POLYMERIC MATERIALS
This invention relates to polymeric materials. Preferred embodiments relate to thermoplastic
composites comprising polymeric materials for use, for example, in the composites industry.
There is a wide range of thermoplastic polymeric material available for use in industry, either
alone or as part of composite materials. However, industry is constantly demanding materials
with properties which are improved in at least some respect over existing materials.
Polyphenylene sulphide (PPS) is a known polymeric material with a relatively low melting
temperature (Tm) of 290°C; however its glass transition temperature (Tg) is 85°C to 100°C
which is too low for some applications. On the other hand, polyetheretherketone (PEEK) has a
suitable Tg of 143°C but its Tm of 343°C is much higher than desirable.
It is an object of the present invention to provide a polymeric material which has a relatively
low Tm (comparable to that of PPS) but which has a higher Tg, closer to that of PEEK.
This invention is based upon the discovery of repeat units which can be combined with other
specified repeat units to produce copolymers which have advantageous properties, particularly
in terms of their glass transition temperatures (Tg) and melting temperatures (Tm).
It is an object of preferred embodiments of the present invention to address the above
described problem.
It is an object of preferred embodiments of the invention to provide advantageous polymeric
materials for example for use in composite materials.
According to a first aspect of the invention, there is provided a polymeric material having a
repeat unit of formula
-X-Ph-(X-Ph-) nX-Ph-CO-Ph- I
and a repeat unit of formula
-X-Y-W-Ph-Z- II
wherein Ph represents a phenyl moiety; each X independently represents an oxygen or
sulphur atom; n represents an integer of 1 or 2 ; Y is selected from a phenyl moiety, a -Ph-Phmoiety
and a naphthalenyl moiety; W is a carbonyl group, an oxygen or sulphur atom, Z is
selected from
-X-Ph-S0 2-Ph-
-X-Ph-S02-Y-S02-Ph- and
-CO-Ph-;
said polymeric material having a Tm of less than 298°C.
The phenyl moieties in each repeat unit may independently have 1,4- linkages to atoms to
which they are bonded or 1,3- linkages. Where a phenyl moiety includes 1,3- linkages, the
moiety will be in amorphous phases of the polymer. Crystalline phases will include phenyl
moieties with 1,4- linkages. In many situations it is preferred for the polymeric material to be
crystalline and, accordingly, said polymeric material preferably includes phenyl moieties with
1,4- linkages.
In a preferred embodiment, each Ph moiety in the repeat unit of formula I has 1,4- linkages to
moieties to which it is bonded.
In a preferred embodiment, each Ph moiety in the repeat unit of formula I I has 1,4- linkages to
moieties to which it is bonded.
In repeat unit I , each X preferably represents an oxygen atom.
Preferably, n represents 1.
In repeat unit I, preferably each phenyl moiety has 1,4- linkages to atoms to which it is bonded.
In repeat unit II , each X preferably represents an oxygen atom.
Preferably, Y is selected from a phenyl moiety and a -Ph-Ph- moiety, wherein each Ph moiety
in said -Ph-Ph- includes 1,4- linkages. More preferably, Y is a -Ph-Ph- moiety wherein each
phenyl moiety has 1,4- linkages.
Preferably, W represents an oxygen atom.
Preferably, Z is -CO-Ph-, suitably wherein Ph has 1,4- linkages.
In a preferred embodiment, said repeat unit of formula I has the structure:
and said repeat unit of formula II has the structure:
The level and extent of crystallinity in a polymer may be measured by wide angle X-ray
diffraction (also referred to as Wide Angle X-ray Scattering or WAXS), for example as
described by Blundell and Osborn (Polymer 24, 953, 1983). Alternatively, crystallinity may be
assessed by Differential Scanning Calorimetry (DSC) in a process such as the following which
is also described in POLYMER Vol. 37, Number 20, 1996, page 4573.
DSC may be used to examine an 8mg plus or minus 3mg sample of polymeric material in a TA
Instruments DSC Q 100 under nitrogen at a flow rate of 40ml/min. The scan procedure may be:
Step 1 Perform and record a preliminary thermal cycle by heating the sample from 30°C to
400°C at 20°C/min, recording the Tg, Tn and Tm.
Step 2 Hold for 2 mins
Step 3 Cool at 20°C/min to 30°C and hold for 5 mins. .
Step 4 Heat from 30°C to 400°C at 20°C/min, recording the Tg, Tn and Tm.
From the resulting curve the onset of the Tg may be obtained as the intersection of lines drawn
along the pre-transition baseline and a line drawn along the greatest slope obtained during the
transition. The Tn is the temperature at which the main peak of the cold crystallisation
exotherm reaches a maximum. The Tm is the temperature at which the main peak of the
melting endotherm reaches a maximum. The Tc is the temperature at which the main peak of
the crystallisation from the melt exotherm reaches a maximum.
The Heat of Fusion (D H (J/g)) may be obtained by connecting the two points at which the
melting endotherm deviates from the relatively straight baseline. The integrated area under the
endotherm as a function of time yields the enthalpy (mJ) of the transition, the mass normalised
Heat of Fusion is calculated by dividing the enthalpy by the mass of the specimen (J/g). The
level of crystallisation (%) is determined by dividing the Heat of Fusion of the specimen by the
Heat of Fusion of a totally crystalline polymer, which for polyetheretherketone is 130J/g.
The aforementioned methods provide the level of crystallinity in a bulk sample. As an
alternative, FTIR may be used to assess crystallinity and this may be used to assess the level
of crystallinity at a surface and/or across the thickness or surface of a sample. Reference is
made to a paper titled "Crystallinity in Poly(Aryl-Ether-Ketone) Plaques Studied by Multiple
Internal Reflection Spectroscopy" (Polymer Bull, V\_, 433 ( 1984)).
In a preferred embodiment, DSC may be used to measure crystallinity of a bulk sample. FTIR
may be used to measure crystallinity at a surface.
The Tm of said polymeric material may be less than 296°C, is suitably less than 293°C, is
preferably less than 290°C. In some embodiments, the Tm may be less than 287°C or less
than 285°C. The Tm may be greater than 270°C, or greater than 275°C, 280°C or 285°C. The
Tm is preferably in the range 280°C to 295°C.
The Tg of said polymeric material may be greater than 120°C, preferably greater than 130°C,
more preferably 133°C or greater. The Tg may be less than 175°C, less than 150°C, less than
140°C or less than 130°C. The Tg is preferably in the range 130°C to 140°C.
The difference (Tm-Tg) between the Tm and Tg may be at least 130°C, preferably at least
140°C, more preferably at least 150°C. The difference may be less than 170°C or less than
16 1°C. In a preferred embodiment, the difference is in the range 150-1 60°C.
In a preferred embodiment, said polymeric material has a Tg in the range 130°C-1 40°C, a Tm
in the range 285°C to 292°C and the difference between the Tm and Tg is in the range 150°C
to 16 1°C.
Said polymeric material may have a crystallinity measured by at least one of the methods
selected from WAXS, DSC or FTIR as described above of at least 10%, preferably at least
20%, more preferably at least 25%. The crystallinity may be less than 50% or less than 40%.
Said polymeric material suitably has a melt viscosity (MV) of at least 0.06 kNsm 2 , preferably
has a MV of at least 0.08 kNsm 2 , more preferably at least 0.085 kNsm 2 , especially at least
0.09 kNsm 2 . MV is suitably measured using capillary rheometry operating at 400°C at a shear
rate of 1000s 1 using a tungsten carbide die, 0.5mm x 3 .175mm. Said polymeric material may
have a MV of less than 1.00 kNsm 2 , suitably less than 0.5
kNsm 2 .
Said polymeric material may have a tensile strength, measured in accordance with ASTM
D790 of at least 40 MPa, preferably at least 60 MPa, more preferably at least 80 MPa. The
tensile strength is preferably in the range 80-1 10 MPa, more preferably in the range 80-1 00
MPa.
Said polymeric material may have a flexural strength, measured in accordance with ASTM
D790 of at least 145 MPa. The flexural strength is preferably in the range 145-1 80 MPa, more
preferably in the range 145-1 65 MPa.
Said polymeric material may have a flexural modulus, measured in accordance with ASTM
D790, of at least 2 GPa, preferably at least 3GPa, more preferably at least 3.5 GPa. The
flexural modulus is preferably in the range 3.5-4.5 GPa, more preferably in the range 3.5-4. 1
GPa.
Said polymeric material may include at least 50mol%, preferably at least 60mol%, more
preferably at least 65mol%, especially at least 70mol% of repeat units of formula I. Particular
advantageous polymeric materials may include at least 72mol%, or, especially, at least
74mol% of repeat units of formula I. Said polymeric material may include less than 85 mole%,
suitably 80mol% or less of repeat units of formula I . Said polymeric material may include 68 to
82 mole%, preferably 70 to 80mol%, more preferably 72 to 77mol% of units of formula I.
Said polymeric material may include at least 15mol%, preferably at least 20mol%, of repeat
units of formula I I . Said polymeric material may include less than 50mol%, preferably less than
40mol%, more preferably less than 35mol%, especially less than 30mol% of repeat units of
formula I I . Particularly advantageous polymeric materials may include 28mol% or less; or
26mol% or less. Said polymeric material may include 18 to 32mol%, preferably 20 to 30mol%,
more preferably 23 to 28mol% of units of formula II .
The sum of the mole% of units of formula I and I I in said polymeric material is suitably at least
95mol%, is preferably at least 98mol%, is more preferably at least 99mol% and , especially, is
about 100mol%.
The ratio defined as the mole% of units of formula I divided by the mole% of units of formula I I
may be in the range 1.8 to 5.6, is suitably in the range 2.3 to 4 and is preferably in the range
2.6 to 3.3.
Said polymeric material may be part of a composition which may include said polymeric
material and a filler means. Said filler means may include a fibrous filler or a non-fibrous filler.
Said filler means may include both a fibrous filler and a non-fibrous filler.
A said fibrous filler may be continuous or discontinuous.
A said fibrous filler may be selected from inorganic fibrous materials, non-melting and highmelting
organic fibrous materials, such as aramid fibres, and carbon fibre.
A said fibrous filler may be selected from glass fibre, carbon fibre, asbestos fibre, silica fibre,
alumina fibre, zirconia fibre, boron nitride fibre, silicon nitride fibre, boron fibre, fluorocarbon
resin fibre and potassium titanate fibre. Preferred fibrous fillers are glass fibre and carbon
fibre.
A fibrous filler may comprise nanofibres.
A said non-fibrous filler may be selected from mica, silica, talc, alumina, kaolin, calcium sulfate,
calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron
oxide, quartz powder, magnesium carbonate, fluorocarbon resin, graphite, carbon powder,
nanotubes and barium sulfate. The non-fibrous fillers may be introduced in the form of powder
or flaky particles.
Said composition may define a composite material which could be prepared as described in
Impregnation Techniques for Thermoplastic Matrix Composites. A Miller and A G Gibson,
Polymer & Polymer Composites 4(7), 459 - 481 ( 1996), EP1 02 158 and EP1 02 159, the
contents of which are incorporated herein by reference. Preferably, in the method , said
polymeric material and said filler means are mixed at an elevated temperature, suitably at a
temperature at or above the melting temperature of said polymeric material. Thus, suitably,
said polymeric material and filler means are mixed whilst the polymeric material is molten. Said
elevated temperature is suitably below the decomposition temperature of the polymeric
material. Said elevated temperature is preferably at or above the main peak of the melting
endotherm (Tm) for said polymeric material. Said elevated temperature is preferably at least
300°C. Advantageously, the molten polymeric material can readily wet the filler and/or
penetrate consolidated fillers, such as fibrous mats or woven fabrics, so the composite material
prepared comprises the polymeric material and filler means which is substantially uniformly
dispersed throughout the polymeric material.
The composite material may be prepared in a substantially continuous process. In this case
polymeric material and filler means may be constantly fed to a location wherein they are mixed
and heated . An example of such a continuous process is extrusion. Another example (which
may be particularly relevant wherein the filler means comprises a fibrous filler) involves
causing a continuous filamentous mass to move through a melt comprising said polymeric
material. The continuous filamentous mass may comprise a continuous length of fibrous filler
or, more preferably, a plurality of continuous filaments which have been consolidated at least
to some extent. The continuous fibrous mass may comprise a tow, roving, braid , woven fabric
or unwoven fabric. The filaments which make up the fibrous mass may be arranged
substantially uniformly or randomly within the mass. A composite material could be prepared
as described in PCT/GB2003/001 872.
Alternatively, the composite material may be prepared in a discontinuous process. In this case,
a predetermined amount of said polymeric material and a predetermined amount of said filler
means may be selected and contacted and a composite material prepared by causing the
polymeric material to melt and causing the polymeric material and filler means to mix to form a
substantially uniform composite material.
The composite material may be formed into a particulate form for example into pellets or
granules. Pellets or granules may have a maximum dimension of less than 10mm, preferably
less than 7.5mm, more preferably less than 5.0mm.
Preferably, said filler means comprises one or more fillers selected from glass fibre, carbon
fibre, carbon black and a fluorocarbon resin. More preferably, said filler means comprises
glass fibre or carbon fibre.
A composition or composite material as described may include 20 to 70 wt% of said polymeric
material and 30 to 80 wt% of filler means. Preferred embodiments include greater than 40
wt% of filler means.
The invention extends to a composite material as described per se.
The polymeric material of the first aspect may be made using an electrophilic route or a
nucleophilic route, but the nucleophilic route is preferred . In a preferred embodiment, the
method comprises polycondensing a compound of formula
with a compound of formula
and with one or more compounds arranged to generate moiety II,
wherein each R is selected from a chlorine and fluorine atom, R2 is selected from an alkali
metal and a hydrogen atom and R3 is selected from an alkali metal and a hydrogen atom.
Moiety I I may be generated by undertaking said polycondensation reaction in the presence of
additional monomers selected from groups (a) to (e) below:
( )
(e)
wherein each R4 is selected from a chlorine and a fluorine atom and each R5 is selected from a
chlorine and a fluorine atom.
Preferably, substantially the only monomers used in the method are those of formulas II I and
IV, together with said one or more compounds (a) to (e) arranged to generate moiety I I .
Suitably, the number of moles of monomers which include chlorine or fluorine atoms which are
polycondensed in the method are in slight molar excess over the number of moles of
monomers which include alkali metal or hydrogen end groups.
The method of making the polymeric material may be as described in EP1 879, mutatis
mutandis.
Any invention described herein may be combined with any aspect of any other invention or
embodiment described herein mutatis mutandis.
Specific embodiments of the invention will now be described, by way of example.
Polymers were prepared as described in Examples 1 to 8 and tested as described in Example
9 .
Example 1 - Preparation of polvetheretheretherketone (PEEEK)-polvetherdiphenyletherketone
(PEDEK) copolymer
A 0.5 litre flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet
and outlet was charged with 4,4'-difluorobenzophenone (89.03g, 0.408mole), 4,4'-
dihydroxydiphenylether (58.62g, 0.280mole), 4,4'-dihydroxybiphenyl (22.35g, 0 .120mole) and
diphenylsulphone (250g) and purged with nitrogen for over 1 hour. The contents were then
heated under a nitrogen blanket to 160°C to form an almost colourless solution. While
maintaining a nitrogen blanket, dried sodium carbonate (42.74g , 0.403mole) and potassium
carbonate (0. 14g , 0.001 mole) were added. The temperature was raised to 3 10°C at 1°C/min
and held for 60 minutes. The reaction mixture which was poured from the flask was viscous.
The reaction mixture was allowed to cool, milled and washed with acetone and water. The
resulting polymer was dried in an air oven at 120°C producing a powder. The polymer had a
melt viscosity at 400°C, l OOOsec of 0.36 kNsm 2.
Examples 2 to 8 - Preparation of other polvetheretheretherketone (PEEEK)-
polvetherdiphenyletherketone (PEDEK) copolymer
The procedure described in Example 1 was repeated except that the ratio of 4,4'-
dihydroxydiphenylether to 4,4'-dihydroxybiphenyl and the polymerisation times were varied to
provide polyetheretheretherketone (PEEEK) - polyetherdiphenyletherketone (PEDEK)
copolymers of different compositions and melt viscosities. The results are given in Table 1
below.
Example 9 - Preparation of polvetheretheretherketone (PEEEK)- polvetheretherethersulphone
(PEEES)-copolvmer
A 0.5 litre flanged flask fitted with a ground glass Quickfit lid, stirrer/stirrer guide, nitrogen inlet
and outlet was charged with 4,4'-difluorobenzophenone (71 .22g, 0.326mole), 4,4'-
dihydroxydiphenylether (80.89g, 0.400mole), 4,4'-dichlorodiphenylsulphone (23.43g ,
0.082mole) and diphenylsulphone (254g) and purged with nitrogen for over 1 hour. The
contents were then heated under a nitrogen blanket to 160°C to form an almost colourless
solution. While maintaining a nitrogen blanket, dried sodium carbonate (42.74g, 0.403mole)
and potassium carbonate (0. 14g, O.OOI mole) were added. The temperature was raised to
3 10°C at 1°C/min and held for 70 minutes. The reaction mixture which was poured from the
flask was viscous.
The reaction mixture was allowed to cool, milled and washed with acetone and water. The
resulting polymer was dried in an air oven at 120°C producing a powder. The polymer had a
melt viscosity at 400°C, l OOOsec 1 of 0.20 kNsm 2 . The polymer had Tg of 133°C, Tn of 194°C
(DHh of 0.92J/g), Tm of 294°C (AHm of 4 1.05J/g), and a crystallinity of 30.9%.
Table 1
Example 10 - Differential Scanning Colorimetry of Polyaryletherketones of Examples 1
to 9
The Glass Transition Temperature (Tg), the Cold Crystallisation Temperature (Tn), the Melting
Temperature (Tm) and Heat of Fusions of Nucleation (DHh ) and Melting (AHm) for the
Polyaryletherketones from Examples 1 to 8 were determined by Differential Scanning
Calorimetry.
A dried sample of each polymer was compression moulded into an amorphous film, by heating
7g of polymer in a mould at 400°C under a pressure of 50bar for 2 minutes, then quenching in
cold water producing a film of dimensions 120 x 120mm, with a thickness in the region of
0.20mm. A 8mg plus or minus 3mg sample of each film was scanned as follows:
Step 1 Perform and record a preliminary thermal cycle by heating the sample from 30°C
to 400°C at 20°C /min.
Step 2 Hold for 2 minutes.
Step 3 Cool at 20°C/min to 30°C and hold for 5mins.
Step 4 Heat from 30°C to 400°C at 20°C/min, recording the Tg, Tn, Tm, DHh and AHm.
From the resulting scan the onset of the Tg was obtained as the intersection of the lines drawn
along the pre-transition baseline and a line drawn along the greatest slope obtained during the
transition. The Tn was the temperature at which the main peak of the cold crystallisation
exotherm reaches a maximum. The Tm was the temperature at which the main peak of the
melting endotherm reach maximum.
The Heats of Fusion for Nucleation (DHh ) and Melting (AHm) were obtained by connecting the
two points at which the cold crystallisation and melting endotherm(s) deviate from the relatively
straight baseline. The integrated areas under the endotherms as a function of time yields the
enthalpy (mJ) of the particular transition, the mass normalised Heats of Fusion are calculated
by dividing the enthalpy by the mass of the specimen (J/g).
Results are provided in Table 2 .
Table 2
nd = not detected
Crystallinity (as reported in Table 2) may be assessed by several methods for example by
density, by ir spectroscopy, by x ray diffraction or by DSC. The DSC method has been used to
evaluate the crystallinity that developed in samples annealed at 300°C for 90 mins in a
nitrogen atmosphere. A heating rate of 20°C/min was used until a temperature of 450°C was
attained. A baseline was then constructed under the melting endotherm and the enclosed
area used to calculate the heat of fusion of the sample in joules/g. Assuming a heat of fusion
of 130 joules/g for the crystalline material present, the degree of crystallinity was calculated.
It will be appreciated that the polymers described in the Examples have low melting points,
high glass transition temperatures and high levels of crystallinity. They may therefore be
advantageously used in preparation of composites for aerospace (and other applications).
Composite materials may be made as described in Impregnation Techniques for
Thermoplastic Matrix Composites. A Miller and A G Gibson, Polymer & Polymer Composites
4(7), 459 - 481 ( 1996), Manufacture of high performance fibre reinforced thermoplastics by
aqueous powder impregnation. A M Vodermayer, J C Kaerger and G Hinrichsen. Composites
Manufacturing 4(3), 123-1 32 ( 1993), Thermoplastic Aromatic Polymer Composites, F N
Cogswell, EP1 021 58 and EP1 021 59.
The invention is not restricted to the details of the foregoing embodiment(s). The invention
extends to any novel one, or any novel combination, of the features disclosed in this
specification (including any accompanying claims, abstract and drawings), or to any novel one,
or any novel combination, of the steps of any method or process so disclosed.
Claims
1. A polymeric material having a repeat unit of formula
-X-Ph-(X-Ph-) nX-Ph-CO-Ph- I
and a repeat unit of formula
-X-Y-W-Ph-Z- II
wherein Ph represents a phenyl moiety; each X independently represents an oxygen or
sulphur atom; n represents an integer of 1 or 2 ; Y is selected from a phenyl moiety, a -Ph-Phmoiety
and a naphthalenyl moiety; W is a carbonyl group, an oxygen or sulphur atom, Z is
selected from:
-X-Ph-S0 2-Ph-;
-X-Ph-S02-Y-S02-Ph- and
-CO-Ph-;
said polymeric material having a Tm of less than 298°C.
2 . A material according to claim 1, wherein each Ph moiety in the repeat unit of formula I
has 1,4- linkages to moieties to which it is bonded.
3 . A material according to claim 1 or claim 2 , wherein each Ph moiety in the repeat unit of
formula II has 1,4- linkages to moieties to which it is bonded.
4 . A material according to any preceding claim, wherein in repeat unit I , each X represents
an oxygen atom.
5 . A material according to any preceding claim, wherein n represents 1.
6 . A material according to any preceding claim, wherein in repeat unit I I , each X represents
an oxygen atom
7 . A material according to any preceding claim, wherein said repeat unit of formula I has
the structure:
and said repeat unit of formula I I has the structure:
8 . A material according to any preceding claim, where the Tm of said polymeric material is
less than 293°C, preferably less than 287°C, more preferably less than 285°C; and/or the Tg of
said polymeric material is greater than 120°C, preferably greater than 130°C, more preferably
greater than 140°C; and/or the difference between the Tm and Tg is at least 140°C.
9 . A material according to any preceding claim, wherein said polymeric material has a
crystallinity measured by DSC of at least 20%.
10. A material according to any preceding claim, wherein the melt viscosity (MV) of said
polymeric material is at least 0.06 kNsm 2 and is less than 1.00 kNsm 2.
11. A material according to any preceding claim, wherein said polymeric material includes at
least 60 mole % of repeat units of Formula I , and less than 40 mole % of repeat units of
Formula II.
12. A material according to any preceding claim, wherein said polymeric material includes
70-80 mole % of units of Formula I and 20-30 mole % of units of Formula II.
13. A material according to any preceding claim, wherein the sum of the mole % of units of
Formula I and I I in said polymeric material is at least 95 mole %.
14. A material according to any preceding claim, wherein the ratio defined as the mole % of
units of Formula I divided by the mole % of units of Formula I I is in the range 2.3 to 4 .
15. A material according to any preceding claim, wherein said polymeric material is part of a
composition which includes said polymeric material and a filler means, wherein said filler
means is optionally selected from a fibrous filler or a non-fibrous filler, wherein preferred filler
means are selected from glass fibre, carbon fibre, carbon black and a fluorocarbon resin.
16. A material according to claim 15, wherein said composition includes 20-70 wt% of said
polymeric material and 30-80 wt% of filler means.
17. A method of making a polymeric material as described in any preceding claim, the
method comprises polycondensing a compound of formula
with a compound of formula
and with one or more compounds arranged to generate moiety II ,
wherein each R is selected from a chlorine and fluorine atom, R2 is selected from an alkali
metal and a hydrogen atom and R3 is selected from an alkali metal and a hydrogen atom.
18 . A method according to claim 17 , wherein substantially the only monomers used in the
method are those of Formulas I I I and IV, together with said one or more compounds arranged
to generate moiety I I .
19 . A method according to claim 17 or claim 18 , wherein said one or more monomers used
in the method are selected from (a) to (e), as follows: