{ "spore": "profile", "id": "momentive-rtv-566", "spore_version": "0.2", "family": "silicone", "name": "Momentive RTV566 low-outgassing silicone", "abbreviation": "RTV566", "role": "low-outgassing two-part room-temperature-cure silicone for bonding, potting and thermal insulation", "category": "seals-adhesives", "type": "potting-compounds", "summary": "Momentive RTV566 is a red, two-part, room-temperature-cure silicone rubber sold for low-outgassing use in vacuum. Momentive's datasheet gives a continuous service range of -115 °C to 260 °C, with short periods up to 316 °C, and a total mass loss of 0.14 % and a volatile condensable material of 0.02 % in the ASTM E595 test (cured 7 days at 25 °C and 50 % R.H.). NASA's outgassing compilation (RP-1124 Rev. 3) lists 18 RTV 566 records, with total mass loss of 0.08 % to 0.13 % for the six records at 0.1 % catalyst.\n", "best_for": "Low-outgassing bonding, potting and thermal insulation of vacuum hardware that runs between -115 °C and 260 °C continuously", "weakest_at": "Strength and cure speed: tensile strength of 56 kg/cm2 (800 psi) and Shore A 61 when cured 7 days at 25 °C, and a primer is needed to bond non-silicone surfaces", "identity": { "formula": "Two-part room-temperature-vulcanising silicone rubber: RTV566A base compound and RTV566B curing agent. The datasheet does not print the polymer or filler chemistry.", "designations": [], "source": "rtv566-tds", "where": "Description; Typical Physical Properties (uncured table, RTV566A and RTV566B columns)" }, "tags": { "environments": [], "stresses": [ "vacuum-and-outgassing", "extreme-cold", "extreme-heat" ], "applications": [ "heat-shields", "thermal-control", "electronics-and-chips", "solar-arrays" ] }, "properties": [ { "benchmark": "max_service_temp", "label": "Continuous maximum service temperature", "value": 260, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "state": "cured RTV566", "basis": "continuous use, printed as 260 °C (500 °F)" }, "method": "Continuous service limit printed in the datasheet key features", "status": "ground", "source": "rtv566-tds", "where": "Key Features and Benefits, last bullet", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "max_service_temp", "label": "Short-period maximum temperature", "value": 316, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "state": "cured RTV566", "basis": "printed as 316 °C (600 °F) for short periods of time; the period is not defined in the datasheet" }, "method": "Short-period limit printed in the datasheet key features", "status": "ground", "source": "rtv566-tds", "where": "Key Features and Benefits, last bullet", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "min_service_temp", "label": "Continuous minimum service temperature", "value": -115, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "state": "cured RTV566", "basis": "continuous use, printed as -115 °C (-175 °F)" }, "method": "Low-temperature limit printed in the datasheet key features", "status": "ground", "note": "Momentive's aerospace page prints -130 °C (-200 °F) to 260 °C (500 °F) as the range for its low-outgassing silicones in general, not for RTV566 specifically. The two low-temperature figures are not reconciled.", "source": "rtv566-tds", "where": "Key Features and Benefits, last bullet", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "specific_gravity", "label": "Specific gravity of the RTV566A base", "value": 1.49, "bound": "exact", "unit": "-", "scope": "material", "conditions": { "state": "RTV566A base compound, uncured", "temperature": "not printed" }, "method": "Printed as specific gravity of the uncured base component", "status": "ground", "note": "The curing agent RTV566B has a specific gravity of 1.15 in the same table.", "source": "rtv566-tds", "where": "Typical Uncured Properties table, Specific Gravity row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "viscosity", "label": "Viscosity of the RTV566A base", "value": 42700, "bound": "exact", "unit": "cps", "scope": "material", "conditions": { "state": "RTV566A base compound, uncured", "temperature": "not printed" }, "method": "Printed as viscosity of the uncured base component", "status": "ground", "source": "rtv566-tds", "where": "Typical Uncured Properties table, Viscosity row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "shore_a_hardness", "label": "Shore A hardness", "value": 61, "bound": "exact", "unit": "Shore A", "scope": "material", "conditions": { "state": "cured 7 days at 25 °C and 50 % R.H.", "test": "Shore A durometer as printed" }, "method": "Printed in the typical cured properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Hardness row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Tensile strength", "value": 56, "bound": "exact", "unit": "kg/cm2", "scope": "material", "conditions": { "state": "cured 7 days at 25 °C and 50 % R.H.", "printed_as": "56 kg/cm2 (800 psi)" }, "method": "Printed in the typical cured properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Tensile Strength row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "elongation", "label": "Elongation", "value": 120, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "state": "cured 7 days at 25 °C and 50 % R.H." }, "method": "Printed in the typical cured properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Elongation row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "lap_shear_strength", "label": "Lap shear strength on primed aluminium", "value": 33, "bound": "exact", "unit": "kg/cm2", "scope": "material", "conditions": { "substrate": "primed aluminium (the primer is not named in the table)", "state": "cured 7 days at 25 °C and 50 % R.H.", "printed_as": "33 kg/cm2 (465 psi)" }, "method": "Printed in the typical cured properties table, lap shear on primed Al", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Lap Shear Strength row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "total_mass_loss", "label": "Total mass loss, Momentive datasheet", "value": 0.14, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "test": "ASTM E595, as stated in the table footnote", "state": "cured 7 days at 25 °C and 50 % R.H." }, "method": "Printed in the typical cured properties table with an ASTM E595 footnote", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Total Weight Loss row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "volatile_condensable_material", "label": "Volatile condensable material, Momentive datasheet", "value": 0.02, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "test": "ASTM E595, as stated in the table footnote", "state": "cured 7 days at 25 °C and 50 % R.H." }, "method": "Printed in the typical cured properties table with an ASTM E595 footnote", "status": "ground", "source": "rtv566-tds", "where": "Typical Cured Properties table, Volatile Condensable Material row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "total_mass_loss", "label": "Total mass loss, NASA records at 0.1 % catalyst (range)", "value": 0.08, "value_high": 0.13, "bound": "range", "unit": "%", "scope": "material", "conditions": { "catalyst": "0.1 % by weight curing agent (BW CAT)", "cure": "7 days at 25 °C in air", "test": "ASTM E595 as tabulated by NASA", "records": "six records: GSFC6230, GSC12835, GSFC6503, GSCI0862, GSCI0865, GSCI0868" }, "method": "Range across the six RTV 566 records at 0.1 % catalyst, read from the table. The 0.3 % and 0.7 % catalyst records (0.34 % and 0.36 % total mass loss) and the primer sandwich records are excluded.", "status": "ground", "source": "nasa-rp1124", "where": "Section 1 (Adhesives), RTV 566 rows at 0.1 % BW CAT", "source_detail": { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 (Campbell and Scialdone, Goddard Space Flight Center)", "id": "NASA RP-1124 Rev. 3; NTRS 19940017416", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "volatile_condensable_material", "label": "Volatile condensable material, NASA records at 0.1 % catalyst (range)", "value": 0, "value_high": 0.02, "bound": "range", "unit": "%", "scope": "material", "conditions": { "catalyst": "0.1 % by weight curing agent (BW CAT)", "cure": "7 days at 25 °C in air", "test": "ASTM E595 as tabulated by NASA", "records": "six records: GSFC6230, GSC12835, GSFC6503, GSCI0862, GSCI0865, GSCI0868" }, "method": "Range across the same six NASA records at 0.1 % catalyst, read from the table", "status": "ground", "source": "nasa-rp1124", "where": "Section 1 (Adhesives), RTV 566 rows at 0.1 % BW CAT", "source_detail": { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 (Campbell and Scialdone, Goddard Space Flight Center)", "id": "NASA RP-1124 Rev. 3; NTRS 19940017416", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "water_vapor_regained", "label": "Water vapour regained, NASA records at 0.1 % catalyst (range)", "value": 0.02, "value_high": 0.05, "bound": "range", "unit": "%", "scope": "material", "conditions": { "catalyst": "0.1 % by weight curing agent (BW CAT)", "cure": "7 days at 25 °C in air", "test": "as tabulated by NASA", "records": "six records: GSFC6230, GSC12835, GSFC6503, GSCI0862, GSCI0865, GSCI0868" }, "method": "Range across the same six NASA records at 0.1 % catalyst, read from the table", "status": "ground", "source": "nasa-rp1124", "where": "Section 1 (Adhesives), RTV 566 rows at 0.1 % BW CAT", "source_detail": { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 (Campbell and Scialdone, Goddard Space Flight Center)", "id": "NASA RP-1124 Rev. 3; NTRS 19940017416", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "work_life", "label": "Work life of the catalysed mix", "value": 1.5, "bound": "exact", "unit": "hrs", "scope": "material", "conditions": { "mix": "100 parts RTV566A to 0.1 part RTV566B by weight", "basis": "printed under typical catalysed properties" }, "method": "Printed in the typical catalysed properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Catalyzed Properties table, Work Life row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "tack_free_time", "label": "Tack-free time of the catalysed mix", "value": 2.2, "bound": "exact", "unit": "hrs", "scope": "material", "conditions": { "mix": "100 parts RTV566A to 0.1 part RTV566B by weight", "basis": "printed under typical catalysed properties" }, "method": "Printed in the typical catalysed properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Catalyzed Properties table, Tack Free Time row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "application_rate", "label": "Application rate through a 0.125 in orifice", "value": 180, "bound": "exact", "unit": "gm/min", "scope": "material", "conditions": { "measured": "45 minutes after mixing, 0.125 in orifice at 90 psi", "mix": "100 parts RTV566A to 0.1 part RTV566B by weight" }, "method": "Printed in the typical catalysed properties table", "status": "ground", "source": "rtv566-tds", "where": "Typical Catalyzed Properties table, Application Rate row", "source_detail": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" } }, { "benchmark": "outgassing_screening_limit", "label": "NASA listing limit for total mass loss and CVCM (a criterion, not an RTV566 measurement)", "value": 1, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "basis": "NASA lists only materials with a total mass loss of 1.0 percent or less and a CVCM of 0.10 percent or less" }, "method": "Criterion stated in the NASA introduction; not a measured value for RTV566", "status": "ground", "source": "nasa-rp1124", "where": "Introduction (selection criteria) and Section C heading", "source_detail": { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 (Campbell and Scialdone, Goddard Space Flight Center)", "id": "NASA RP-1124 Rev. 3; NTRS 19940017416", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "flash_point", "label": "Flash point of the Part A base compound (SDS)", "value": 125, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "state": "RTV566 Part A, liquid base component, as printed in the SDS", "test": "Pensky-Martens closed cup, as printed" }, "method": "Printed in the safety data sheet physical and chemical properties section", "status": "ground", "source": "sds-rtv566-32", "where": "Section 9, Physical and chemical properties, Flash Point row", "source_detail": { "title": "Momentive Performance Materials RTV566 Safety Data Sheet, version 3.2 (revised 02/20/2025), Part A, copy hosted by blacksky.com", "id": "SDS_US, version 3.2, revision date 02/20/2025; Momentive Performance Materials USA LLC", "url": "https://blacksky.com/wp-content/uploads/2026/02/MomentivePerformance_RTV566-Dimethyl-Diphenyl_2025-02.pdf", "year": 2025, "kind": "datasheet", "license": "manufacturer safety data sheet, cited and not reproduced" } } ], "corrosion": [ { "environment": "Heated in air above 150 °C", "headline": "Oxidative degradation above 150 °C in air forms small amounts of formaldehyde, per the Part A SDS.", "effect": "Measurements above 150 °C in air found that small amounts of formaldehyde form through oxidative degradation. The SDS gives no amount, time or rate.", "rating": "unknown", "conditions": { "temperature": "above 150 °C", "atmosphere": "air (oxygen)", "basis": "SDS statement; no time, amount or rate is printed" }, "source": "sds-rtv566-32", "where": "Section 10, Stability and reactivity, Hazardous Decomposition Products" } ], "risks": { "hazards": [ { "text": "Momentive's SDS for RTV566 Part A (version 3.2, revised 02/20/2025) gives the product as not classified under 29 CFR 1910.1200, with no signal word, no hazard symbol and no hazard statement. Hazard(s) not otherwise classified is None.", "ghs": [], "source": "sds-rtv566-32", "where": "Section 2, Hazard(s) identification" }, { "text": "A second copy of the Part A SDS (version 3.1, revised 08/30/2023) gives the same not-classified status and the same 125 °C flash point.", "ghs": [], "source": "sds-rtv566-31", "where": "Section 2, Hazard Classification; Section 9, Flash Point" }, { "text": "The same Part A SDS lists the product as not classified for acute oral, dermal or inhalation toxicity, and gives no data for skin or eye irritation, sensitisation, carcinogenicity or mutagenicity.", "ghs": [], "source": "sds-rtv566-32", "where": "Section 11, Toxicological information" }, { "text": "Part A ingredients per the SDS, all by weight: red iron oxide (CAS 1309-37-1) 20 to under 50 %, kieselguhr, soda ash flux-calcined (CAS 68855-54-9) 10 to under 20 %, and silicic acid, ethyl ester (CAS 11099-06-2) 1 to under 5 %. The SDS notes workplace exposure limits for red iron oxide and kieselguhr.", "ghs": [], "source": "sds-rtv566-32", "where": "Section 3, Composition/information on ingredients; Section 8, Exposure controls" }, { "text": "PubChem's GHS summary for silicic acid, ethyl ester (CID 9877350, CAS 11099-06-2) lists H226 flammable liquid and vapour (75.1% of notifications), H302 harmful if swallowed (16.7%), H319 causes serious eye irritation (70%), H332 harmful if inhaled (10.5%), H335 may cause respiratory irritation (27.2%) and H411 toxic to aquatic life with long lasting effects (47.1%). PubChem also notes that 24.9% (64 of 257) of reports do not meet GHS hazard criteria. These are notifications for the single ingredient, not a classification of the Part A product.", "ghs": [ "H226", "H302", "H319", "H332", "H335", "H411" ], "source": "pubchem-ethyl-silicate", "where": "Safety and Hazards, GHS Classification (CID 9877350)" } ], "failure_risks": [ { "mode": "Voids in the cured product from entrapped air", "trigger": "Mixing or pouring without deaeration", "consequence": "Air bubbles stay in the cured part. The datasheet calls for a vacuum of 25 mm (29 inches) of mercury minimum, and says deaeration after pouring may be needed in complex potted assemblies.", "severity": "low", "source": "rtv566-tds", "where": "Processing Recommendations, Deaeration" }, { "mode": "Poor adhesion to non-silicone surfaces", "trigger": "Bonding without a primer", "consequence": "The datasheet says RTV566 requires a primer to bond to non-silicone surfaces; it names SS4155 silicone primer.", "severity": "moderate", "source": "rtv566-tds", "where": "Processing Recommendations, Bonding" } ], "side_effects": [ { "text": "Hanrahan and Ianno (2014) analysed RTV566 among five spacecraft RTV silicones by Raman and FTIR spectroscopy. They report that the outgassing products of each material are polydimethylsiloxane (PDMS) and tetra-n-propylsilicate (NPS).", "affects": "Nearby optical surfaces, where the paper addresses photofixed films from outgassing", "source": "unl-rtv-composition", "where": "Abstract" } ], "handling": [ { "text": "Mix 100 parts RTV566A with 0.1 part RTV566B curing agent by weight, in a container 4 to 5 times larger than the volume of the compound. Scrape the sides and bottom so the mix is homogeneous, and avoid high mixer speeds that entrap air or overheat the mix.", "source": "rtv566-tds", "where": "Processing Recommendations, Mixing" }, { "text": "Deaerate the mixed compound under a vacuum of 25 mm (29 inches) of mercury minimum until the bubbles break and the compound settles back.", "source": "rtv566-tds", "where": "Processing Recommendations, Deaeration" }, { "text": "The compound cures enough for gentle handling after 24 hours at 25 °C and 50 % R.H. For best outgassing and adhesion, cure for 7 days at the same conditions.", "source": "rtv566-tds", "where": "Processing Recommendations, Curing" }, { "text": "For service above 150 °C (302 °F), condition the cured part first: 8 hours at 100 °C, then an extra 8 hours at each 28 °C (80 °F) step up to the service temperature. Larger or deeper parts need longer at each step.", "source": "rtv566-tds", "where": "Processing Recommendations, Curing (conditioning paragraph)" }, { "text": "Part A SDS handling advice: do not taste or swallow, avoid contact with eyes, skin and clothing, wash hands after handling, keep the container closed, and keep away from sources of ignition.", "source": "sds-rtv566-32", "where": "Section 7, Handling and storage" } ], "mitigations": [ { "text": "Clean non-silicone substrates with naphtha or methyl ethyl ketone (MEK) and let them dry. Apply a uniform thin film of SS4155 primer, air dry it for one hour or more until a uniform chalky white haze shows, then apply freshly mixed RTV566.", "source": "rtv566-tds", "where": "Processing Recommendations, Bonding" } ] }, "uses": [ { "application": "heat-shields", "device": "Cast-in-place heat shielding", "example": "Momentive lists cast-in-place heat shielding among the potential applications of RTV 566 Paste. The page names no mission or flight.", "source": "momentive-aero-page", "where": "Key Features, RTV 566 Paste" }, { "application": "thermal-control", "device": "Cast-in-place thermal insulation", "example": "Momentive lists thermal insulation among the potential applications of RTV 566 Paste.", "source": "momentive-aero-page", "where": "Key Features, RTV 566 Paste" }, { "application": "electronics-and-chips", "device": "Potting and encapsulation of electrical assemblies", "example": "Momentive lists potting and encapsulating electrical assemblies as potential uses. The datasheet adds that deaeration may be needed after pouring in complex assemblies.", "source": "momentive-aero-page", "where": "Key Features, RTV 566 Paste; datasheet Processing Recommendations, Deaeration" }, { "application": "solar-arrays", "device": "Photovoltaic module assembly", "example": "Momentive lists assembly of photovoltaic (PV) modules as a potential application of RTV 566 Paste.", "source": "momentive-aero-page", "where": "Key Features, RTV 566 Paste" }, { "application": "electronics-and-chips", "device": "Adhesive and potting records in NASA's outgassing list", "example": "NASA RP-1124 Rev. 3 lists 18 RTV 566 records, of which 15 are labelled ADHESIVE, 2 POTTING-ADH and 1 POTTING. The list gives outgassing test results for each record, not flight results.", "source": "nasa-rp1124", "where": "Section 1 (Adhesives), RTV 566 rows" } ], "supply": [ { "subject": "Silicon (silicon metal, the feedstock for silicone polymers)", "abundance": "USGS: world and domestic resources for making silicon metal are abundant, and the source of the silicon is silica in natural forms such as quartzite.", "producers": [ { "country": "China", "share_percent": 87, "year": 2025 }, { "country": "Brazil", "share_percent": 3.9, "year": 2025 }, { "country": "Norway", "share_percent": 2.8, "year": 2025 }, { "country": "France", "share_percent": 1.5, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 Final List of Critical Minerals (silicon added in the 2025 list)", "listed": true } ], "recycling": "USGS: recycling of silicon is insignificant.", "substitutes": [ "USGS: gallium arsenide and germanium are the principal substitutes for silicon in semiconductor and infrared applications; the chapter does not discuss silicone feedstock." ], "source": "usgs-mcs2026-silicon", "where": "World Production table, silicon metal, 2025 (world total 4,600 thousand t of silicon content; shares calculated by Space Mushroom from the printed figures: China 4,000, Brazil 180, Norway 130, France 68); Domestic Production and Use (silicones named as a main consumer); Recycling; Substitutes; Events, Trends, and Issues (critical list)" } ], "media": [], "documents": [ { "title": "RTV566 Technical Data Sheet, Momentive Performance Materials (HCD-RTV566, Rev. 2021-05-05), copy hosted by chemical-concepts.com", "type": "datasheet", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021 }, { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124 Revision 3", "type": "report", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993 }, { "title": "Momentive Performance Materials RTV566 Safety Data Sheet, version 3.2 (revised 02/20/2025), Part A, copy hosted by blacksky.com", "type": "sds", "url": "https://blacksky.com/wp-content/uploads/2026/02/MomentivePerformance_RTV566-Dimethyl-Diphenyl_2025-02.pdf", "year": 2025 }, { "title": "Momentive Performance Materials RTV566 Safety Data Sheet, version 3.1 (revised 08/30/2023), Part A, copy hosted by a BigCommerce product file", "type": "sds", "url": "https://cdn11.bigcommerce.com/s-jifykode7m/product_images/uploaded_images/msds/SGP210218.pdf", "year": 2023 }, { "title": "Mineral Commodity Summaries 2026, Silicon (USGS, February 2026)", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf", "year": 2026 }, { "title": "PubChem: Silicic acid, ethyl ester (CID 9877350), GHS classification summary", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/9877350", "year": 2026 }, { "title": "Relationship between photofixed condensate, effluent and bulk composition of several common RTV materials (Hanrahan and Ianno, Journal of Spacecraft and Rockets 51:3, April 2014)", "type": "paper", "url": "https://digitalcommons.unl.edu/electricalengineeringfacpub/541", "year": 2014 } ], "gaps": [ "Part A (base compound) is the only RTV566 part with a safety data sheet read here, and both copies are third-party hosted (version 3.2 and version 3.1). No safety data sheet for the curing agent RTV566B was read, Momentive's own SDS library was not checked, and no GHS label is printed for the product.", "The silicone polymer is named only in the 2014 Raman and FTIR study (polydimethylsiloxane, silicic acid, tetraethyl orthosilicate and others, found in all five RTV silicones tested). The study gives no quantities for RTV566, and no CAS number was read for the RTV566 product itself; the CAS numbers in the record belong to Part A ingredients.", "The supply rows are for silicon metal, the feedstock the USGS names for silicones. No producer, capacity or supply data for Momentive's own RTV566 were read.", "No UV, humidity, radiation or atomic-oxygen result for RTV566 was found. The only degradation statement is the SDS note on oxidation above 150 °C in air, which gives no amount or time. The NASA table gives outgassing only.", "No flight result, thermal-vacuum result or space environment test beyond ASTM E595 outgassing was read. Momentive's aerospace page names crew capsules and satellites for the low-outgassing line in general, not for RTV566, so no environment tags are set.", "Low-temperature limit is -115 °C in the datasheet and -130 °C on the Momentive page (for the product line in general). The two are not reconciled.", "The NASA table has 18 RTV 566 records, not dozens. Ranges use only the six clean records at 0.1 % catalyst; OCR-damaged values (for example 0.ii and 0 O2) and the 0.3 %, 0.7 % and lot ED221 records were not used as RTV566 values.", "The datasheet's 0.14 % total mass loss and 0.02 % VCM are a single set of values and are not matched to a NASA record; no lot number is printed for them.", "The primer used for the lap shear result is not named in the datasheet table.", "Viscosity, Shore A hardness, work life, tack-free time, application rate and the outgassing screening limit are not in property-canon.yaml. They use the snake_case names above, and outgassing_screening_limit is a new name.", "The sources now cover the datasheet, the Momentive aerospace page, NASA RP-1124, two Part A SDS copies, USGS silicon, PubChem and the 2014 study. The two SDS copies are third-party hosted copies, not Momentive's own library, and no ESA paper on RTV566 was found." ], "story": { "why": "Momentive RTV566 is a red, two-part, room-temperature-cure silicone rubber from Momentive Performance Materials, sold for low-outgassing use in vacuum. Its datasheet gives a continuous service range from -115 °C to 260 °C and up to 316 °C for short periods. The datasheet reports a total mass loss of 0.14 % and a volatile condensable material of 0.02 % in the ASTM E595 test. NASA's outgassing compilation lists 18 RTV 566 records, which is why the material is a common reference for spacecraft adhesives and potting.", "uses": [ { "where": "Cast-in-place heat shielding and thermal insulation", "line": "Momentive lists cast-in-place heat shielding and thermal insulation among the potential applications of RTV 566 Paste. The page names no mission or flight." }, { "where": "Potting and encapsulating electronics", "line": "Momentive lists potting and encapsulation of electrical assemblies, and the assembly of photovoltaic modules, among its potential applications. The datasheet adds that deaeration may be needed after pouring in complex assemblies." }, { "where": "Outgassing-tested spacecraft adhesives and potting", "line": "NASA's outgassing list (RP-1124 Rev. 3) has 18 RTV 566 records: 15 labelled ADHESIVE, 2 POTTING-ADH and 1 POTTING. These are ground test results, not flight results." } ], "can_do": [ { "label": "Temperature range", "line": "The datasheet gives continuous service from -115 °C to 260 °C, and up to 316 °C for short periods. The Momentive aerospace page prints -130 °C as the low end for its low-outgassing silicones in general, which is not reconciled with the -115 °C figure.", "benchmark": "max_service_temp", "scope": "material", "value": "-115 °C to 260 °C continuous" }, { "label": "Outgassing", "line": "The datasheet reports 0.14 % total mass loss and 0.02 % volatile condensable material under ASTM E595, after 7 days at 25 °C. The six NASA records at 0.1 % catalyst range from 0.08 % to 0.13 % total mass loss.", "benchmark": "total_mass_loss", "scope": "material", "value": "0.14 % total mass loss" }, { "label": "Adhesion", "line": "The datasheet gives a lap shear of 33 kg/cm2 (465 psi) on primed aluminium, a tensile strength of 56 kg/cm2 and 120 % elongation for the same cured compound.", "benchmark": "lap_shear_strength", "scope": "material", "value": "33 kg/cm2 on primed aluminium" }, { "label": "Working time", "line": "The catalysed mix has a work life of 1.5 hrs and a tack-free time of 2.2 hrs, both printed in the datasheet.", "benchmark": "work_life", "scope": "material", "value": "1.5 hrs work life" } ], "compare": "RTV566 is a moderate-strength silicone (tensile strength 56 kg/cm2, Shore A 61), not a structural adhesive. On outgassing it sits at the listing limit: the datasheet's total mass loss of 0.14 % is just above the 0.08 % to 0.13 % range that NASA records show at 0.1 % catalyst, and both are well under the NASA listing limits of 1.0 % total mass loss and 0.10 % volatile condensable material. The silicone-rtv profile in this collection describes a different product, so its values are not compared here.", "compare_rows": [ { "label": "Continuous maximum service temperature", "benchmark": "max_service_temp", "scope": "material" }, { "label": "Total mass loss", "benchmark": "total_mass_loss", "scope": "material" }, { "label": "Continuous minimum service temperature", "benchmark": "min_service_temp", "scope": "material" } ], "handling": [ "Mix 100 parts RTV566A with 0.1 part RTV566B curing agent by weight, in a container 4 to 5 times the compound volume.", "Degas under a vacuum of 25 mm (29 inches) of mercury minimum. Use a primer on non-silicone surfaces, SS4155 per the datasheet.", "Cure 24 hours at 25 °C and 50 % R.H. before gentle handling, and 7 days for best outgassing and adhesion.", "Above 150 °C in service, condition the cured part: 8 hours at 100 °C, then 8 hours at each 28 °C step up to the service temperature.", "Read the latest safety data sheet before handling. The Part A SDS says not to taste or swallow the product, to avoid contact with eyes and skin, and to wash hands afterwards. No safety data sheet for the curing agent is among this profile's sources." ], "good_for": [ "Low-outgassing bonding and potting where a service range of -115 °C to 260 °C is needed. NASA records at 0.1 % catalyst show 0.08 % to 0.13 % total mass loss.", "Cast-in-place heat shielding and thermal insulation, the uses Momentive names for RTV 566 Paste." ], "watch_out": [ "Non-silicone surfaces need a primer, SS4155 per the datasheet.", "Two low-temperature limits are printed: -115 °C in the datasheet and -130 °C on the Momentive page, which covers the product line in general.", "Outgassing varies with catalyst level. NASA's 0.3 % and 0.7 % catalyst records show 0.34 % and 0.36 % total mass loss, well above the 0.1 % records." ], "verdict": "RTV566 is a moderate-strength, low-outgassing silicone for thermal insulation, heat shielding and potting in vacuum hardware. Its datasheet total mass loss of 0.14 % sits next to NASA's 0.08 % to 0.13 % range. The Part A SDS gives no hazard classification, and the silicon supply rows describe the feedstock rather than this product. No supply data for RTV566 itself and no ageing data beyond the SDS note on oxidation above 150 °C were read, so those parts stay incomplete.", "recipe": { "line": "RTV566 is a two-part silicone rubber that cures at room temperature. The base compound RTV566A is mixed with the curing agent RTV566B at 100 parts base to 0.1 part curing agent by weight, the most commonly used ratio. The Part A safety data sheet lists red iron oxide, kieselguhr and silicic acid, ethyl ester as ingredients, and a 2014 Raman and FTIR study names polydimethylsiloxane in RTV566.", "parts": [ { "name": "RTV566A base compound", "role": "The silicone base compound. It is a red paste with a viscosity of 42700 cps and a specific gravity of 1.49 before cure." }, { "name": "RTV566B curing agent", "role": "Starts the room-temperature cure once mixed into the base. It is yellow-brown and has a specific gravity of 1.15 as printed." }, { "name": "Red iron oxide (Part A ingredient)", "role": "Listed as the ingredient with the widest range in the Part A safety data sheet. The SDS gives a workplace exposure limit for it and does not state its function in the compound." }, { "name": "Kieselguhr, soda ash flux-calcined (Part A ingredient)", "role": "Listed in the Part A safety data sheet with a workplace exposure limit. The SDS does not state its function." }, { "name": "Silicic acid, ethyl ester (Part A ingredient)", "role": "Listed in the Part A safety data sheet. PubChem gives GHS hazard statements for it, and the 2014 Raman and FTIR study reports silicic acid and tetraethyl orthosilicate in RTV566." } ] }, "risk_groups": [ { "title": "For people", "lead": "Momentive's Part A safety data sheet gives the product as not classified under 29 CFR 1910.1200, with no signal word and no hazard statement. No safety data sheet for the curing agent RTV566B is among the sources of this profile.", "points": [ { "label": "Part A", "line": "The SDS gives no hazard class, no signal word and no hazard statement. Its flash point is 125 °C, and it has no data for skin or eye irritation." }, { "label": "Ingredient", "line": "PubChem lists GHS hazard statements for silicic acid, ethyl ester, a Part A ingredient at 1 to under 5 %: flammable liquid and vapour, harmful if swallowed, causes serious eye irritation, harmful if inhaled, may cause respiratory irritation, and toxic to aquatic life." }, { "label": "Primer", "line": "The bonding primer SS4155 is named in the datasheet. Its own hazards were not read, and the datasheet says other materials may need additional precautions." } ], "level": 0, "verdict": "Not classified under 29 CFR 1910.1200 (Part A SDS)" }, { "title": "Bonding and processing", "lead": "These steps come from the Momentive datasheet and set how the compound is mixed, degassed and bonded.", "points": [ { "label": "Mixing", "line": "Mix 100 parts RTV566A with 0.1 part RTV566B by weight, in a container 4 to 5 times larger than the compound volume." }, { "label": "Air bubbles", "line": "Degas under a vacuum of 25 mm (29 inches) of mercury minimum. Potted assemblies may need deaeration after pouring." }, { "label": "Bonding", "line": "Non-silicone surfaces need a primer. Clean with naphtha or methyl ethyl ketone (MEK), apply a thin film of SS4155 primer, let it air dry for one hour or more, then apply freshly mixed RTV566." } ] }, { "title": "Cure and heat", "lead": "The cure schedule sets how long a part must wait before it is handled or used hot.", "points": [ { "label": "Cure", "line": "The compound is handleable after 24 hours at 25 °C and 50 % R.H. The datasheet recommends 7 days for best outgassing and adhesion." }, { "label": "Above 150 °C", "line": "Condition the cured part before service above 150 °C: 8 hours at 100 °C, then 8 more hours at each 28 °C step up to the service temperature." } ] } ] }, "updated": "2026-11-02", "review": { "status": "draft", "method": "assistant", "checked_values": 19, "unreachable": 0, "caveats": 3, "note": "Written by an AI assistant on 2026-11-01 from three sources and deepened on 2026-11-02 with two Part A safety data sheets, USGS Mineral Commodity Summaries 2026 (silicon), PubChem GHS data and a 2014 Raman and FTIR study. Values are copied as printed. The Momentive datasheet and the NASA table are unchanged." }, "sources": { "rtv566-tds": { "title": "RTV566 Technical Data Sheet (HCD-RTV566, Rev. 2021-05-05), Momentive Performance Materials", "id": "HCD-RTV566 (Rev. 2021-05-05); copy hosted by chemical-concepts.com", "url": "https://www.chemical-concepts.com/wp-content/uploads/2022/12/RTV566-TDS.pdf", "year": 2021, "kind": "datasheet", "license": "manufacturer datasheet, cited and not reproduced" }, "momentive-aero-page": { "title": "Low Outgassing Silicones, Momentive Performance Materials aerospace page", "id": "undated web page, read 2026-11-01", "url": "https://www.momentive.com/en-us/industry/aerospace-aviation-defense/aerospace/low-outgassing-silicones", "year": 2026, "kind": "web", "license": "manufacturer web page, cited and not reproduced" }, "nasa-rp1124": { "title": "Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 (Campbell and Scialdone, Goddard Space Flight Center)", "id": "NASA RP-1124 Rev. 3; NTRS 19940017416", "url": "https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf", "year": 1993, "kind": "report", "license": "public domain (NASA)" }, "sds-rtv566-32": { "title": "Momentive Performance Materials RTV566 Safety Data Sheet, version 3.2 (revised 02/20/2025), Part A, copy hosted by blacksky.com", "id": "SDS_US, version 3.2, revision date 02/20/2025; Momentive Performance Materials USA LLC", "url": "https://blacksky.com/wp-content/uploads/2026/02/MomentivePerformance_RTV566-Dimethyl-Diphenyl_2025-02.pdf", "year": 2025, "kind": "datasheet", "license": "manufacturer safety data sheet, cited and not reproduced" }, "sds-rtv566-31": { "title": "Momentive Performance Materials RTV566 Safety Data Sheet, version 3.1 (revised 08/30/2023), Part A, copy hosted by a BigCommerce product file", "id": "SDS_US, version 3.1, revision date 08/30/2023", "url": "https://cdn11.bigcommerce.com/s-jifykode7m/product_images/uploaded_images/msds/SGP210218.pdf", "year": 2023, "kind": "datasheet", "license": "manufacturer safety data sheet, cited and not reproduced" }, "usgs-mcs2026-silicon": { "title": "Mineral Commodity Summaries 2026, Silicon", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silicon.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "pubchem-ethyl-silicate": { "title": "PubChem, Silicic acid, ethyl ester (CID 9877350, CAS 11099-06-2): GHS classification and regulatory information", "id": "CID 9877350; CAS 11099-06-2", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/9877350", "year": 2026, "kind": "database", "license": "public database entry, cited and not reproduced" }, "unl-rtv-composition": { "title": "Relationship between photofixed condensate, effluent and bulk composition of several common RTV materials (Hanrahan and Ianno, Journal of Spacecraft and Rockets 51:3, April 2014, pp 978-982)", "id": "University of Nebraska-Lincoln repository, electricalengineeringfacpub/541", "url": "https://digitalcommons.unl.edu/electricalengineeringfacpub/541", "year": 2014, "kind": "paper", "license": "published paper, open repository copy, cited and not reproduced" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/momentive-rtv-566/" }