| HS Code | 310377 |
| Productname | Vinyl Terminated Silicone Oil RH-Vi304 |
| Chemicalname | Vinyl-terminated polydimethylsiloxane |
| Casnumber | 68083-19-2 |
| Terminalfunctionalgroup | Vinyl |
| Polymerstructure | Linear polydimethylsiloxane |
| Appearance | Colorless transparent liquid |
| Viscosityat25c | 300-500 mPa.s |
| Vinylcontent | 0.4-0.6 wt% |
| Specificgravityat25c | 0.96-0.98 |
| Refractiveindexat25c | 1.400-1.410 |
| Flashpoint | >100 °C |
| Volatilecontent | ≤1.0 wt% |
As an accredited Vinyl Terminated Silicone Oil RH-Vi304 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RH-Vi304 is supplied in 200 kg steel drums or 25 kg plastic pails, sealed for safe chemical transport and storage. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL): Vinyl Terminated Silicone Oil RH-Vi304 in sealed drums, securely stowed and braced for transport. |
| Shipping | Vinyl Terminated Silicone Oil RH-Vi304 is typically shipped in clean, sealed 200 L steel drums or IBC containers. Keep containers closed, dry, and protected from extreme heat, moisture, and contamination. Handle as a non-hazardous industrial chemical unless the SDS or local regulations state otherwise; comply with applicable transport and labeling requirements. |
| Storage | Store in a cool, dry, well-ventilated place away from direct sunlight, heat, sparks, and open flames. Keep containers tightly closed when not in use to prevent contamination and moisture ingress. Separate from strong oxidizers and acids. Maintain stable ambient temperature; avoid freezing or excessive heat. Use clean, compatible containers and follow local regulations. |
| Shelf Life | Typically 12 months when stored in a cool, dry, well-ventilated area in tightly sealed, unopened original containers. |
For medical fluid-path and short-term contact applications, two-part platinum-catalyzed LSR produced with RH-Vi304 as the terminal-vinyl dimethylpolysiloxane base fluid is used in injection-molded components that require ISO 10993-5:2009 cytotoxicity and ISO 10993-10:2013 skin sensitization data, with cured parts tested to USP <87> and USP <88> Class VI criteria and to FDA 21 CFR 177.2600 for food-contact elastomers. The formulation window for RH-Vi304 is 55–75 wt% of the total two-part system; fumed silica is introduced at 15–30 wt% to provide injection molding green strength and shear-thinning behavior, the hydride crosslinker is added at an SiH:Vi molar ratio of 1.4:1–2.0:1, platinum catalyst concentration is 2–10 ppm by mass of complete formulation, and 1-ethynylcyclohexanol inhibitor is loaded at 0.002–0.05 wt% to maintain working life. The material is processed on a 150 t all-electric LSR injection molding cell with barrel temperature 20–25 °C, platen temperature 165–185 °C, injection pressure 80–200 bar, and cure time 30–120 s depending on wall thickness. The dominant process bottleneck is heat transfer through thick sections; when wall thickness exceeds 8 mm, the center reaches complete cure only after the surface has entered the onset of thermal oxidative degradation, and mold temperature variation across cavities greater than ±3 °C generates measurable compression set variation under ISO 815-1:2019. Post-curing at 200 °C for 4 h reduces volatile cyclic siloxane species, which is required for pharmaceutical fluid-path or wound-contact applications. Terminal products include needle-free valve diaphragms, peristaltic pump tubing, respiratory mask cushions, septum disks, Y-site injection ports, and wearable medical device seals.
Underhood sealing and charge-air path parts molded from RH-Vi304-based addition-cure LSR are specified when the cured elastomer must retain ≤35% compression set after 22 h/150 °C per ASTM D395-18 Method B and maintain tensile strength above 7.0 MPa per ASTM D412-16 after oil immersion. The compliance baseline is derived from SAE J200 / ASTM D2000 classification for heat-resistant silicone elastomers, with additional characterisation by ASTM D624-00 tear, ASTM D2137-17 low-temperature brittleness, and ISO 188:2011 heat-ageing. The two-part LSR formulation places RH-Vi304 at 60–80 wt% of the polymer fraction, fumed silica at 15–30 wt%, quartz filler at 0–20 wt%, hydride crosslinker at SiH:Vi 1.2:1–1.8:1, and platinum catalyst at 10–50 ppm. Production is conducted on a 180 t LSR injection machine with a cold-runner block, mold temperature 160–185 °C, injection pressure 80–180 bar, and cycle time 45–90 s; the material is pre-dried or vented in the barrel because fumed silica moisture above 0.1 wt% causes porosity and increases viscosity drift in the static mixer. A line-specific failure mode is premature crosslinking in the static mixer when inhibitor is consumed by local hot spots above 35 °C; therefore barrel coolant must maintain 20–25 °C and mixer pressure drop is monitored at 3–8 MPa. Terminal parts include turbocharger bypass actuator diaphragms, charge-air duct gaskets, oil-separator gaskets, ignition boot sleeves, and automotive sensor grommets.
In thermally conductive gap fillers, the primary constraint is not the intrinsic thermal conductivity of the RH-Vi304 silicone matrix, approximately 0.15 W/m·K, but the ability to pack alumina or aluminum nitride filler without destroying an elastic crosslinked network. The final pad or dispensable gel is tested under ASTM D5470-17 at 1.0 mm thickness and 10 psi contact pressure, with flame class tested to UL 94 V-0 at the minimum installed thickness; RoHS 2011/65/EU compliance is documented for lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE. The polymer binder phase containing RH-Vi304 is limited to 5–15 wt% of total formulation because filler loadings of 80–95 wt% alumina are required for bulk conductivity in the 1.0–4.0 W/m·K range. Within the binder phase, RH-Vi304 is used at 70–85 wt%, hydride crosslinker at 2–8 wt%, adhesion promoter at 0.5–2.0 wt%, and platinum catalyst at 5–50 ppm; the SiH:Vi molar ratio is maintained between 0.9:1 and 1.5:1 because surface hydroxyl groups on the filler can consume hydride and shift the effective ratio. Compounding is performed in a planetary vacuum mixer with a helical dispersing blade running at 0.8–1.5 m/s tip speed and vacuum of −0.095 MPa; after alumina with D50 5–10 μm is added, viscosity rises from several hundred millipascal-seconds to 500,000–1,500,000 mPa·s, requiring bowl temperature not exceeding 45 °C to prevent premature hydrosilylation. For sheet pads, the compound is calendered to 1–5 mm and die-cut; for form-in-place gap fillers, two-component cartridges with static mixing tips are dispensed at 2–6 mL/s onto battery cooling plates or power electronics housings. Published comparative data for RH-Vi304 in aluminum nitride-filled systems is limited; aluminum nitride surface treatment must be confirmed by rheometry and thermal conductivity screening. Terminal products include 1–5 mm pre-cured thermal pads for EV battery module cooling interfaces, form-in-place gap fillers for IGBT base modules, and compressible thermal interface layers for 5G AU/AAU heat spreaders.
Optical-grade addition-cure encapsulants based on RH-Vi304 are limited to applications in which the refractive index of 1.40–1.41 for dimethyl-type silicone is acceptable; phenyl-containing vinyl fluids are used when higher light extraction efficiency requires a higher refractive index. In LED encapsulation, the cured silicone must exhibit yellowness index below 2 after 150 °C/1000 h ageing per ASTM E313-20, haze below 1% per ASTM D1003-21, and adhesion to silver-plated leadframes, with compliance testing under IEC 62717 for LED module endurance and RoHS 2011/65/EU. The formulation uses RH-Vi304 at 80–95 wt% of the Part A base, hydride crosslinker at 3–8 wt%, adhesion promoter at 0.5–1.5 wt%, and platinum catalyst at 1–5 ppm, with an SiH:Vi molar ratio of 1.0:1–1.3:1 to avoid under-cured surface tack and minimize outgassing. The production process includes vacuum defoaming at 50–100 mbar for 10–20 min, needle dispensing into an SMD leadframe, and staged cure at 100 °C for 1 h followed by 150 °C for 3 h; the staged cure reduces bubble nucleation caused by volatile low-molecular-weight siloxane fractions. A processing conflict arises on high-speed die-bonding lines: gold-coated surfaces and amine-containing die-attach residues can inhibit platinum catalyst, leading to soft corners and wire-bond movement. Terminal products include SMD LED encapsulant, COB encapsulation, and optical sensor window bonding.
For pressure-sensitive adhesive release liners, RH-Vi304 is formulated into a platinum-catalyzed, solvent-free two-component release coating. Compliance is evaluated under FDA 21 CFR 175.320 and EU 1935/2004 where food-contact or indirect-contact status is claimed, and the cured coating is tested for release force and subsequent PSA adhesion using ASTM D1894-14 and ASTM D3359-17. The addition ratio is set at 100 parts RH-Vi304, 3–8 parts hydride crosslinker, 0.1–0.5 parts inhibitor, and platinum catalyst at 50–120 ppm; the SiH:Vi molar ratio is maintained at 1.6:1–2.2:1. The fluid is applied on a multi-roll gravure coater at 0.8–2.5 g/m² coating weight and cured in a forced-air oven at 120–160 °C for 3–15 s, with line speed 100–300 m/min. Because bath life at 35 °C can drop below 8 h without inhibitor adjustment, the coating reservoir is cooled to 20–25 °C. Terminal products include release liners for label stock, graphic films, hygienic and medical PSA laminates. Published comparative data for RH-Vi304 on corona-treated polyester substrates is limited; release performance must be confirmed on the target substrate because surface energy and corona density alter platinum catalyst adsorption.
Room-temperature addition-cure mold-making silicone formulated with RH-Vi304 is used for reproduction of gypsum, wax, and limited low-exotherm polyurethane casting parts. The cured mold elastomer is tested to ASTM D412-16 for tensile strength, ASTM D624-00 for tear resistance, and ASTM D395-18 Method B for compression set; the uncured components are evaluated against REACH Annex XVII restrictions on restricted siloxane species. Part A contains RH-Vi304 at 60–75 wt%, fumed silica at 10–20 wt%, and quartz filler at 10–25 wt%; Part B contains hydride crosslinker at 3–6 wt% and platinum catalyst at 5–20 ppm, with the two parts mixed at 1:1 by volume and the SiH:Vi ratio set at 1.5:1–2.5:1. Processing consists of vacuum degassing of the mixed compound at −0.09 MPa for 5–10 min, pouring over a sealed model, and curing at 25 °C for 12–24 h; optional heat acceleration at 60 °C for 2–4 h reduces demold time. The main production failure is platinum catalyst poisoning caused by sulfur-containing modelling clay, condensation-cure RTV residues, or natural rubber templates; therefore a barrier varnish or a post-cure bake of the model is required before pouring. Terminal products include block molds for gypsum casting, wax pattern molds, concrete form liners, and short-run polyurethane casting tools.
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Vinyl Terminated Silicone Oil RH-Vi304 is introduced as a linear polydimethylsiloxane fluid carrying dimethylvinylsiloxy termination at both siloxy chain ends. The product is manufactured by equilibration or condensation of cyclosiloxane monomers, followed by end-capping with 1,3-divinyltetramethyldisiloxane, yielding a reactive silicone intermediate rather than a non-functional dimethylsilicone fluid. The model code RH-Vi304 identifies a viscosity grade with a nominal kinematic viscosity near 300 mm²/s at 25 °C; the “Vi” segment denotes terminal vinyl reactivity, and the 304 suffix is a manufacturer-specific grade indicator rather than an ASTM or ISO registered designation. Terminal vinyl groups permit the fluid to participate in platinum-catalysed hydrosilylation with polymethylhydrogensiloxane, forming covalent network linkages instead of remaining as an extractable diluent. This behaviour separates RH-Vi304 from methyl-terminated polydimethylsiloxane oils and from silanol-terminated intermediates. Published data for this specific configuration is limited; the numerical ranges presented below are representative of commercial linear vinyl-terminated polydimethylsiloxanes with similar viscosity grades and are anchored to the test methods referenced.
Incoming quality control for RH-Vi304 centers on four independent parameters: rheological consistency, vinyl content, volatile fraction, and optical clarity. Kinematic viscosity is determined at 25 °C by capillary viscometry according to ASTM D445-21; the method is preferred over rotational viscosity because it is less sensitive to shear history and permits direct comparison with supplier certificates. Vinyl content is quantified by iodine monochloride titration adapted from drying-oil iodine value methodology; the result is expressed in millimoles of vinyl per gram of fluid. Since vinyl silicone fluids are non-volatile polymers, the method requires toluene or xylene dilution and a blank correction for iodine consumption by siloxane backbone species. Non-volatile content is measured by gravimetric residue after heating at 150 °C for 3 h according to ISO 3251:2019, which detects low-molecular-weight cyclic siloxanes that can cause haze and surface deposits in cured elastomers. Refractive index is checked by refractometry under ASTM D1218-21, and density by digital density meter under ASTM D4052-22. Water content is monitored by coulometric Karl Fischer titration using ASTM D1533-20, because water can poison platinum catalysts and cause Si-H consumption in addition-cure systems. The table below lists representative release ranges for a linear vinyl-terminated silicone fluid with a nominal viscosity of 300 mm²/s; these are not guaranteed specification limits for RH-Vi304 unless confirmed by the manufacturer’s certificate of analysis.
| Property | Test method | Representative range or value |
|---|---|---|
| Appearance | Visual inspection | Clear, free of suspended matter |
| Kinematic viscosity at 25 °C | ASTM D445-21 | 280–320 mm²/s |
| Vinyl content | Iodine monochloride titration, internal adaptation of ASTM D1959 | 0.30–0.40 mmol/g |
| Non-volatile content | ISO 3251:2019, 150 °C, 3 h | ≥ 99.0 % |
| Refractive index at 25 °C | ASTM D1218-21 | 1.4010–1.4050 |
| Density at 25 °C | ASTM D4052-22 | 0.968–0.975 g/cm³ |
| Water content | ASTM D1533-20 | < 100 mg/kg |
In addition-cure formulations, the terminal vinyl groups of RH-Vi304 serve as chain-extension sites rather than pendant crosslink hubs. Each molecule contributes two reactive moieties, so the fluid behaves as a bifunctional linear prepolymer. During hydrosilylation, the silicon–hydrogen bond of a polymethylhydrogensiloxane crosslinker adds across the terminal carbon–carbon double bond to form an ethylene bridge between siloxane chains. Reaction is catalyzed by platinum complexes, commonly Karstedt catalyst at 5–15 ppm platinum relative to the total silicone mass. The vinyl content near 0.30–0.40 mmol/g provides a controlled crosslink-density increment when the fluid is blended at 10–30 parts per hundred resin by mass. Below 5 phr, viscosity reduction in a high-consistency rubber base is limited; above 40 phr, chain-end dilution can create elastically inactive network defects and increase compression set. These boundaries are formulation-specific and require rheometer confirmation. Compared with branched or pendant vinyl silicone fluids, RH-Vi304 has a more uniform bifunctional structure; pendant-vinyl fluids create higher crosslink density and can embrittle the network when used at equal vinyl content.
Production-scale experience with similar viscosity grades indicates that the fluid meters cleanly through positive-displacement piston pumps when feed-zone temperature is maintained at 25 ± 1 °C. On an injection molding machine with a 110-ton clamp and closed-loop barrel control, a nozzle temperature of 120 ± 2 °C is typical for two-component liquid silicone rubber compounds containing this fluid. Cure rate is highly sensitive to stock temperature: increasing barrel temperature by 5 °C can reduce scorch time by 30–40 % in fast-curing grades, so the processing window is often held within ±5 °C of the optimized set point. These observations are from production-scale moulding lines, not from a single laboratory coupon.
Cure kinetics under non-isothermal differential scanning calorimetry at 10 K/min are commonly evaluated for platinum-catalysed silicone networks. In published studies on linear vinyl-terminated polydimethylsiloxane formulations, apparent activation energies between 80 kJ/mol and 110 kJ/mol are reported for the hydrosilylation exotherm. The peak exotherm for a compound containing 20 phr of a 300 mm²/s vinyl-terminated fluid typically falls between 90 °C and 130 °C, depending on inhibitor type and platinum concentration. No single activation-energy value should be assigned to RH-Vi304 without direct calorimetric analysis of the finished formulation, because filler surface chemistry and inhibitor package shift the reaction profile.
Compounding of RH-Vi304 into filled silicone bases on a co-rotating twin-screw extruder with an L/D ratio of 48:1 is performed by side-feed injection after the silica incorporation zone. The low viscosity of the fluid assists filler wetting and reduces the torque required to disperse fumed silica at loadings between 20 wt% and 35 wt%. In continuous mixing, the fluid is introduced at a barrel temperature of 80–100 °C; higher injection temperatures can volatilize low-molecular-weight cyclic siloxanes and shift the target non-volatile content. Batch-to-batch variation in vinyl content is detected by the change in cure rheometer torque: an increase of 0.02 mmol/g in vinyl content raises the maximum torque of an addition-cure compound by approximately 3–5 % when the Si-H:Si-Vi molar ratio is held constant. This is a measurable but controllable drift on standard moving-die rheometers operated under ASTM D5289-19.
For two-component liquid silicone rubber dispensing, the RH-Vi304-containing Part A is mixed with a hydride-functional Part B in a static mixer with 32 elements. Pot life at 25 °C is typically between 4 h and 24 h depending on platinum concentration and inhibitor level. Viscosity recovery after storage is checked by the supplier because vinyl-terminated fluids can undergo slow headspace oxygen uptake. When shipping and storage are prolonged, nitrogen blanketing of pails is required to prevent a yellow tint and a reduction in hydrosilylation reactivity.
In electronic encapsulation and thermal interface materials, RH-Vi304 is incorporated into the A-side of a two-part addition-cure system at 10–20 wt% relative to total silicone mass. The fluid lowers the initial mix viscosity from the base-gum range of 500,000–1,200,000 mPa·s to a dispensable range of 50,000–200,000 mPa·s at 25 °C. Such viscosity reductions are measured by cone-and-plate rheometry under ISO 3219:2021 at a shear rate of 10 s⁻¹. The terminal vinyl groups then react into the network, which is critical for long-term thermal cycling stability. If an equivalent viscosity reduction were achieved with a non-reactive methyl silicone oil, that oil would remain mobile and migrate to the interface, increasing contact resistance and reducing adhesion after 1000 h at 125 °C. Extraction testing of cured samples by ASTM D5712-15 with isopropanol can quantify the difference; reactive diluents in fully cured systems typically leave extractable fractions below 2 wt%, while non-reactive diluents can exceed 10 wt% under the same cure conditions. Published data for this specific configuration is limited, so the extraction threshold should be verified for each formulation.
Methyl-terminated polydimethylsiloxane fluids are non-reactive and remain as mobile, extractable liquids when formulated into cured silicone networks. RH-Vi304 is not a drop-in replacement for such fluids in lubricant or release applications because its terminal vinyl groups can undergo oxidative crosslinking at elevated temperatures and can participate in unintended platinum-catalysed reactions. In release-coating applications, a methyl-terminated silicone oil leaves a stable low-surface-energy film; a vinyl-terminated fluid at similar viscosity may smear or partially cure when exposed to ambient sulfur-containing air or to residual platinum from previous batches. For silicone-based release liners, thermal cure kinetics and surface cure completeness are measured by rub-off and by extraction according to ASTM D5712-15; a reactive vinyl-terminated fluid may reduce extractables only if it is fully co-cured into the network. If used as an internal lubricant in a peroxide-cured system, the terminal vinyl groups can consume peroxide radicals and alter vulcanization kinetics. The table below compares RH-Vi304 with silanol-terminated and methyl-terminated fluids across the variables that control substitution decisions.
| Parameter | RH-Vi304 type | Silanol-terminated PDMS | Methyl-terminated PDMS |
|---|---|---|---|
| Terminal group | Dimethylvinylsiloxy | Dimethylhydroxysiloxy | Trimethylsiloxy |
| Reactivity | Addition cure with Si-H and platinum | Condensation cure with alkoxy/oxime or moisture | Non-reactive under silicone cure conditions |
| Typical viscosity at 25 °C | 280–320 mm²/s | 100–350 mm²/s for comparable molecular weight | 10–1000 mm²/s |
| Cure by-product | None in ideal hydrosilylation | Water, alcohol, or oxime depending on crosslinker | Not applicable |
| Extractables in cured network | Low when fully reacted | Low to moderate after complete condensation | High if not removed |
| Typical application role | Reactive diluent and chain extender | Release agent or condensation base polymer | Lubricant, release film, or non-reactive diluent |
Because terminal vinyl groups are consumed during hydrosilylation, RH-Vi304 does not generate water or methanol during cure under ideal stoichiometric conditions. This is significant in electronic potting and optical encapsulation, where condensation by-products can create bubbles or cause adhesion loss. In contrast, silanol-terminated fluids used with alkoxy or oxime crosslinkers release alcohol or oxime compounds; if the condensation cure is incomplete, the released species can remain trapped in thick sections and produce solvent-induced stress cracking. For RH-Vi304, volatile outgassing after cure is normally evaluated by headspace gas chromatography with flame ionization detection at 150 °C for 30 min; typical non-reactive cyclic siloxane residues are controlled to below 0.5 wt% in products with a non-volatile content of ≥ 99.0 %.
Platinum-catalyst compatibility imposes stricter raw-material limits than condensation-catalyst systems. Amine-based additives, sulfur-containing organics, and certain tin salts deactivate platinum and should be excluded from formulations containing RH-Vi304. The same contaminants can be tolerated at higher levels in tin-catalysed condensation systems, which is one reason a condensation-cure fluid cannot be randomly substituted in an addition-cure process. In mixed-metal manufacturing environments, residual tin on shared dosing equipment can poison platinum even at trace levels; dedicated metering systems or verified cleaning between products is required. Thermal cure conditions for RH-Vi304-containing compounds are typically 100–150 °C; below 80 °C the hydrosilylation rate is too slow for high-output molding, and above 180 °C oxidative chain scission can occur in the siloxane backbone.
Storage and handling limits for RH-Vi304 are defined by moisture exclusion, headspace nitrogen, and avoidance of acidic or basic condensation catalysts. The product is supplied in sealed HDPE pails or epoxy-phenolic lined steel drums; ambient storage at ≤ 35 °C for 12 months is common for vinyl-terminated silicone oils of this viscosity grade, but headspace moisture should be excluded after opening. If the product is stored in high-humidity environments with a relative humidity greater than 60 %, pre-drying of the fluid is unnecessary because the fluid itself is not hygroscopic; however, downstream fillers and bases may require pre-drying to prevent trapped volatiles in molded parts. Avoid contact with alkoxysilanes, acetoxysilanes, and strong acids because these can rearrange the terminal vinyl groups or catalyze siloxane equilibration. When adding platinum catalyst to a blend containing RH-Vi304, the mixture should be used within the pot life determined by rheometer cure curve; catalyzed material should not be left in unvented closed containers, because cumulative heat release can raise the temperature to the cure onset. Operational boundaries for this product therefore arise less from the fluid itself than from the sensitivity of the addition-cure package to catalyst poisons and stoichiometric imbalance.
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