Delein Derlin And Delron Where Misspelled Delrin Searches Land
Polyoxymethylene (POM): delein, derlin and delron—Where Misspelled Delrin Searches Land
Polyoxymethylene (POM) is a semicrystalline engineering thermoplastic whose repeating –CH₂O– units form a linear chain with crystallinity typically reported between 75% and 85% for homopolymer grades when measured by differential scanning calorimetry according to ISO 11357-3:2018. The search strings “delein,” “derlin,” and “delron” do not identify separate resin families; they are misspellings of the Delrin trade name for POM homopolymer. The phrase “delein, derlin and delron: Where Misspelled Delrin Searches Land” therefore converges on the same material category defined by ISO 9988-1:2006 as POM-H for homopolymer and POM-C for copolymer. ASTM D6778-20 provides the parallel North American classification for POM molding and extrusion materials. The homopolymer base polyoxymethylene chain is identified by CAS registry number 9002-81-7. Material inquiries entering specification workflows under these corrupted spellings should be normalized to POM-H or POM-C with accompanying melt volume-flow rate, filler content, and stabilizer designation.
POM is supplied as unfilled, glass-fiber reinforced, mineral-filled, carbon-black loaded, lubricated, and impact-modified compounds. Density for unfilled grades falls between 1.40 and 1.43 g/cm³ according to ISO 1183-1:2019 or ASTM D792-20, depending on crystallinity and comonomer content. The polymer is used in injection molding, extrusion, compression molding, and machined stock shapes. The property profile includes high tensile stiffness, low moisture absorption, low dynamic friction against steel without external lubrication, and reproducible dimensional behavior after mechanical loading. Performance statements require test-method qualification as specified in the sections below.
What Distinguishes Homopolymer Acetal from Copolymer POM Under ISO 9988-1 Classification?
POM-H is polymerized from formaldehyde or trioxane and consists almost entirely of oxymethylene repeating units. POM-C incorporates a small proportion of cyclic ether comonomer, commonly ethylene oxide or dioxolane, which introduces oxyethylene units into the chain. The comonomer reduces sequence regularity, lowers melting point, and improves resistance to thermal-oxidative degradation and hot-water attack. Homopolymer grades generally exhibit higher tensile strength, flexural modulus, and crystallinity, but copolymer grades tolerate broader processing temperature excursions and aggressive aqueous environments more reliably.
Table 1 summarizes property ranges for unfilled general-purpose injection molding grades. The values are compiled from published material datasheets and should not be extrapolated to filled, impact-modified, or tribologically modified compounds.
| Property | Test method | POM-H range | POM-C range |
|---|---|---|---|
| Density | ISO 1183-1:2019 / ASTM D792-20 | 1.41–1.43 g/cm³ | 1.40–1.42 g/cm³ |
| Tensile stress at yield | ISO 527-2:2012 / ASTM D638-14 | 68–72 MPa | 60–65 MPa |
| Tensile modulus | ISO 527-2:2012 / ASTM D638-14 | 3000–3400 MPa | 2600–3000 MPa |
| Flexural modulus | ISO 178:2019 / ASTM D790-17 | 2800–3300 MPa | 2400–2800 MPa |
| Notched Izod impact | ISO 180:2019 / ASTM D256-10(2018) | 6–8 kJ/m² | 5–7 kJ/m² |
| Heat deflection temperature at 1.8 MPa | ISO 75-2:2013 / ASTM D648-18 | 95–110 °C | 90–105 °C |
| Water absorption, 24 h immersion | ISO 62:2008 / ASTM D570-98(2018) | 0.20–0.30% | 0.25–0.40% |
Filled grades depart significantly from these ranges. A 25% glass-fiber reinforced POM-C compound can exceed 120 MPa in tensile stress at break under ISO 527-2:2012, while elongation at break commonly falls below 2–3%. Tribological grades containing PTFE or silicone modify the wear and friction behavior independently of the base resin tensile properties. Published data for specific formulations such as slip-modified or anti-static POM should be obtained from raw-material suppliers, particularly when the final part operates near the upper service temperature limit.
In injection molding operations using general-purpose screws of 20:1 to 25:1 L/D, melt temperature at the nozzle is normally controlled within 195–220 °C for POM-H and 180–215 °C for POM-C. A mold temperature of 80–100 °C is required to develop adequate surface crystallinity and reproducible post-mold shrinkage. The upper processing boundary is sharp. A nozzle setpoint of 220 °C with a ±5 °C overshoot reaches the 225–230 °C range where depolymerization accelerates, generating formaldehyde and reducing molecular weight. Melt temperature excursions above 230 °C for more than a few minutes produce a measurable increase in melt volume-flow rate and a drop in impact strength after repeated recycling. Production lines therefore use closed-loop nozzle-band control and shot-size monitoring; screw-recovery time is an indirect indicator of melt viscosity shift.
POM does not require predrying solely because of hygroscopicity. Equilibrium moisture content at 50% relative humidity is generally below 0.25%, but surface condensation occurs when cold pellets are moved into a warm molding area. At plant relative humidity above 60%, desiccant drying at 80 °C for 3–4 h to a maximum moisture content of 0.10% is standard prior to melt processing. Melt volume-flow rate for standard injection molding grades ranges from 2 to 25 cm³/10 min when measured at 190 °C under 2.16 kg load according to ISO 1133-1:2022. High-flow grades at the upper end are used for thin-wall parts below 1 mm nominal wall thickness, while lower-flow grades are used for thick-section rods and plate stock. POM exhibits pseudoplastic flow at shear rates typically encountered during filling from 1,000 to 10,000 s⁻¹, so higher injection shear reduces apparent viscosity. Vent depths in mold tooling are usually kept below 0.015 mm to minimize flash while allowing gas escape. Hot runner manifolds must be designed without stagnant zones; trapped resin degrades to formaldehyde and creates voids or surface blush in subsequent shots.
| Processing variable | Recommended range | Failure boundary or observed effect |
|---|---|---|
| Melt temperature, POM-H | 195–220 °C | Above 230 °C depolymerization accelerates; below 180 °C solidification risk in nozzle |
| Melt temperature, POM-C | 180–215 °C | Upper limit similar; residence time must be minimized above 220 °C |
| Mold temperature | 80–100 °C | Below 60 °C reduces crystallinity and increases post-mold shrinkage variation |
| Drying | 80 °C for 3–4 h | Moisture above 0.10% produces splay and surface streaks |
| Hot runner manifold | 200–210 °C | Stagnant zones generate formaldehyde and void formation |
| Vent depth | ≤ 0.015 mm | Deeper vents create flash; insufficient venting produces gas burns |
When Queries for delein, derlin and delron Move from Search Logs to Material Specifications
The corrupted search terms delein, derlin and delron do not correspond to entries in ISO 1043-1:2011, which uses the symbol POM for polyoxymethylene. Procurement records containing these misspellings should be converted into ISO 1043-1 polymer symbols, ISO 9988-1 designation blocks, melt volume-flow rate, and filler content. A specification expressed as “Delrin” without a grade is insufficient because homopolymer POM spans multiple molecular weight grades from high-viscosity extrusion grades to high-flow thin-wall injection grades. The ISO 9988-1 designation block includes material type, comonomer content, viscosity number, and stabilizer package; ASTM D6778-20 provides the North American equivalent. Without this normalization, a search for “delron sheet” may return mixed results across acetal homopolymer, acetal copolymer, glass-filled POM-C, and unrelated polyacetal grades.
Dry-running friction of unfilled POM against machined steel surfaces is influenced by counterface roughness and pressure–velocity conditions. Values measured under ASTM D1894-14 fall typically between 0.20 and 0.35 dynamic coefficient of friction. Thrust washer wear factors under ASTM D3702-94(2019) are generally reported in the 10⁻⁶ mm³/N·m range at moderate PV values, but published data for heavily loaded gear contact above 10 MPa·m/s is limited. POM resists fuels, aromatic hydrocarbons, ketones, esters, and many neutral aqueous solutions. Immersion testing under ASTM D543-21 is used to establish specific chemical resistance; dimensional change in 5% acetic acid or 5% sodium hydroxide at 23 °C can exceed 0.5% depending on grade and exposure duration. Strong acids below pH 4, oxidizing media, chlorine water, and bromine attack the acetal backbone. Continuous hot-water immersion above 60 °C is not recommended for homopolymer grades because hydrolysis reduces molar mass; copolymer grades tolerate slightly higher moisture exposure but are not specified for long-term service above 80 °C under load.
Unstabilized POM exposed outdoors degrades by photo-oxidation. Carbon-black filled or UV-stabilized formulations are specified for exterior components. Weathering performance is evaluated by xenon-arc exposure according to ISO 4892-2:2013 or ASTM G155-13. Electrical gear and pulley applications use unfilled POM because volume resistivity typically exceeds 10¹⁴ Ω·cm under IEC 62631-3-1:2016. Conductive carbon-filled grades are used where static dissipation is required, but these grades exhibit reduced dielectric strength and higher moisture uptake.
Compliance Matrix for Food-Contact and Electrical Enclosure Applications
POM homopolymer intended for repeated food-contact use is evaluated under 21 CFR 177.2480; POM copolymer is evaluated under 21 CFR 177.2470. The European Regulation (EU) No 10/2011 requires compliance with overall migration limits and a specific migration limit for formaldehyde of 15 mg/kg food simulant. POM used in medical device housings is often tested under ISO 10993-5:2009 for cytotoxicity and USP Class VI protocols where applicable; biocompatibility is formulation-specific and not all POM grades meet these requirements.
Electrical enclosure materials are evaluated by UL 94 for flammability. Unfilled POM typically obtains HB at 1.5 mm thickness; V-0 ratings require flame-retardant modifications that may reduce thermal stability and complicate processing. Dielectric strength determined under IEC 60243-1:2013 is typically reported between 20 and 40 kV/mm for unfilled 3 mm specimens. Volume resistivity above 10¹⁴ Ω·cm supports low leakage current in dry electrical insulation. Under RoHS 2011/65/EU, POM grades must meet limits for lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE; REACH SVHC declarations are grade-dependent and must be confirmed against the specific compound.
Machined POM plate and rod are selected for prototype gears, jigs, and food-processing guides because the stock material can be cut with conventional metalworking equipment. Rockwell M hardness of unfilled POM stock is typically 80–85 under ASTM D785-98(2024). Cutting speeds and feed rates must be limited to avoid surface temperatures above 90 °C; because POM has low thermal conductivity and a melting point of 165–175 °C, excessive tool dwell melts the surface and produces raised burrs. Adhesive bonding is constrained by low wetting tension in the 36–40 mN/m range as measured by contact-angle methods under ISO 19403-2:2017. Corona, plasma, or flame treatment raises surface energy before painting or bonding, but solvent welding is generally ineffective on POM because of its resistance to common solvents. Hot-plate, ultrasonic, and vibration welding are used for joining POM parts; joint geometry must accommodate a semicrystalline freeze layer and melt layer thickness of less than 0.5 mm for reproducible weld strength.
Dimensional stability after machining can be affected by residual stress from extrusion. Annealing at 150–160 °C for 30 min per 10 mm thickness in circulating air is commonly applied to stress-relieve POM plate before precision machining. Part tolerances below 0.05 mm require conditioned measurement because POM absorbs surface moisture and expands slightly with ambient humidity changes.
