing
and performing the important experiments for this research. I am also grateful to
National Science Foundation, the Department of Chemical Engineering of Drexel
University and Marshall Laboratory of DuPont, without whose financial support,
this research would not have been possible. Last, but not least, I would like to thank
my family for their love, understanding and support.
iv
Table of Contents
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Significance of the Research . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Organization of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Theoretical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Free-Radical Polymerization . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Low Temperature Polymerization of nBA . . . . . . . . . . . . . . . . 7
2.3.1 Kinetic Studies of nBA Polymerization . . . . . . . . . . . . . 8
2.3.2 PLP/MWD Measurements of k . . . . . . . . . . . . . . . . . 9
p
2.3.3 Intramolecular Chain Transfer . . . . . . . . . . . . . . . . . . 10
2.4 High Temperature Polymerization of nBA . . . . . . . . . . . . . . . 14
3 Experimental Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.2 Experimental Design . . . . . . . . . . . . . . . . . . . . . . . 17
v
3.2 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.3 Experimental Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.4 Characterization Techniques . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.1 Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4.2 Molecular Weight Analysis . . . . . . . . . . . . . . . . . . . . 21
3.4.3 Electrospray Ionization Mass Spectroscopy . . . . . . . . . . . 23
3.4.4 NMR Spectrometry . . . . . . . . . . . . . . . . . . . . . . . . 24
4 Polymer Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 Experimental Section . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.1 Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.2 Electrospray Ionization Mass Spectroscopy . . . . . . . . . . . 35
4.2.3 NMR Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . 35
4.3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.3.1 Chain Composition Analysis by ESI/FTMS . . . . . . . . . . 37
4.3.2 1D NMR Analysis . . . . . . . . . . . . . . . . . . . . . . . . 44
4.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5 Modeling of nBA High-Temperature Polymerization . . . . . . . . . . . . . 54
5.1 Introduction and Literature Review . . . . . . . . . . . . . . . . . . . 55
5.2 Experimental Section . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.3 Experimental Results and Discussion . . . . . . . . . . . . . . . . . . 57
5.4 Mathematical Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.4.1 Reaction Mechanism . . . . . . . . . . . . . . . . . . . . . . . 64
5.4.2 Molecular Weight Distribution . . . . . . . . . . . . . . . . . . 69
5.4.3 Species Mass Balance . . . . . . . . . . . . . . . . . . . . . . . 74
vi
5.4.4 Parameter Estimation and Discussion . . . . . . . . . . . . . . 76
5.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6 Conclusions and Future Research Directions . . . . . . . . . . . . . . . . . 86
6.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.2 Future Research Directions . . . . . . . . . . . . . . . . . . . . . . . . 88
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Vita . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
vii
List of Tables
2.1 Basic steps of free-radical polymerization . . . . . . . . . . . . . . . . 7
2.2 Typical reaction mechanism of acrylate polymerization. . . . . . . . . 10
3.1 List of chemicals used. . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2 Reaction conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 Recipes of thermal polymerization of nBA. . . . . . . . . . . . . . . . 57
5.2 Kinetic mechanism for n-butyl acrylate polymerization at high tem-
peratures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.3 Leading moments of the proceses initiating new chains. . . . . . . . . 72
5.4 Reactions producing macromolecules. . . . . . . . . . . . . . . . . . . 73
5.5 Model parameter values taken from the literature. . . . . . . . . . . . 77
5.6 Values of estimated model parameters at 140, 160 and 180 ◦C. . . . . 78
viii
List of Figures
2.1 Backbiting by intramolecular hydrogen abstraction. . . . . . . . . . . 11
3.1 The branching structure of poly-nBA (Bu=butyl ester group). . . . . 25
3.2 The terminal double bond of poly-nBA. . . . . . . . . . . . . . . . . . 26
4.1 Intramolecular (top) and intermolecular routes to mid-chain tertiary
radicals in acrylate homo-polymerization. . . . . . . . . . . . . . . . 30
4.2 β-scission and propagation of the mid-chain radicals formed in acry-
late homo-polymerization. . . . . . . . . . . . . . . . . . . . . . . . . 31
4.3 nBA homo-polymerization results. . . . . . . . . . . . . . . . . . . . . 37
4.4 ESI/FTMS spectra of poly(ethyl acrylate) sample made by sponta-
neous polymerization at 180◦C and 40 weight % monomer on solution
in the range between 250 and 2250 Daltons. Also shown is the ex-
panded view of ESI/FTMS results around the peak 1124 Daltons.
The expanded range is 1060 to 1200 Daltons. . . . . . . . . . . . . . . 38
4.5 Possible molecular weights of the single ionic species generated during
ESI/FTMS analysis of poly(EA) and poly(nBA). . . . . . . . . . . . 39
4.6 ESI/FTMS spectra of poly(n-butyl acrylate) sample made by sponta-
neous polymerization at 180◦C and 40 weight % monomer on solution
in the range between 800 and 2000 Daltons. Also shown is the ex-
panded view of ESI/FTMS results around the peak at 1048 Daltons.
The expanded range is 1020 to 1060 Daltons. . . . . . . . . . . . . . . 42
4.7 13C NMR spectra of poly(EA) made at 180◦C, and 40 weight % EA
in xylene without added thermal initiator. . . . . . . . . . . . . . . . 45
4.8 1H NMR spectra of poly(EA) made at 180◦C and 40 weight % EA in
xylene without added thermal initiator. . . . . . . . . . . . . . . . . . 46
4.9 13C NMR spectra of poly(nBA) made at 180◦C and 40 weight % nBA
in xylene without added thermal initiator. . . . . . . . . . . . . . . . 47
ix
4.10 Peakassignmentsandintegratedareasfor13C NMRanalysisofpoly(EA)
made at 180◦C in xylene without added thermal initiator. . . . . . . 48
4.11 Predicted peak integration areas for a beta-scission radical initiated
macromonomer terminated poly(EA) chain as a function of the num-
ber of branch points. The area for the methyl group in the C H ester
2 5
linkage on the EA molecule is assumed to be 11.67 (per Figure 4.9)
and the molecular weight of the chain is 4001. . . . . . . . . . . . . . 51
4.12 beta-scission radical initiated, macromonomer terminated poly(EA)
chain with 2 branch points. The wiggly chain represents a run of
ethylacrylatemonomerunitsCH -CH(CO Et). Forthe4000number-
2 2
average molecular weight poly(EA) with 2 branch points the run
would contain 33 EA units. The CH (CO Et)CH CH(CO Et) repre-
2 2 2 2
sents the -scission radical initiating species, which can also be written
as CH (CO Et)EA. The CH C(CO Et)=CH represents the terminal
2 2 2 2 2
macromonomer. CH C(CO Et)(CH )CH(CO Et)CH CH (CO Et)rep-
2 2 2 2 2 2 2
resents the branch point. . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.1 Measurements of conversion (40 wt% nBA at 140◦C, 160◦C, and
180◦C; Relative standard deviation ≤ 5.0%). . . . . . . . . . . . . . . 58
5.2 Measurements of M (40 wt% nBA at 140 ◦C, 160 ◦C and 180 ◦C;
w
Relative of standard deviation ≤ 15.0%). . . . . . . . . . . . . . . . . 59
5.3 Measurements of terminal double bond/100 monomer units (40 wt%
nBA at 160◦C and 180◦C; Relative standard deviation ≤ 15.0%) . . . 60
5.4 Measurements of branching point/100 monomer units (40 wt% nBA
at 160◦C and 180◦C; Relative standard deviation ≤ 15.0%). . . . . . 61
5.5 Measurements of concersion (40 wt%, 20 wt%, and 10 wt% nBA at
160 ◦C; Relative standard deviation ≤ 5.0%). . . . . . . . . . . . . . 62
5.6 Measurements of M (40 wt%, 20 wt%, and 10 wt% nBA at 160◦C;
w
Relative standard deviation of experimental data ≤ 15.0%). . . . . . 63
5.7 Comparison of model prediction and measurements of concersion ( 40
wt% nBA at 140◦C, 160◦C and 180◦C; Relative standard deviation
of experimental data ≤5.0%). . . . . . . . . . . . . . . . . . . . . . . 80
5.8 Comparison of model prediction and measurements of M (40 wt%
w
nBA at 140◦C, 160◦C and 180◦C; Relative standard deviation ≤
15.0%). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
5.9 Comparisonofmodelpredictionandmeasurementsofterminaldouble
bond/100 monomer units (40 wt% nBA at 140◦C, 160◦C and 180◦C;
Relative standard deviation ≤ 15.0%). . . . . . . . . . . . . . . . . . 82