| HS Code | 363372 |
| Productname | Vinyl Terminated Silicone Oil RH-Vi320 |
| Chemicaltype | Vinyl-terminated polydimethylsiloxane |
| Appearance | Colorless transparent liquid |
| Viscosityat25c | 300–500 mPa·s |
| Vinylcontent | 0.45–0.55 wt% |
| Specificgravityat25c | 0.97–0.98 |
| Refractiveindexat25c | 1.403–1.405 |
| Flashpoint | ≥100 °C |
| Volatilecontent | ≤1.0% at 150 °C for 3 h |
| Color | ≤30 Hazen |
| Odor | Slight characteristic odor |
| Storagetemperature | 5–30 °C |
| Shelflife | 12 months |
As an accredited Vinyl Terminated Silicone Oil RH-Vi320 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RH-Vi320 Vinyl Terminated Silicone Oil is packaged in 25 kg sealed plastic drums and 200 kg steel drums. |
| Container Loading (20′ FCL) | Vinyl Terminated Silicone Oil RH-Vi320 loaded in a 20-foot FCL container, securely packed, labeled, and sealed for shipment. |
| Shipping | Vinyl Terminated Silicone Oil RH-Vi320 is shipped in sealed steel drums or IBCs under dry, ambient conditions, protected from moisture, heat, and contamination. It is generally non-hazardous for transport unless otherwise specified; handle according to the SDS. Keep containers closed, upright, labeled, and ensure proper ventilation while avoiding spillage. |
| Storage | Store Vinyl Terminated Silicone Oil RH-Vi320 in a cool, dry, well-ventilated area away from heat, sparks, flames, and strong oxidizers. Keep containers tightly closed to prevent contamination and moisture ingress. Protect from direct sunlight, freezing, acids, and alkalis. Maintain labeled containers with secondary containment, inspect regularly for leaks or damage, and follow local regulations and the manufacturer’s SDS. |
| Shelf Life | Vinyl Terminated Silicone Oil RH-Vi320 typically has a 12-month shelf life in its original sealed container, stored cool, dry, and protected from light. |
In two-component platinum-catalyzed liquid silicone rubber, RH-Vi320 is charged into the vinyl-functional Part A stream and, where a split vinyl/hydride architecture is used, into the hydride-rich Part B stream. The material functions as a reactive diluent and terminal crosslink-site carrier; the vinyl groups participate directly in hydrosilylation with poly(methylhydrogensiloxane). Molding is performed on a 1:1 piston-metering injection unit equipped with a static mixer and cold runner, with mass temperature controlled at 25 °C to 40 °C before entering a barrel held at 60 °C to 90 °C. Cure time at 170 °C for a 2 mm section is typically 15 s to 30 s, but the actual value depends on the hydride-to-vinyl ratio. The SiH:SiVi ratio is maintained between 1.2:1 and 2.0:1 in production-scale formulations; ratios below 1.1:1 produce surface tack and elevated compression set, while ratios above 2.2:1 risk post-cure surface crosslink density drift and hydrogen evolution. A vinyl-specific inhibitor such as 1-ethynyl-1-cyclohexanol is introduced at 0.05 wt% to 0.15 wt% of total compound to extend pot life and widen the processing window. The terminal product is a transparent or translucent elastomeric seal, gasket, or valve component. Compliance for food-contact seals is evaluated under FDA 21 CFR 177.2600, and medical-grade components are assessed according to ISO 10993-5:2009 and ISO 10993-10:2010 after post-cure at 200 °C for 4 h. Batch-to-batch variation in vinyl concentration can shift moving-die rheometer t90 values by several seconds; therefore in-line cure validation at 170 °C is advised for each incoming lot when molding multi-cavity closures on clamp-force equipment above 800 kN. Venting is set deeper than 0.02 mm to avoid trapped volatile methyl siloxane fractions. Contamination with amine-containing mold release agents, sulfur-crosslinked rubber residues, or tin-catalyzed silicone traces is not permitted because these species are known platinum inhibitors that cause localized undercure and extractable fractions in the cured part.
High-consistency rubber compounds formulated with RH-Vi320 are processed on two-roll mills at nip temperatures of 30 °C to 50 °C before being fed to a cold-feed extruder with L/D 14:1 to 20:1. The silicone oil reduces compound Mooney viscosity, measured according to ISO 289-1:2018, by approximately 2 to 8 Mooney units per 5 phr addition. It is used in wire and cable insulation jackets, oven door seals, and industrial tubing. Addition levels from 3 phr to 8 phr are common in filled compounds; above 10 phr, uncured surface exudation increases and vulcanizate tensile strength can fall below 8 MPa when tested per ASTM D412-16. Scorch safety is controlled with 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane at 0.8 phr to 1.5 phr, with vinyl groups from RH-Vi320 increasing peroxide cure efficiency through additional crosslink sites. The compound exits the die at 70 °C to 100 °C and enters a hot-air vulcanization line at 300 °C to 450 °C, where line speeds of 20 m/min to 50 m/min are used. A production-scale failure mode is premature crosslinking in the extruder head when fillers such as zirconium phosphate or aluminum hydroxide contain adsorbed moisture; pre-drying of the combined compound is required if moisture content exceeds 0.2 %. Compliance for wire insulation is validated under UL 758 AWM style requirements, automotive cable thermal aging under ISO 6722-1:2023, and flame resistance where specified under UL 94 V-0. The terminal product is a matte or semi-gloss cured jacket retaining at least 50 % of original elongation after 2,000 h air aging at 180 °C, as evaluated by ASTM D2625. The use of RH-Vi320 in peroxide-cured systems is not recommended with amine-functionalized stabilizers, which react preferentially with acidic silica surfaces and can deactivate the peroxide decomposition sequence.
Solventless release coating formulations for polyester and glassine liners incorporate RH-Vi320 as a low-viscosity chain extender; the blend is coated at 35 °C to 45 °C on a five-roll solventless coater with a chrome-plated backing roll and a ceramic anilox metering roll. The target coat weight is 0.8 g/m² to 1.5 g/m², yielding a dry film below 1.2 µm. Cure is initiated by a platinum-divinyltetramethyldisiloxane complex at 60 ppm to 120 ppm platinum based on total compound, with SiH:SiVi ratio held at 1.5:1 to 2.5:1. Oven residence time at 150 °C is 3 s to 6 s. Incomplete conversion is measured by solvent extraction per ASTM D4218; cured film extractables must remain below 0.5 mg/m² for indirect food contact under FDA 21 CFR 176.170 and 176.180, with overall migration testing according to EU Regulation 10/2011 where applicable. The terminal product is a release liner for pressure-sensitive labels, medical dressings, and optical film protection. Failure modes observed on production coaters include misting at line speeds above 300 m/min when the formulation viscosity exceeds 150 mPa·s at coat head temperature; RH-Vi320 is therefore blended with higher-vinyl gum polymers to maintain an apparent viscosity of 80 mPa·s to 120 mPa·s. Addition of amine-functional defoamers is not permitted because trace amines deactivate the platinum catalyst and increase web-side cure inhibition. Light release, easy release, and tight release profiles are obtained by adjusting the vinyl-to-hydride ratio and adding controlled release additive resin at 5 wt% to 20 wt% of the coating compound. Published peel data for this specific RH-Vi320 configuration is limited; release force should be measured per FINAT FTM 3 on the target adhesive laminate before full-width coating.
For IGBT power modules and transformer housings, two-part addition-cure encapsulants based on RH-Vi320 are dispensed into preheated carriers after the base polymer is compounded with 40 wt% to 60 wt% spherical alumina to raise thermal conductivity to 0.8 W/m·K to 1.2 W/m·K. The compound is vacuum-degassed at −0.095 MPa for 10 min to 20 min to remove entrained air; degassing ceases when residual bubble rise is no longer visible in the feed vessel. Metering is performed with a progressive cavity dispenser having a volumetric ratio tolerance of ±1 %. The mixed viscosity at 25 °C is commonly 2,000 mPa·s to 8,000 mPa·s, and the usable pot life is 30 min to 90 min. Cure begins at 70 °C for 30 min and is completed with a post-cure at 120 °C for 1 h to 2 h. The terminal product is a resilient, low-modulus encapsulant with Shore hardness 40 A to 60 A measured per ASTM D2240-15. The principal operational limit is platinum poisoning from solder flux residues; no-clean flux containing rosin and amine activators can produce localized undercure at the PCB interface. Compatibility is therefore verified by differential scanning calorimetry cure exotherm comparison per ISO 11357-1:2023 and ISO 11357-5:2023, with acceptable conversion above 95 % of total reaction enthalpy.
| Application Zone | Standard/Regulation | Test Condition | Measured Parameter |
|---|---|---|---|
| Printed circuit board adhesion | IPC-CC-830B | 85 °C/85 % RH, 500 h | No delamination or corrosion |
| Flame retardance | UL 94 | 3.0 mm specimen | V-0 rating with alumina trihydrate |
| Thermal shock | IEC 60068-2-14 | −40 °C to +150 °C, 500 cycles | Hardness change ≤ 10 Shore A |
| Comparative tracking index | IEC 60112:2020 | 4.0 mm thickness | CTI ≥ 600 V |
On production lines, the primary defect observed is void formation at filler loadings above 60 wt% when the static mixer pressure drop exceeds 0.7 MPa; this is mitigated by reducing filler to 50 wt% or increasing dispense needle diameter to 0.8 mm. Pre-drying of alumina at 120 °C for 4 h is required if ambient RH exceeds 60 %, because surface moisture consumes Si-H groups and alters the effective stoichiometric ratio. Adhesion to aluminum, anodized steel, and PBT substrates is tested after cure by lap shear per ASTM D1002-10; values below 0.5 MPa are considered insufficient for power-cycle stability.
During hydrogen-evolving platinum-cured silicone foam expansion, RH-Vi320 serves as the primary vinyl-functional base fluid for battery gap fillers and flame-retardant gaskets. The blowing reaction competes with the crosslinking reaction; therefore the SiH:SiVi ratio is intentionally raised to 2.5:1 to 4.0:1, and deionized water is added at 0.3 wt% to 1.0 wt% to generate hydrogen gas via Si-H hydrolysis. The foam is cast or bead-dispensed through a two-component static mixer and expanded at 70 °C to 100 °C. Density is controlled between 0.20 g/cm³ and 0.60 g/cm³ by changing water content and platinum level; lower density reduces compression set stability, while density above 0.60 g/cm³ eliminates the cellular collapse resistance required for dynamic gap variation. In production equipment with short dwell times below 40 s, premature viscosity rise is prevented by introducing platinum catalyst in the water-containing component only after static mixing. The terminal product is a closed-cell or mixed-cell foam gasket with compression deflection measured per ASTM D1056-20 and compression set tested after 22 h at 100 °C per ISO 815-1:2019. Flame retardance where required is obtained by adding 20 wt% to 30 wt% aluminum hydroxide, but this filler reduces cell wall mobility and raises expanded density; evaluation under UL 94 HBF is performed on 3.0 mm sheets. Avoid incorporating zinc oxide or ferric oxide pigments in water-containing foam compounds; these metal oxides accelerate hydride hydrolysis and can produce uncontrolled foaming before application.
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Vinyl Terminated Silicone Oil RH-Vi320 is a linear polydimethylsiloxane fluid whose terminal silicon atoms are substituted with reactive vinyl groups. The molecular structure is represented as CH2=CH–Si(CH3)2–O–[Si(CH3)2–O]n–Si(CH3)2–CH=CH2, and the fluid is registered under CAS 68083-19-2. Unlike trimethylsilyl-terminated polydimethylsiloxanes, which are non-functional and remain extractable in cured networks, RH-Vi320 provides a difunctional telechelic structure for addition-cure chemistry. The nominal kinematic viscosity is 320 mm²/s at 25 °C when measured according to ISO 3104. Typical terminal vinyl content is between 0.10 mmol/g and 0.16 mmol/g by proton nuclear magnetic resonance end-group analysis, corresponding to a number-average molecular weight range of approximately 12 500 g/mol to 20 000 g/mol for a perfect difunctional architecture. The product is a clear, colorless liquid with negligible silanol content and no hydride functionality, which means it does not cure by condensation or act as a hydride donor. In platinum-catalyzed hydrosilylation, RH-Vi320 reacts with methylhydrosiloxane-dimethylsiloxane crosslinkers to form a three-dimensional elastomer without water or alcohol byproducts. Its main industrial uses include solventless liquid silicone rubber, high-consistency rubber modification, optical and electronic encapsulants, and release coatings where a low-viscosity vinyl base polymer is required.
Placement of the vinyl group controls network topology during hydrosilylation. In RH-Vi320, the vinyl groups are located exclusively at the chain termini, yielding a bifunctional telechelic polymer. When it reacts with a multifunctional Si–H crosslinker, the terminal olefin groups participate in step-growth chain extension and crosslinking simultaneously; because each polymer molecule contains only two reactive sites, a given Si–H concentration produces a lower crosslink density than a pendant vinyl silicone oil of the same viscosity. A vinylmethyl silicone copolymer, by contrast, contains multiple pendant vinyl groups along the backbone and functions as a higher-functionality network former, which reduces solvent swell and extensibility. This difference can be quantified by tensile testing according to ISO 37 and by equilibrium solvent swell after extraction in toluene at 25 °C for 72 h. In cured elastomers, a terminal vinyl base fluid typically shifts the failure mode toward higher elongation at break and lower tensile modulus at identical hydride stoichiometry, while a pendant vinyl fluid increases the elastic modulus and reduces elongation. The difunctional architecture also reduces the concentration of unreacted internal vinyl groups that can undergo post-cure oxidative embrittlement. However, the same low functionality requires tight control of SiH:vinyl ratio; an excess of hydride can leave residual Si–H groups that react slowly with moisture or air, affecting long-term durometer stability. This architecture is therefore selected when linear chain extension, low shrinkage, low outgassing, and low compression set are more important than maximum crosslink density or rapid modulus buildup.
The table below lists nominal lot release limits for RH-Vi320. These values are not maximum or minimum absolute guarantees; they represent typical release criteria used for compounding calculations. The SiH:vinyl ratio must be corrected for the actual vinyl content of each batch because a change from 0.10 mmol/g to 0.16 mmol/g alters crosslinker demand by 60 % for a fixed mass of base polymer.
| Property | Nominal value/range | Test method |
|---|---|---|
| Appearance | Clear, colorless liquid | Visual inspection under cool white light |
| Kinematic viscosity at 25 °C | 320 mm²/s ± 10 % | ISO 3104 |
| Vinyl content | 0.10–0.16 mmol/g | 1H NMR end-group analysis, 400 MHz |
| Density at 25 °C | 0.965–0.975 g/cm³ | ISO 2811-1 |
| Refractive index nD25 | 1.403–1.405 | ISO 280 |
| Volatile matter | ≤ 0.5 % | ISO 3251 |
| Water content | ≤ 200 mg/kg | ASTM E203 |
Control of volatile matter and water content is necessary when RH-Vi320 is used in optically clear encapsulants or in high-consistency rubber lines with long residence time. Water above 200 mg/kg can reduce platinum catalyst activity and shorten pot life, particularly in closed-loop meter-mix equipment. The refractive index of 1.403–1.405 is consistent with a dimethyl silicone fluid of this viscosity and can be used as a rapid incoming inspection tool alongside ISO 3104 viscosity.
Formulation of two-part platinum-catalyzed liquid silicone rubber with RH-Vi320 is performed by preparing a vinyl-containing Part A and an Si–H-containing Part B. Part A typically contains RH-Vi320, fumed silica, filler treatment agent, and platinum catalyst; Part B contains the same vinyl base polymer, hydride crosslinker, and an inhibitor. Metering through a static mixer with 12 to 24 elements at 25 °C is possible because the 320 mm²/s viscosity remains pumpable without solvent dilution. The recommended SiH:vinyl molar ratio is from 1.2:1 to 2.0:1; higher ratios increase initial cure rate and Shore hardness but can leave unreacted hydride that releases hydrogen on aging. Platinum catalyst concentrations of 5 ppm to 10 ppm by mass are typical for injection molding. Cure kinetics are measured on a moving die rheometer according to ISO 6502-2 at 120 °C to 180 °C; ts2 and tc90 are used to set injection mold cycle time. The material does not generate condensation byproducts, so linear shrinkage is lower than that of condensation-cure systems; density before and after cure can be compared per ISO 1183. In high-consistency rubber compounding, RH-Vi320 is used as a wetting fluid for fumed silica on a two-roll mill with a friction ratio of 1.2:1, or in a twin-screw extruder with L/D ratio 40:1 and barrel temperatures from 80 °C to 140 °C before catalyst addition. Silica incorporation under vacuum at 10–20 kPa removes entrained air and moisture; failure to apply vacuum often produces visible bubbles and inconsistent durometer in molded parts.
Filler dispersion in RH-Vi320 is a threshold step because the low viscosity of 320 mm²/s does not generate the same shear heat as a gum polymer. Fumed silica with BET surface area between 150 m²/g and 300 m²/g is incorporated in a planetary mixer or twin-screw extruder; untreated silica raises storage modulus and yield stress, but can produce network formation that interferes with catalyst dispersion. Hexamethyldisilazane is often added as an in-situ filler treatment agent; the reaction releases ammonia, which must be removed under vacuum before the platinum catalyst is introduced because ammonia is a cure inhibitor. Dispersion quality is judged by grindometer fineness of grind below 20 µm and by differential scanning calorimetry of the uncured compound to verify that no low-temperature crystallization from segregated soft segments occurs. The molding temperature window of an inhibited compound is often narrow; increasing the mold temperature by 5 °C can reduce tc90 by 40 % to 60 % depending on the inhibitor package, leading to premature gelation in the runner. Hot-runner systems are generally avoided for addition-cure LSR based on low-viscosity vinyl fluids because the residence time at 150 °C can exceed the gel time. This sensitivity is evaluated by moving die rheometer per ISO 6502-2 before production start-up.
Seals and gaskets formulated with RH-Vi320 are typically evaluated by compression set testing per ISO 815-1 after 22 h at 175 °C. The terminal vinyl architecture, combined with a hydride crosslinker and treated fumed silica, can produce networks with a low fraction of unreacted free chain ends; this reduces permanent set when the part is held under compression at elevated underhood temperatures. Achieving compression set below 20 % usually requires SiH:vinyl ratios of 1.4:1 to 1.8:1, complete silane treatment of the silica surface, and no residual tin or amine contamination. Solvent extraction of cured specimens per ISO 6427 measures the soluble fraction, which correlates inversely with network completeness. Tear strength, measured by ASTM D624 die B, is sensitive to the regularity of chain spacing produced by the terminal vinyl difunctional architecture. A narrow molar mass distribution supports more uniform crosslink spacing than a broad distribution of the same average viscosity; however, the relatively low molar mass of a 320 mm²/s base fluid limits the tensile strength available at low filler loading. High-durometer seal compounds often blend RH-Vi320 with a higher-viscosity vinyl-terminated gum to increase tear resistance while preserving the processability of the low-viscosity fluid. Injection molding of precision seals using this base fluid is conducted with mold cavity pressure sufficient to prevent flash; process capability studies using ISO 9001 statistical controls are applied to compression set data because batch-to-batch vinyl content drift can shift cure state and scrap rate.
Direct replacement of a condensation-cure hydroxyl-terminated polydimethylsiloxane with RH-Vi320 is not a simple drop-in. Hydroxyl-terminated fluids cure through tin- or titanium-catalyzed condensation, releasing water or alcohol and requiring moisture control in the workplace. RH-Vi320 does not cure by condensation; it requires platinum-catalyzed hydrosilylation, which is inhibited by organic sulfur compounds, amines, organotin residues, and certain unsaturated plasticizers. Therefore, shared mixing equipment previously used for tin-catalyzed RTV must be cleaned to avoid catalyst poisoning. Compared with hydrogen-terminated silicone oil, RH-Vi320 provides the vinyl component rather than the hydride donor; the two products are not interchangeable because their functional groups sit on opposite sides of the hydrosilylation equation. Compared with vinylmethyl silicone copolymers, RH-Vi320 has terminal vinyl groups rather than pendant vinyl groups, so it produces chain extension rather than dense crosslinking. The following table summarizes selection differences for common silicone fluids.
| Silicone fluid type | Reactive group position | Typical cure mechanism | Principal byproduct | Network role |
|---|---|---|---|---|
| Vinyl-terminated silicone oil RH-Vi320 | Terminal | Platinum-catalyzed hydrosilylation | None | Difunctional chain extender/base polymer |
| Vinylmethyl silicone copolymer | Pendant and terminal | Platinum-catalyzed hydrosilylation | None | Multifunctional crosslinker or high-crosslink base |
| Hydrogen-terminated silicone oil | Terminal hydride | Platinum-catalyzed hydrosilylation or dehydrogenative coupling | Hydrogen | Chain extender or reducing component |
| Hydroxyl-terminated polydimethylsiloxane | Terminal silanol | Condensation | Water/alcohol | Condensation base polymer |
| Trimethylsilyl-terminated polydimethylsiloxane | Non-reactive | None | None | Processing plasticizer or lubricant |
Machine cleaning and material handling constraints are therefore more important than simple viscosity matching. If a condensation-cure line is converted to RH-Vi320, residues of amine-based mold release agents or sulfur-containing rubber accelerators can poison platinum even below 100 ppm. Published data for this specific conversion configuration is limited; trial batches should be rejected or released based on moving die rheometer cure curves per ISO 6502-2 and ISO 815-1 compression set after validation.
Unopened containers of RH-Vi320 are stable for 12 months from the date of manufacture when stored between 5 °C and 30 °C in dry, unopened containers. Because terminal vinyl groups can undergo slow atmospheric oxidation, partially used containers should be blanketed with dry nitrogen and sealed. Exposure to relative humidity above 60 % does not dissolve water into the bulk polymer to a large extent, but surface condensation can form and contaminate the fluid when containers are opened in uncontrolled rooms. For high-reliability electronic encapsulants, vacuum drying at 100 °C to 120 °C under 10–20 kPa is recommended before catalyst addition. The fluid is non-corrosive and non-flammable under normal handling, but thermal processing above 150 °C can release trace cyclosiloxane volatiles; local ventilation is therefore required in injection molding and compounding areas. Regulatory inventory compliance should be confirmed for CAS 68083-19-2 under REACH, TSCA, and applicable national chemical inventories. The product should not be blended with amine-based organic additives or sulfur-containing compounds, because these inhibit platinum-catalyzed cure and cause tacky, undercured surfaces.
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