| HS Code | 909577 |
| Chemical Type | vinyl-terminated polydimethylsiloxane |
| Appearance | colorless transparent liquid |
| Color | ≤20 Pt-Co |
| Viscosity At 25 C | 300 mPa·s |
| Vinyl Content | 0.85–1.05 wt% |
| Density At 25 C | 0.96–0.98 g/cm³ |
| Refractive Index At 25 C | 1.403–1.406 |
| Flash Point | >200 °C |
| Volatile Matter 150 C 3 H | ≤2.0 wt% |
| Acid Value | ≤0.05 mg KOH/g |
| Specific Gravity At 25 C | 0.96–0.98 |
As an accredited Vinyl Terminated Silicone Oil RH-Vi303 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packed in 25 kg plastic drums, RH-Vi303 Vinyl Terminated Silicone Oil is also available in 5 kg sample containers. |
| Container Loading (20′ FCL) | 20′ FCL container is loaded with Vinyl Terminated Silicone Oil RH-Vi303 in suitable packaging, properly secured for ocean shipment. |
| Shipping | RH-Vi303 is shipped as a non-hazardous silicone oil in sealed 200 L drums or 1000 L IBC totes. Containers should be labeled and protected from moisture, contamination, and direct sunlight. Store in a cool, dry, ventilated area away from oxidizers. It is generally not regulated for transport. |
| Storage | Store Vinyl Terminated Silicone Oil RH-Vi303 in a cool, dry, well-ventilated area away from direct sunlight, heat, ignition sources, and strong oxidizers. Keep containers tightly closed, clearly labeled, and protected from moisture and contamination. Use original containers and follow local regulations. Do not store near food, drink, or feed; inspect containers regularly for leaks or damage. |
| Shelf Life | Typically 12 months in unopened original packaging, stored cool, dry, and away from direct sunlight; retest after expiration. |
In two-component addition-cure liquid silicone rubber processed on horizontal or vertical injection molding machines with cold-runner systems and clamp force ranging from 800 kN to 3,000 kN, RH-Vi303 functions as the vinyl-terminated polydimethylsiloxane base polymer whose terminal vinyl groups enter hydrosilylation with methylhydrogen crosslinker. Part A compound for liquid injection molding is built around 55–70 wt% RH-Vi303, 20–30 wt% fumed silica with BET surface area 200–300 m²/g, 0.5–3.0 wt% water or silanol processing fluid, and 0.02–0.05 wt% 1-ethynyl-1-cyclohexanol inhibitor; Part B carries methylhydrogen crosslinker to a final Si-H:Si-Vi molar ratio of 1.1:1 to 1.5:1 and Karstedt platinum catalyst dosed to 5–15 ppm Pt in the mixed 1:1 system. Mixed Part A viscosity at 25 °C is typically held between 200,000 mPa·s and 600,000 mPa·s before static mixing. Production molding is performed with mold cavity surface temperatures of 120–180 °C and cure times of 3–30 s depending on wall section; the processing window at the mold surface is narrow because temperatures below 115 °C leave incomplete hydrosilylation and high outgassing, while temperatures above 190 °C accelerate inhibitor depletion and may trigger premature gelation in the cold runner. Shot-to-shot viscosity variation of mixed A+B is maintained within ±5% using servo-driven metering pumps and closed-loop temperature control on the static mixer. Compliance anchoring for food-contact and medical-grade output depends on the post-cure protocol: FDA 21 CFR 177.2600 extraction limits, ISO 10993-5:2009 cytotoxicity, ISO 10993-10:2010 delayed-type hypersensitivity, and ISO 13485:2016 quality systems. Terminal product types include infant feeding nipples, medical plunger seals, automotive connector seals, and precision gaskets for fluid-handling equipment.
| Standard / regulation | Scope | Critical test condition | Typical requirement |
|---|---|---|---|
| FDA 21 CFR 177.2600 | Repeated-use rubber articles in food contact | Total extractives in chloroform and water | Complies with extraction limits |
| ISO 10993-5:2009 | Cytotoxicity | MEM elution, L-929 cells | ≥ 70% viability |
| ISO 10993-10:2010 | Sensitization | GPMT or LLNA | No sensitization response |
| ASTM D412-16 | Tensile strength, elongation | Die C, 500 mm/min | 6–10 MPa, 400–800% |
| ASTM D2240-15e1 | Hardness | Shore A | 30–70 |
| ISO 815-1:2019 | Compression set | 22 h / 177 °C | ≤ 20% |
Replacement of a mid-chain vinyl silicone fluid with terminal vinyl-functional RH-Vi303 in addition-cure silicone gels shifts the network topology from branched transient networks toward linear segment networks with more predictable gel-point conversion. The effect is most pronounced in soft gels for power electronics where elastic modulus must remain below 10 kPa at 25 °C while maintaining adhesion to polyphthalamide housings and copper leadframes. In this application, RH-Vi303 is added at 40–60 wt% of the total gel formulation, with 5–12 wt% methylhydrogen siloxane crosslinker, 0.1–1.0 wt% 1-ethynyl-1-cyclohexanol inhibitor, and 0.5–2.0 wt% adhesion promoter based on epoxy-functional trialkoxysilane. Platinum catalyst is held at 5–20 ppm to balance pot life against complete cure in thick sections. Process equipment includes planetary vacuum mixers operating below −0.095 MPa for 10–30 min and pail-level degassing before potting; materials are dispensed through volumetric pumps into module housings and cured in forced convection ovens at 100–150 °C for 30–120 min. A critical threshold exists in the cure schedule: if ramp rate exceeds 5 °C/min above 80 °C, the lower-viscosity resin front can wet the substrate before gel point is reached, creating untracked resin bleed paths along copper leadframes. Post-cure inspection under IEC 60068-2-14:2009 thermal cycling (−40 °C to +125 °C, 1,000 cycles) and UL 94 V-0 vertical burn classification is used to qualify the gel. Thermal conductivity measurements follow ASTM D5470-17; unfilled silicone gels typically read 0.15–0.25 W/m·K unless fillers are added. Terminal product types include IGBT encapsulant gels, EV on-board charger potting compounds, and silicone seal rings for power module lids.
Solventless thermal-cure release coating lines for pressure-sensitive label liners run RH-Vi303 as a reactive vinyl-terminated fluid within platinum-catalyzed 100% solids formulations that are applied by multi-roll coaters or direct gravure at coat weights of 0.8–2.5 g/m². The formulation addition ratio of RH-Vi303 to total release bath is 20–45 wt%; the balance comprises a vinyl-functional polyorganosiloxane polymer, 1–5 wt% methylhydrogen crosslinker, 0.01–0.05 wt% 1-ethynyl-1-cyclohexanol inhibitor, and platinum catalyst at 50–150 ppm. The release bath is maintained at 25–40 °C with continuous recirculation to prevent settling of silica matting agents. Cure is performed in a gas-fired or electrically heated air impingement oven at 150–180 °C for 5–15 s; actual dwell time is determined by line speed, which may range from 100–500 m/min. The process window is sensitive: oven temperature deviation of more than ±5 °C across the web width creates differential release force, and web moisture above 60% RH can carry condensation into the coating head and produce local cure inhibition at the liner interface. Compliance requirements center on FDA 21 CFR 175.300, FDA 21 CFR 176.170, FDA 21 CFR 176.180, and, for EU supply, REACH Regulation (EC) No 1907/2006 Article 31/33 safety data sheet and SVHC disclosure duties. Terminal product types include release liners for self-adhesive labels, silicone-coated PET film for die-cut adhesive parts, and single-sided release paper for hygiene articles.
High-consistency silicone rubber processing on a co-rotating twin-screw extruder with L/D 48:1 and segmented barrel configuration requires a base gum with terminal vinyl functionality to control molecular weight building during the hydrosilylation reaction. RH-Vi303 is incorporated at 60–80 wt% of total gum stock, with 15–35 wt% fumed silica, 1–3 wt% methylhydrogen crosslinker, 0.5–2.0 wt% vinyl-functional processing aid, and platinum catalyst at 5–15 ppm. Compounding is carried out at barrel temperatures of 30–100 °C with screw speed 200–500 rpm; the upper temperature limit is constrained by premature crosslinking in the rear zones. A side feeder is used for silica addition after the gum has been masticated for 10–15 L/D of screw length to reduce powder carryover into the vent port. Production-line variance is observed in first-pass silica dispersion: when finer silica with BET surface area above 300 m²/g is used, throughput must be reduced by 20–30% to prevent uncontrolled temperature rise and localized gel particles. Post-extrusion the compound is calendered or extruded through a heated head into profiles, then cured in a hot-air vulcanization oven at 250–400 °C for 10–60 s for thin walls. Published data specific to RH-Vi303 in this exact extruder configuration is limited; the operating window stated above is derived from industrial calibration runs on equivalent terminal vinyl PDMS gums. Compliance standards include ASTM D2000 M classification for elastomer properties, SAE J200 for automotive elastomer designation, and ISO 6722-1:2016 for low-voltage cable insulation in road vehicles. Terminal product types include silicone wire and cable insulation, turbocharger hoses, oven door gaskets, and extruded profiles for mass transit seat connectors.
Medical silicone gel networks prepared from RH-Vi303 rely on terminal vinyl functionality to form a low-extractables network when cured with methylhydrogen crosslinker under cleanroom conditions. The formulation addition ratio for short-term skin-contact gels is 50–70 wt% RH-Vi303, 5–10 wt% methylhydrogen crosslinker, 0.02–0.10 wt% platinum catalyst, and 0.05–0.20 wt% 1-ethynyl-1-cyclohexanol inhibitor, with no silica in visual-clear gel grades. Mixing is performed in planetary centrifugal mixers under vacuum below −0.095 MPa to suppress bubble entrainment; the mixed gel is then dispensed into mold cavities or directly onto backing films and cured at 80–120 °C for 15–60 min. The post-cure protocol includes outgassing at 150–200 °C for 2–4 h to reduce volatile siloxane content below 0.5 wt% by thermal gravimetric analysis. Compliance is driven by ISO 10993-1:2018 biological evaluation planning, ISO 10993-5:2009 cytotoxicity, ISO 10993-10:2010 sensitization, ISO 10993-23:2021 irritation testing, and FDA 21 CFR 177.2600 when the device functions as a repeat-contact rubber article. Operation is constrained by the incompatibility of platinum-catalyzed hydrosilylation with sulfur-containing compounds, amine-rich substrates, and organotin release agents; these species deactivate the catalyst and produce tacky, partially cured gel surfaces. Terminal product types include respiratory mask cushions, wound contact layers in negative-pressure dressings, short-term dermal electrodes, and drug-delivery device seals classified as limited-contact devices.
Addition-cure RTV-2 silicone tooling rubbers formulated with RH-Vi303 are used where tin-catalyzed condensation systems are excluded because of inhibition, odor, or reversion in closed molds. The formulation addition ratio is 30–50 wt% RH-Vi303, 10–25 wt% fumed silica, 5–15 wt% methylhydrogen crosslinker, 1–5 wt% dimethylsilicone oil plasticizer, and 5–15 ppm platinum catalyst, with inhibitor adjusted to deliver 20–60 min pour life at 25 °C. Mixing is performed in a vacuum planetary mixer at −0.095 MPa to deaerate the batch, followed by a slow-rise cure at room temperature for 16–24 h; a post-cure at 60–80 °C for 4–8 h completes the network and removes residual volatile siloxanes. Linear shrinkage during cure is typically below 0.2% by comparative mold-cavity measurement. Compliance is referenced against REACH Regulation (EC) No 1907/2006 Annex XVII restrictions and RoHS Directive 2011/65/EU Annex II where tooling components are employed in electrical or electronic part casting. Terminal product types include polyurethane casting molds, epoxy resin casting molds, concrete formliners, and foundry patterns for short-run metal-casting operations.
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Vinyl Terminated Silicone Oil RH-Vi303 is an α,ω-divinyl-terminated polydimethylsiloxane with CAS registry number 68083-19-2. The product is a telechelic reactive silicone fluid in which each chain terminus carries a vinyl dimethylsilyl group. This structure allows the fluid to participate in platinum-catalyzed hydrosilylation reactions with methylhydrogen polysiloxanes, making it suitable as a base polymer or reactive diluent in addition-cure liquid silicone rubber, high-consistency rubber, solventless release coatings, and two-part electronic potting gels. The RH-Vi303 designation identifies a low-to-medium-viscosity grade rather than a single molecular weight; viscosity and vinyl content are selected to match the crosslink density target of the cured elastomer. Lot-level values are reported on the certificate of analysis using the test methods listed in the specification table. The product is distinct from hydroxy-terminated polydimethylsiloxane, methyl-terminated dimethyl silicone fluid, and pendant-vinyl silicone oil because the vinyl groups are located exclusively at the terminal positions and therefore produce a controlled chain-extension effect rather than a highly crosslinked or unreactive network.
In RH-Vi303, the vinyl group is located at the chain ends, not randomly along the siloxane backbone. This structural feature controls the mechanical response of the cured elastomer. Networks formed by reacting terminal vinyl fluids with linear methylhydrogen polysiloxanes develop lower effective crosslink density and higher segmental mobility between junction points. Comparative data for terminal vinyl systems tested under ISO 37:2017 show elongation at break values commonly between 200% and 700%, depending on chain length and Si-H:Si-vinyl ratio. Pendant vinyl silicone oils, in which vinyl groups are distributed along the chain, create networks with higher crosslink density and lower elongation at break. Thus RH-Vi303 functions as a chain extender and modulus control fluid in addition-cure elastomers, whereas pendant vinyl fluids are used when hardness and solvent resistance take priority.
Hydroxy-terminated polydimethylsiloxane condenses through silanol groups under tin or titanium catalysis. Silanol groups do not participate in platinum-catalyzed hydrosilylation and may interfere with addition-cure reactivity if residual condensation catalyst is present. Methyl-terminated polydimethylsiloxane is non-reactive. If methyl-terminated fluid is added at 5–10 phr, it acts as a plasticizer but is prone to surface migration and solvent extraction. RH-Vi303 avoids this exudation mechanism when the vinyl content is stoichiometrically matched to the Si-H crosslinker because the terminal chains are incorporated into the network as structural segments rather than remaining as extractable diluents.
| Fluid type | Reactive group position | Cure route | Network role | Failure mode if misused |
|---|---|---|---|---|
| Vinyl-terminated PDMS, RH-Vi303 | α,ω terminal | Pt-catalyzed hydrosilylation | Chain extension and controlled crosslink density | Incomplete cure if Si-H ratio below 0.8 |
| Methyl-terminated PDMS | None | None | Plasticizer | Surface migration and extraction |
| Hydroxy-terminated PDMS | Terminal silanol | Condensation | Moisture-cure chain extension | Catalyst poisoning in Pt systems |
| Pendant vinyl silicone oil | Along chain | Pt-catalyzed hydrosilylation | High crosslink density | Brittle network and scorch |
| Methylhydrogen polysiloxane | Si-H along chain or terminal | Pt-catalyzed hydrosilylation | Crosslinker | Hydrogen release with moisture and bubble formation |
Incoming quality control for RH-Vi303 typically includes kinematic viscosity at 25°C, vinyl content, volatile matter, specific gravity, and refractive index. Kinematic viscosity is determined in accordance with ASTM D445-21. Volatile content is measured by the hot-air method of ASTM D4559-19, typically after 2 h at 150°C. Specific gravity is determined by ASTM D4052-22 digital density meter, and refractive index by ASTM D1218-21. Vinyl content is reported from halogen-addition titration; the method is generally described in silicone supplier specifications as an internal variation of Wijs iodine monochloride titration. The absence of a harmonized ISO or ASTM method for vinyl content means that inter-laboratory comparisons require the exact titration protocol and the molecular weight assumption used to convert iodine value to millimoles per gram.
| Property | Test method | Typical target range |
|---|---|---|
| Appearance | Visual inspection | Clear, free of suspended solids |
| Kinematic viscosity at 25°C | ASTM D445-21 | 100–1,000 mm²/s, grade dependent |
| Vinyl content | Iodometric titration, supplier method | 0.25–0.85 mmol/g, grade dependent |
| Volatile matter | ASTM D4559-19 | ≤ 0.5% |
| Specific gravity at 25°C | ASTM D4052-22 | 0.965–0.975 |
| Refractive index at 25°C | ASTM D1218-21 | 1.4030–1.4060 |
Addition-cure liquid silicone rubber formulations meter Part A and Part B through a static mixer at a mixing ratio of 1:1. Part A typically contains the vinyl-functional base polymer, platinum catalyst, and inhibitor; Part B contains the same vinyl polymer, methylhydrogen crosslinker, and reinforcing silica. RH-Vi303 may be assigned to Part A or used in both parts as a reactive viscosity modifier. Metering equipment should maintain barrel temperatures at 20–30°C to avoid premature gelation. Mold temperatures are normally set between 130°C and 180°C; at the lower end, cure time in a 10 g cavity may exceed 120 s, while at 180°C demolding can occur in 30–60 s. These values are equipment-dependent and must be confirmed by scorch tests on the specific injection molding machine.
In liquid injection molding, the clamp force requirement follows projected cavity area and injection pressure. LSR formulated with low-viscosity RH-Vi303 in the 100–500 mm²/s range generally reduces required injection pressure compared with a high-viscosity base polymer, which can lower clamp force demand in multi-cavity tools. However, excessive reduction in molecular weight increases flash formation because the compounded LSR remains fluid under cavity pressure until the gel point is reached.
High-consistency rubber compounding on a two-roll mill or a twin-screw extruder with L/D 40:1 uses RH-Vi303 as a reactive plasticizer. The liquid is added after silica incorporation to prevent the filler from absorbing the vinyl polymer before dispersion. When compounded on an open mill at 25–40°C, the addition of 5–10 phr RH-Vi303 lowers the Williams plasticity by 10–30% and improves mold flow. Published data for this specific configuration is limited to machine-specific studies; the plasticizing effect should therefore be verified with a Brabender torque rheometer or two-roll mill rheometer before production scale-up.
For solventless release coating applications, RH-Vi303 can be formulated with a methylhydrogen crosslinker and an inhibitor package. Coating trials on solventless coating heads show that a low-viscosity grade reduces transfer roller misting and permits coat weights of 0.8–1.5 g/m² on clay-coated paper. Cure is conducted in a forced-air oven at 150–180°C with residence time of 15–30 s; release force after conditioning is measured by FINAT FTM 3 or FINAT FTM 4. These values are line-speed dependent and require verification on the specific coater because oven temperature profile and air impingement alter surface cure rate.
In addition-cure formulations, the silicon hydride-to-vinyl ratio is typically controlled between 1.0:1 and 1.4:1. Excess Si-H compensates for losses from moisture and side reactions. If RH-Vi303 has a vinyl content of 0.30 mmol/g, the required methylhydrogen polysiloxane level is calculated by dividing the total moles of vinyl by the Si-H content of the crosslinker and multiplying by the selected ratio. A ratio below 0.8:1 produces an under-cured network with low tensile strength and high extractables. A ratio above 1.6:1 may cause post-cure embrittlement and hydrogen evolution at elevated temperature.
Platinum concentration in the compounded formulation is typically 5–20 ppm by weight of total silicone. Concentrations below 5 ppm produce slow and incomplete cure, particularly in the presence of inhibitor or trace contaminants. Concentrations above 20 ppm rarely improve cure speed and may increase color formation on thermal aging. The inhibitor 1-ethynyl-1-cyclohexanol, typically dosed at 0.01–0.05 wt%, extends pot life at 25°C but raises the minimum full-cure temperature. If inhibitor concentration is above the specified range, the system may remain tacky at mold temperatures below 120°C.
Viscosity selection should be made after measuring zero-shear viscosity of the unfilled formulated system on a rotational rheometer at 25°C in accordance with ISO 3219-1:2021. Filled systems require an apparent viscosity curve over shear rates from 0.1 s⁻¹ to 100 s⁻¹ to identify shear-thinning behavior in the runner and gate. Batch-to-batch variation in vinyl content within ±0.02 mmol/g can shift the demold time at a fixed mold temperature by 10–20 s. This shift is generally acceptable for parts with cycle times above 45 s; for thin-wall parts running at 30 s or less, the Si-H:Si-vinyl ratio should be adjusted lot-to-lot or the incoming fluid should be pre-blended to a tighter internal titration tolerance.
RH-Vi303 is not compatible with condensation-cure tin or titanium systems because the terminal vinyl groups do not react with silanol or alkoxysilane curing agents. The fluid should not be used as a reactive diluent in acetoxy or neutral-cure silicone sealant formulations without a platinum catalyst and Si-H crosslinker. In addition-cure systems, platinum catalyst inhibition occurs in the presence of sulfur-containing compounds, amines, amine-terminated siloxanes, organotin compounds, and certain unsaturated organic esters. Compounding equipment that has previously processed sulfur-vulcanized rubber or amine-containing epoxy should be cleaned with a silicone-compatible purge compound before introducing platinum-catalyzed silicone stock.
Moisture sensitivity is lower than in condensation systems, but excess silanol-containing fillers or water above 0.3 wt% on silica can consume methylhydrogen crosslinker through hydrolysis, releasing hydrogen and reducing the effective Si-H:Si-vinyl ratio. This can leave a tacky under-cured surface. Pre-drying of precipitated silica at 150°C for 2 h is required when ambient relative humidity exceeds 60% and the filler moisture content exceeds the control limit. Storage of RH-Vi303 should be in closed containers under dry nitrogen. Recommended storage temperature is 5–40°C; cold storage below 0°C may increase viscosity but does not damage the product, provided it is warmed to 25°C and homogenized before use.
Vinyl-functional MQ resins are solid or high-viscosity branched siloxanes with vinyl groups on the M or Q units. They raise hardness and modulus. RH-Vi303 is a linear fluid and does not provide the same reinforcement. Replacement of vinyl MQ resin with RH-Vi303 at equal vinyl moles will produce a softer and more extensible elastomer. Conversely, partial replacement of RH-Vi303 with vinyl MQ resin raises Shore A hardness and reduces elongation at break. Some suppliers offer vinyl silicone oils with vinyl contents above 1.0 mmol/g; such products are typically designed as adhesion promoters or high-hardness reactive diluents. RH-Vi303 is supplied in the low-to-medium vinyl range and is intended for controlled crosslink density rather than maximum reactivity. Formulators should not interchange grades solely on viscosity because higher vinyl content changes the stoichiometric Si-H demand and can shift the cured network from elastomeric to resinous.
In two-part silicone potting gels, RH-Vi303 is combined with a low-crosslink-density hydride fluid to produce cured Shore 00 hardness below 30. The low crosslink density reduces shrinkage and stress on solder joints during thermal cycling from -40°C to 125°C. However, linear terminal vinyl fluids with low vinyl content may swell in hot hydrocarbon fluids if not protected by higher crosslink density or a fluorosilicone barrier. Published data for this specific configuration is limited, and compatibility with specific coolants should be screened by immersion testing per ASTM D471-16a. Electrical encapsulant grades should also include headspace gas chromatography with mass spectrometry to control residual cyclic siloxanes; a control limit below 0.1% is typical where relay contacts or optical surfaces are exposed to thermal aging.
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