Semi-crystalline thermoplastic built on an ether-ketone backbone, giving an exceptional balance of thermal, mechanical, and chemical performance. Its semi-crystalline structure sets it apart from the amorphous polyimides: dynamic mechanical testing shows storage modulus dropping sharply at the glass transition (~143°C), but the crystalline fraction then sustains a working plateau of 250–500 MPa all the way to the melt at 343°C — a behaviour unique among the imidised and ketone-based UHPP group. Glass-fibre filling nearly triples room-temperature stiffness (+6,400 MPa), while carbon fibre compounds reach moduli above 18 GPa. Compounding PBI with PEEK adds approximately 700 MPa to the storage modulus profile at all temperatures through to 250°C, as PBI immobilises the amorphous zones.

Inherent V-0 flame rating, LOI ~35%, continuous service to 260°C, and outstanding resistance to hydrolysis (including pressurised steam to 200°C), fuels, and most organic solvents. The medical grades (PEEK-OPTIMA) are radiolucent, biocompatible, and offer a bone-matched elastic modulus ideal for spinal implants.

Structurally similar to PEEK but with an additional ketone group, giving a higher Tg (~156–163°C depending on the T:I isomer ratio) and Tm (300–360°C). The key practical advantage of PEKK is its controllable crystallisation rate — at the 60:40 T:I ratio (Kepstan 6002), crystallisation is slow enough to allow FDM additive manufacturing without the warping that afflicts PEEK. PBI-PEKK blends (Celazole TK-60) show a glass transition of 169°C by DMA — measurably higher than equivalent PBI-PEEK blends at 154°C, reflecting PEKK's superior Tg contribution to the compound.

Increasingly specified in aerospace structural 3D printing (Airbus and Boeing supply chains) and as a thermoplastic composite matrix for continuous-fibre laminates, where its higher Tm vs PEEK enables processing at elevated temperatures.

PEK (Victrex ST) sits above PEEK on the performance pyramid with a higher Tg (~165°C) and Tm (~370°C), achieved by removing one ether linkage from the repeat unit. PAEK is the generic family descriptor. PEKEKK (Victrex HT) pushes further still — Tm ~387°C — and is specified for the most demanding continuous-service temperature requirements in oil and gas downhole tools and aerospace.

The highest-strength melt-processable thermoplastic, combining imide rings with amide linkages for extraordinary stiffness and compressive strength. DMA testing places the glass transition at 288°C (onset of E' drop), at which point the storage modulus is still around 2,300 MPa — comparable to unfilled PEEK at room temperature. Below that transition, room-temperature E' runs at approximately 3,400 MPa for neat resin, rising to around 5,400 MPa for the lubricated 4301 grade where the MoS₂/PTFE filler package stiffens the matrix. Unlike purely amorphous systems, the lube package unexpectedly raises modulus as well as reducing friction.

All Torlon grades require a post-cure programme after moulding: a staged ramp from 168°C to 220°C held over several days develops full imidisation and mechanical properties. Un-cured parts can show 30–40% lower strength and must not be used in service. Outstanding creep resistance and compressive strength make it the material of choice for precision bearings, valve seats, and structural aerospace brackets.

Amorphous polyetherimide — the cost-effective entry point to the imidised UHPP tier. Characteristic amber transparency in unfilled form. DMA shows the glass transition at 217°C (onset of E' drop), with room-temperature storage modulus around 3,400 MPa dropping to ~2,200 MPa at the Tg — mirroring the convergence behaviour seen across all amorphous imidised polymers: PBI, PAI, and PEI all arrive at approximately 2,000–2,600 MPa at their respective Tg, irrespective of starting modulus. The 30% glass-filled 2300 grade doubles room-temperature stiffness to ~6,000 MPa (+2,600 MPa).

No sharp melting point (amorphous) — no crystallisation protocol required, and no crystallinity-dependent post-processing needed. Autoclave sterilisable. FDA-compliant grades (Ultem 1010) are widely used in medical devices and food contact applications. The aerospace-certified Ultem 9085 meets FAR 25.853 for aircraft cabin interiors and is the standard material for high-performance FDM aerospace printing.

Polyimides occupy the highest tier of the imidised family. Vespel (DuPont) is the benchmark: a thermoset-like compression-sintered PI that exhibits a remarkable DMA behaviour — no detectable glass transition to 500°C, with storage modulus decaying almost linearly from approximately 2,200 MPa at room temperature. This is unique among all UHPPs tested and reflects the rigid, highly crosslinked nature of the fully imidised PI backbone. The lube grade SP-21 (15% MoS₂) shows ~180% of SP-1's modulus across 100–300°C, adding 1,100–2,000 MPa, another counterintuitive strengthening effect from a lubrication package.

Melt-processable thermoplastic PI (TPI) grades such as Aurum (Mitsui) and Matrimid offer similar thermal stability to Vespel in injection-mouldable form but at higher raw material cost. P84 (Evonik) is a polyimide available as fibre and powder, widely used in high-temperature filtration applications (cement, steel, waste incineration bag filters).

The apex of the thermoplastic performance pyramid. Polybenzimidazole holds the highest glass transition temperature of any commercially available thermoplastic: 411°C by DMA (onset of E' drop). At room temperature, storage modulus runs at approximately 4,000 MPa — around 250% of Vespel SP-1 PI, 190% of Ultem 1000 PEI, and 170% of Torlon 4203 PAI over the equivalent temperature ranges. Even at its Tg of 411°C, the modulus is still 2,600 MPa. PBI does not melt in any conventional sense — it chars rather than flows, which is why neat PBI shapes are made by compression sintering from powder.

The commercially important Celazole TU-60 grade blends PBI with PEEK in a melt-processable injection-mouldable compound. DMA reveals that PBI's presence adds approximately 700 MPa to the PEEK storage modulus at every temperature up to 250°C — because PBI physically immobilises the amorphous regions of PEEK that would otherwise soften above the glass transition. Carbon-fibre-filled PBI-PEEK (TF-60C) reaches approximately 470% of the unfilled compound's modulus at room temperature, adding ~14,800 MPa — the largest filler enhancement recorded across all UHPP systems studied. LOI of 58% for neat PBI: it simply does not support combustion.

Three amorphous thermoplastics sharing the aryl-sulfone backbone: PSU (Udel), PPSU (Radel), and PESU (Ultrason E). All are transparent to amber, autoclave-sterilisable, and FDA/USP compliant in medical grades. Tg ranges from 185°C (PSU) to 220°C (PPSU/PESU). The amorphous structure means no crystallisation management during processing and excellent dimensional predictability — tolerances achievable that would be impossible in semi-crystalline materials.

PPSU (Radel) is the premium grade — its bisphenol-S backbone gives superior hydrolytic stability, allowing 1,000+ steam autoclave cycles at 134°C without degradation. This makes it the dominant material for surgical instrument housings, trays, and medical device components subjected to repeated hospital sterilisation. PESU offers a Tg equivalent to PPSU with better chemical resistance than PSU. PSU is the cost-effective grade for food processing, water filtration membranes, and less demanding medical applications.

The melt-processable fluoropolymer family spans from fully fluorinated PFA/FEP (near-PTFE chemical inertness, processable on modified thermoplastic equipment) to partially fluorinated PVDF and ETFE (broader processing window, lower cost). All share the C–F backbone chemistry that gives outstanding chemical resistance, low surface energy, UV stability, and flame retardance without additives.

PFA (Teflon PFA, Chemours; Neoflon PFA, Daikin) and MFA (Hyflon, Solvay) sit at the top of the value hierarchy — fully perfluorinated, melt-processable, highest-purity semiconductor and pharmaceutical applications. Scrap from fab decommissioning commands premium recycling value. PVDF (Kynar, Solef) was historically the flagship fluoropolymer collection stream, but sustained price compression has repositioned it as a volume-over-value material. Homopolymer Tm 170°C; copolymer Tm 155–162°C — DSC essential before reprocessing. Piezoelectric properties in copolymer grades.

ETFE (Tefzel) and ECTFE (Halar) are found in wire insulation and chemical tank liners. FEP and PFA are used in ultra-pure semiconductor wetprocess and pharmaceutical fluid handling. THV is a soft terpolymer used for flexible tubing. EFEP and MFA are specialty grades for specific chemical and optical applications.

Crosslinked fluorinated rubber grades offering chemical resistance approaching PTFE in a compliant, sealable form. FKM (Viton) is the standard oil-resistant fluoroelastomer used in O-rings, seals, and gaskets throughout the petrochemical, aerospace, and automotive industries. FFKM (Kalrez, Chemraz) is the perfluorinated apex — essentially inert to virtually all chemicals and solvents, with continuous service to 327°C. FEPM (Aflas) is a tetrafluoroethylene-propylene copolymer with superior resistance to steam, acids, and amine-containing fluids.

All three are thermoset — they cannot be remelted or reprocessed conventionally. IRM collects these as powder-recycling or functional filler material rather than as melt-reprocessable streams.

The original fluoropolymer — chemically inert to essentially all substances except molten alkali metals and fluorine gas. PTFE does not melt in any processable sense (it sinters at ~327°C with virtually no flow); all PTFE articles are made by compression sintering or paste extrusion. In UHPP compounding, PTFE appears primarily as a lubricating filler (typically 10–20% by weight) in PEEK, PAI, and PPS wear compounds, where it dramatically reduces coefficient of friction without significantly compromising mechanical strength.

Semi-crystalline aromatic thermoplastic with one of the broadest chemical resistance profiles of any engineering polymer — no known organic solvent attacks PPS below 200°C. Inherently V-0 without flame retardant additives (LOI ~44%), low moisture uptake (<0.05%), and dimensional stability that makes it a favourite for precision connectors and sensors that must survive SMT reflow solder profiles (260°C peak). Unfilled PPS has moderate stiffness (~3.8 GPa), but the commercially dominant GF40 grade reaches 14 GPa and 200 MPa tensile — approaching reinforced PEEK at a fraction of the cost.

Note: PPS can be mildly corrosive to standard steel tooling at elevated temperatures — chrome or Hastelloy lining is recommended for production tooling. Also, PPS can crosslink at high barrel temperatures with extended residence time — avoid residence times above 10 minutes at processing temperature.

Amorphous engineering polymer with good dimensional stability, low density (~1.06 g/cm³), and excellent electrical properties. Rarely used neat — almost always as modified blends with HIPS or PA for impact resistance. Noryl (SABIC) is the dominant commercial form. Tg ~215°C for pure PPO, but blends are typically 100–150°C service. Not a UHPP material but appears in E&E and automotive waste streams that IRM/GCMG encounters as secondary material.

Semi-aromatic and fully aromatic polyamides bridge the gap between commodity engineering nylons and the top-tier UHPP materials. They all share the key UHPP attribute of service temperatures above 150°C under load, while retaining the processing characteristics and chemical versatility of the polyamide family. PA46 (Stanyl) achieves very high HDT through exceptional crystallinity. PA6T/6I copolymers (Amodel, Grivory) balance processability with thermal performance. PA9T (Genestar) and PA10T offer distinctly lower moisture uptake (~1.8–2.5%) compared to standard polyamides — a critical advantage in dimensional stability and electrical applications.

The engineering polyamide family covers a wide spectrum from high-volume commodity PA6 and PA66 through bio-based long-chain grades (PA11 from castor oil, PA1010, PA410) to specialty transparent grades (Trogamid, GRILAMID TR). All share the amide linkage chemistry giving strong hydrogen bonding, good mechanical properties, and natural hydrophilicity (water absorption varies from ~0.2% for PA12 to ~9% for PA6). PEBA (polyether block amide) and COPA are flexible elastomeric grades used in sports, medical tubing, and flexible cable jacketing.

While these fall below the UHPP service temperature threshold, they appear routinely in IRM/GCMG waste collection — particularly GF30 and GF40 grades from automotive structural parts and E&E components — and serve as compound matrix resins in lower-cost product lines.

LCPs form ordered, rod-like molecular arrangements in the melt — a behaviour entirely distinct from conventional random-coil thermoplastics. The result is extraordinary in-flow mechanical properties (tensile strength up to 230 MPa in flow direction for filled grades), ultra-thin wall capability (0.1–0.2 mm), near-zero moisture absorption (stable electrical properties at frequency), and a coefficient of thermal expansion closely matching copper — invaluable for direct-attach electronics. Inherently V-0. Melting points range from ~280°C (Type I, Vectra) to ~350°C (Type III, Sumikasuper).

The critical weakness is severe anisotropy: cross-flow tensile strength and stiffness can be 30–50% of in-flow values, and weld-line strength as low as 20–30% of parent material. Part and gate design must be engineered to eliminate weld lines in any load-bearing path. LCPs are increasingly specified for 5G/mmWave antenna substrates due to near-zero moisture uptake giving ultra-stable dielectric constant (Dk) and loss (Df) at millimetre-wave frequencies.

Aliphatic polyketone (Schuler/Hyosung M330) is a semi-crystalline engineering thermoplastic with an alternating ethylene-propylene-CO backbone. Distinguished by excellent wear resistance, low friction, good chemical resistance to fuels and oils, and noticeably better impact resistance than POM at low temperatures. Tg ~–15°C, Tm ~220°C, continuous service ~100°C. Not a UHPP material, but appears in automotive fuel system and bearing applications that intersect with IRM/GCMG collection streams.

Semi-crystalline acetal thermoplastic with exceptional stiffness-to-weight ratio, fatigue resistance, and low friction in sliding contact. The copolymer grade (Delrin competes with Celcon/Hostaform) offers better thermal stability and easier processing vs homopolymer. Tm ~165°C, continuous service ~90–100°C. Limited thermal performance excludes it from UHPP territory, but it is one of the highest-volume precision engineering plastics globally and appears frequently in automotive and consumer goods waste streams.

The thermoplastic polyester family ranges from packaging-grade amorphous PET-A through semi-crystalline PBT (the dominant engineering polyester) to the higher-thermal PCT (polycyclohexylene dimethylene terephthalate, Tm ~290°C) and specialty PEN (polyethylene naphthalate, better barrier and thermal vs PET). PTT (polytrimethylene terephthalate) bridges PET and PBT with superior elastic recovery, used in fibre and film.

PBT-GF30 is ubiquitous in automotive connectors and E&E — it is one of the most commonly encountered materials in Sumter SC collection waste alongside UHPP materials. High crystallisation rate makes PBT easy to process and demould quickly. PCT alloys (Eastman Tritan for food contact, Eastman PCTAs for structural/automotive) extend service temperature to ~150°C under load.

Polycarbonate (PC) and PMMA (acrylic) are the dominant transparent engineering thermoplastics. PC (Makrolon, Lexan) offers outstanding impact resistance, Tg ~147°C, and optical clarity with good UV resistance (coated grades). PMMA offers superior optical clarity, scratch resistance, and weathering vs PC but is brittle. PC alloys — PC/ABS, PC/PBT, PC/PET, PC/ASA — combine PC's toughness with the processability and chemical resistance of the blend partner.

These materials do not reach UHPP service temperatures but are common in electronic device housings, automotive glazing, and medical device enclosures that co-mingle with UHPP waste in collection streams. PC/ABS is one of the highest-volume E&E polymer alloys globally.

Thermoplastic elastomers combine rubber-like compliance with thermoplastic processability — no vulcanisation required, reprocessable from scrap. TPC/TPEE (Hytrel, Arnitel) are polyester-based with good chemical and thermal resistance (up to 130–150°C continuous). TPU is the workhorse — outstanding abrasion resistance, broad hardness range (Shore A 60–Shore D 80), widely used in seals, cable jacketing, hose, and printing components. TPV (Santoprene) is a dynamically vulcanised PP/EPDM alloy for automotive sealing. Styrenic TPE (SEBS, SBS) grades are the lowest-cost flexible option for consumer and packaging applications.

TPU appears in some IRM/GCMG UHPP-TPU blend work for flexible components requiring chemical resistance with compliance. TPC/TPEE arises in waste from automotive flexible connector components.

Para-Aramid (Kevlar, Twaron, Technora) — ballistic and structural composite fibre. Tensile ~3,600 MPa (Kevlar 49), modulus 70–125 GPa, density 1.44 g/cm³, LOI ~29%. IRM Sumter SC and India: post-service vest Kevlar retains 60–80% virgin tensile, pulped for UHPP compound reinforcement and friction materials. Precision chopping and sizing at South Jordan UT.

PBI Fibre (Celazole, PBI Performance Products) — ultimate heat protection. LOI 58%, rated to ~560°C short-term. Blended with para-aramid in firefighter turnout gear. Active IRM collection from PPE waste.

PBO Fibre (Zylon AS/HM, Toyobo) — highest tensile (5,800 MPa) and modulus (270 GPa) of any commercial organic fibre. Critical: UV and moisture degradation is irreversible. Dry, UV-screened storage mandatory. Ballistic soft armour and high-performance sports.

Carbon Fibre (PAN-based T-300 to T-800, IM7/IM9, pitch-based Thornel P-55/P-100, 380–750 GPa) — dominant structural composite reinforcement. IRM South Jordan UT: precision CF sizing for UHPP-compatible matrices (PI, PA, phenolic, PEEK sizings — commercial CF is epoxy-sized, incompatible with PEEK/PAI), precision chopping 0.1–12 mm, carbon powder from swarf.

UHMWPE Fibre (Dyneema SK60/SK75/SK99, Spectra 900/1000) — ultra-high MW polyethylene drawn fibre. Tensile 2,400–3,600 MPa, density 0.97 g/cm³, outstanding cut resistance. Ballistic soft armour, marine ropes. LOI ~17% — flammable, process with care. Active IRM collection from ballistic vest and rope/cable EOL.

PEEK Fibre (Zyex, Victrex WG101) — Tg 143°C, Tm 343°C, outstanding chemical resistance. PI Fibre (P84 NT-1/NT-2, Kermel PAI-PI) — hot-gas bag filters, Tg 315–340°C, LOI 38%. PTFE Fibre (ePTFE monofilament, Gore) — chemical filtration, LOI ~95%.

Phenolic Fibre (Kynol NF-100/NF-200) — LOI 55%, non-melting. Carbon precursor, friction pads, fire-blocking. Preox / Oxidised PAN (SGL, Toray) — LOI ~50%, fire-blocking interliner in composite sandwiches.

Basalt Fibre (Basaltex, Kamenny Vek) — extruded from volcanic rock, tensile ~4,800 MPa, to ~700°C, density 2.7 g/cm³. Chemical/UV resistance superior to E-glass at modest cost premium. Meta-Aramid (Nomex T411/T450, Teijin Conex, Kermel) — Tg ~275°C, LOI ~29%, heat-protective workwear, aircraft cabin, electrical insulation. Silica Fibre (Quartzel) — 99.9% SiO₂, to 1,050°C. Ceramic Fibre (Nextel 610/720, Saffil) — Al₂O₃/mullite, to 1,260°C.

Glass Fibres — the commodity workhorse reinforcement across the entire filled polymer compound industry. E-Glass (electrical grade) — tensile ~3,450 MPa, modulus 72 GPa, density 2.54 g/cm³ — the baseline reinforcement for PA6, PA66, PBT, PPS, and most engineering compound families. S-Glass / S-2 Glass (AGY) — 4,580 MPa, 86 GPa — ~30% strength improvement for aerospace and ballistic compounds. ECR-Glass (Advantex, Owens Corning) — corrosion-resistant, boron-free, for chemical plant composites and pipe winding.

Natural Fibres — Jute, flax, hemp, and sisal are bio-based reinforcements gaining use in green composites (automotive interior panels, packaging) due to low density (~1.3–1.5 g/cm³), CO₂ neutrality, and adequate specific stiffness. Tensile 300–800 MPa (variable by species and processing). Moisture uptake is the main limitation — surface treatment and drying mandatory before compounding. Flax/PP and jute/bio-PA composites are active in GCMG circular economy automotive programme.

Mineral Fillers — used as reinforcing functional fillers: Wollastonite (calcium silicate, acicular, A/R up to 20:1) improves stiffness, dimensional stability, and surface finish in PA, PBT, PPS. Talc (platy magnesium silicate) for PP/PA stiffness, nucleation, and warpage reduction. Mica (phlogopite/muscovite) gives high A/R reinforcement and dielectric performance. Calcined Kaolin improves electrical properties and surface finish in engineering compounds.

Standard Polymer Fibres — Polyester fibre (PET, recycled rPET) in nonwoven reinforcement, filtration, and geotextile. PA6 / PA66 fibre in tyre cord (PA66), carpet tufting (PA6), airbag fabric — IRM/GCMG PA6 regrind from carpet and tyre cord waste is an active secondary polymer stream, with rPA6 (Aquafil Econyl equivalents) from EU carpet EOL collected at GCMG Croatia. Polypropylene fibre in concrete reinforcement, geotextile, and hygiene nonwovens.