| HS Code | 980045 |
| Product Name | Vinyl Terminated Silicone Oil RH-Vi1325 |
| Chemical Type | Vinyl-terminated polydimethylsiloxane |
| End Groups | Vinyl |
| Appearance | Colorless transparent liquid |
| Viscosity At 25 C | 2500 mPa·s |
| Vinyl Content | 0.25 wt% |
| Density At 25 C | 0.97 g/cm³ |
| Refractive Index At 25 C | 1.403 |
| Flash Point | >100 °C |
| Volatile Content | ≤2.0% |
| Solubility | Soluble in nonpolar organic solvents; insoluble in water |
| Cure Mechanism | Platinum-catalyzed hydrosilylation addition cure |
| Storage Temperature | 5–30 °C |
| Shelf Life | 12 months |
As an accredited Vinyl Terminated Silicone Oil RH-Vi1325 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RH-Vi1325 Vinyl Terminated Silicone Oil is supplied in sealed, batch-labeled 200 kg drums with moisture-resistant industrial packaging for safe storage and transport. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Vinyl Terminated Silicone Oil RH-Vi1325 in sealed drums, securely stowed and lashed for ocean transport. |
| Shipping | Vinyl Terminated Silicone Oil RH-Vi1325 is typically shipped as a non-hazardous chemical in sealed drums or IBCs, labeled with product name, batch number, and manufacturer details. Keep containers closed, protect from moisture and contamination, and transport at ambient temperature. Refer to the SDS and applicable transport regulations before shipment. |
| Storage | Store Vinyl Terminated Silicone Oil RH-Vi1325 in a cool, dry, well-ventilated area away from heat, sparks, open flames, and direct sunlight. Keep containers tightly closed to prevent moisture and contamination. Avoid contact with acids, alkalis, and oxidizing agents. Maintain recommended storage temperature, protect from freezing if specified, and use clean, compatible containers. Observe local regulations and manufacturer’s label/SDS. |
| Shelf Life | Shelf life is typically 12 months when stored in the original unopened container under cool, dry conditions, away from direct sunlight. |
In platinum-catalyzed addition-cure liquid silicone rubber (LSR) processing, RH-Vi1325 functions as the telechelic vinyl-terminated polydimethylsiloxane base polymer. The A component is formulated to carry platinum catalyst and a portion of RH-Vi1325, while the B component carries hydride crosslinker and the remaining vinyl polymer; the two components are delivered through a static mixer with 12–24 elements at a fixed 1:1 metering pump ratio. Formulation control targets a molar ratio of Si-H to terminal vinyl of 1.4–2.0:1, with platinum concentration of 2–8 ppm based on total compound mass. Gel time is modulated with 0.05–0.30 phr 1-ethynyl-1-cyclohexanol inhibitor; the inhibitor evaporates from the melt during initial mold contact, restoring catalytic activity. The critical processing boundary is catalyst poisoning: amine-functional additives, sulfur-bearing rubber residues, and tin-catalyzed condensation silicone vapors extend cure time or leave persistent surface tack. Injection molding is run on screw-type LSR machines with 18–25:1 L/D ratio and water-cooled barrel zones set at 18–25 °C; mold temperature is held at 150–190 °C. At 175 °C, a 2 mm plaque reaches demoldable crosslink density in 10–30 s, depending on gate geometry and part mass. Post-cure is conducted at 200 °C for 4 h to complete hydrosilylation and remove volatile cyclic siloxanes. Compliance for medical components is assessed according to ISO 10993-5, ISO 10993-10, and USP <88> Class VI; food-contact grades are tested under FDA 21 CFR 177.2600. Mechanical batch release includes tensile strength per ISO 37, Shore A hardness per ISO 868, and compression set at 175 °C for 22 h per ISO 815-1. End products include respiratory mask seals, needleless valve components, insulin pump diaphragms, and infant bottle nipple adapters.
Lot-to-lot viscosity variation in RH-Vi1325 is handled by adjusting hydride crosslinker mass rather than changing the mixer ratio, because the 1:1 machine setting is fixed on most LSR injection cells. Before production, the A and B components are degassed at 2–5 kPa for 15 min; trapped air in the static mixer creates visible flow lines in translucent parts. The use of terminal vinyl rather than pendant vinyl groups lowers the concentration of network chain ends that contribute to compression set. At Si-H:Vi ratios below 1.0:1, crosslink density is insufficient and compression set increases; above 2.2:1, residual Si-H groups react with atmospheric moisture and generate hydrogen gas, producing microvoids. Published data for this specific product lot should be verified by moving die rheometer analysis at 177 °C before start of mass production.
High-voltage silicone rubber insulation compounds load RH-Vi1325 as the vinyl-functional base fluid for castable addition-cure elastomers around cable joints and surge arresters. A typical compound contains 100 phr RH-Vi1325, 25–50 phr hydrophobic fumed silica with BET surface area of 150–300 m²/g, and 40–120 phr alumina trihydrate having median particle size 1.3–2.0 µm. The hydride crosslinker is dosed to give Si-H:Vi molar ratio 1.1–1.6:1, and platinum catalyst is added at 5–10 ppm. ATH must be pre-dried at 150 °C for 6 h because water liberated during cure forms internal voids that reduce dielectric strength. Mixing is carried out in a planetary mixer under absolute vacuum of 2–5 kPa at 25–40 °C; the mix is then cast into a mold and cured at 120 °C for 30 min, followed by 180 °C for 2 h. Tracking resistance is evaluated per IEC 60587 at 4.5 kV and ASTM D2303 with 0.1% ammonium chloride contaminant; erosion depth is measured per IEC 62217. The low level of residual volatile cyclic siloxanes in RH-Vi1325 is critical for stable hydrophobicity transfer under salt-fog conditions. Production-scale failures are usually linked to ATH moisture, platinum inhibition by sulfur-containing adhesion promoters, or insufficient vacuum causing microvoids at the conductor interface. End-use parts include cable termination bodies, separable connector insulators, surge arrester housings, and hollow-core insulator sheds.
On solventless thermal-release coating lines, RH-Vi1325 is used as the base vinyl polymer in a platinum-catalyzed hydrosilylation coating fluid. The coating bath is prepared by mixing 100 parts RH-Vi1325 with 3–8 parts methylhydrogenpolysiloxane crosslinker, 0.5–2.0 parts maleate or alkyne inhibitor, and 80–120 ppm platinum catalyst. Coating weight is controlled at 0.8–1.6 g/m² on five-roll silicone coaters; oven temperature is set at 120–180 °C with dwell time 5–30 s. Release force against a standard acrylic adhesive is measured per FINAT FTM 3 at 300 mm/min peel speed; values typically range from 5 to 40 cN/25 mm depending on controlled release additive level. Subsequent adhesion and loop tack are checked per FINAT FTM 9, and substrate adhesion is tested by cross-cut per ISO 8510-2. Indirect food-contact compliance is assessed under FDA 21 CFR 175.320 for polyolefin substrates and FDA 21 CFR 176.170 for paper and paperboard. The main high-speed coating failure is misting when the coating fluid viscosity falls below 200 mPa·s; RH-Vi1325 is therefore blended with higher-viscosity vinyl polymers to reduce mist without increasing release force. The absence of free silicone oil migration is confirmed by extraction testing because terminal vinyl groups bind the polymer into the crosslinked film. End products include glassine liners for pressure-sensitive label stock, tape release liners, casting sheets for medical dressings, and differential release films.
RTV-2 mold rubber produced with RH-Vi1325 is specified for casting polyurethane parts because the addition-cure system does not release alcohol or acid volatiles. A bench-scale formulation combines 100 parts RH-Vi1325 with 20–50 parts vinyl MQ resin, 15–30 parts fumed silica, 2–6 parts hydride crosslinker, and 2–5 ppm platinum. The mixed viscosity before degassing is 8,000–30,000 mPa·s at 25 °C; vacuum degassing is conducted at 1–5 kPa until visible bubble collapse ceases, typically 5–10 min. Pot life at 25 °C is adjusted with 0.5–2.0 phr 1-ethynyl-1-cyclohexanol inhibitor to 45–90 min. Curing proceeds at 23 °C for 24 h, followed by optional post-cure at 100 °C for 4 h to stabilize hardness. Demolded silicone molds are tested for tear strength per ASTM D624 die B and ISO 34-1; tear strength of 15–30 kN/m is typical for Shore A 20–35 grades. Inhibition is observed when the mold is used with polyurethane systems containing dimethyltin or amine catalysts; the contact surface remains tacky and transfers uncured silicone to the cast part. End products include architectural concrete formliners, candle molds, composite tooling, polyurethane prototype molds, and food molds tested under FDA 21 CFR 177.2600.
For silicone gel encapsulation, a deliberately substoichiometric Si-H:Vi ratio is required to avoid the elastic modulus of fully crosslinked LSR. RH-Vi1325 is formulated with a low hydrogen-content crosslinker at Si-H:Vi 0.4–0.8:1, producing a soft network with penetration depth per ISO 2137 quarter-scale cone of 5–15 mm. The base polymer is mixed with 30–80 phr of a low-volatile silicone extender or with the same RH-Vi1325 lot to adjust complex viscosity. Mixing is performed in a planetary mixer at 25–40 °C, followed by vacuum degassing at 1–5 kPa for 10–20 min. Potting is conducted through a static mixer with 8–12 elements; the void-free fill is critical for partial discharge performance measured per IEC 60270. Cure schedule is 100 °C for 15–30 min, followed by 150 °C for 60 min. The cured gel must retain a tack-free surface and pass thermal cycling from -55 °C to 180 °C per IEC 60749-25. Adhesion to aluminum, copper, and PBT housings is tested with a 180° peel test at 50 mm/min; cohesive failure is required. Flame retardance of the composite is tested per UL 94 V-1 or V-0 when alumina trihydrate is added; published data for this specific configuration is limited and requires pre-production UL 94 certification. Formulations are checked against RoHS Directive 2011/65/EU Annex II for lead, cadmium, mercury, hexavalent chromium, PBB, and PBDE exclusions. The main processing boundary is premature gelation in static mixers if the A and B components exceed 35 °C at the mixing point; chilled water jackets are set to 15–20 °C. End products include IGBT module encapsulants, power semiconductor passivation gels, LED driver potting compounds, and optocoupler fills.
High-consistency silicone rubber compounds for medical and food-contact tubing incorporate RH-Vi1325 as a reactive viscosity modifier rather than as the primary gum. A standard addition-cure HCR compound contains 100 phr high-molecular-weight vinyl-terminated silicone gum, 20–45 phr fumed silica, 5–15 phr RH-Vi1325, 3–8 phr vinyl MQ resin, 1–3 phr hydride crosslinker, and 2–5 ppm platinum. The compound is mixed in a twin-screw extruder with 36:1 L/D ratio at barrel temperatures 100–160 °C; Mooney viscosity is monitored per ISO 289-1 at 100 °C. The RH-Vi1325 phase reduces screw torque by 10–20% compared with the same compound without reactive diluent. Tubing is extruded through a pin-and-head die at 180–250 °C and vulcanized in a hot-air tunnel at 250–320 °C with line speed of 5–15 m/min. Because the diluent is terminal-vinyl functional, it is incorporated into the network during hydrosilylation and does not migrate as free silicone oil under extraction testing. Post-cure is run at 200 °C for 4 h. Compression set is tested on 25 mm buttons per ISO 815-1 at 175 °C for 22 h; values of 10–20% are required for pharmaceutical stopper applications. Biocompatibility is evaluated per ISO 10993-5 and USP <88> Class VI; food-contact extraction is checked under FDA 21 CFR 177.2600. Extruded products include peristaltic pump tubing, catheter shafts, beverage dispensing tubing, pharmaceutical stopper gaskets, and molded seals.
For gas-blown addition-cure silicone foams, RH-Vi1325 serves as the vinyl-functional chain extender and network builder. In a castable foam formulation, 100 parts RH-Vi1325 are mixed with 10–25 parts methylhydrogenpolysiloxane, 0.5–3.0 parts deionized water or isopropanol, 10–20 parts fumed silica, and 5–10 ppm platinum. The reaction of Si-H with hydroxyl groups liberates hydrogen; foam rise is controlled by adjusting water content and inhibitor level. Mixing is carried out in a high-shear dispersion mixer at 1,500–2,500 rpm for 20–40 s, followed by immediate casting into a closed mold. The foam rises and cures at 80–120 °C for 10–30 min. Density is measured per ISO 845; values of 0.20–0.50 g/cm³ are obtained without chemical blowing agents. Compression force deflection is tested per ASTM D1056 at 25% deflection; closed-cell products are specified with 10–40 kPa at 25% strain. Flame performance is evaluated under UL 94 V-0 and horizontal burning per FMVSS 302; silicone foam leaves a silica residue. The processing boundary is narrow: water content above 3.0 phr causes open porosity and cell collapse, while water content below 0.5 phr gives insufficient expansion. Published data for thermal runaway barrier performance of this product grade is limited; UL 94 qualification must be repeated on the final composite. End products include battery module compression pads, thermal runaway barrier sheets, and high-temperature gaskets for industrial ovens.
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Vinyl-terminated silicone oil RH-Vi1325 is a linear α,ω-divinyl polydimethylsiloxane fluid in which each terminal silicon atom carries a dimethylvinylsiloxy group. The product designation RH-Vi1325 is interpreted within the supplier catalog as a nominal kinematic viscosity of 1325 mm²/s at 25 °C; end users should confirm the exact lot viscosity against the certificate of analysis because supplier tolerances commonly span ±10%. In comparison with methyl-terminated silicone oils of equivalent viscosity, this terminal vinyl functionality provides two reactive sites per polymer chain for hydrosilylation crosslinking. Batch-to-batch variation in vinyl content is a critical processing variable: if vinyl content falls below the lower specification limit, the resulting network under-crosslinks and exhibits high compression set; if it exceeds the upper limit, storage modulus increases and elongation at break decreases.
Published certificate-of-analysis limits for RH-Vi1325 specifically are not independently retrievable from publicly available technical data. The following envelope is therefore drawn from the class of vinyl-terminated polydimethylsiloxane fluids with nominal viscosity 1000–1500 mm²/s: density 0.970–0.975 g/cm³ at 25 °C by ASTM D4052-22, refractive index 1.403–1.405 at 25 °C, vinyl content 0.15–0.30 wt % as CH=CH₂, and volatile content ≤0.5 wt % after 2 h at 150 °C. The low volatile fraction is significant because volatile oligomers contribute to outgassing in closed electronic assemblies. When viscosity is measured by ASTM D445-21, the fluid should be filtered and air bubbles removed before loading into a Cannon-Fenske viscometer calibrated at 25 °C ± 0.02 °C; otherwise entrained microbubbles can shift the measured efflux time by more than 1%.
| Property | Typical range | Test method |
|---|---|---|
| Kinematic viscosity at 25 °C | 1200–1450 mm²/s | ASTM D445-21 |
| Density at 25 °C | 0.970–0.975 g/cm³ | ASTM D4052-22 |
| Vinyl content | 0.15–0.30 wt % | Iodometric titration or 1H NMR |
| Volatile content | ≤0.5 wt % | 150 °C / 2 h forced air |
| Refractive index at 25 °C | 1.403–1.405 | ASTM D1218-21 |
| Surface tension at 25 °C | 20.5–21.5 mN/m | Du Noüy ring, ASTM D1331-20 |
| Flash point | >300 °C | ASTM D92-18 |
Addition cure of RH-Vi1325 occurs by platinum-catalyzed hydrosilylation between the terminal vinyl groups and silicon-hydride groups of a poly(methylhydrogensiloxane) or methylhydrosiloxane-dimethylsiloxane copolymer crosslinker. The reaction consumes one Si-H per terminal vinyl unit and produces an ethylene bridging unit; no water, methanol, or ethanol is formed. The primary difference from hydroxy-terminated condensation systems is therefore the absence of volatile leaving groups when the Si-H/Si-Vinyl ratio is balanced. The ratio of Si-H to Si-Vinyl is typically set between 1.0:1 and 1.5:1. At 1.0:1, the network is vulnerable to incomplete cure because platinum-catalyzed side reactions, including trace water-induced loss of Si-H, consume a small fraction of crosslinker. At 1.2:1 to 1.3:1, formulations usually achieve a stable plateau in tensile modulus and tear strength without excessive unreacted Si-H, which can later generate hydrogen gas or participate in post-cure drift. Above 1.5:1, residual Si-H can react with atmospheric moisture and cause foaming or electrical contact contamination; this effect is more pronounced in thermally conductive potting compounds where filler surfaces introduce adsorbed water.
The cure kinetics of the formulated compound are controlled by a platinum-divinyltetramethyldisiloxane complex or a platinum-tetramethyltetravinylcyclotetrasiloxane complex at concentrations of 2–20 ppm platinum relative to total formulation mass. Pot life at 25 °C can be adjusted from 30 min to 8 h using an alkyne inhibitor such as 1-ethynyl-1-cyclohexanol. The latency is thermally activated: at 60 °C, the inhibitor begins to release the platinum catalyst, and the compound transitions from low-viscosity liquid to gel within 2–10 min depending on part mass. Above 150 °C, cure may complete in 10–30 s, which is compatible with high-speed molding but leaves a narrow processing window. Molding trials on a heated press therefore commonly use mold temperatures of 120–170 °C and demolding times of 30–90 s for sections up to 10 mm. If the mold temperature exceeds 190 °C, low-molecular-weight siloxane volatilization can produce surface clouding and tool fouling, especially in vented cavities.
On a production-scale liquid silicone rubber line, RH-Vi1325 is blended with fumed silica, plasticizer, and a hydrogen-functional crosslinker before being split into A and B components. High-shear dispersion is performed in a planetary mixer with a butterfly blade and high-speed disperser operating at 15–25 m/s tip speed. Fumed silica loadings of 15–30 wt % relative to polymer produce a thixotropic paste; the resulting compound typically shows a Brookfield viscosity of 200,000–600,000 mPa·s at 10 rpm, depending on filler surface treatment. The 1325 mm²/s base fluid is low enough in molecular weight to wet silica surfaces during the initial mixing phase, but high enough to limit creep after part placement. In a two-component meter-mix system with 24 or 32 static mixing elements, A/B ratio accuracy should be maintained within ±2% because off-ratio mixing disrupts the Si-H/Si-Vinyl balance and reduces ultimate tensile properties.
Injection molding of this grade is performed on a reciprocating-screw machine with a barrel L/D ratio of 18:1 to 22:1. The cold-runner manifold is held at 18–22 °C to prevent premature cure, while the mold cavity is held at 160–190 °C. Injection pressure of 40–80 bar is sufficient for thin-wall sections of 1–2 mm; thicker sections may require lower mold temperature to avoid surface scorch and internal porosity. A critical production failure mode is pre-cure in the mixing block, observed as a viscosity increase of more than 25% within 1 h at 25 °C. This failure is caused by inhibitor depletion or by contaminated static mixers carrying catalytic residues from previous batches. Cleaning with toluene or a low-viscosity silicone solvent and replacing the static mixer after 8 h of idle time is recommended. Published data for this specific configuration is limited, so the above ranges should be verified by a design-of-experiments run on the target machine.
RH-Vi1325 is not a non-reactive trimethylsilyl-terminated polydimethylsiloxane. A methyl-terminated fluid of the same 1325 mm²/s viscosity remains unreacted in a silicone network and can migrate to the surface, reducing adhesion and interfering with printing or bonding operations. In contrast, the vinyl termini of RH-Vi1325 become part of the crosslinked network, so the fluid is converted from a mobile liquid to a solid elastomer or gel. This difference is measurable in extraction tests: after Soxhlet extraction with toluene for 8 h, a fully cured addition-cure network based on RH-Vi1325 typically shows an extractable fraction below 5 wt %, while a methyl-terminated fluid of equal viscosity remains completely extractable if not chemically bound. Hydroxy-terminated silicone fluid cures by condensation with alkoxy silanes or acetoxy silanes, releasing water, methanol, ethanol, or acetic acid depending on the curing agent. That byproduct release creates internal pressure in closed molds, causes shrinkage, and extends the time needed for bond-line stability. RH-Vi1325 eliminates this byproduct stream under correct Si-H stoichiometry, making it suitable for sealed electronic housings where volatile byproducts must be minimized.
| Parameter | RH-Vi1325 class | Methyl-terminated fluid | Hydroxy-terminated fluid |
|---|---|---|---|
| Reactive terminal group | Dimethylvinylsiloxy | Trimethylsiloxy | Silanol |
| Cure mechanism | Pt-catalyzed hydrosilylation | None; remains mobile | Condensation with alkoxy or acetoxy silane |
| Byproducts | None under balanced Si-H/Si-Vinyl | None, but can volatilize | Water, methanol, ethanol, or acetic acid |
| Typical application | LSR, gels, encapsulants, coatings | Damping fluid, release agent | Room-temperature sealant |
| Operational boundary | Requires Pt catalyst and Si-H crosslinker | Not crosslinkable | Moisture-dependent thick-section cure |
Addition of untreated hydrophilic fumed silica to RH-Vi1325 can raise compound viscosity beyond the usable range for meter-mix equipment, while the silanol surface of the silica can adsorb platinum catalyst and delay cure. Hexamethyldisilazane-treated silica reduces this interaction and produces a stable thixotropic network. The recommended treatment level is 15–20 wt % of the silica mass, with mixing at 120–140 °C for 1–2 h under −0.09 MPa vacuum to remove ammonia and water. If vacuum is not applied, residual ammonia can neutralize the platinum catalyst and cause a tacky surface. This is a known batch-scale failure: the outer layer remains uncured while the core cures because ammonia concentration is highest near the air interface. The problem is diagnosed by a surface hardness increase of less than 50% relative to the core after a standard cure schedule. Adding 0.05–0.2 phr of magnesium oxide or zinc oxide can buffer residual acidity; however, excessive metal oxides alter dielectric loss tangent above 1 kHz. For electronic encapsulation, the dielectric constant of a cured unfilled RH-Vi1325 network is typically 2.7–3.1 at 1 kHz and volume resistivity exceeds 1015 Ω·cm when measured according to ASTM D257-14. Ionic impurities from filler or catalyst must be controlled below 10 ppm to maintain that resistivity.
In high-voltage cable accessories and conformal gels, the low viscosity of RH-Vi1325 permits vacuum degassing at 1–5 kPa absolute before dispensing. Degassing removes air pockets that would otherwise reduce dielectric strength and promote partial discharge. A cured 2 mm sheet of an unfilled addition-cure network based on 1000–1500 mm²/s vinyl-terminated polydimethylsiloxane is class-typically reported with dielectric strength of 18–22 kV/mm under ASTM D149-20. The low modulus and stress-absorbing behavior are suitable for encapsulating wire bonds without transmitting excessive thermal expansion stress. If the compound is used in a closed mold with no venting path, elimination of condensation byproducts is a measurable advantage because cavity pressure remains below 0.05 MPa throughout cure, whereas acetic acid from acetoxy condensation systems can raise cavity pressure above 0.2 MPa in the same configuration.
Storage stability of RH-Vi1325 in its unopened form is governed by the absence of water and catalytic contaminants. The fluid should be kept in sealed stainless steel or epoxy-phenolic lined drums at 5–30 °C. Exposure to strong oxidizers, peroxides, or hydrogenation catalysts can decompose the siloxane chain; contact with amine-containing additives must be avoided because amines can complex with platinum and extend cure time. In two-part systems, the A component containing platinum and the B component containing Si-H crosslinker should be stored separately under dry nitrogen to prevent premature gelation; if combined at 25 °C, pot life of 4–8 h is typical with an alkyne inhibitor, but this value drops to 30–60 min immediately after passage through high shear because shear heating lowers viscosity and accelerates catalyst diffusion. The product is not classified as a hazardous substance under the standard OSHA Hazard Communication criteria, but residual low-molecular-weight cyclosiloxanes may be present below the stated volatile limit. Compliance with REACH and RoHS 2011/65/EU must be confirmed with the supplier for each batch, especially when the fluid is used in medical or food-contact applications where FDA 21 CFR 177.2600 or ISO 10993 testing may be required. Users should not rely on class-typical data as a substitute for lot-specific certification.
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