Polymers Taxonomy — Family Index

Polymers are long-chain macromolecules built from repeating monomer units. Engineering practice partitions them into three primary classes by thermal/mechanical response — thermoplastics, thermosets, elastomers — then sub-classifies by performance tier (commodity, engineering, high-performance) and chain morphology (amorphous vs semicrystalline). This note is the family index for polymer selection: it lists 60+ named resins with trade names, manufacturers, key transition temperatures, mechanical properties, and selection heuristics. Use it before doing fresh search; drill into individual resin notes for grade-by-grade datasheets.

1. At a glance

The three primary classes

• Thermoplastic — linear or branched chains held together by van der Waals / hydrogen bonding (no covalent crosslinks between chains). Heat melts the polymer (or softens it through Tg in amorphous grades); cool, it re-solidifies. Reflowable, recyclable, weldable, injection-mouldable. Examples: PE, PP, PA, PEEK, PC, PVC. Subdivided into:

  • Amorphous — chains tangled but disordered. Properties dominated by glass transition Tg. Transparent. Low shrinkage on cooling (~0.5%). Examples: PC, PMMA, PS, ABS, PSU, PEI.
  • Semicrystalline — chains pack into ordered crystalline regions interspersed with amorphous tie zones. Properties dominated by Tm (melt) and Tg. Opaque or translucent (unless thin film). Higher shrinkage (~1-2%) and chemical resistance. Examples: PE, PP, PA, POM, PEEK, PBT, PPS.

• Thermoset — chains chemically crosslinked into a 3-D network during cure. Heat does not re-melt; instead it chars or decomposes. One-shot processing, higher Tg, dimensional stability, chemical resistance. Examples: epoxy, phenolic, unsaturated polyester, BMI, cyanate ester, silicone elastomer, PUR thermoset. Crosslink density (mol/cm³) controls modulus and Tg — lightly crosslinked → rubbery; densely crosslinked → glassy and brittle.

• Elastomer — lightly crosslinked (or physically entangled in TPE case) chains with Tg far below service temperature. Chain segments are highly mobile and the network is reversible — large recoverable strains (100-700%). Includes thermoset rubbers (NR, SBR, EPDM, FKM, silicone) and thermoplastic elastomers (SBS, TPU, TPV).

Performance tiers

• Commodity — ~5 polymers covering ~80% of plastics tonnage worldwide. PE (LDPE/HDPE), PP, PVC, PS, PET. Cost $1-2/kg. Use temps ≤80-100 °C.
• Engineering — moderate-temp structural and bearing applications. PA (nylon), POM, PC, ABS, PBT, modified PPE. Cost $3-8/kg. Use temps 100-150 °C.
• High-performance / specialty — high-temp, high-strength, chemical/electrical specialty. PEEK, PEI, PSU, PPS, PI, LCP, PAI, fluoropolymers (PTFE, PFA, PVDF). Cost $20-200/kg. Use temps 150-300+ °C.

ISO designation codes (ISO 1043-1)

Standard short codes used on data sheets and parts. PE = polyethylene. PP = polypropylene. PA66 = polyamide 6,6. POM = polyoxymethylene. PC = polycarbonate. PEEK = polyetheretherketone. PTFE = polytetrafluoroethylene. PVDF = polyvinylidene fluoride. EPDM = ethylene propylene diene monomer. FKM = fluorocarbon rubber. Cf. ASTM D1418 for elastomer codes.

2. Property cheat sheet (top 30 polymers)

Approximate values for typical unfilled grades, SI units. Tg = glass transition; Tm = melt (semicrystalline only); T_max = continuous service temp; E = tensile modulus; σ_y = yield or tensile strength; ε_b = elongation at break.

Polymer	Class	Cryst.	Tg °C	Tm °C	T_max °C	E (GPa)	σ_y (MPa)	ε_b (%)
Commodity thermoplastics
LDPE	TP	semi	-110	110	70	0.2	10	400
HDPE	TP	semi	-110	130	80	1.0	25	600
UHMWPE	TP	semi	-110	135	80	0.8	23	350
PP (homo)	TP	semi	-10	165	100	1.6	35	300
PVC (rigid)	TP	amor	80	—	60	3.0	55	30
GPPS	TP	amor	100	—	80	3.3	45	3
HIPS	TP	amor	95	—	70	2.2	25	40
PET (bottle)	TP	semi	80	255	60	3.0	70	70
PMMA	TP	amor	105	—	80	3.2	70	5
Engineering thermoplastics
PA6	TP	semi	50	220	100	2.8	75	50
PA66	TP	semi	70	265	120	3.0	85	30
PA12	TP	semi	50	178	90	1.4	50	200
POM (homo)	TP	semi	-60	175	100	3.1	70	25
POM (copo)	TP	semi	-60	165	100	2.6	65	35
PC	TP	amor	150	—	120	2.4	65	110
ABS	TP	amor	105	—	85	2.2	45	25
PBT	TP	semi	50	225	120	2.6	55	200
mPPE (Noryl)	TP	amor	145	—	105	2.5	55	60
High-performance
PSU	TP	amor	190	—	150	2.5	70	50
PES	TP	amor	225	—	180	2.6	85	40
PEI (Ultem)	TP	amor	215	—	170	3.0	105	60
PPS	TP	semi	90	285	220	3.3	80	3
PEEK	TP	semi	145	343	250	3.6	100	50
PAI (Torlon)	TP	amor	280	—	260	4.5	190	15
LCP (Vectra)	TP	semi	90	280	220	10	165	3
PI (Vespel)	TS/TP	—	360	—	290	3.2	90	8
PTFE	TP	semi	-100	327	260	0.5	25	350
PVDF	TP	semi	-40	178	150	2.0	50	50
Thermosets
Epoxy (DGEBA)	TS	amor	120-180	—	130	3.0	70	4
UPR (polyester)	TS	amor	80	—	80	3.5	55	2
Phenolic (PF)	TS	amor	200	—	180	6.0	60	1

3. Commodity thermoplastics

Polyethylene (PE)

The largest-volume polymer globally (~100 Mt/yr). Repeat unit –(CH₂–CH₂)–. Grades distinguished by branching and density:

• LDPE (low-density, 0.91-0.93 g/cm³) — long-chain branched, made by high-pressure radical process. Soft, ductile, flexible film for grocery bags, squeeze bottles, wire jacketing. Tm ~110 °C.
• LLDPE (linear low-density, 0.91-0.94 g/cm³) — short-chain branched via Ziegler-Natta or metallocene catalysis with α-olefin comonomer (1-hexene, 1-octene). Higher tear/puncture than LDPE; stretch wrap, films.
• HDPE (high-density, 0.94-0.97 g/cm³) — essentially linear, made by Ziegler-Natta or Phillips Cr catalyst. Stiffer, higher Tm ~130 °C. Bottles, pipe, tanks, geomembranes.
• UHMWPE (ultra-high molecular weight, Mw 3-6 million) — extremely long chains, exceptional abrasion resistance, very low friction (μ ~0.1). Cannot be conventionally injected — RAM-extruded or compression-moulded. Conveyor liners, joint replacement bearings (acetabular cups), Dyneema/Spectra fibre. Trade names: Tivar (Quadrant), GUR (Celanese).
• MDPE — pipeline grade between LDPE and HDPE.
• XLPE / PEX — peroxide- or silane-crosslinked PE; thermoset behaviour. Hot-water plumbing, wire insulation.

Polypropylene (PP)

Repeat unit –(CH₂–CH(CH₃))–. Tg ~-10 °C, Tm 160-170 °C. Three architectures:

• Homopolymer PP — isotactic chains, stiffest and highest Tm. Brittle below ~0 °C. Houseware, automotive trim.
• Random copolymer PP-R — 1-7% ethylene randomly inserted; lower Tm, improved clarity and impact. Hot-water pipe, medical, blow-moulded containers.
• Impact (block / heterophasic) copolymer PP-C — alternating PP + EP rubber blocks; tough at low temperature. Bumpers, battery cases.

Polystyrene (PS)

Repeat unit –(CH₂–CH(C₆H₅))–. Tg ~100 °C, amorphous, transparent.

• GPPS (general purpose) — clear, brittle. Petri dishes, CD cases (historic), disposables.
• HIPS (high impact) — polybutadiene rubber dispersed (~5-15%); opaque, ductile. Refrigerator liners, appliance housings.
• EPS / XPS — expanded / extruded foam, packaging and rigid insulation.

Polyvinyl chloride (PVC)

Repeat unit –(CH₂–CHCl)–. Tg ~80 °C, amorphous. Plasticizer content sets behaviour:

• Rigid (uPVC) — unplasticized, stiff. Pipes, window frames, siding.
• Flexible (pPVC) — 20-50% plasticizer (phthalate or trimellitate). Flooring, cable insulation, medical tubing (note phthalate regulation under REACH and EU MDR).

Thermally sensitive — releases HCl when over-processed; requires Ca/Zn or Sn stabilizers.

Polyethylene terephthalate (PET)

Aromatic polyester from terephthalic acid + ethylene glycol. Tg ~80 °C, Tm 255 °C.

• Bottle-grade PET — IV (intrinsic viscosity) 0.74-0.85 dL/g; stretch-blow-moulded into beverage bottles with biaxial crystallization for clarity + barrier.
• APET (amorphous) — quenched, thermoformable; food trays, blister packs.
• Fibre-grade PET — lower IV ~0.6; polyester textile fibre (Dacron, Terylene).
• PETG — glycol-modified copolyester (CHDM substitution); fully amorphous, easier thermoforming, clear medical packaging.

Polymethyl methacrylate (PMMA)

Repeat unit –(CH₂–C(CH₃)(COOCH₃))–. Tg ~105 °C, amorphous, glass-clear (92% light transmission). Brittle but UV-stable and weatherable. Cast (Perspex, Lucite) for sheet; extruded or moulded for parts. Aircraft canopies, automotive lenses, signage. Trade names: Plexiglas (Röhm/Trinseo), Acrylite (Mitsubishi), Lucite (Lucite Intl).

4. Engineering thermoplastics

Polyamide (PA / nylon)

The aliphatic polyamide family. Two numbering conventions:

• PA-X — single number = ω-amino-acid or lactam monomer with X carbons. PA6 (caprolactam), PA11 (11-aminoundecanoic acid, bio-sourced from castor oil), PA12 (laurolactam).
• PA-XY — X carbons in diamine, Y carbons in diacid. PA66 (hexamethylenediamine + adipic acid), PA46, PA610, PA612, PA1010.

Key grades:

• PA6 — Tm ~220 °C, hygroscopic (3-9% moisture). Lower cost than PA66.
• PA66 — Tm ~265 °C, higher strength and stiffness than PA6. Automotive intake manifolds, gears, fasteners. Trade names: Zytel (DuPont), Ultramid (BASF), Stanyl (DSM PA46), Vydyne (Ascend).
• PA11 / PA12 — lower moisture uptake (~1.5%), better dimensional stability and low-temp impact. Fuel line, brake tube. Rilsan PA11 (Arkema), Grilamid PA12 (EMS).
• PA46 — Tm 295 °C; high-temp electrical (Stanyl, DSM).
• PA4/6 / PA6/10 / PA4T / PA6T / PA9T / PA10T — high-temp aromatic-modified polyphthalamides (PPA). Tm 290-320 °C. Connector applications. Amodel (Solvay), Zytel HTN (DuPont).
• MXD6 — m-xylylene adipamide; very high gas barrier; multilayer bottle layer with PET.

Moisture plasticizes nylon — “dry-as-moulded” vs “conditioned” properties differ significantly. Always specify which.

Polyoxymethylene (POM / acetal)

Repeat unit –(O–CH₂)–. Tm 165-175 °C, highly crystalline, low friction (μ ~0.2-0.3), excellent fatigue.

• POM homopolymer — Delrin (DuPont/Celanese). Higher crystallinity and strength; slightly less thermal stability.
• POM copolymer — random ethylene-oxide insertions (~2%). Hostaform / Celcon (Celanese), Ultraform (BASF), Tenac (Asahi). Better thermal/oxidative stability and chemical resistance; standard for fluid contact.

Gears, snap-fits, conveyor parts, fuel pumps. Notch-sensitive — generous radii. Outgasses formaldehyde when overheated.

Polycarbonate (PC)

Aromatic carbonate of bisphenol-A. Tg ~150 °C, amorphous, clear. Exceptional impact (notched Izod ~700 J/m), highest among transparent thermoplastics.

Optical lenses, safety glazing, helmet shells, medical housings, electronic enclosures. Trade names: Makrolon (Covestro), Lexan (SABIC), Panlite (Teijin), Calibre (Trinseo). PC/ABS blends (Bayblend, Cycoloy) for cost and processability.

Hydrolysis-sensitive in hot/wet service; bisphenol-A migration controversial in food contact (regulatory pressure pushing alternatives such as Tritan).

ABS — acrylonitrile-butadiene-styrene

Two-phase: SAN matrix + grafted polybutadiene rubber domains. Tg ~105 °C, amorphous, opaque. Tough, easily moulded, paintable, plateable (electroless Ni then Cu/Ni/Cr for trim).

Appliance housings, automotive interior parts, Lego bricks, FDM 3-D printing filament. Trade names: Magnum (Trinseo), Terluran (INEOS Styrolution), Cycolac (SABIC), Toyolac (Toray).

ASA, SAN, related styrenics

• SAN — acrylonitrile-styrene; clear, stiffer than PS, less impact than ABS. Tg ~110 °C. Lighter covers, drinkware.
• ASA — acrylate (acrylic ester rubber) replaces the butadiene of ABS; UV-stable. Outdoor housings, satellite dishes, RV trim. Luran S (INEOS).
• MABS — methyl-methacrylate-modified ABS; transparent ABS.

Polybutylene terephthalate (PBT)

Aromatic polyester analogous to PET, semicrystalline with faster crystallization. Tm 225 °C, Tg ~50 °C. Electrical connectors (excellent dielectric and dimensional stability), automotive under-hood. Trade names: Crastin (DuPont), Ultradur (BASF), Valox (SABIC), Pocan (LANXESS). PBT/PC blends (Xenoy) for impact + heat.

Modified PPE / PPO (Noryl)

Polyphenylene ether on its own is unprocessable (Tg 215 °C, decomposes at melt). Blending with HIPS (~50/50) gives processable amorphous resin with Tg 145-160 °C, low moisture, intrinsic flame retardancy. Electrical, telecom. Trade name: Noryl (SABIC, originated GE Plastics).

Modified-impact PMMA

Acrylic + impact-modifier core-shell rubber. Plexiglas Resist (Röhm), Altuglas Impact (Trinseo). Reduces brittleness while retaining ~85% clarity.

5. High-performance / specialty thermoplastics

Polysulfones — PSU, PES, PPSU

Amorphous, transparent (slight amber), autoclavable.

• PSU (Udel, Solvay) — Tg 190 °C; bisphenol-A sulfone backbone. Membrane filtration (haemodialysis), hot-water plumbing manifolds.
• PES / PESU (Veradel, Sumikaexcel) — Tg 225 °C; pure sulfone-ether. Highest continuous-use temp of the family.
• PPSU (Radel, Solvay) — Tg 220 °C; biphenyl backbone. Best impact and hydrolytic stability, repeated steam-autoclave (1000+ cycles). Surgical instrument trays, sippy cups.

PEEK — polyetheretherketone

Semicrystalline, Tg 145 °C, Tm 343 °C, continuous service ≥250 °C. Outstanding chemical resistance (only attacked by conc H₂SO₄), hydrolytic stability, fatigue, wear, radiation tolerance. Aerospace structural brackets, oil & gas seals, spinal implants, semiconductor wafer carriers. Trade names: Victrex PEEK (Victrex), Ketaspire (Solvay), Vestakeep (Evonik), Zeniva (Solvay medical grade).

Carbon-fibre reinforced PEEK (PEEK/CF, e.g. APC-2) is the structural composite of choice for high-temp thermoplastic composites.

PEKK — polyetherketoneketone

Sister polymer with two ketone groups; faster crystallization than PEEK enabling broader processing window. Aerospace fuselage clips (Boeing 787 / Airbus A350). Trade names: Kepstan (Arkema), HT-Series (Victrex).

PEI — polyetherimide (Ultem)

Amorphous, transparent amber, Tg 215 °C. Inherent flame retardance (V-0) without additives. Aircraft cabin interior (panels, ducting — meets FAR 25.853 OSU heat-release). Trade name: Ultem (SABIC, originated GE).

PPS — polyphenylene sulfide

Semicrystalline, Tm 285 °C, continuous 220 °C. Inherent flame retardance, dimensional stability, chemical resistance second only to fluoropolymers. Highly notched-sensitive (filled grades almost always used). Automotive electrical (sensors, ignition), pump impellers, chip trays. Trade names: Ryton (Solvay), Fortron (Celanese), Torelina (Toray).

PI — polyimide

Heteroaromatic. Tg 360+ °C, decomposition >500 °C. Available as:

• Thermoset moulding — Vespel (DuPont) bearing/seal parts; expensive ($300+/kg).
• Thermoplastic-processable PI — Aurum (Mitsui) PEI-imide hybrid; limited.
• Film — Kapton (DuPont) for flexible PCB, thermal blankets, MLI on satellites; chosen for the Webb sunshield.
• PMR-15 / RP-46 — thermoset polyimide composite resin for high-temp aero engine components.

LCP — liquid-crystal polymer

Wholly aromatic polyester with rigid-rod backbone that orients in melt — Tm 280-330 °C, near-zero shrinkage, ultra-thin-wall mouldability. Microelectronic connectors (0.4-mm pitch), MEMS, mm-wave PCB substrates. Trade names: Vectra (Celanese), Xydar (Solvay), Sumikasuper (Sumitomo), Zenite (DuPont).

PAI — polyamide-imide

Amorphous, Tg 280 °C. Highest strength + temperature combination of any melt-processable thermoplastic (σ_y ~190 MPa, T_max 260 °C). Bearings, thrust washers, semiconductor test sockets. Trade name: Torlon (Solvay). Requires post-cure cycle (~5 days at 245 °C) to develop full properties.

Fluoropolymers

CF₂ backbones — best chemical resistance and low friction, modest mechanical strength.

• PTFE — fully fluorinated. Tm 327 °C but non-melt-processable (very high melt viscosity); compression-sintered like ceramic. μ ~0.04, T_max 260 °C, dielectric loss extremely low. Wire, gaskets, chemical-line liners, cookware coating. Teflon (Chemours/DuPont).
• PFA — perfluoroalkoxy modification of PTFE; melt-processable, similar properties. Semiconductor wet-bench tubing. Teflon PFA (Chemours), Hyflon PFA (Solvay).
• FEP — fluorinated ethylene propylene; melt-processable, T_max 200 °C (lower than PTFE). Wire jacketing, plenum cable.
• ETFE — ethylene-tetrafluoroethylene copolymer; mechanically stronger, T_max 150 °C. Architectural ETFE pillows (Allianz Arena, Eden Project), aircraft wiring. Tefzel (Chemours), Fluon (AGC).
• ECTFE — ethylene-chlorotrifluoroethylene; Halar (Solvay). Chemical-resistant lining.
• PVDF — polyvinylidene fluoride; semicrystalline, Tm 178 °C. Pyroelectric/piezoelectric β-phase used for sensors. Architectural coatings (Kynar 500 PVDF for metal roofing, 30-year UV warranty). Chemical-process piping. Kynar (Arkema), Solef (Solvay).
• CTFE — chlorotrifluoroethylene; barrier blister packs.

6. Thermosets

Epoxy

By far the most common engineering thermoset. Resin = epoxide-functional oligomer; the workhorse is DGEBA (diglycidyl ether of bisphenol-A) from bisphenol-A + epichlorohydrin. Cure = polyaddition with curing agent:

• Amine cures — aliphatic (DETA, TETA, IPDA) at RT for adhesives; cycloaliphatic (Jeffamine) for clarity; aromatic (DDS, MDA) at 150-180 °C for aerospace prepreg.
• Anhydride cures — MTHPA, NMA, HHPA with imidazole accelerator. Long pot life, electrical encapsulation.
• Phenolic / novolac cures — for higher Tg (~200 °C).

Tg 80-250 °C depending on chemistry. Carbon-fibre prepregs (Hexcel 8552, Cytec CYCOM 977, Toray 3900-series), structural adhesives (Hysol, Araldite, Loctite EA), coatings, electronic encapsulation.

Unsaturated polyester (UPR)

Linear polyester with maleic-anhydride unsaturation crosslinked through styrene by peroxide initiator. Cheap, ambient-cure. Glass-reinforced (FRP) boat hulls, bath tubs, automotive SMC body panels, corrosion-resistant tanks. Two backbones:

• Orthophthalic — general purpose.
• Isophthalic — better water/chemical resistance, marine.

Vinyl ester

Methacrylate-terminated epoxy backbone, crosslinked in styrene like polyester. Better chemical resistance and elongation than UPR. Pipe lining, chemical tanks, wind-turbine blade root structures.

Phenolic (PF)

Phenol-formaldehyde. The first fully synthetic plastic (Bakelite, Leo Baekeland, 1907.) Two routes:

• Resol (single-stage, base-catalyzed, excess formaldehyde) — liquid resin that cures on heat. Plywood adhesive, foundry sand binder.
• Novolac (two-stage, acid-catalyzed, excess phenol) — solid resin that needs added crosslinker (hexamethylenetetramine). Moulding compound with mineral or wood-flour filler.

High Tg (200 °C), inherent flame retardance, char former (used in ablatives), low cost. Brake pads, brake-friction parts, aerospace cabin interiors, ammonia-resistant tanks, phenolic prepreg.

Urea-formaldehyde (UF) and melamine-formaldehyde (MF)

Amino resins. UF for low-cost particleboard adhesive (releases formaldehyde, regulatory concern). MF for decorative laminates (Formica), tableware (Melamine), powder coatings. MF/PF hybrids for char-resistant laminates.

Polyurethane (PUR / PU) — thermoset versions

Reaction of polyol + polyisocyanate (MDI, TDI, HDI). Property covers entire spectrum:

• Rigid PU foam — insulation (refrigerators, building panels).
• Flexible PU foam — bedding, automotive seats.
• Cast PU elastomer — wheels, rollers, gaskets (50-95 Shore A); Vulkollan (Covestro).
• PU coatings / adhesives — moisture-cure or 2K aliphatic.
• RIM PU — reaction injection moulded body panels.

Isocyanate toxicity (sensitizer) governs handling.

Bismaleimide (BMI)

Two maleimide groups on aromatic spacer, cure by addition without volatiles. Tg 250-290 °C. Higher-temp aerospace composite than epoxy (engine cowl, missile components). Compimide (Evonik), Cytec 5250-4.

Cyanate ester

Aromatic dicyanate cures by trimerization to triazine network. Low dielectric loss (used for radar-transparent radome, satellite electronics), Tg 250-290 °C, low moisture absorption. AroCy (Huntsman/Lonza), PT-30 (Lonza).

Polyimide thermosets

PMR-15 (formerly NASA, now Hexcel), addition-cured via norbornene end-caps. Tg 340 °C. Aero engine bypass duct, missile.

Silicone thermosets

Si–O backbone with methyl/vinyl side groups. High-temp (200-300 °C continuous), UV-stable, low Tg (-120 °C → flexible to cryo). Sealants, gaskets, electrical insulation, medical implants, kitchenware. Two cure routes: condensation (acetoxy or alkoxy, RTV-1) and addition (Pt-catalyzed hydrosilylation, no by-product, LSR liquid silicone rubber).

Alkyd

Glycerol + phthalic anhydride + drying oil. Air-cure via oil-oxidation. Architectural enamel paints, varnishes. Largely displaced by acrylic latex except in industrial trim.

Crosslink density

Mechanical and thermal response scale with crosslink density ν (mol/cm³). Rubbery modulus E_r ≈ 3νRT; Tg rises with ν until segmental motion is suppressed. For an epoxy: ν ~ 1-3 ×10⁻³ mol/cm³; for a tire rubber: ν ~ 1-2 ×10⁻⁴ mol/cm³. Higher ν → glassier, higher Tg, more brittle.

7. Elastomers

Natural and diene rubbers

• NR — natural rubber (cis-1,4-polyisoprene from Hevea brasiliensis). Outstanding tensile strength and tear, low compression set. Tires, vibration mounts, conveyor belts. Sensitive to ozone, oil, UV.
• IR — synthetic polyisoprene; Ziegler or anionic Li catalysed. Equivalent to NR for medical (no protein allergen).
• SBR — styrene-butadiene (~23% styrene). Cheapest synthetic; tire treads (~50% global rubber consumption). Lower tensile than NR.
• BR — polybutadiene (cis-1,4). Lowest Tg (~-100 °C), best abrasion. Tire tread blend component, golf-ball cores.

Specialty rubbers

• NBR — nitrile / Buna-N (butadiene + acrylonitrile, 18-50% ACN). Oil/fuel/hydraulic-fluid resistance; the workhorse fuel-hose rubber. Higher ACN → better oil resistance, worse low-temp.
• HNBR — hydrogenated NBR — selectively hydrogenated to remove backbone unsaturation. Better heat and oxidation. Therban (Arlanxeo), Zetpol (Zeon). Automotive timing belts, oilfield seals.
• EPDM — ethylene propylene diene — fully saturated, exceptional weather/ozone/UV resistance, no oil resistance. Roofing membrane, automotive weather seal, radiator hose, brake-system rubbers, dishwasher gaskets.
• CR — chloroprene / neoprene — chlorine on backbone. Balanced oil, weather, flame resistance. Wetsuits, air-spring bellows, transmission belts. Originally DuPont 1931.
• IIR — butyl (isobutylene + ~2% isoprene). Lowest gas permeability of any rubber → tire innerliner. Damping seal applications.
• CIIR / BIIR — halogenated butyl; vulcanizable into other rubbers (tire compound).

Silicone rubber

• VMQ — methyl-vinyl-silicone, standard grade. -55 to +220 °C, UV/ozone-resistant, biocompatible.
• PVMQ — phenyl-methyl-vinyl; extended low-temp (-100 °C).
• FVMQ — fluorosilicone — trifluoropropyl side groups; oil resistance like NBR + temperature range of silicone.
• LSR — liquid silicone rubber, 2-K injection moulded; medical, baby bottles, cookware.

Fluoroelastomers

• FKM (Viton) — VDF + HFP ± TFE. T_max 200-230 °C, excellent fuel/oil/chemical resistance, narrow gap on amines. Engine seals, fuel injectors, chemical-processing o-rings. Viton (Chemours/DuPont), Dai-El (Daikin), Tecnoflon (Solvay). Grades A (dipolymer), B/F (terpolymer), GF/GFLT (peroxide-cure for steam/methanol).
• FFKM — perfluoroelastomer — all C–F backbone. T_max 300-325 °C. Chemically inert across virtually all media. Semiconductor process o-rings, aerospace high-temp seals. Kalrez (Chemours/DuPont), Chemraz (Greene Tweed), Perlast (Precision Polymer). Very expensive ($5000+/kg).

Thermoplastic elastomers (TPE)

Block or two-phase polymers behaving as rubber but melt-processable.

• SBS / SIS — styrene-butadiene-styrene / styrene-isoprene-styrene block copolymers. Shoe soles, asphalt modifier. Kraton (Kraton Polymers).
• SEBS — hydrogenated SBS; UV-stable. Medical handles, soft-touch overmoulding.
• TPU — thermoplastic polyurethane — hard (urethane) + soft (polyether or polyester) segments. Phone cases, ski boots, conveyor belts. Pellethane (Lubrizol), Texin (Covestro), Estane (Lubrizol), Elastollan (BASF).
• TPV — thermoplastic vulcanizate — dynamically vulcanized EPDM particles in PP matrix. Replaces EPDM thermoset in many automotive sealing applications. Santoprene (Celanese, originated Monsanto).
• COPE / TPC — polyether-ester copolymer (Hytrel, DuPont; Arnitel, DSM). Bellows, hose, fibre.
• COPA / TPA — polyether-amide block (Pebax, Arkema). Sports footwear midsoles, catheter shafts.

Polysulfide

–(R–S–S)– backbone. Excellent fuel resistance and aircraft sealant (Thiokol). Largely displaced by silicones and polyurethanes for civil sealants.

8. Fibre polymers

Aramid

Aromatic polyamides spun from sulfuric-acid solution.

• Para-aramid — rigid-rod chains, ultra-high-modulus + tensile. Kevlar (DuPont), Twaron (Teijin), Technora (Teijin). Body armour, ropes, ballistic, optical-fibre strength member. σ_t ~3 GPa, E ~70-130 GPa.
• Meta-aramid — less rigid, flame-resistant. Nomex (DuPont), Conex (Teijin). Firefighter turnout gear, electrical insulation paper for transformers.

PBO — polybenzoxazole

Heterocyclic rigid-rod. σ_t ~5.8 GPa, E ~280 GPa — highest of organic fibres. Zylon (Toyobo). UV degradation issue restricts to indoor / protected applications.

UHMWPE fibre

Gel-spun ultra-high-molecular-weight PE. σ_t 3-4 GPa, E 100-170 GPa, density 0.97 (floats!). Dyneema (Avient/DSM), Spectra (Honeywell). Ballistic armour, mooring lines, fishing.

Polyester fibre

PET, the workhorse synthetic textile fibre. Dacron (Invista), Terylene historical.

Nylon fibre

PA6, PA66. Carpet (BCF), hosiery, parachute, tire cord, rope.

Acrylic fibre

Polyacrylonitrile (PAN) homopolymer or copolymer with methyl-acrylate / vinyl-acetate. Wool replacement (Orlon, Acrilan). PAN is also the precursor for ~96% of carbon fibre worldwide — oxidized + carbonized at 1000-2000 °C.

Bioplastic fibres / resins

• PLA — polylactic acid — from corn-derived lactic acid, ring-opened. Tg 60 °C, Tm 170 °C. Compostable, food packaging, 3-D printing filament, sutures, scaffolds. NatureWorks Ingeo, TotalEnergies-Corbion Luminy.
• PHA — polyhydroxyalkanoates — bacterial fermentation. PHB, PHBV. Truly marine-biodegradable. Higher cost; emerging packaging.
• Bio-PE / Bio-PET — same polymer, sugarcane-derived feedstock.

9. Selection heuristics

Clear strong → PC (best impact, somewhat lower modulus) or PMMA (highest clarity, scratch-resistant, brittle). PETG for thermoformed transparent.

High-temperature structural → PEEK (250 °C continuous, excellent chemical/fatigue), PPS for electrical, PEI for radiation/sterilization, PAI for highest strength, PI / Vespel for >290 °C bearings.

Chemical resistance → fluoropolymers in order PFA ≥ PTFE > FEP > PVDF > ETFE. PEEK is good for everything except concentrated H₂SO₄. PPS for moderate chemical with mechanical.

Low friction / bearings → UHMWPE (low load, hi speed), POM (general gears), PEEK (high temp/load), PAI Torlon 4301 (severe).

Food contact → PE, PP, PET, certified grades only; FDA 21 CFR / EU 10/2011. PA, POM also approved. PC under bisphenol-A pressure → Tritan or PMP or PEI.

Outdoor / UV-stable → ASA, PVDF coatings (Kynar 500), silicone, EPDM, fluoroelastomer, PMMA acrylic. Add carbon-black-stabilizer to nylons, PE, PP for outdoor.

Flexible fuel hose → NBR (cheap), FKM (better temp/methanol blends), FVMQ (cold-weather aerospace), HNBR (best for HFC refrigerant + temp).

High-temp seal → FKM (200 °C engine), FFKM Kalrez (300 °C semiconductor / chemical), silicone (300 °C dynamic for low load).

Silicone bake-tray / cookware → VMQ Pt-cure LSR, FDA grade.

Tire compounding — passenger tread: SBR/BR blend; tread cap: NR or NR/BR; innerliner: butyl; sidewall: NR/BR with antiozonant; bead: HNBR or NR; off-road truck: NR-rich for tear.

Bearings (oil-free) → POM (under 100 °C), PEEK + PTFE + CF (Victrex 450FC30), PAI Torlon 4301/4275, PI Vespel SP-21 (graphite-filled).

Electrical connector → PBT (cost), PA66 GF (low-cost engineering), PPA / PPS / LCP for SMD reflow (260 °C), LCP for thin-wall high-frequency.

Medical implant → UHMWPE (joint articulating surface), PEEK Zeniva (spine cage), silicone medical (drains, pacemaker leads), PSU/PPSU for autoclavable trays.

10. Compatibility and processing

Injection moulding

• Easy — PP, PE, ABS, PS, POM, PA, PC, PBT, PMMA. Cycle 20-60 s. Conventional 25-300 ton presses.
• Moderate — PSU, PEI, PPS, PPA. Hot tools (>120 °C), drying critical, higher melt temps.
• Demanding — PEEK, PEKK, LCP, PAI. Melt 360-410 °C, tool 170-200 °C, fast-fill thin sections, expensive hot runners.

Shrinkage

• Semicrystalline typically 1.0-2.5% (PA 1.5%, POM 2.0%, PP 1.5%, PEEK 1.2%). Anisotropic when fibre-filled or LCP-melt-flow oriented.
• Amorphous typically 0.4-0.7% (PC 0.6%, ABS 0.5%, PS 0.5%, PSU 0.7%).

Drying

Hygroscopic polymers absorb moisture which hydrolyses during melt → MW drop and bubbles. Mandatory dehumidifying drying before processing: PA (4 h, 80 °C, dewpoint ←40 °C), PC (4 h, 120 °C), PBT (4 h, 120 °C), PEI (4 h, 150 °C), PEEK (3 h, 150 °C).

UV resistance ranking (unstabilized)

ASA ≫ PVDF ≫ PC, PMMA > PA (with HALS) > ABS, PP, PE.

Gamma sterilization (25-40 kGy)

• Tolerant — PE, PP (with HALS), PSU, PPSU, PEI, PEEK, PEKK, PC (some yellowing), PVC (yellowing).
• Degraded — POM (chain scission, severe MW drop), PTFE (chain scission), PA (modest), PMMA (modest).

Steam autoclave (134 °C, 100% humidity)

• OK indefinitely — PSU, PPSU, PEI, PEEK, silicone, PTFE/PFA, stainless tooling.
• Limited cycles — PC (~100 cycles hydrolysis), PA (50-100), PMMA (a few).
• Not OK — POM, ABS, PVC, PS.

Joining

• Welding thermoplastics — ultrasonic (PP, ABS easy; nylon 6 OK; semicrystallines harder), vibration (large parts), hot plate, IR/laser (clear-to-absorber pair), spin (cylindrical), induction (with metal insert), solvent (amorphous only: PC, PMMA, ABS).
• Adhesives — epoxy and acrylic for most engineering plastics with surface prep; cyanoacrylate for instant bonds; silicone-MS for low-energy PE/PP after flame or plasma treatment.
• Fasteners — heat-stake, ultrasonic insert, self-tapping (Plastite, Delta-PT) sized for plastic.

11. Recycling codes (SPI 1-7)

ASTM D7611. Stamped inside the chasing-arrow triangle on consumer packaging:

Code	Polymer	Typical use	Recyclability
1	PET / PETE	Bottles, fibre	Excellent — mechanical or chemical (glycolysis)
2	HDPE	Milk jugs, detergent	Excellent — mechanical
3	PVC / V	Pipe, blister, vinyl	Limited — Cl interferes with downstream
4	LDPE	Film, squeeze bottles	Moderate — mechanical
5	PP	Yogurt cups, closures	Improving — mechanical and chemical
6	PS	Trays, foam	Limited mechanical; chemical via depolymerization
7	Other	PC, PA, ABS, PMMA, bio-resin, multilayer	Case-by-case

Newer schemes (CEFLEX flexible packaging, eXtended Producer Responsibility, EU SUP Directive 2019/904) push toward mono-material packaging design for recyclability. Chemical recycling (pyrolysis, glycolysis, methanolysis, enzymatic depolymerization) gaining for PET, PS, PE/PP.

12. Cross-references

• materials-polymers — top-level polymers reference.
• composites-taxonomy — fibre-reinforced polymer matrices and continuous-fibre composites.
• materials-composites — composite mechanics and design.
• steel-grades — metal alternatives for the same applications.
• ceramics-taxonomy — ceramic alternatives.
• polymers-taxonomy — deeper elastomer reference.
• forming-processes — extrusion, injection, blow, thermoforming.
• joining-taxonomy — adhesive selection for polymer substrates.
• surface-treatments — surface coating chemistry.

13. Citations

• ASM Handbook Vol. 21 — Composites (2001). Polymer matrices for PMC.
• ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials. Polymer comparison data.
• CAMPUS plastics database (campusplastics.com) — industry-standard ISO 10350 single-point datasheets from material producers.
• Brydson, J. A. — Plastics Materials, 7th ed., Butterworth-Heinemann (1999). Canonical resin-by-resin reference.
• ISO 1043-1 — Plastics — Symbols and abbreviated terms. Polymer designation codes.
• ASTM D1418 — Standard Practice for Rubber and Rubber Latices — Nomenclature. Elastomer code letters (NR, SBR, EPDM, FKM, etc.).
• ISO 1629 — Rubber and latices — Nomenclature.
• ASTM D7611 — Standard Practice for Coding Plastic Manufactured Articles for Resin Identification.
• MatWeb (matweb.com) — searchable property database (free single-point; paid full).
• Omnexus / SpecialChem (omnexus.specialchem.com) — vendor-aggregated plastics selection portal.
• IDES Prospector / UL Prospector — vendor datasheet aggregator (subscription).
• Domininghaus / Eyerer — Plastics Reference Handbook (Hanser).
• Mark, Bikales, Overberger, Menges — Encyclopedia of Polymer Science and Technology (Wiley).
• Wypych, G. — Handbook of Polymers, 3rd ed. (ChemTec, 2022).