5 Alkyl Substituted Poly (Phenylene Oxides) Including PPO

Alkyl Substituted Poly(pheny1ene oxides) including PPO



r



/R,



587



1



In 1965 the poly-(2,6-dimethyl-p-phenylene

ether) was introduced as polyphenylene oxide (misleadingly!) and also as PPO by the General Electric Co. in

the USA and by AKU in Holland. The commercial materials had a molecular

weight of 25 000-60 000.

Using the processes described above, complex products are obtained if a

monosubstituted phenol is used instead of a 2,6-substituted material. However,

by using as the amine4 a 2-disubstituted pyridine such as 2-amylpyridine, more

linear and, subsequently, useful polymers may be obtained.



oxide)

21.5.1 Structure and Properties of Poly-(2,6-dimethyl-p-phenylene

(PPO)

The rigid structure of the polymer molecule leads to a material with a high Tg of

208°C. There is also a secondary transition at -116°C and the small molecular

motions that this facilitates at room temperature give the polymer in the mass a

reasonable degree of toughness.

When polymerised the polymer is crystalline but has a surprisingly low

reported melting point (T,) of 257°C. The ratio T,/T, of 0.91 (in terms of K) is

uniquely high. Because of the small difference in Tg and T, there is little time for

crystallisation to occur on cooling from the melt and processed polymer is

usually amorphous. However, if molecular movements are facilitated by raising

the temperature or by the presence of solvents, crystallisation can occur.

The solubility parameter is in the range 18.4-19MPa’” and the polymer is

predictably dissolved by halogenated and aromatic hydrocarbons of similar

solubility parameter. Stress cracking can occur with some liquids.

Being only lightly polar and well below the Tg at common ambient

temperatures the polymer is an excellent electrical insulator even at high

frequencies.

The commercial polymers are of comparatively low molecular weight (E =

25 000-60 000) and whilst being essentially linear may contain a few branches or

cross-links arising out of thermal oxidation. Exposure to ultraviolet light’ causes

a rapid increase in gel content, whilst heating in an oven at 125°C causes gelation

only after an induction period of about 1000 hours. For outdoor applications it is

necessary to incorporate carbon black. The polymers, however, exhibit very good

hydrolytic stability.



m

4%

4

aQ



5



m



f



m



S



E



a



x v i



m

c)



09



m



m



X



Ei



x

I



'I

I



I

n



x



k



e



Alkyl Substituted Poly(pheny1ene oxides) including PPO



589



One particular feature of PPO is its exceptional dimensional stability amongst

the so-called engineering plastics. It has a low coefficient of thermal expansion,

low moulding shrinkage and low water absorption, thus enabling moulding to

close tolerances.

Typical properties of PPO are given in Table 21 . I .



21.5.2 Processing and Application of PPO

Since PPO has a high heat distortion temperature (deflection temperature under

load) it is not surprising that high processing temperatures are necessary.637

Typical cylinder temperatures are about 280-330°C and mould temperatures

100-250°C. If overheated the material oxidises, resulting in poor finish and

streakiness. Because of this it is advisable to purge machines before they are

cooled down after moulding. The melts of PPO are almost Newtonian, viscosity

being almost independent of shear rate.

PPO forms one of a group of rigid, heat-resistant, more-or-less selfextinguishing polymers with a good electrical and chemical resistance, low water

absorption and very good dimensional stability. This has led to a number of

applications in television such as tuner strips, microwave insulation components

and transformer housings. The excellent hydrolytic stability has also led to

applications in water distribution and water treatment applications such as in

pumps, water meters, sprinkler systems and hot water tanks. It is also used in

valves of drink vending machines.

Unfortunately for PPO its price is too great to justify more than very restricted

application and this led to the introduction of the related and cheaper Noryl

materials in 1966 by the General Electric Corporation. These will be discussed in

the next section. In recent years the only sources of unmodified PPO have been

the USSR (Aryloxa) and Poland (Biapen).



21.5.3 Blends Based in Polyphenylene Oxides (Modified PPOs)

If poly-(2,6-dimethyl-p-phenylene

oxide) (Tg208°C) is blended with polystyrene

(Tgc. 90°C) in equal quantities a transparent polymer is obtained which by

calorimetric and dielectric loss analysis indicates a single Tg of about 150°C.

Such results indicate a molecular level of mixing but this view is somewhat

disturbed by the observation of two transitions when measured by dynamical

methods.*These results lead to the conclusion that although the degree of mixing

is good it is not at a segmental level. Since both polystyrene and the poly(2,6-dimethyl-p-phenylene

oxide) have similar secondary transitions at about

116°C the blends also show this transition. In the case of the main Tg this tends

to vary in rough proportion to the ratio of the two polymers. Since the electrical

properties of the two polymers are very similar the blends also have similar

electrical characteristics. Since polystyrene has a much lower viscosity than the

phenylene oxide polymer at the processing temperatures relevant to the latter the

viscosity of the blends is reduced at these temperatures when compared to the

polyphenylene oxide resin. Like polystyrene but unlike PPO the blends are

highly pseudoplastic, the apparent viscosities falling with increased rates of

shear.

Although the first commercial modified PPOs may be considered as derived

from such PPO-polystyrene blends, today three distinct classes of material can

be recognised:



590 Other Thermoplastics Containing p-Phenylene Groups



(1) Blends of PPO with a styrenic material, usually, but not always, high-impact

polystyrene. (Referred to below as Styrenic PPOs.)

( 2 ) Blends of PPO with polyamides. (Referred to below as polyamide PPOs.)

(3) Other blends such as with poly(buty1ene terephthalate) and poly(pheny1ene

sulphide) which are niche materials not further discussed in this chapter.



21.5.4 Styrenic PPOs

By 1994 there were over 60 grades of Noryl and in addition a number of

competitive materials. In Japan, Asahi Glass introduced Xyron in the late 1970s

and Mitsubishi introduced Diamar in 1983. More recently, BASF have marketed

Luranyl and Huls introduced Vestoran. By 1996 three further Japanese suppliers

came on stream. In the late 1990s global capacity was of the order of

320 000 t.p.a. Although this figure probably also includes the more specialised

polyamide PPOs discussed later, the Styrenic PPOs are clearly significant

materials amongst the so-called engineering polymers.

Like polystyrene these blends have the following useful characteristic^:^

(1) Good dimensional stability (and low moulding shrinkage)-thus allowing

the production of mouldings with close dimensional tolerances.

( 2 ) Low water absorption.

( 3 ) Excellent resistance to hydrolysis.

(4) Very good dielectric properties over a wide range of temperature.

In addition, unlike polystyrene:



(5) They have heat distortion temperatures above the boiling point of water, and

in some grades this is as high as 160°C.

The range of blends now available comprises a broad spectrum of materials

superior in many respects, particularly heat deformation resistance, to the general

purpose thermoplastics but at a lower price than the more heat-resistant materials

such as the polycarbonates, polyphenylene sulphides and polysulphones. At the

present time the materials that come closest to them in properties are the ABS/

polycarbonate blends. Some typical properties are given in Table 21 . I ,

In common with other 'engineering thermoplastics' there are four main groups

of modified PPOs available. They are:

( 1 ) Non-self-extinguishing grades with a heat distortion temperature in the range



110-160°C and with a notched Izod impact strength of 200-500 J/m.

( 2 ) Self-extinguishing grades with slightly lower heat distortion temperatures

and impact strengths.

(3) Non-self-extinguishing glass-reinforced grades (10, 20, 30% glass fibre)

with heat distortion temperatures in the range of 120-140°C.

(4) Self-extinguishing glass-reinforced grades.

Amongst the special grades that should be mentioned are those containing blowing

agents for use in the manufacture of structural foams (see Chapter 16).

Modified polyphenylene oxides may be extruded, injection moulded and blow

moulded without undue difficulty. Predrying of granules is normally only

necessary where they have been stored under damp conditions or where an



Alkyl Substituted Poly(pheny1ene oxides) including PPO



59 1



optimum finish is required. As with other materials care must be taken to avoid

overheating and dead spots, whilst the machines must be sufficiently rugged and/

or with sufficiently powered heaters. Processing conditions depend on the grade

used but in injection moulding a typical melt temperature would be in the range

250-300°C.

The introduction of self-extinguishing, glass-reinforced and structural foam

grades has led to steady increase in the use of these materials in five main

application areas. These are:

(1) The automotive industry.

(2) The electrical industry.

(3) Radio and television

(4) Business machines and computer housings.

(5) Pumps and other plumbing applications.



Use in the automotive industries largely arises from the availability of highimpact grades with heat distortion temperatures above those of the general

purpose thermoplastics. Specific uses include instrument panels, steering column

cladding, central consoles, loudspeaker housings, ventilator grilles and nozzles

and parcel shelves. In cooling systems glass-reinforced grades have been used for

radiator and expansion tanks whilst several components of car heating systems

are now also produced from modified PPOs. The goods dimensional stability,

excellent dielectric properties and high heat distortion temperatures have also

been used in auto-electrical parts including cable connectors and bulb sockets.

The materials are also being increasingly used for car exterior trim such as air

inlet and outlet grilles and outer mirror housings.

In the electrical industry well-known applications include switch cabinets, fuse

boxes and housings for small motors, transformers and protective circuits.

Radio and television uses largely arise from the ability to produce components

with a high level of dimensional accuracy coupled with good dielectric

properties, high heat distortion temperatures and the availability of selfextinguishing grades. Specific uses include coil formers, picture tube deflection

yokes and insert card mountings.

Glass-reinforced grades have widely replaced metals in pumps and other

functional parts in washing equipment and central heating systems. In the

manufacture of business machine and computer housings structural foam

materials have found some use. Mouldings weighing as much as 50 kg have been

reported.

21.5.5



Processing of Styrenic PPOs



The processing of blends of an amorphous material (polystyrene) and a

crystalline material with a high melting point (PPO) reflects the nature of the

constituent materials. The processing is mainly by injection moulding, and the

major points to be considered when processing Noryl-type materials are:

(1) The low water absorption. Moulding can usually be undertaken without the



need for predrying the granules.

(2) The polymer has a good melt thermal stability. It is claimed that up to 100%

regrind may be used. Under correct processing conditions the polymers have

been shown to produce samples with little change in physical properties even

after seven regrinds.



592 Other Thermoplastics Containing p-Phenylene Groups



(3) For such a heat-resisting material, a modest enthalpy requirement to reach

the processing temperature of about 434 J. This also means that quite short

cooling cycles are possible.

(4) Melt temperatures depend on the grade of material used. One rule of thumb

is to use the formula ( H + 125)"C, where H is the heat deflection

temperature. Typical melt temperatures are in the range 250-290°C.

( 5 ) The melts, unlike unmodified PPO, are very pseudoplastic. At 280°C one

standard grade (Noryl 110) has a viscosity of 675Ns m-2 at 100 s-l but a

value of only 7 N s m-2 at 100 000 s-'. The flow depends considerably on the

grade but flow path ratios tend to be in the same range as for ABS

materials

(6) A low moulding shrinkage (0.005-0.007 cm/cm) in unfilled grades down to

about 0.002 cm/cm in 30% glass-fibre-filled grades.

(7) To reduce strains in mouldings, fairly high mould temperatures are

recommended ( 6 5 9 5 ° C in unfilled and up to 120°C in glass-filled

grades).



21.5.6 Polyamide PPOs

The blending of PPO and polyamides requires special grafting techniques to give

a good bond between the two polymers, as otherwise the two polymers are

incompatible. Whilst these polymers show the good dimensional stability and

toughness of styrenic PPOs, they also have



(1) Better heat resistance (Vicat softening points of 190-225°C).

(2) Better melt flow characteristics.

(3) Better resistance to many chemicals associated with the automobile industry.

This covers not only commonly used automobile fuels, oils and greases, but

detergents, alcohols, aliphatic and aromatic hydrocarbons and alkaline

chemicals.

As a consequence of these advantages, these blends are finding particular

application for car parts that can be painted on-line side by side with metals at

high temperatures.

Disadvantages include the following:

(1) The higher water absorption (typically 3.5% compared with about 0.3% at

saturation for a styrenic PPO).

(2) At the time of writing (1999) the best available flame retardance is to UL94

V I rating but the incandescent wire resistance of up to 960°C makes the

materials of interest in such electrical applications as plug and socket

containers.

Polyamide PPOs are manufactured by General Electric (Noryl GTX), BASF

having now withdrawn from marketing their product (Ultranyl). Usage of the

blends has so far been mainly in the automobile field for such applications as

valance panels, wheel trims, grilles, rear quarter panels, front bumpers and

tailgates.



21.5.7 Poly(2,6-Dibromo-1,4-Phenylene

Oxide)

The dibromo equivalent of PPO is commercially manufactured by Velsicol

Chemical Corporation under the trade name Firemaster. As the trade name



Polyphenylene Sulphides



593



suggests, the material is recommended as a fire retardant; in particular for glassreinforced nylons, thermoplastic polyesters and other engineering thermoplastics

requiring high processing temperatures and thus an additive with a high level of

thermal stability, a property shown by this polymer. With a bromine content of

63-65.5%, the commercial product has a high softening range of 200-230°C in

spite of a somewhat low molecular weight of about 3150. One consequence of

this low molecular weight is that it also appears to act as a flow promoter in

blends with engineering thermoplastics. This polymeric fire retardant, which has

a specific gravity of 2.07, is incorporated by melt blending.

21.6 POLYPHENYLENE SULPHIDES''

These materials have been prepared by polymerisation of p-halothiophenoxide

metal compounds both in the solid state and in solution. They have also been

prepared by condensation of p-dichlorobenzene with elemental sulphur in the

presence of sodium carbonate while the commercial polymers are said to be

produced by the reaction of p-dichlorobenzene with sodium sulphide in a polar

solvent.

The first commercial grades were introduced by Phillips Petroleum in 1968

under the trade name Ryton. These were of two types, a thermoplastic branched

polymer of very high viscosity which was processed by PTFE-type processes and

an initially linear polymer which could be processed by compression moulding,

including laminating with glass fibre, and which was subsequently oxidatively

cross-linked.

When introduced in Europe in 1973 the main emphasis was on moderate

molecular weight grades which could be injection moulded at 340 to 370°C and

then if desired cross-linked by air aging. In the moulding stage mould

temperatures of 25-40°C were said to give the greatest impact strength whilst a

high surface gloss is obtained at 120°C. Coating grades also became available.

With the expiry of the basic Phillips patents in 1985, other companies entered

the market so that in the early 1990s there were six producers. Besides Phillips,

these included Bayer (Tedur), Hoechst-Celanese (Fortron) and General Electric

(Supec). This has led to some overcapacity but production rose from about 10 000

tonnes in 1985 to about 35 000 tonnes in 1997. Such competition has stimulated the

production of improved grades of materials. In particular, many of the newer

grades are less branched than the early materials, making possible fibre forming,

production of biaxially stretched film and mouldings of improved impact

resistance. Newer grades also have a much lower level of ionic contaminants. At

the same time that the newer grades of PPS were being introduced, Phillips also

produced some interesting related amorphous polymers.

Whilst the properties of poly(pheny1ene sulphides) vary between grades,

particularly because of varying molecular linearity and presence of contaminants,

they generally show the following special characteristics:

Heat resistance (for a thermoplastics material).

Flame resistance.

Chemical resistance, although surpassed by some other polymers such as

PTFE.

Electrical insulation characteristics, although also surpassed by some other

polymers such as PTFE and polyethylene.



594 Other Thermoplastics Containing p-Phenylene Groups

The linear polymers are highly crystalline, with T, in the range 285-295°C.

Quoted values for the Tg range from 85°C to 150°C. Unfilled materials have

rather low heat deflection temperatures but filled grades can have values in

excess of 260°C. This is in line with common experience that the deflection

temperatures of unfilled crystalline polymers are close to the glass transition

temperature, whilst the deflection temperatures of fibre-filled polymers are closer

to the T,. The US Underwriters Laboratories have awarded PPS grades

temperature indices as high as 240°C-the highest ratings awarded to date to a

commercial thermoplastics material. Thermogravimetric analysis shows no

noticeable weight loss either in nitrogen or oxygen at temperatures below

500°C.

The resistance to burning is also very good indeed, this being reflected by

oxygen indices as high as 53% and Underwriters Laboratories 94 V-0 and 94-5V

classifications without the use of additives. The UL94 V-0 ratings are achieved

with minimum wall thicknesses as low as 0.4mm, putting the material into a

highly select class that includes the polyethersulphones, the polyester liquid

crystal polymers, the polyketones and the polyetherimides.

Outstandingly, all the grades of at least one manufacturer pass the demanding

glow wire test at 960°C at 3.2mm.

In addition to the inherent flame resistance, the polymers are also interesting

because of the low smoke generation and low levels of toxic and corrosive

emissions when exposed to fire.

The chemical resistance of the linear polymers is also very good. Resistant to

most acids, aqueous bases, hydrocarbons, most halogenated hydrocarbons,

alcohols and phenols, they are attacked by concentrated sulphuric acid, formic

acid, some amines, benzaldehyde, nitromethane and a few other reagents. They

will dissolve in 1-chloronaphthaleneat elevated temperatures but in general have

excellent solvent resistance. The polymer is cross-linked by air oxidation at

elevated temperatures.

Typical properties of poly(pheny1ene sulphides) are shown in Table 21.2.

Whilst rigidity and tensile strength are similar to those of other engineering

Table 21.2 Typical properties of injection moulded PPS, PAS-1 and PAS-2 thermoplastics

I



Property



I

I



I



Units



I



I



I



%



MPa

Jlm

Jlm

YO



ohm.cm



-



%

%

I



pps

85

135

64-17

33

3

3900

320

20

44

3.1

0.004

2.5 X 10l6



"C

"C

MPa

MPa



T,

Heat distortion temp. (Method A)

Tensile strength (21°C)

(204°C)

Elongation at break

Flexural modulus

Izod impact (unnotched)

(notched)

Limiting oxygen index

Dielectric constant (103-106Hz)

Dissipation factor (1 kHz)

Volume resistivity

Water absorption 24 h

Saturation at 23°C



PPSIGF



I



PAS-I



(60140)

-



265

150

33

2

10 500

350

-



47

3.8

0.0037

0.01

1.01



PAS-2



145

170



I1



215

190

92



-



-



3400

223

21

46



>10

3200

1200

50

46



-



-



-



-



-



-



-



-



Polyphenylene Sulphides



595



plastics, the poly(pheny1ene sulphides) do not possess the toughness of

amorphous materials such as the polycarbonates and the polysulphones and are

indeed somewhat brittle. On the other hand they do show a good level of

resistance to environmental stress cracking.

The unfilled grades are of little importance, with the following filled grades

being of commercial interest:

(1) Glass-reinforced grades (at 30 and 40% glass content loading).

(2) Glass-fibre/particulate-mineral-filled

grades. These may offer cost savings

and in some cases give the highest temperature ratings. Arc and tracking

resistance, somewhat limited as with most aromatic polymers, is greatest

with these grades, although with some loss in volume resistivity and

dielectric strength.

(3) Glass-fibre/mineral-filled colour compounds.

(4) Carbon-fibre-reinforced grades. These are useful because of their high tensile

strength and rigidity, improved EM1 shielding and static electricity

dissipation. They are also more effective than glass fibre in reducing the

coefficient of friction against steel.

(5) Lubricated fibre-filled grades containing, typically, 15% of PTFE and

occasionally about 2% of a silicone. These materials yield very high PV

values (see Chapter 19), with published data indicating PV values of 30000

(using the units of Chapter 19) at surface velocities of 1OOOfpm. These

figures appear to be better than for any other engineering thermoplastic

material.

The heat and flame resistance coupled with good electrical insulation

characteristics, which includes in some grades good arcing and arc tracking

resistance, has led to PPS replacing some of the older thermosets in electrical

parts. These include connectors, coil formers, bobbins, terminal blocks, relay

components, moulded bulb sockets for electric power station control panels,

brush holders, motor housings, thermostat parts and switch components.

In the industrial mechanical field PPS was soon established for use in chemical

processing plant such as gear pumps. More recently it has found application in

the automotive sector as a result of its ability to resist corrosive engine exhaust

gases, ethylene glycol and petrol (gasoline). Specific uses include exhaust gas

return valves to control pollution, carburettor parts, ignition plates and flow

control valves for heating systems.

The material also finds use in cooking appliances, sterilisable medical, dental

and general laboratory equipment, and hair dryer components.

Compared with other glass-reinforced thermoplastics, PPS materials are

generally considered as showing good processability. Easy-flow properties at

processing temperatures with flow path ratios of the order of 150 allow thin-wall

sections to be produced. It is a consequence of such easy-flow behaviour that

care has to be taken to minimise mould flashing and this had led to marketing of

‘low-flash’ grades. Furthermore, as shown in Table 8.1, the amount of heat

required to be removed before an injection moulding can be extracted from a

mould is quite low and this makes possible short cycle times.

Typical melt temperatures are in the range 300-360°C (e.g. 320°C). Mould

temperatures are usually about 135°C in order to optimise the amount of

crystallinity and hence give mouldings of greatest stiffness, dimensional stability,

thermal stability and surface finish. It is, however, possible to use relatively cold



596 Other Thermoplastics Containing p-Phenylene Groups

moulds, as low as 30”C, to reduce crystallinity to yield products of higher

toughness and durability but with lower heat resistance and with a matt surface

finish.

The thermosetting materials are said to be initially linear but are cross-linked

by heating in air to a temperature of at least 345°C. It is claimed that they have

a useful working range up to 3 15°C. The materials may be used in compression

mouldings powders, as the binder resin in glass cloth laminates and as the

polymer base in heat-resistant metal coatings.



21.6.1. Amorphous Polyarylene Sulphides

The Phillips Corporation have recently introduced interesting copolymers related

to PPS. In addition to the use of p-dichlorobenzene and Na,S,, a second aromatic

dichloro compound is used. For the marketed material PAS-2 this is 4,4’dichlorodiphenylsulphone whilst for the developmental products PAS- 1 and

PAS-B the compounds are 4,4’-dichlorodiphenyl and 4,4’-dichlorodiphenylketone. Each of these copolymers is amorphous, so that a high heat deformation

resistance requires a high value for Tg,

PAS-2 is particularly notable for its high level of chemical and hydrolysis

resistance in addition to a Tg of 215°C. Some typical properties of the copolymers

PAS-1 and PAS-2 are given in Table 21.2 in comparison with data for PPS.

2 1.7 POLYSULPHONES

Although it is somewhat of an oversimplification, the polysulphones are best

considered as a group of materials similar to the aromatic polycarbonates but

which are able to withstand more rigorous conditions of use. Because of their

higher price they are only considered when polycarbonates or other cheaper

polymers are unsuitable.

The simplest aromatic polysulphone, poly-@-phenylene sulphone) (formula I

of Table 21.3) does not show thermoplastic behaviour, melting with decomposition above 500°C. Hence in order to obtain a material capable of being processed

on conventional equipment the polymer chain is made more flexible by

incorporating ether links into the backbone.

The first commercial polymer (Table 21.3, 11) was offered in 1965 by Union

Carbide as Bakelite Polysulfone, now renamed Udel. In 1967 Minnesota Mining

and Manufacturing introduced Astrel 360 (Table 21.3, V), which they referred to

as a polyarylsulfone. In 1972 IC1 brought a third material onto the market which

they called a polyethersulphone (111) and which they then marketed as Victrex.

They also introduced a material intermediate between I11 and V known as

Polyethersulphone 720P (IV) but which has now been withdrawn. In the late

1970s Union Carbide introduced Radel (VI), which has a higher level of

toughness. Around 1986 Union Carbide sold their interest in polysulphones to

Amoco. In addition the Astrel materials were produced by Carborundum under

licence from ICI.

In 1992 IC1 withdrew from the polysulphone market, with BASF (Ultrason)

joining Amoco as manufacturers whilst a small plant operated by Sumitomo was

due to come on stream in the mid-1990s.

It will be seen that by varying the degree of spacing between the p-phenylene

groups a series of polymers may be obtained with a spectrum of Tgs, which



Polysulphones 597

Table 21.3 Aromatic polysulphones



-



Tyre



rrade name



Tg (“C)



I



-



(melts with

decomposition

above 500°C)



-@so:-



190



Udel



11

1



230



Victrex



IV



250



Polyethersulphone



I1

CH,



720P

285



V



VI



Astrel 260



Radel



-



determine the heat distortion temperature (or deflection temperature under load,

since the materials are also amorphous). It is also to be noted that all of the

commercial materials mentioned above may be described as polysulphones,

polyarylsulphones, polyether sulphones or polyaryl ether sulphones.

In principle there are two main routes to the preparation of polysulphones:

(1) Polyetherification.

( 2 ) Polysulphonylation.



In the polyetherification route the condensation reaction proceeds by reactions

of types (1) and ( 2 ) where M is an alkali metal and X a halide.

(1) MO-Ar-OM

(2) MO-Ar-X



+ XAr’X -+ -(-0-Ar-0-Ar‘-)-+ -0Ar+ MX



+ MX



The Ar and/or Ar‘ group(s) will contain sulphone groups and if Ar = Ar‘ then

identical products may be obtained by the two routes. Polyetherification

processes form the basis of current commercial polysulphone production

methods. These will be discussed further below.

Polysulphonylation reactions are of the following general types:

H-Ar-H



Friedel-Crafts



+ C1-SO2*Ar‘-SOZCl



H*Ar*SO2*C1 -ArS02+



+ HCl



Catalyst



-Ar*S02-Ar’-SOz-



+ HC1