MATS 64561 Advanced Composites MaterialsDr A.N. Wilkinson, Dr P.J. Mummery, Dr R.J. Day , Professor P. Hogg Welcome to this unit of the MSc in Advanced Engineering Materials, which will be taught by four lecturers: Dr Richard Day – topics to be covered are introduction to composites and composite micromechanics. Dr Paul Mummery - topics to be covered are the production, structure and properties of metal- and ceramic-matrix composites. Dr Arthur Wilkinson - topics to be covered are reinforcements and matrices for polymer-based composites, manufacturing techniques for polymer-based composites, curing of thermosetting polymer matrices. Professor Paul Hogg - topics to be covered are tooling for structural polymer-based composites, economics of advanced polymer composites and the manufacturing process chain (material-process-tooling). MANUFACTURING OF POLYMER COMPOSITES - Reinforcing Fibres – overview of common types - Matrices - overview of available types - Processing of polymer composites - Contact moulding (Hand lay-up, Spray-up) - Filament winding - Pultrusion - Press and Compression moulding - Injection moulding - RTM/ Resin injection - RIM/RRIM/SRIM - Thermoplastics Reinforcing Fibre Types Available • Fibrous arrays can be in the from of woven or non woven cloths or layers. • Both tows and cloths can be pre-impregnated with resin, processed and then used as ‘prepregs’ during composite manufacture. • In general, there are only a small number of fibre types available. • Some of the most used high modulus or high strength fibres are: Fibre types Aramid e.g. Kevlar®, Twaron®, Technora® Carbon fibres Glass e. g. S, A, R, E type glasses fibres Polyethylene e.g. Spectra®, Dyneema® Aramid fibres • Aramid fibres - aromatic polyamides and where at least 85% of the amide groups are connected directly to an aromatic group. • For composites, the para-aramids with their superior tensile properties are preferred and the general chemical formula is typified by that for poly (p-phenylene terephthalamide) (PPT). • Commercial aramid fibres are represented by Kevlar® of Du Pont, Twaron® by Akzo and Technora® by Teijin. Chemical formula for poly(p-phenylene terephthalamide) (PPT) • Three basic variants produced by the same general method from the same polymer. • The variation in properties is due to processing (molecular orientation is improved for higher modulus fibres), achieved by an annealing process. Solution of PPT in concentrated sulphuric acid Pump Spinneret Coagulation bath Dry-jet wet-spinning process . In this a solution of the polymer in concentrated sulphuric acid (about 20% polymer) is extruded from an orifice into a coagulation bath of water and the fibre is then taken up onto reels.Processing The basic process for making the fibre is known as dry-jet wet spinning.Aramid fibres . thus specific modulus = ~26 GPa m3 kg-1) Aramids – web links http://en.org/wiki/Nomex http://en.9 1.dupont.org/wiki/Kevlar http://en.Aramid fibres – Properties of Kevlar® Fibre Density g/cm3 1.wikipedia.63 Kevlar 29 Kevlar 49 Kevlar 149 c.44 1.html .47 Tensile modulus GPa 75 117 160 Tensile Strength GPa 3.pslc. Tensile modulus = 210 GPa.wikipedia.wikipedia.31 1.org/wiki/Technora http://www.8 g/cm3. density = ~7.3 2.ws/macrog/aramid.4 Specific modulus GPa m3kg-1 52 81 109 Specific strength GPa m3kg-1 2. Steel.wikipedia.45 1.htm http://www2.org/wiki/Twaron http://en.f.com/Kevlar/en_US/index.8 2. • Extremely low creep rate. • Difficult to dye – usually solution dyed. • Maximum use temperature 160oC. Disadvantages • Sensitive to degradation by UV light which reduces strength. • Low thermal conductivity. • Poor compression properties due to kink band formation (a common problem in this type of polymer fibre made from liquid crystalline solutions which gets worse as the tensile modulus is improved). • High water uptake (can absorb 6% moisture at 100% R. • Sensitive to moisture and salts. • Good ballistic properties in lower modulus varieties. Begins to carbonise at 427oC. and 23oC) but does not have much effect upon the mechanical properties. • Does not melt or support combustion. . • High chemical resistance except some strong acids and alkalis.Aramid fibres .H.Characteristics Advantages • High specific modulus. • High vibrational damping. Dyneema® Chain orientation > 95 % Crystallinity ≈ 85 % . • In this gel it is easy for the polymer chains to slide pass each other. These are known as Ultrahigh molecular weight PE (UHMWPE). • Another approach is to wet spin a gel of polyethylene. • This produces fibres which do not have outstanding properties. • Fibres are now available from Allied Signal (Trade name Spectra) Chemical structure of Polyethylene (PE) fibre Normal Polyethylene fibre Low chain orientation Crystallinity < 60 % UHMWPE fibres. • The manufacturing process for gel-spun polyethylene fibres consists of wet spinning of the gel followed by drawing of the fibre and subsequent removal of the solvent.Polyethylene (PE) • Conventionally polyethylene fibres are produced by melt spinning. • Properties can be improved significantly by drawing fibres made from very high molecular weight PE close to their Tg. • The first gel spun fibre was Dyneema® manufactured by DSM. htm .Polyethylene . 2.147oC.dsm.19 2. • High specific modulus. PE fibres – web links *c.97 0. • Maximum use temperature 80-90oC. • Poor adhesion to matrices.78 Spectra 900 Spectra 1000 Dyneema Advantages • High specific strength.com/en_US/html/hpf/home_dyneema.65 3.good for ballistic applications.97 Tensile modulus GPa 117 172 87 Tensile strength GPa 2. • High impact resistance .Properties Fibre Density g/cm3 0.f.09 2.97 0.wikipedia.7 Specific Specific modulus* strength GPa m3 kg-1 GPa m3 kg-1 121 177 90 Disadvantages • Low melting point . • High abrasion resistance. Steel. • Low moisture uptake (1%). specific modulus = ~26 GPa m3 kg-1) http://en.org/wiki/Dyneema http://www.73 3. • The precursors are PAN. rayon or pitch (which consists of polynuclear aromatic molecules). graphite fibres are 99% carbon • The planes of carbon atoms in the graphitic component are stiff and held together by strong covalent bonds.Carbon Fibres •A large number of grades of carbon fibre are available from manufacturers. • Between the planes there is only weaker van der Waals bonding . The former gives the fibre its stiffness. • Carbon fibres are 93-95% carbon. •The resulting fibre contains a mixture of graphitic carbon and amorphous carbon. • They are produced by one of three types of polymer precursors. .• One manufacturing process consists of passing a tow of filaments through carbonisation and graphitisation furnaces • In the case of some of the precursors it is necessary to crosslink them by heating in air before the carbonisation process. 31-7.89-3.94 2.87-1.Advantages •High specific strength •High specific modulus •Retention of properties at high temperature (in inert atmospheres) •Biocompatible 6µm carbon fibre •Largely chemically inert Human hair Disadvantages •Unstable at high temperatures in oxidising atmospheres •Expensive Fibre Density g/cc 1.52 Specific modulus * GPa m3 g-1 130-303 190-349 272 Specific strength GPa m3 g-1 1.33 PAN Pitch Rayon *c.88 0.f.06 1.73-3.9 Tensile modulus GPa 228-588 379-740 517 Tensile strength GPa 3.0-2.17 1. specific modulus = ~26 GPa m3 kg-1) . Steel.22 2.52 1.75-1. Fibre type E-glass S-glass SiO2 54. •Based on different chemical compositions. g. various grades of glass are available e.Glass fibres • Glass fibres are probably the most commonly used fibres in polymer composites because they represent a combination of reasonable cost and performance.5 26 CaO 17 MgO 4. E-. S.and R-glass.5 Na2O 0.(Electrical resistance) and S. •The most common types are E.5 10 B2O3 8.5 64 Al2O3 14. •There is also a less expensive version of S-glass known as S-2 glass and a glass fibre with high resistance to chemical environments called C-glass.(high strength) glass.5 - . •The molten glass is extruded through holes in a platinum bush. cooled by a water mist. and immediately coated with a size prior to further processing. which bind together between 200 and 2000 filaments from a single bushing to form a strand. and coupling agents to develop fibre-matrix bonding. •A size may also contain anti-static agents and lubricants to facilitate handling. • Sizes are solutions of a suitable polymer in water. then heated to ≈ 1370oC. • Fine filaments are drawn down to between 5-20 mm in diameter. .The manufacturing process consists of: • The dry components are mixed. • Strength is very sensitive to defect and therefore handling.Glass fibres . Steel.81 E-glass S-2 glass *c. specific modulus = ~26 GPa m3 kg-1) Advantages • Low cost.62 2. Disadvantages • Low tensile modulus. • High density for a reinforcing fibre.52-2. • High hardness .4 4. .5 Specific modulus* GPa m3 kg-1 28 34. • Strength reduced by presence of water or loads (static fatigue). • Excellent insulation properties.Properties Fibre Density g/cc 2. • High chemical resistance.f.31 1. • Low fatigue resistance.49 Tensile modulus GPa 73 86 Tensile strength GPa 3.causes wear. • High tensile strength.5 Specific strength GPa m3 kg-1 1. or bonded) Knitted Preforms & Fabrics Braided Preforms & Fabrics .A wide range of glass fibre products for reinforcing polymers are produced from the basic continuous strands. Parallel Winding Continuous Strand Long Chopped Strands (CSG) Continuous Filament Mat (CFM) Short Chopped Strands (CSG) Hammer-Milled Strands (HMG) Chopped SMC Strand & Mat DMC (CSM) Twisting & Doubling Continuous Yarn Injection Moulding Compounds (Thermoplastics & Thermosets) Continuous Roving Non-Woven Woven Fabrics Fabrics (Stitched. in which the strands may either be loose or fixed by more size. • Whereas the longer CSG grades are mainly used in the manufacture of dough (DMC) and sheet moulding (SMC) compounds of thermosetting plastics. • Where a heavier fibre bundle is required several strands are combined in parallel to form a roving. • In a process akin to textile fibres. • Chopped strand glass (CSG) is produced in a range of lengths between 3-100 mm.• Discontinuous reinforcements are produced by either hammer-milling or chopping to break the strands. • An alternative to CSM is continuous filament mat (CFM). such as pultrusion and filament winding. then coated with a binder to impart some integrity to the mat. . hammer-milled glass (HMG) is usually passed through a sieve and therefore has a distribution of strand lengths from the order of ~30 mm up to the maximum dictated by the sieve grid (≤ 3 mm). which may be woven. especially when wet. • Continuous rovings are used as reinforcements in a number of processes. knitted or braided. • Long chopped strands (up to 100 mm) are also used in chopped-strand mat (CSM). • Hammer-milling produces a wide range of strand lengths. This is formed from continuous strands which are chopped and deposited randomly on a moving bed. and to produce reinforcing fabrics for composites. • HMG and the shorter length grades of CSG (3-6 mm) are used to reinforce injection moulding compounds of thermoplastics and thermosets. and has a very much narrower distribution of fibre lengths. and is often preferred for techniques involving resin flow through the mat. CFM has greater integrity than CSM. thus. formed from continuous strands which are coated with a binder and randomly deposited (swirled) onto a moving bed. glass filaments may also be twisted to form a continuous yarn. used in compression moulding. ws/macrog/carfsyn.htm .org/wiki/Twaron http://en.org/wiki/Kevlar http://en.html PE fibres – weblinks http://en.wikipedia.htm http://www2.com/en_US/html/hpf/home_dyneema.wikipedia.dsm.htm http://www51.com/sm/afc/products-details/fiber.html Carbon fibres – weblinks http://en.com/Kevlar/en_US/index.wikipedia.wikipedia.org/wiki/Technora http://www.org/wiki/Carbon_fiber http://pslc.org/wiki/Nomex http://en.org/wiki/Dyneema http://www.weblinks http://en.Aramids .wikipedia.honeywell.pslc.dupont.ws/macrog/aramid.wikipedia. "balance" (the ratio of fibres oriented in the warp and weft directions) and "drape" (a measure of the ability of the fabric to follow a shape). weight per m2. . two-dimensional fibre structures which may be produced by a variety of techniques including braiding. • The mechanical properties imparted to a composite by fibres are optimised when they are straight and in-line with any applied load. but most commonly by weaving. knitting and stitching. but often improves out-of-plane properties such as impact resistance. • Fabrics are flat.• Both yarns and rovings of reinforcing fibres are used to form fabrics and preforms. • A wide variety of fabric weave patterns are available. • Crimping of the fibres provides scope for significant fibre movement and thus reduces the modulus and strength of the composite in the plane of the fabric. which vary in degree of crimp (the "kink" in the fibres as they go over or under the other yarns or rovings). but these processes (and 3-D weaving) are more suited to the production of shaped fibre structures (typical textile products being ropes.Different weave patterns of textile fabrics Ref) Mat. Sci. . • Twill weaves essentially provide a compromise between these two extremes. • Braiding and knitting techniques may be used to produce fabrics.fibre structures which approximate the shape of the final product. • Whereas the 8-end satin has low crimp and high drape (easily shaped) but is highly unbalanced. sweaters and socks!). and therefore are used to manufacture preforms . and Eng. B 132 (2006) 79-84 • Plain weave is balanced but has the highest degree of crimp. prepregs) • Deep draw mouldability/shapability • Easy shipping/storage of preforms • Reduced manufacturing (layup) time Disadvantages • Fibre distortion (crimping. changes or orientation.f. pinching at crossovers.Why Use Preforms? Advantages • Easily automated processing large cost reduction • Better dimensional stability/conformability • Better out-of-plane properties • Improved impact/damage resistance (c. z-pinning) can reduce mechanical properties from ideal • Some difficulty in achieve high fibre volume fractions • Resin rich and sparse regions throughout part • Micro-cracking can occur during cool down (which may propagate in-service . • UD fabrics held together with a fibre mesh backing. propeller blades. • Braided carbon structures have been used for many years in aerospace applications e. spars or stiffeners. Carbon woven fabric Unidirectional carbon fabric Braiding . knitted. the main composite material used is unidirectional (UD) carbon fibre pre-preg. which is usually coated with an epoxy resin or a thermoplastic binder. braided. UD fabrics are commonly used for adding stiffness in structures of wing skins. g. stitched and Z-pinned. Although.Developments in woven fabric applications • The common textile composites in the aerospace industry are woven. there is the improvement in standard fabric technology for non-prepreg processing. 5. This can be carried out in multiple layers to achieve a 3D preform shape. ‘Warp’ and ‘weft’ yarns are interlaced . the shuttle inserts the weft yarn between warp yarns (the ‘shed’) and held in place. . When the harness returns to its original position.typically on a loom. As the harness is moved up and down by the lifting shaft. 2. Warp yarns are rolled off a beam under tension and fed through an ‘eye’ in a ‘heddles. it locks the weft in the fabric which continues to produce a roll of fabric.Weaving 1. 4. 3. the yarns interlace and a conform to the surface of the mandrel Multiple sets of spools can be used (more than the two opposing sets) to produce 3D braided structures . the yarns are taken up in a helical pattern Each time opposing spools meet. 2. Spools carrying yarns move in a circular path in opposing directions around a mandrel As the mandrel moves perpendicular to the circle.Braiding 1. 4. 3. A row of closely spaced needles pulls loops of yarn through the knit loops 4.Knitting 1. . The same applies for ‘warp knitting’ except that multiple yarns enter the machine in the same direction as fabric production and many rows of knit loops are formed. As the yarn carrier moves across the width of the fabric. the yarn is drawn into needles further along the fabric bed. a single feed of yarn enters the machine at 90˚ to the direction of fabric production 2. In ‘weft knitting’. 5. This yarn forms a row of knit loops across the width 3. is inserted through a stack of fabric layers (dry or prepreg) to form a 3D structure. with heat and pressure the foam collapses and the fibres are pushed into the layup. carrying the stitching thread. • The stitching yarn is not necessarily the same material as the planar fabric due to fibre brittleness. • An alternative to stitching is ‘Z-pinning’ where fibres are positioned in a thermoplastic foam on top of dry fabric or pre-preg. • During the cure process. .Stitching • A needle. Prepregs • Fibre structure infiltrated with premixed resin • Advantage – resin mixed and applied to reinforcement by supplierensures correct volume fraction of resin and correct mixture of resin and hardener. • Disadvantages – limited fibre structures available and no through thickness reinforcement. . – Storage in a freezer until needed-shelf life is limited. Prepregs -store in freezer . Sandwich Panels • Simplest arrangement – two layers of fibre-reinforced composite separated by a low density core • Reduces weight (improves specific modulus still further) • Common cores are foamed polymers or resin coated paper “honeycombs” . • The matrix contributes significantly to the toughness and the shear and compressive strengths of structural composites. • The encapsulation of the reinforcing fibres by the matrix acts to protect them from degradation due to abrasion or environmental attack.Matrix Resin Systems for Structural Polymer-Composites The matrix constitutes a significant volume fraction of a composite and performs a number of critical functions: • The matrix binds the reinforcements together. . • In addition. acting to resist delamination between layers of reinforcements and inhibit fibre buckling during compression. the ability of a composite to maintain its mechanical properties at high temperatures is determined by the thermal stability of the matrix. acting to maintain the shape of a component and as a stress-transfer medium to distribute any applied load to the reinforcing fibres. a highly-crosslinked matrix imparts good solvent resistance and thermal-mechanical behaviour to the composite. uncured. • Thermosetting resin systems consist of liquid mixtures of relatively low molar mass reactants. such as monomers and/or prepolymers.• Matrices for structural composites are mainly thermosetting plastics. . network polymers. intractable. • The general chemistry of thermosetting systems is well suited to the formation of structural composites. 2. the initial. which polymerise (or cure) upon heating to form highly-crosslinked. 1. state is characterised by relatively low viscosity which aids the impregnation of high loadings of fibrous reinforcements. • Competition for matrix applications is provided by thermoplastics (see later). which are being used increasingly for certain applications but still constitute a relatively small sector of the structural composite market. albeit at the expense of toughness. combining chemical resistance.and tetra-functional epoxy resins are common in aerospace resin formulations Network formation (curing) can take place at room temperature or at elevated temperatures. Tri.g. ease of processing and good mechanical properties at an acceptable material cost. depending on the formulation.Epoxy Resins (c) Epoxy Resins O CH2 CH CH2 O CH3 C CH3 OH OCH2CHCH2 O n curing agent e. Most common epoxy-resin systems are based upon DGEBA (n=0 above) and higher molar mass prepolymers (n≥1). and is commonly achieved using one of a wide range of "curing agents" which contain groups reactive towards the terminal epoxide groups of the epoxy prepolymer. diamine or anhydride CH3 C CH3 NH2 O C C O O O OCH2 CH CH2 DGEBA-based prepolymer H2N Epoxy resin systems are the largest-volume thermosetting resins used in structural aerospace composites. NETWORK NETWORK . which yield systems with a wide range of processing behaviour and mechanical properties depending on their structure and reactivity. Advantages •Wide variety of properties available •No volatiles evolved during curing •Low shrinkage of resin during cure •Good resistance to chemicals and solvents •Good adhesion Disadvantages •Expensive •Long cure times •Can have poor hot/wet performance •High moisture absorption •Can be brittle . which often incorporate functionalised elastomers or thermoplastics.The most common of these are multifunctional amines and acid anhydrides. Amines are fast curing and give good chemical resistance but most are skin irritants Anhydrides are less toxic than the amines but will not react at room temperature Further structural diversity occurs with toughened epoxy-systems. 5000 g mol -1 (b) Vinyl-ester Resins Vinyl-ester resins O CH2 CH CH 2 O DGEBA CH 3 C CH 3 OCH2 CH O CH2 + CH3 CH2 C C HO O Methacrylic Acid Vinyl-ester Prepolymer CH3 O CH 2 CH C O CH2 CH CH 2O HO CH3 C CH3 n= 1-2 HO O CH 3 O CH2CH CH2O C CH CH2 See supplementary notes for details .(a) Unsaturated Polyester Resins Unsaturated Polyester Resins O C O O C + HO CH CH CH + 2 3 HO Propylene Glycol O CH CH3 O C OCH2 CHO C C O O Maleic Anhydride O OC CH C Phthalic O Anhydride O C O NETWORK NETWORK Styrene & Initiator CH CH2 Polyester Prepolymer Mn 2000 . UPE Advantages •Range of properties available •Low viscosity •Fast cure •Low cost Disadvantages Vinyl-Ester Advantages • Excellent chemical resistance •Lower properties than epoxies •Presence of styrene •High shrinkage on curing 5-12% (epoxy < 5%) • Good tensile strength • Low viscosity • Fast cure • Higher flexibility and fracture toughness than polyester Disadvantages • Moderate adhesion • High shrinkage on curing 5-10% • Presence of styrene . (d) Phenol-formaldehyde resins Phenol-Formaldehyde Resins Acid catalyst Excess phenol Novolac Formaldehyde CH2 O + HO OH HO CH 2 CH2 HO CH2 CH2 OH Curing Agent Heat & Pressure HO CH 2 Phenol Basic catalyst Excess formaldehyde CH 2HO Resole HO CH2 HO CH2 CH 2 HO HO NETWORK NETWORK Heat & Pressure Novolaks are formed by reacting the starting materials in acid conditions. Resols are formed by reacting the starting materials in basic conditions. Each ring contains an hydroxyl group. . The resin formed contains benzene rings joined together by methylene groups. usually hexamethylene tetramine to allow reaction and crosslinking. When heated the molecules cannot react with each other so a hardener is added. The molecules formed contain methylol groups by which they can crosslink on heating. used for transport applications Disadvantages • Poor tracking resistance • Volatiles released on curing . • Thus. and are therefore more difficult to handle than UP or epoxy systems. and formaldehyde and ammonia from the decomposition of the novolac curing agent. • However. water from the condensation reaction of resoles. PF-resin systems must be processed at relatively high pressures to prevent foaming and excessive porosity.• Possibly the earliest polymer matrices for composites. Advantages • Can have good thermal stability • Low emission of toxic gas on burning. both systems generate volatile by-products. PF-resins have found new applications in recent years due mainly to their inherent combustion resistance. Polyurethanes (PU) • Formed by the reaction of an isocyanate with a polyfunctional alcohol.polyurethanes can be made in rubbery forms through to hard materials. • The range of properties available is enormous .health and safety considerations • low service temperature (80oC) . •Application of PUs mainly in reaction injection moulding of composites Advantages • Excellent adhesion • Considerable variation in properties possible Disadvantages • Isocyanates . OCN + HO OH O 2nd Stag e 1s t Stage N R O CN OCN NCO O C N R C NCO NCO R N C Common isocyanate –based systems for the production of composites O Network Network NCO where R = or .Polyurethanes Polyurethanes O CN N C O NCO "Snap-cure" HO OH + Conversion Rapid cure H OCN O H N CO O N H O C O polyurethane PU network Network Low initial viscosity Time Urethane-acrylates Urethanes-acrylatesO OCN NCO + O O CH2 C C O CH2 C O C CH CH C O CH2 CH OH n CH3 unsaturated CH3 CH 3 prepolymer ROOR free-radical initiator unsaturated polyurethane Network Network Isocyanurate copolymers Isocyanurate Copolymers xs. and are used predominantly in the aerospace industry. cyanate and bismaleimide resin systems are more "exotic" resin systems designed for high temperature applications.(e) Polyimides Polyimides O C O C O monomers OH O C NH C O C O OH C O HN C prepolymer O O C N O C N C O + H2N NH2 O (g) Cyanates N CO Cyanates OC monomer N CO O C N N C N C O O OC N Prepolymer O C N network C O O C N N C O network O n n OC N Bismaleimides (f) Bismaleimides O C N C O monomer O N C O C O C C NETWORK NETWORK Polyimides. . High temperature thermoplastics are suitable for higher service temperatures having high crystalline melting points and/or high glass transition temperatures. .6) Polycarbonate (PC) Poly(ethylene terephthalate) (PET) Polyacetal (POM) The most common use for these thermoplastics are as matrices in moulding compounds containing short glass fibres (less commonly – carbon fibres) which are used for injection moulding. however. They are more expensive than conventional thermoplastics. Common examples include: Commodity Thermoplastics Polypropylene Engineering Thermoplastics Polyamides (Nylons – most common PA6 and PA6.Thermoplastics A large number of thermoplastic materials are used as composite matrices. continuous use temperature 250oC Good resistance to chemicals C O O O n Victr ex P E EK Tg 1 4 4 C Tm 3 3 5 C Poly(phenylene sulphide) PPS Max. continuous use temperature 160oC Excellent resistance to hot/wet conditions Attacked by polar solvents S O2 n S n PPS Tm 285-295 C Tg 85-150 C Poly ( p -p h en y len e su lph o n e) m el t s / d ec o m p o s e s > 5 0 0 C In order to obtain a thermoplastic aromatic polysulphone the polymer chain must be made less rigid by incorporating flexible groups into the backbone: For example Poly(ether sulphone) .Examples of High Temperature Thermoplastics: Poly(ether ether ketone) PEEK Max. continuous use temperature 240oC Excellent chemical resistance Polysulphone Max.