11308967

REVIEW

Free Radical Graft Polymerization

James L. White* and Akinobu Sasaki

Institute of Polymer Engineering, University of Akron,

Akron, Ohio, USA

ABSTRACT

A critical review of the development of free radical graft copolymerization

is presented. This is done in the context of a broader review of free radical

polymerization. We consider in particular (1) free radical polymerization

and copolymerization of two monomers, (2) grafting onto natural rubber

primarily to improve its oil resistance and mechanochemical phenomenon

in natural rubber, (3) grafting onto polystyrene to improve its mechanical

toughness, (4) reactive extrusion to improve properties of polyolefins and

make reactive polymers, (5) kinetics of graft polymerization, and (6)

grafting of multiple monomers.

*Correspondence: James L. White, Institute of Polymer Engineering, University of

Akron, Akron, OH 44325-0301, USA; E-mail: [email protected].

POLYMERPLASTICS TECHNOLOGY AND ENGINEERING

Vol. 42, No. 5, pp. 711735, 2003

DOI: 10.1081=PPT-120024992 0360-2559 (Print); 1525-6111 (Online)Copyright # 2003 by Marcel Dekker, Inc. www.dekker.com

711

INTRODUCTION

Free radical graft polymerization or copolymerization is an important

industrial process whose origins are part of, or perhaps lost in the early history

of the polymer industry. To fully appreciate the development of this technol-

ogy, we believe it is important to first concisely review the beginning of this

area, notably free radical polymerization and copolymerization. We then move

on to consider grafting of monomers onto elastomer and thermoplastic

backbones. First, we consider early studies of grafting onto natural rubber,

grafting as related to high-impact polystyrene, reactive extrusion of molten

thermoplastics, kinetics of grafting, tabulation of the grafting literature, and

grafting of multiple monomers.

EARLY WORK ON FREE RADICALS AND

POLYMERIZATION (19001945)

Free Radicals[1]

The word radicals was widely used by 19th century chemists,[2] but

usually not in the modern sense of a molecular fragment. The true chemistry of

free radicals as they are now visualized begins with the papers of Gomberg[3]

in 1900. He reacted triphenyl chloride with finely divided silver, producing a

yellow solution that on precipitation gave a white crystalline product hexa-

phenylethane. It soon became clear that the reactions of the yellow solution

were those of a triphenyl radical, Ph3C with an unpaired electron, rather than

hexaphenylethane. Reaction with air caused the yellow color to disappear and

triphenyl peroxide, Ph3COOCPh3, to be formed. The solution could besimilarly reacted with iodine to produce Ph3I or with nitrous oxide to form

Ph3CNO.From 1929 to 1935, Paneth et al.[4,5] studied the thermal decomposition

of various volatile organometallic compounds including (CH3)4Pb and

(PhCH2)4Sn carried by an inert gas through glass tube. A metallic mirror of

Pb or Sn was deposited on the glass, which disappeared in time. It was inferred

that the compounds decomposed into Pb and Sn and free radicals CH3 and

PhCH2, which later reunited with the metal. The Paneth mirror technique was

used by later investigators[6,7] to detect the presence of free radicals.

In the late 1930s, the free radical mechanism in chemistry became well

accepted. The occurrence of rapid as well as slow free radical reactions came

to be realized. Chain reactions occurred among low molecular weight species.

Researchers such as Kharasch and Mayo published detailed mechanism for

various reactions showing the involvement of free radicals.

712 White and Sasaki

Polymerization

Many organic compounds, especially ethylene derivatives

CH2CHjX

and butadiene derivatives

CH2CCHCH2jX

underwent what seemed to be spontaneous polymerization by various

researchers in the early 20th century. This may be seen in the efforts of

the Farbenfabriken Bayer team of Hofmann and Coutelle[814] to produce

synthetic rubber.

It was subsequently made clear by researchers such as Chalmers,[15]

Staudinger and Frost,[16] and Mark and Raff[17] that these polymerization

reactions involved chain growth processes. In 1925, H. S. Taylor[18] suggested

that free radicals might play a role in organic reactions including polymeriza-

tion. However, he did not develop this idea. Flory[19] in 1937 appeared to be

the first to clearly argue and show that these reactions proceeded by free

radical mechanisms such as

Initiation I!ki R R0Propagation R

M!kp RM

RM M!kp RMM

RMn M!kp RMn1

Termination RMn R0Mm!

ktcRMnmR0

RMn R0Mm!

ktdRMn R0Mm

(I)

This leads to

rp d[M ]

dt kp

ki

kt

s[I ]1=2[M ] (1)

In this same period, Schulz et al.[2023] showed in studies of polymeriza-

tion of styrene that (1) molecular weight was independent of conversion for

Free Radical Graft Polymerization 713

most of the reactions, (2) rate of conversion was proportional to the square root

of the initiator concentration, and (3) the molecular weight of the polymer

formed was inversely proportional to the square root of the initiator concen-

tration. All of these results follow from the free radical polymerization scheme

described above.

By the early 1940s, the mechanism of free radical polymerization was

generally accepted. During the next decade, there were extensive investiga-

tions by many researchers, much of it associated with the American Govern-

ment Synthetic Rubber Reserve program.[2427]

It was found in the course of these activities that the polymerizing

polymer chains could transfer their electrons to solvents, which in turn

would initiate further polymerization.[28,29] This situation was considered by

Flory[19] and Mayo.[28] Here,

RMn S!RMnH S (II)

where S is a solvent molecule. Sthen reacts with monomer and continue the

polymerization process.

S M!SM

SM M!SMM (III)

This should be seen to result in a lowering of molecular weight as the number

average degree of polymerization Pn is

Pn kp[RMn

][M ]

kt[RMn]2 ks[RMn ][S]

(2)

Monomer or dead polymer might play a similar role.

Copolymerization

Efforts to produce new materials by polymerizing two monomers with

each other date at least to a 1912 patent of Farbenfabriken Bayer.[30] In the

late 1920s, I. G. Farbenindustrie researchers filed patent applications for

the emulsion polymerization of various combination of monomers.[3134]

These included butadienestyrene copolymer,[32] butadieneacrylonitrile

copolymer,[33] and copolymers of acrylates.[34] Many of these copolymers

were soon commercialized, the first being butadieneacrylonitirile copolymer

as an oil-resistant rubber. Kinetics studies began with Dostal[35] in 1936 who

modeled the chain addition polymerization of two monomers. Norrish and


Brookman[36,37] reported various fundamental experimental studies on copoly-

merization of different monomers later in the 1930s.

The above activities continued into the 1940s with the focus of the

modeling research shifting from Europe to the United States and interest

concentrating on developing a kinetic scheme to explain the difference

between monomer composition and the polymer compositions produced.

This was associated with the American World War II synthetic rubber program

which was developing butadienestyrene copolymer rubber for tires.

Following Florys 1937 article,[19] the free radical mechanism of copoly-

merization was realized. Various investigators recognized the work of

Dostal[35] where there were four propagation reactions

RM1 M1!kp11

RM1M1

RM2 M2!kp22

RM2M2

RM1 M2!kp12

RM1M2

RM2 M1!kp21

RM2M1

and that

d[M1]

d[M2] [M1]

[M2] kp11[RM1

] kp21[RM2 ]

kp22[RM2] kp12[RM1 ]

(3)

Efforts were made to simplify Eq. (3). Wall[38] suggested in 1941 the

hypothesis

kp11

kp12 kp21

kp22 a (4)

which simplifies Eq. (3) to

d[M1]

d[M2] a [M1]

[M2](5)

This did not correlate with experimental data. Subsequently, in 1944, Alfrey

and Goldfinger,[39] Mayo and Lewis,[40] and Wall[41] suggested the alternative.

kp12[M2][RM1] kp21[M1][RM2] (6)


which gives in place of Eq. (3)

d[M1]

d[M2] [M1]

[M2] r1[M1] [M2][M1] r2[M2]

(7)

where r1 and r2 are monomer reactive ratios,

r1 kp11

kp12, r2

kp22

kp21(8)

Equation (8) was proven quite successful in predicting the relationship

between monomer composition and copolymer composition in free radical

copolymerization. It allows for various possibilities, including azeotropic

polymerization where d[M1]=d[M2] [M1]=[M2]. Free radical copolymeriza-tion is dealt with in more detail in books published in the 1950s by Mark and

Tobolsky,[24] Flory,[25] Burnett,[26] and Alfrey, Bohrer, and Mark.[42]

STUDIES OF GRAFTING ONTO NATURAL RUBBER

Grafting Natural Rubber Latex

Following the development of oil-resistant butadieneacrylonitrile synthetic

rubber by the I. G. Farbenindustrie,[30,33] chemists sought to modify natural

rubber in its latex state with polar monomers to enhance its oil resistance.

Efforts to polymerize methyl methacrylate in natural rubber latex were reported

by Bacon et al.[43] in 1938. They used benzoyl peroxide as an initiator. More

successful polymerizations were later attempted using soluble peroxides.

Compagnon et al.,[4447] sought to modify natural rubber latex with acryloni-

trile. These studies produced modified natural rubber elastomers, which were

among the first grafted polymers. Later, commercial products were developed

on the basis of modified natural rubber latex.

Mastication-Induced Degradation of Natural Rubber

A very old observation of the processing characteristics of natural rubber

was that the material softened with mastication and the viscosity of its solutions

was reduced.[48,49] In 1930, Staudinger[50] showed that this effect was due to

reduction of the molecular weight caused by the mastication. Staudinger and

Bondy[51] argued that cold mastication was not a simple thermal chemical

reaction but was associated with the mechanical energy of the mastication.


Subsequently, in a 1940 article, Kauzmann and Eyring[52] argued that the

mastication process ruptured the polymer chains and produced free radicals.

The picture was filled out by various experiments. In 1938, Busse and

Cunningham[53] showed that a plot of molecular weight reduction as a function

of temperature exhibited a minimum. This was confirmed by Pike and

Watson.[54] This pointed to two different mechanisms, one at low temperature

and the second at higher temperature. The low-temperature mechanism was

that of Kauzmann and Eyring.[52] Busse[55] and Cotton[56] independently

showed that using a nitrogen atmosphere greatly suppressed mastication-

induced degradation. This indicated that the severed polymer chains contain-

ing free radicals were terminated by oxygen from the air. The high-temperature

degradation was oxidative.

Pike and Watson[54] showed that if mastication was carried out in nitrogen

with free radical accepters such as thiophenol, extensive degradation was also

found. If no free radical accepters were present, gel formation occurred.[57] All

of this points to the mechanism:

P P0!stress P P0P

O2!PO2 (inert)P

A!PA (inert)P

P P0!gel

(IV)

where A is a radical accepter.

Angier and Watson[5864] now began to masticate natural rubber swollen

with various monomers such as methacrylic acid, methyl methacrylate,

ethylmethacrylate, and various other methacrylates. Chloroprene and styrene

were studied as well. Interpolymers or better block copolymers were formed

presumably by the mechanism:

P P0!P P0P

M!PM PM

M!PMM PMn

M!PMn1 PMn

P00Mm!PMnmP00!PMn P00Mm

(V)

Attempts were made by Angier and Watson to separate and analyze the

products. Polymerization was also induced by mastication of a wide range of

other polymers including polystyrene, polymethyl methacrylate, and polyvinyl

acetate.[63]


There were also investigations of mastication of natural rubber blends

with synthetic rubber by Angier and Watson.[64] They found evidence of the

formation of interpolymers using natural rubber, polychloroprene, butadiene

styrene rubber, and butadieneacrylonitrile copolymers. This presumably

occurs by the mechanism:

RR0!R R0SS0!S S0R

S!RSR

SS0!SS0jR

S RR0!RR0j

S

(VI)

GRAFT POLYMERIZATION IN MONOMER SOLUTIONS

AND HIGH-IMPACT POLYSTYRENE

Researchers reported studies of polymerization of monomers in polymer

solutions as early as in the 1920s. Usually, the polymer was natural rubber.

Ostromislensky[65] described in a 1927 patent the polymerization of styrene

in a natural rubber solution of styrene producing a tough white polymer.

Amos[66] roughly 20 years later reproduced Ostromislenskys experiment and

found the polymer to be insoluble. This clearly indicated that the polymerizing

styrene had reacted with the natural rubber and the product was cross-linked.

Associated with the development of butadienestyrene synthetic rubber

(BunaS, GR-S, SBR), extensive styrene production facilities came into

existence in the late 1930s and early 1940s. It was an inexpensive polymeriz-

able monomer. However, its products were rigid and brittle, and their

application was severely limited. From the mid 1940s, various chemical

companies, notably The American Dow Chemical,[60] made extensive inves-

tigations of rubber-modifying polystyrene. Other companies competing with

Dow were BASF (Germany), Distiller, Ltd. (UK), Monsanto (USA), and

Pechiney St. Gobain (France). These efforts involved, (1) mechanically mixing

SBRs of varying styrene content into polystyrene, (2) mixing lattices of

polystyrene and SBR, and (3) polymerizing styrene solutions of SBR.

The most successful process was the last, which was patented by Amos

and his coworkers of Dow Chemical.[67] This involved a monomer-grafting

process. There were many lawsuits and much litigation.[66] Investigations

of the rubber-modified polystyrene showed micron-scale rubber globules


containing smaller polystyrene particles. The polystyrene is both grafted to the

rubber and present as homopolymer.

Various other monomers were grafted onto polymers in solution in this

period. Merrett and Allen[68,69] investigated the reaction of methyl methacry-

late with masticated natural rubber in benzene solutions and showed the

occurrence of graft copolymer products.

BEGINNING OF REACTIVE EXTRUSION

Beginning in 1960, there were extensive efforts to develop continuous

screw extrusion-based processes for free radical grafting, using peroxides, to

attach monomers such as acrylic acid, methacrylic acid, and maleic acid onto

polyolefins and other polymer.[7082] These products were desirable because of

their superior adhesive characteristics to neat polyolefins. They are also

reactive polymers. In 1960, Nowak and Jones of Dow Chemical[70,71] filed

patents on grafting acrylic and methacrylic acid onto polyolefins. They used

single-screw extruder. In 1962, Zeitlin of Allied Chemical[72] filed a patent on

maleation of polyethylene and its copolymers. They also used a single screw

extruder. In 1963, Nowak[73] filed a patent on grafting acrylic and methacrylic

acids onto polyolefins. In this patent, they did not use peroxides. Instead, they

irradiated polyolefins such as polyethylene by high-speed electrons, before the

polymers were fed to a extruder. In 1968, Asahi Kasei[74] filed a patent on graft

copolymers of polyolefins and its production by single-screw extruders. They

used polypropylene and ethylenepropylene block copolymer as polymers,

lauryl methacrylate and n-butyl methacrylate as monomers, and dicumyl

peroxide as a peroxide.

A second generation of studies began in the 1970s. In 1972, Steinkamp

and Grail of Exxon[75] filed a patent on grafting acrylic acid onto polypropy-

lene in a single extruder. They used different configurations of a single-screw

extruder. Some configurations are clearly shown in the patent. In the same

year, Bartz et al.[76] of Exxon filed a patent on polyolefin graft copolymers. In

this patent, they referred the continuous production by single-screw extruders,

and the configurations were clearly shown in it. Ide and Sasaki of Mitsubishi

Rayon[77] filed a patent also in 1972 on grafting maleic anhydride and acrylic

acid onto polyolefins and polystyrene. In 1973, Stenmark and Heinrich[78] of

Exxon filed a patent on acrylic acid grafting onto polypropylene by single-

screw extruder. In 1974, Steinkamp and Grail,[79] filed a patent on grafting

various monomers onto polyolefins. This patent is very similar to their patent

filed in 1972.[75] In 1974, Zeitler et al.[80] of BASF filed a patent on acrylic

acid grafting onto polyethylene.


In 1972, Wu et al.[81] of Chemplex filed a patent on grafting of various

anhydrides and carboxylic acids onto polyolefins. They used a modular

corotating twin extruder. Presumably, this patent is the first use of a twin-

screw extruder for polymer-grafting reaction. Since this patent was filed, the

use of twin-screw extruders seemingly has dominated in this field. In 1973,

Caywood[82] of Du Pont filed a patent on grafting maleic anhydride onto

EPDM by twin-screw extruder.

In the 1980s, these activities continued but increasingly involved modular

twin-screw extruders, especially corotating machines rather than single-screw

extruder.

MODELING GRAFTING KINETICS

Kinetics studies of graft copolymerization seem to have first been carried

out about in 1960 in association with grafting monomers onto natural

rubber.[83] These kinetic schemes grew out of the work of Flory[19] and

Mayo.[28] The rate of chain transfer is ktr [P] [RMn], where [RMn] is theconcentration of the polymerizing radical species, and [P] is the solvent or

dead polymer. Mayo presumed a steady state on free radicals.

A new generation of investigations of the kinetics of grafting concerned

with high-impact polystyrene began in the 1970s. In 1975, Manaresi et al.[84]

proposed a kinetic scheme of styrene grafting onto cis-1,4-polybutadiene. In

their study, polybutadiene and peroxide were resolved in styrene, and poly-

merization was carried out. They assumed that radicals could be generated by

decomposition of initiator and thermal initiation of monomer, and initiator

radical attacks polymer chain to abstract hydrogen. They took into considera-

tion propagation of homopolymerization and graft polymerization, and chain

transfer to both monomer and polymer. In 1976, Kotaka[85] proposed a simpler

kinetic scheme for grafting reaction of vinyl monomer onto polydiene. In the

kinetics he proposed, radical could be generated only by decomposition of

initiator, and termination reactions consist of graft formation, cross-linking

and homopolymer formation. This has the form

1: Decomposition of initiator I!kd 2R2: Initiation

Radical attack on monomer R M!ki1 RM

Radical attack on polymer R P!ki2 P RH

Polymer radical attack P M!ki3 PM

on monomer


3: Propagation RM M!kp RMM !kp RMn

PM M!kp PMM !kp PMn

4: Termination (by combination)

Graft forming PMn RMm !

kt1PM(nm)R

Cross-linking PMn PMm !

kt2PM(nm)P

Homopolymer formation RMn RMm !

kt3RM(nm)R

(VII)

In the 1980s, kinetic analysis of grafting reaction of polyolefin, such as

polyethylene and polypropylene were proposed by many groups. In 1982 and

1983, Gaylord et al.[86,87] proposed the kinetic scheme for maleic anhydride

grafting onto polyethylene. Peroxide radicals attack polyethylene to generate a

PE macroradical. This macroradical might form cross-links or add maleic

anhydride. Maleic anhydride-attached PE radicals can also cause cross-linking

to yield higher molecular weight. The cross-linking reactions they proposed

were summarized as shown below.

P!R

P

P M!P M

P P!P P

P P M !P M P

P M P M !P M M P

(VIII)

Subsequently, Gaylord and Mishra[88] considered the kinetics of maleation of

polypropylene. They assumed that peroxide radicals attack this polymer to

abstract hydrogen. Maleic anhydride undergoes excitation due to the rapid

peroxide decomposition. Maleic anhydride excimer also abstracts hydrogen

from polypropylene. Then polypropylene macroradicals couple with maleic

anhydride and its excimer. In this case, cross-linking was not observed

experimentally. Rather, polypropylene undergoes degradation.

In 1995, Huang and Sundberg[89,90] studied grafting of styrene, methyl

acrylate, and methyl methacrylate monomers onto cis-polybutadiene and

proposed detailed kinetics. They classified the reactions as initiator dissocia-

tion, polymer chain initiation, graft site initiation, chain transfer reactions,

chain propagation reactions, and chain termination reactions. They presumed

that grafting site could be generated by hydrogen abstraction from polymer

chains by initiator radical, monomer radical, grafted polymer radical, and

solvent radical. In 1997, Kim and White[91] proposed more simplified kinetics


of polypropylene maleation. In their experiments, homopolymerization of

maleic anhydride was absent, because the temperature conditions were above

the ceiling temperature of this monomer.

More recently, Cha and White[92] made a careful investigation of the

kinetics of grafting various monomers onto polypropylene. They compared

experiments in a batch mixer and a twin-screw extruder. Generally, higher

levels of monomer incorporation occurred in the batch reactor than in the

twin-screw extruder. This was associated with inhibitors in the monomers,

which were killed by oxygen from the air in the batch reactor, but not in the

twin-screw extruder. The basic scheme of grafting copolymerization is

I!kd 2R

R P!ktr RH P

P M!kg PM

PM M!kp PMM

PMn PMm!

ktPM(nm)P

(IXa)

If there is homopolymerization, we must add

R M!kp RM

RMn M!kp RMn1

RMn R0Mm!

ktRMmnR

0

RMn PMm!

ktRMnmP

(IXb)

For the case of maleic anhydride, Cha and White[92] noted that in polyolefin

melt, kp 0.This led to

d[M ]dt

kg1 f

2 kdkt

s [I ]1=2 [M ] (9)

where

f [PM]

[P](10)

Cha and White[92] determined the rate constants experimentally.


Cha and White[93] also examined the kinetics of styrene grafting onto

polypropylene. Here, kp is not zero and one forms both homopolymer and

graft copolymer. The rate of monomer conversion in this case is

d[M ]dt

kg[M ] [P] kp[M ] [[PMn ] [RMm]] (11)

The value of the radical concentration comes from a balance over

initiation and destruction of radicals. The amount of monomer consumed by

chain polymerization in homopolymerization is considerably greater than in

grafting. They found Eq. (11) to become

d[M ]dt

kp 2 kdkt

s [I ]1=2 [M ] (12)

OTHER POLYMERS

Most research activities on grafting have involved poly-

olefins.[7082,8688,91134] However, studies of grafting have also been carried

out on other thermoplastics and elastomers. Some that involve polyisoprene

and polybutadiene are old and were discussed earlier. We summarize free

radical grafting of various polymers in Table 1. Of special interest are studies

for polyphenylene ether,[135145] polystyrene copolymers,[146148] acrylonitrile

butadienestyrene terpolymer,[149,150] polycarbonate,[151] and polyalkylene

terephthalates.[152154]

GRAFTING MULTIPLE MONOMERS

One of the problems of free radical grafting in reactive extrusion is the

inability of many monomers to react with themselves at the temperature

involved. Thus, grafting levels with monomers such as maleic anhydride and

acrylic acid are quite low. By using multiple monomers, it is possible to

incorporate quantities of poorly reactive monomers. This was proposed as

early as in 1972 by Steinkamp and Grail,[75] even though an example of dual

monomer grafting was not reported in their patent. This was subsequently

accomplished by Toyama et al.[135] in 1978. This patent was followed by

Binsack et al.,[98] Togo et al.,[116] and Andersen.[127] Typically, styrene was

used as a second monomer.


Table

1.

Method

Company

Person

Year

Reference

Polyethylene

Film

grafting

W.R.Grace

Thompsonand

Christoffels

1964

94

Single-screw

extruder

Dow

Nowak

andJones

1965

70

Single-screw

extruder

Dow

Jones

andNowak

1965

71

Ethylene-butene-1

copolymer

Single-screw

extruder

AlliedChem

ical

Zeitlin

1966

72

Single-screw

extruder

Dow

Nowak

1966

73

Ethylene-butene-1

copolymer

Single-screw

extruder

AlliedChem

ical

Anonymous

1969

95

HDPE,LDPE

Twin-screw

extruder

Chem

plex

Wuet

al.

1975

81

Extruder

MitsubishiRayon

IdeandSasaki

1977

77

Batch

reactor

Cham

pionInternational

Gaylord

1978

96

LDPE,HDPE

Batch

reactor

Gaylord

ResearchInst.

Gaylord

andEnder

1980

97

LDPE

Twin-screw

extruder

Bayer

Binsack

etal.

1981

98

Bayer

Korber

etal.

1982

99

Batch

reactor

General

Electric

GallucciandGoing

1982

100

Ethylene-butene-1

copolymer

Extruder

MitsubishiChem

ical

Ohmura

etal.

1982

101

Batch

reactor

Gaylord

ResearchInst.

Gaylord

1985

102

Ultrahighmolecular

Extruder

MitsuiPetrochem

ical

Motookaand

Mantoku

1986

103

HDPE

Twin-screw

extruder

Dow

TaborandAllen

1987

104


HDPE

Twin-screw

extruder

Mitsubishi

Petrochem

ical

Inoueet

al.

1987

105

Twin-screw

extruder

Dow

Straitet

al.

1988

106

Twin-screw

extruder

Stamicarbon

Vroomans

1988

107

Batch

reactor

Gaylord

ResearchInst.

Gaylord

andMetha

1988

108

Batch

reactor

QueensUniv.

Sim

monsandBaker

1989

109

LLDPE,HDPE

Twin-screw

extruder

DuPont

Wong

1989

110

HDPE

Twin-screw

extruder

Univ.ofAkron

Sam

ayet

al.

1995

111

Polypropylene

Single-screw

extruder

Dow

Nowak

andJones

1965

70

Single-screw

extruder

AsahiKasai

Anonymous

1970

74

Single-screw

extruder

Exxon

Steinkam

pandGail

1975

75

Single-screw

extruder

Exxon

Bartz

etal.

1975

76

Extruder

MitsubishiRayon

IdeandSasaki

1977

77

Single-screw

extruder

Exxon

Stenmarkand

Heinrich

1975

78

Single-screw

extruder

Exxon

Steinkam

pandGail

1976

79

Extruder

Ube

Ogiharaet

al.

1977

112

Extruder

ToaNenryo

Yam

amoto

etal.

1979

113

Twin-screw

extruder

CentreNational

Michel

1984

114

Batch

reactor

Gaylord

ResearchInst.

Gaylord

1985

102

Montedison

Clementiniand

Spagnoli

1986

115

Batch

reactor

Gaylord

ResearchInst.

Gaylord

andMetha

1988

108

Twin-screw

extruder

MitsubishiGas

Chem

ical

Togoet

al.

1988

116

(continued)


Table

1.

Continued.

Method

Company

Person

Year

Reference

Batch

reactor

StabdardOil

ShyuandWoodhead

1988

117

Extruder

ChiangandYang

1988

118

Twin-screw

extruder

DuPont

Wong

1989

110

Extruder

HoechstCelanese

Chen

etal.

1992

119

Twin-screw

extruder

InstitutCharlesSadron

Cartier

andHu

1998

120

Twin-screw

extruder

Univ.ofAkron

ChaandWhite

2002

121

Ethylene-propylenecopolymer

Single-screw

extruder

Dow

Nowak

andJones

1965

70

Single-screw

extruder

AsahiKasei

Anonymous

1970

74

Extruder

Ube

Ogiharaet

al.

1977

112

Extruder

ToaNenryo

Yam

amoto

etal.

1979

113

Twin-screw

extruder

Bayer

Binsack

etal.

1981

98

Twin-screw

extruder

Rohm

andHaas

Staas

1981

114

Batch

reactor

General

Electric

GallucciandGoing

1982

100

Batch

reactor

Gaylord

ResearchInst.

Gaylord

1985

102

Single-screw

extruder

Ube

Fukuiet

al.

1985

122

Batch

reactor

Gaylord

ResearchInst.

Greco

etal.

1989

123

Ethylene-propylene-

dienem

onomer

copolymer

Ethylene-propylene-

cyclic

dien

Twin-screw

extruder

Chem

plex

Wuet

al.

1975

81

Ethylene-propylene-

hexadiene

Twin-screw

extruder

DuPont

Caywood

1975

82


Ethylene-propylene-

1,5-hexadiene

Twin-screw

extruder

DuPont

Caywood

1977

124

DuPont

Epstein

1979

125

Twin-screw

extruder

Bayer

Binsack

etal.

1981

98

Twin-screw

extruder

Rohm

andHaas

Staas

1981

126

Ethylene-propylene-

dicyclopentadien

Twin-screw

extruder

Uniroyal

Andersen

1984

127

Batch

reactor

Gaylord

ResearchInst.

Gaylord

1985

102

Twin-screw

extruder

DuPont

Waggoner

1987

128

Batch

reactor

Gaylord

ResearchInst.

Gaylord

etal.

1987

129

Twin-screw

extruder

General

Electric

Phadke

1987

130

Extruder

SumitomoChem

ical

Nishio

etal.

1988

131

Twin-screw

extruder

Gaylord

ResearchInst.

Oostenbrinket

al.

1989

132

Polyethylenecopolymer

Ethylene=butyl

acrylate

copolymer,

Ethylene=vinyl

acetatecopolymer

Extruder

BASF

Zeitler

etal.

1976

80

Ethylene=vinylacetate

copolymer

Bayer

Korber

etal.

1982

99

Ethylene=methyl

acrylate

Batch

reactor

Gaylord

ResearchInst.

Gaylord

1985

102


copolymer

Twin-screw

extruder

Rohm

andHaas

Staas

1981

126


copolymer

Twin-screw

extruder

Bayer

Waniczek

1986

133

(continued)


Table

1.

Continued.

Method

Company

Person

Year

Reference

Ethylene=butylacrylate

copolymer

Twin-screw

extruder

Neste

Oy

Bergstrom

and

Palmgren

1987

134

Polyphenyleneether

Twin-screw

extruder

Asahi-Dow

Toyam

a1978

135

Single-screw

extruder

Asahi-Dow

Izaw

aet

al.

1979

136

Twin-screw

extruder

Asahi-Dow

Kasaharaet

al.

1982

137

Twin-screw

extruder

BASF

Taubitzet

al.

1987

138

Twin-screw

extruder

BASF

Taubitzet

al.

1987

139

Twin-screw

extruder

BASF

Taubitzet

al.

1987

140

Twin-screw

extruder

BASF

Taubitzet

al.

1988

141

Single-screw

extruder

Allied-Signal

Akkappeddiet

al.

1988

142

Twin-screw

extruder

General

Electric

Johnsonet

al.

1989

143

Twin-screw

extruder

BASF

Taubitzet

al.

1989

144

Twin-screw

extruder

BASF

Taubitzet

al.

1989

145


Polystyrenecopolymer

Styrene-isoprenecopolymer

Single-screw

extruder

Asahi

Saito

etal.

1981

146

SEBS

Twin-screw

extruder

ShellOil

Gergen

1986

147

Styrene-butadienecopolymer

Twin-screw

extruder

BASF

Taubitzet

al.

1988

148

Acrylonitrile-butadiene-styrene

terpolymer

Twin-screw

extruder

BASF

Taubitz

1988

149

Twin-screw

extruder

Borg

Warner

GrantandHowe

1988

150

Polycarbonate

Solution

General

Electric

Cantrill

1969

151

Polyalkyleneterephthalates

Polyethyleneterephthalate

Aqueoussolution

Kyoto

Univ.

Uchidaet

al.

1989

152

Polyethyleneterephthalate

Aqueoussolution

Kyoto

Univ.

Uchidaet

al.

1993

153

Polybutyleneterephthalate,

Polytrim

ethylene

terephthalate

Batch

reactor

Univ.ofAkron

SasakiandWhite

2003

154


Cha and White[121] studied the grafting of styrene and maleic anhydride

onto polypropylene and styrene and methyl methacrylate onto polypropylene.

They showed the increase in styrene and methyl methacrylate contents in the

resulting grafted polypropylene by introducing styrene. Cha and White[121]

developed a kinetic scheme for the addition of two monomers during a

grafting reaction. They derived an expression regarding the ratio of grafting

of monomer 1 [M1], and monomer 2 [M2];

d[M2]

d[M1]

(kg2=kp21) (2kd kt [I ]

p kp22[M2] kp21[M1])=kg2[M2][M2]=[M1] r2[M2]=[M1] 1

(kg1=kp21) (2kd kt [I ]

p kp22[M2] kp21[M1])=kg2[M2] r1[M1]=[M2] 1

(13)

CONCLUSIONS

We have sought to review free radical graft polymerization in the contest

in a broader review of free radical polymerization. We recognize the various

stages of this development including grafting onto natural rubber, polymeriz-

ing styrene solution of elastomer, and reactive extrusion of polyolefins.

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