1H-Pyrrole-2,5-Dione, 1,1'-(1,6-Hexanediyl)Bis- (9Ci)
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HS Code |
437853 |
| Chemical Formula | C14H20N2O4 |
| Molecular Weight | 280.32 g/mol |
| Appearance | Solid |
| Melting Point | N/A |
| Boiling Point | N/A |
| Solubility In Water | Insoluble |
| Solubility In Organic Solvents | Soluble in common organic solvents like dichloromethane |
| Density | N/A |
| Flash Point | N/A |
| Stability | Stable under normal conditions |
| Hazardous Decomposition Products | Upon decomposition, may release toxic nitrogen oxides |
As an accredited 1H-Pyrrole-2,5-Dione, 1,1'-(1,6-Hexanediyl)Bis- (9Ci) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 100g of 1H - Pyrrole - 2,5 - Dione, 1,1'-(1,6 - Hexanediyl)Bis - (9Ci) in sealed chemical - grade packaging. |
| Shipping | 1H - Pyrrole - 2,5 - Dione, 1,1'-(1,6 - Hexanediyl)Bis - (9Ci) is shipped in containers suitable for chemicals. Ensured proper packaging to prevent leakage, with compliance to safety regulations for transport of such substances. |
| Storage | 1,1'-(1,6-Hexanediyl)bis(1H-pyrrole - 2,5 - dione) should be stored in a cool, dry, well - ventilated area, away from heat sources and open flames. Keep it in a tightly - sealed container to prevent moisture absorption and exposure to air. Store separately from incompatible substances like strong oxidizers and bases to avoid potential chemical reactions. |
In the production of peroxide-cured ethylene propylene diene monomer (EPDM) compounds destined for long-life automotive coolant seals and turbocharger air duct sleeves, the incorporation of 1,1'-(1,6-hexanediyl)bis-1H-pyrrole-2,5-dione at levels ranging from 0.8 to 3.0 parts per hundred rubber (phr) functions as a co-agent that diverts free-radical degradation toward interchain bridge formation. The crosslinked architecture generated by dicumyl peroxide (typical dosage 2.5–4.0 phr, assay 99% on inert carrier) alone suffers from chain scission dominance above 160°C, leading to a compression set exceeding 65% after 168 hours at 150°C under 25% constant deflection when measured per ASTM D395 Method B. When the aliphatic bismaleimide is introduced and pre-dispersed as a 50 wt% masterbatch in ethylene-propylene copolymer binder on a two-roll mill with a friction ratio of 1:1.2 and nip gap set to 2 mm, the fraction of elastically active network chains increases by roughly 40–50%, as inferred from equilibrium swelling data in methyl ethyl ketone using the Flory–Rehner equation with an interaction parameter χ of 0.36. The adiabatic temperature rise measured on an oscillating disc rheometer (ODR, ±1°C arc, 1.67 Hz) drops from 4.8°C to 2.1°C when the bismaleimide is dosed above 1.5 phr, indicating suppressed exothermic macroalkyl coupling, which mitigates scorch safety loss on the production floor.Molding is conducted on a 500-ton vertical compression press with multicavity tools set to 175°C platen temperature and 15 MPa clamping pressure maintained for 12 minutes, followed by a forced-air post-cure stage of 4 hours at 150°C ramped in 20°C steps. The tensile strength at break ( ISO 37 Type 2 dumbbell) moves from 9.8 MPa with peroxide-only cure to 12.3 MPa with 2.0 phr bismaleimide, while elongation at break remains above 320%, a balance seldom achieved with aromatic bismaleimides that embrittle the matrix. Tear resistance assessed by ISO 34-1 (trouser, 500 mm/min) similarly climbs from 22 kN/m to 34 kN/m. The resulting parts—coolant expansion tank seals, charge-air cooler gaskets, and dynamic shaft lip profiles—comply with the volatile organic compound emission ceilings defined by VDA 270 variant B3 (100°C, 24 hours) and with the migration limits of EU REACH Annex XVII entries 50 through 63 for polycyclic aromatic hydrocarbons. Processors note that pre-drying the masterbatch at 60°C to a moisture content below 0.1 wt% is mandatory when relative humidity in the batching area exceeds 55%, otherwise steam-pore defects appear at knit lines during injection transfer molding.
What Drives the Glass Transition Temperature of Hexamethylene Bismaleimide Copolymers Above 280°C?A prepolymer is obtained by charging 100 parts of the 1,1'-(1,6-hexanediyl)bis-1H-pyrrole-2,5-dione monomer together with 45 parts of 4,4'-diaminodiphenylmethane into a resin kettle equipped with a helical ribbon agitator operating at 80 rpm. The temperature is staged from 110°C to 145°C over 90 minutes under a nitrogen sweep of 0.5 L/min, and the reaction is arrested at a Brookfield viscosity of 14,000 mPa·s at 80°C using a thermocouple-fitted spindle #27. The resultant oligomeric syrup is degassed in a vacuum oven (−0.095 MPa) at 80°C for 30 minutes before being hot-coated onto 3K plain-weave carbon fabric (areal mass 200 g/m², sizing compatible with bismaleimide chemistry). Lay-up is performed on a flat steel tool with a caul plate, and the laminate is consolidated in an autoclave applying 0.7 MPa external pressure under full vacuum until 130°C, then held at 180°C for 2 hours and post-cured free-standing at 250°C for 6 hours following a ramp of 1.5°C/min. Dynamic mechanical analysis ( ASTM E1640, single cantilever, 1 Hz, 5°C/min) records a peak in E″ indicating a glass transition temperature Tg of 312°C, which is 40–50°C higher than an equivalent formulation based on a methylene-linked aromatic bismaleimide because the aliphatic hexamethylene spacer reduces steric constraint and enables full imidization before network vitrification halts diffusion.The cured composite satisfies the flammability requirements of FAR 25.853 Appendix F Part I ( 12-second vertical burn) with a self-extinguishing time below 2 seconds and a char yield by thermogravimetric analysis ( ASTM E1131, nitrogen) of 48 wt% at 900°C. In-plane shear strength determined by ASTM D5379 (Iosipescu, ±45° laminate) is 78 MPa at 23°C and retains 68% of that value when measured at 260°C after 10-minute soak. The combination of high thermal endurance and low moisture uptake ( 0.9 wt% after 48-hour water boil per ASTM D570) qualifies the prepreg for radome structural panels and engine nacelle stiffener ribs where dielectric constant (ε′ measured at 10 GHz via split-post resonator) must remain below 3.4. Production readiness requires controlled storage of the prepreg at −18°C with a tack-life out of the freezer limited to 14 days at 23°C and 50% RH, verified by a qualitative thumb-impression tack test correlated against a rheological gel time of 18 minutes at 150°C.Modifying Epoxy Molding Compounds for IC Packaging with 10–25 phr Aliphatic BismaleimideIn semiconductor encapsulating materials meeting IPC-4101 specification sheets /21 and /126, the hexamethylene bismaleimide is pre-reacted with a portion of the cresol novolac epoxy resin (EEW 195– 210 g/eq) and a phenolic novolac hardener (hydroxyl equivalent 105 g/eq) at 140°C for 40 minutes in a sigma-blade mixer until the melt viscosity stabilizes at 800 Pa·s at 150°C as measured by a Shimadzu CFT-500 capillary rheometer (die diameter 1.0 mm, 10 kg load). The pre-polymerized adduct is then compounded on a hot two-roll mill with spherical silica filler (average particle size 12 µm, 87 wt% loading), antimony trioxide (2 phr), and carnauba wax release agent. During transfer molding at 175°C and 7 MPa, the spiral flow length increases from 90 cm for an unfilled control to 125 cm at a 20-phr bismaleimide loading, attributed to the low-melting-point aliphatic spacer that plasticizes the network before gelation. Post-mold curing at 180°C for 8 hours brings the degree of conversion above 94%, monitored by differential scanning calorimetry ( ASTM E1356, 20°C/min) through disappearance of the residual exotherm.The molded quad flat no-lead (QFN) packages sustain 260°C peak reflow per JEDEC J-STD-020 Level 1 without delamination, as confirmed by scanning acoustic microscopy (C-SAM, 30 MHz) performed before and after 96 hours of 85/85 testing (85°C/85% RH). Coefficient of thermal expansion below glass transition (α1, thermomechanical analyzer, 0.05 N load) is held to 12 ppm/K, while the α2 above 165°C Tg is 35 ppm/K, minimizing wire sweep on 25-µm gold bond wires. Electrical insulation resistance after 168 hours at 130°C/85% RH under 100 V DC bias remains at 2.6 × 1011 Ω, meeting the IPC-6012 Class 3 requirement for high-reliability automotive engine-control modules.A formulation combining this bismaleimide with a high-ortho novolac epoxy resin and dicyandiamide hardener (particle size 4 µm, latent) has been applied in brake pad bonding fixtures where continuous operating temperature reaches 280°C. The adhesive is blended on a three-roll mill to a Hegman grind of 6 and is applied at a film thickness of 150 µm onto grit-blasted steel substrates with Ra 3.2 µm surface roughness. Curing proceeds under 0.3 MPa clamp pressure at 200°C for 60 minutes. Tensile lap-shear strength on degreased 1.6-mm cold-rolled steel coupons tested per ASTM D1002 at a crosshead speed of 1.3 mm/min registers 24.7 MPa at 23°C and retains 17.1 MPa at 250°C after soak, with cohesive failure mode dominant above 200°C as evidenced by Fourier-transform infrared reflectance microscopy of the fracture surface showing imide carbonyl peaks at 1710 cm−1 and no bare metal exposure. The system complies with the volatile content limits of EU 2019/1021 for persistent organic pollutants and with GB 18583- 2008 for free formaldehyde emission (below 0.01 mg/m³ by desiccator method), allowing use in aftermarket truck brake assemblies exported to markets with stringent indoor air quality regulations. Storage stability of the premixed adhesive is 6 months at −10°C; ambient-temperature pot life measured on a Brookfield DV3T with T-bar spindle at 25°C drops below 300 Pa·s viscosity within 55 minutes, dictating automated meter-mix-dispense equipment for high-volume lines.Twin-screw extruders with a 40:1 L/D ratio equipped with liquid injection nozzles at barrel zone 5 of 12 are utilized to reactively modify polyamide 66 (relative viscosity 2.7 in 96% sulfuric acid) with the hexamethylene bismaleimide at addition levels of 0.5 to 1.8 wt%. The maleimide groups undergo Alder-ene addition with the amine end-groups and backbone secondary amide hydrogens of the polyamide, generating long-chain branches that elevate the melt complex viscosity at 1 rad/s from 480 Pa·s to 1,850 Pa·s as the bismaleimide weight fraction moves to 1.5 wt%. The screw configuration downstream of the injection port employs three dispersion-type kneading blocks with 90° staggering followed by a distributive gear mixer to prevent gel specks that nucleate above 285°C. Processing at a melt temperature held strictly between 272°C and 278°C by barrel cooling blowers is critical: excursions above 280°C initiate imide ring homopolymerization, visible as 0.5 mm black inhomogeneities in the strand and leading to a 20% drop in notched Izod impact strength ( ISO 180/1A, 23°C, 4.0 kJ/m² vs. 5.0 kJ/m² for the ungelled control). The extruded pellets are dried to 0.02% moisture in a desiccant dryer (−40°C dew point) before injection molding engine cam covers that demand 175°C continuous heat resistance under class F (155°C) insulation system requirements per IEC 60085. Dimensional stability after 500 hours at 160°C in air oven shows shrinkage below 0.15%, while unmodified copolymer shrinks 0.8% owing to post-crystallization.When Polyesterimide Wire Enamels Require Soldering Heat Resistance Beyond 400°CUnfilled enamel formulations based on tris(2-hydroxyethyl)isocyanurate (THEIC)-modified polyesterimide are reconstituted with the hexamethylene bismaleimide as a masked crosslinker at 7–15 wt% on total solids, dissolved in cresol/xylene (60:40) to a final viscosity of 1,200 mPa·s at 30°C. The enamel is applied to 0.50 mm copper wire on a vertical wire enameling tower with 8 dies in series, each pass depositing 6 µm of dry film and passing through a forced-convection zone with temperature profile ramped from 380°C at entry to 520°C at the bottom, at a line speed of 52 m/min. The bismaleimide thermally unmasks during the curing flash, releasing the maleimide groups that co-react with residual hydroxyls and generate a hybrid network with an imide concentration gradient that peaks at the conductor interface—verified by nanoindentation (Berkovich tip, 500 µN load) hardness rising from 0.28 GPa in the bulk to 0.43 GPa within the first 3 µm adjacent to copper.The resulting magnet wire passes IEC 60317-0-1 class 200 thermal endurance testing extrapolated to 20,000 hours at 200°C with a lower confidence limit above 5,000 hours, while thermoplastic flow measured by the cut-through test ( IEC 60851-5) at 320°C is reduced from 0.8 mm for the unmodified enamel to 0.2 mm with a 12 wt% bismaleimide loading. Solderability testing at 400°C for 3 seconds using Sn 96.5Ag 3.0Cu 0.5 alloy shows a wetting angle below 15° and zero blistering, a threshold that enables the enamel to be used in compressor motor windings for low-temperature refrigeration where rapid winding short prevention is linked to steeper thermal diffusivity. The only operational boundary observed is an incompatibility with certain polyvinyl formal primer layers; the high maleimide content extracts formaldehyde from the primer during co-cure, generating trapped solvent blisters at 1,500× optical magnification, so direct-to-copper application is advised.
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1H-Pyrrole-2,5-Dione, 1,1'-(1,6-Hexanediyl)Bis- (9Ci), systematically identified as N,N′-(1,6-hexanediyl)bismaleimide and commonly abbreviated as HMBM or HD-BMI, is supplied as a pale-yellow to off-white crystalline powder with a molecular weight of 276.29 g/mol. The compound carries Chemical Abstracts Service registration number 4856-87-5. Typical lot assays determined by high-performance liquid chromatography against an external standard (ASTM E682) yield a purity of not less than 98.0%, with the predominant impurity being the monomaleamic acid intermediate. Residual solvent content, primarily ethyl acetate or dimethylformamide depending on the synthetic pathway, is controlled to below 500 ppm as verified by headspace gas chromatography. The material exhibits a sharp melting endotherm peak by differential scanning calorimetry at 138–142 °C under nitrogen purge at 10 K/min ramp rate. In comparison to shorter-chain bismaleimides such as N,N′-ethylenebismaleimide, the six-carbon spacer in HMBM reduces the crosslink density obtained per unit mass and simultaneously lowers the glass transition onset of the network, a characteristic exploited where maintaining low-temperature flexibility is critical. Unlike peroxide-based crosslinking systems, HMBM does not generate low-molecular-weight decomposition volatiles during cure, eliminating porosity in thick-section moldings.
Differential scanning calorimetry of HMBM blended into ethylene-vinyl acetate copolymer (EVA, 28% vinyl acetate content) at 1.5 phr shows a cure exotherm onset at 168 ± 3 °C, approximately 20–25 °C higher than that observed for N,N′-m-phenylenebismaleimide under identical conditions. This thermal lag translates into a widened processing window on L/D 30 single-screw extruders equipped with barrier screws, where barrel zone temperatures of 110–125 °C are maintained without registering a torque rise indicative of premature crosslinking. On a 65-mm twin-screw compounding line processing silica-filled EVA at a throughput of 320 kg/h, the compound reached 90% of maximum torque (M90) at 185 °C after 2.8 min of residence time, as recorded by an oscillating-die rheometer per ISO 6502. The scorch time ts2 measured at 150 °C exceeded 18 min, a value that permits interrupted production without material loss due to gel formation in the die head. When processing conditions drift above 135 °C in the compression zone, a viscosity increase of less than 12% is measured, whereas an equivalent loading of dicumyl peroxide at the same temperature triggers a viscosity spike exceeding 200% within 90 s.
Processing operators on three independent manufacturing shifts report batch-to-batch variability in melt flow index of less than 0.25 g/10 min (measured at 190 °C, 2.16 kg load per ISO 1133-1:2022) when HMBM is fed via a gravimetric side feeder downstream of the melt seal. This consistency is attributed to the absence of volatile decomposition side-products that otherwise nucleate microbubbles and shift apparent viscosity. For wire and cable insulation lines running at line speeds up to 400 m/min with continuous vulcanization tubes, pre-drying of the HMBM powder is mandated at 60 °C for a minimum of 4 h whenever ambient relative humidity exceeds 60%, as absorbed moisture at levels above 0.15 wt% leads to surface pitting in the finished jacket layer visible under 20× magnification.
In comparison to N,N′-4,4′-diphenylmethane bismaleimide (BMI resin), HMBM imparts substantially lower melt viscosity when incorporated at 15 wt% into a cyanate ester co-cure system. Capillary rheometry data at 120 °C under a shear rate of 100 s⁻¹ yields a steady-shear viscosity of 4.2 × 10² Pa·s for the HMBM-toughened blend, against 1.8 × 10³ Pa·s for the aromatic BMI analog. This rheological advantage facilitates void-free penetration of carbon fiber fabric stacks in resin transfer molding without the need to preheat tooling beyond 90 °C. Thermal mechanical analysis of the cured network confirms a sub-ambient secondary relaxation at −65 °C, absent in wholly aromatic systems, that correlates with peel strength retention of ≥85% after 1,000 thermal cycles between −40 °C and 125 °C on aluminum adherends tested according to ASTM D1002.
Published data for the specific configuration of HMBM combined with engineering thermoplastics such as polyamide 6 in reactive extrusion is limited; however, model compound studies using monofunctional N-hexylmaleimide analogs indicate that grafting efficiency onto the polyamide backbone exceeds 72% in the presence of 0.5 wt% organic peroxide initiator at a residence time of 120 s. Caution is warranted when formulating HMBM with amine-terminated liquid rubbers, as a Michael addition reaction between the maleimide double bond and primary amine functionalities proceeds exothermically at room temperature, evidenced by a temperature rise of 34 °C recorded in a 100 g batch mixed in a planetary mixer within 3 min of contact. Such premature crosslinking renders the bulk material unprocessable and necessitates segregating reactive components during storage and meter-mixing.
| Crosslinker | Onset Temp. (°C) | ts2 at 150°C (min) | Gel Content (%)* | Volatile Byproducts |
|---|---|---|---|---|
| HMBM (1.5 phr) | 168 | 18.2 | 82 | None detected |
| N,N′-m-phenylenebismaleimide (1.5 phr) | 143 | 7.6 | 84 | Trace |
| Dicumyl peroxide (2.0 phr) | 152 | 9.1 | 79 | Acetophenone, methane |
| Trimethylolpropane trimethacrylate (3.0 phr) | 161 | 12.4 | 76 | None |
*Gel content determined by 24 h xylene extraction at 140 °C; values rounded to nearest percent.
Regulatory conformance for electrical insulation applications is supported by the absence of substances listed under REACH Annex XVII entries 28–30 and by compliance with RoHS Directive 2011/65/EU recast as amended by (EU) 2023/1437. Migration testing into food simulants per Commission Regulation (EU) No 10/2011 Annex V, performed with crosslinked polyethylene film in contact with 10% (v/v) ethanol, gave an overall migration limit below 0.8 mg/dm², well within the 10 mg/dm² statutory ceiling. The compound possesses a flash point above 240 °C (Pensky-Martens closed cup, ISO 2719) and is not classified as a flammable solid under the Globally Harmonized System, although fine dust dispersed in air at concentrations exceeding 30 g/m³ can form an explosive atmosphere.
Dynamic vapor sorption analysis conducted on micronized HMBM with a mean particle diameter (d50) of 35 µm reveals an equilibrium moisture content of 0.07 wt% at 25 °C and 50% relative humidity. When relative humidity is raised to 85%, moisture uptake increases to 0.34 wt% within 180 min, following Fickian diffusion kinetics with a diffusivity coefficient of 4.7 × 10⁻¹⁴ m²/s. This hygroscopicity is significantly lower than that of polyfunctional aziridine crosslinkers stored under identical conditions, which liquify after 72 h at 85% RH. Package stability studies indicate that hermetically sealed aluminum-lined foil bags maintain the material within specification for a shelf life of 24 months from the date of manufacture when stored in unopened containers at temperatures not exceeding 30 °C and relative humidity below 70%. Opened containers must be re-sealed under nitrogen blanket and consumed within 60 days; bulk silo storage without climate control is not recommended due to the risk of caking when moisture absorption surpasses 0.2 wt%.
When HMBM is formulated into moisture-sensitive polyester powder coatings applied by electrostatic spray, pre-mixing with the base resin at 120 °C in a co-rotating twin-screw extruder enables the maleimide to react partially with the unsaturated backbone, effectively grafting the crosslinker onto the polymer chain. This step reduces free HMBM content in the extrudate to below 0.3 wt% and eliminates bloom formation on the finished coating surface after 28 days of storage at 40 °C/ 90% RH. The resulting gel time measured on a hot plate at 200 °C according to ASTM D4217 is extended by 45 s compared to the dry-blended control, a shift that improves flow-out without compromising the methyl ethyl ketone double-rub resistance, which remains above 200 cycles.
Industrial hygiene monitoring during pilot-scale handling confirms that the airborne dust concentration in the breathing zone of operators equipped with tight-fitting FFP2 respirators remains below 0.5 mg/m³ timed-weighted average over an 8 h shift, provided the local exhaust ventilation maintains a capture velocity of 0.8 m/s at the powder transfer point. Dermal sensitization potential is classified as low; however, a 48 h occlusive patch test conducted under the criteria of OECD Guideline 442 in a cohort of 200 human volunteers identified a single case of transient erythema, leading to a recommendation to wear nitrile gloves with a breakthrough time exceeding 240 min during manual weighing operations.
| Standard / Regulation | Relevant Scope | Critical Parameter |
|---|---|---|
| EU 10/2011 Annex II | Food contact plastics | Specific migration limit for maleic acid ≤ 30 mg/kg |
| FDA 21 CFR 177.2600 | Rubber articles for repeated food contact | Total non-volatile extractives in hexane < 5.5 mg/in² |
| IEC 60092-351 | Shipboard cable insulation | Hot tensile elongation retention > 50% after 7 days at 150 °C |
| ASTM D624 (Die C) | Tear strength of cured elastomers | Notched tear resistance ≥ 35 kN/m |
| ISO 37:2017 | Tensile stress-strain of vulcanizates | Elongation at break ≥ 300% |
In ethylene-silane copolymer moisture-cure systems, the addition of 0.8–1.2 wt% HMBM functions as both a radical trap during the peroxide-initiated grafting step and a supplementary crosslink site during the subsequent humidity-driven condensation phase. Processing on a reactive extrusion line with a L/D 42 co-rotating twin-screw extruder operating at a melt temperature of 195 °C demonstrates that HMBM suppresses undesired polyethylene crosslinking during silane grafting, maintaining a melt flow rate ( 190 °C, 21.6 kg) above 8 g/10 min, compared to 1.3 g/10 min in control formulations relying solely on the silane condensation pathway. Hot-set testing under 0.2 MPa load at 200 °C for 15 min on compression-molded plaques reveals an elongation under load of less than 85% with permanent set below 5%, meeting the Class 1 requirement of HD 603 S1 for medium-voltage power distribution cables. A failure mode observed in certain production runs involved surface cracking of the cured insulation when the HMBM was added through a dry-blend hopper rather than metered as a melt-side injection, attributed to poor dispersion resulting in local crosslink density fluctuations exceeding ±15% of the bulk average, as evidenced by swelling ratio mapping using n-decane immersion. To mitigate this, a masterbatch pre-compounded at 160 °C and pelletized prior to dilution is employed on lines where side-feeding capillary rheometry confirms pressure variations below 0.5 bar.
Combining HMBM with organofunctional silanes containing amino groups is contraindicated unless a functional spacer is interposed, since the maleimide ring undergoes nucleophilic addition with primary amines at a rate constant of 1.2 × 10⁻³ L·mol⁻¹·s⁻¹ at 25 °C in aprotic media. When such a combination is unavoidable—for example, in multi-layer pipe coatings requiring graded adhesion—the components are fed through separate extruders delivering melt streams that converge inside the co-extrusion die block, allowing contact time of less than 10 s before shaping, which limits conversion to below 5% as determined by differential scanning calorimetry residual enthalpy integration.
