One cannot simply rely on the fact that the heat-resistant and flame-retardant solid rubber SH-8660 can achieve the UL94V-0 flame-retardant level or the 250℃×72h heat resistance data to directly conclude that it is suitable for all wire and cable, automotive parts or gasket systems. One must first confirm the molding process, the ratio of double diene and tetrafluoroethylene, the kneading conditions, the vulcanization temperature and time, the thickness of the product, and the usage environment before making such a judgment. Then, one should determine whether the issue is due to the non-compliance of the flame-retardant level, the performance degradation after high-temperature aging, or the poor matching of the rubber compounding and vulcanization process.


Why does heat-resistant and flame-retardant solid silicone rubber often fail to achieve the expected results during molding or long-term high-temperature use?


The addition ratio of the double diene and tetrafluoroethylene vulcanizing agent deviates from the recommended 1.2%, or the compounding is not uniform, resulting in insufficient crosslinking density or over-vulcanization.


The vulcanized rubber that has been in storage for too long causes dead material, making it unable to vulcanize properly or resulting in performance degradation.


When adding the double diene and tetrafluoroethylene vulcanizing agent at the edge of the kneader without kinking the rubber, the compounding is insufficient, affecting the dispersion of the flame retardant and fillers.


When the vulcanization temperature or time is insufficient for 120℃×10min, or the 120℃×1H vulcanization is incomplete, the mechanical properties and flame retardant properties are not fully exerted.


When the thickness of the product is large, the heat transfer during vulcanization is insufficient, the crosslinking density in the interior is low, and the flame retardant level and heat resistance performance decline.


The flame retardant or filler batch variations affect the stability of the UL94V-0 flame-retardant level and mechanical properties.


After 250℃×72h high-temperature aging, the hardness, tensile strength, and elongation at break exceed the acceptable range, and the actual usage temperature has not been verified.


When switching from ordinary silicone rubber or other flame-retardant silicone rubber, the addition amount of double diene and tetrafluoroethylene, the kneading process, and the vulcanization conditions are not adjusted, resulting in performance deviations from the target.


The storage conditions are improper, with environmental temperatures exceeding 30℃ or being damp, causing changes in the plasticity and vulcanization activity of the rubber.


When the product is used in wire and cable or automotive parts, it is exposed to oils, solvents, or undergoes long-term vibration, and the media resistance and dynamic fatigue performance are not evaluated.


Working in an environment with poor ventilation, the decomposition products of double diene and tetrafluoroethylene affect the health of the operators.


First, determine at which stage the flame retardant or vulcanization problem occurs.


Failure stage Possible causes Priority inspection direction
When the rubber at the edge of the kneader sticks or does not disperse properly during kneading Improper timing of double diene and tetrafluoroethylene addition, high or low roller temperature Knitting process, roller temperature, feeding sequence
Insufficient hardness or strength after vulcanization Low addition amount of double diene and tetrafluoroethylene, uneven compounding, insufficient vulcanization Amount of double diene and tetrafluoroethylene addition, compounding time, vulcanization conditions
Brittle or over-vulcanized after vulcanization High addition amount of double diene and tetrafluoroethylene, high vulcanization temperature or long vulcanization time Amount of double diene and tetrafluoroethylene addition, vulcanization temperature, time
Flame retardant level not reaching UL94V-0 Flame retardant dispersion is poor, product thickness affects, batch variation of the rubber Flame retardant dispersion, product thickness, incoming inspection
Fast performance degradation after high-temperature aging Unstable crosslinking network, insufficient heat resistance of the flame retardant or filler 250℃ aging verification, formula optimization
Dead material or rubber cannot be reprocessed Too long storage time after adding vulcanizing agent, high storage temperature Storage time of vulcanized rubber, storage conditions
There are air holes or defects inside the product Insufficient exhaust, improper mold design, moisture in the rubber Exhaust procedure, mold structure, rubber drying
Batch-to-batch fluctuations in flame retardant or mechanical properties Flame retardant or filler batch variations, uneven compounding Incoming inspection, compounding process, vulcanization record
If only focusing on "whether the product SH-8660 has been used", but without recording the addition amount of double diene and tetrafluoroethylene, the kneading process, vulcanization conditions, and product thickness, it is usually difficult to accurately determine whether it is a material problem or a process problem.


What are the public parameters of the product SH-8660?


Item Product SH-8660
Appearance (unvulcanized) White
Malleability 320
Double 24 increase amount 1.20%
Vulcanization conditions 120℃ for 10 minutes of vulcanization, 120℃ for 1 hour of baking
Density (25℃, g/cm³) 1.22
Hardness (Shore A) 63
Tensile strength (MPa) 10.2
Elongation (%) 370
Tear strength (kN/m) 36
Heat resistance (250℃/72 hours) Hardness change +2, tensile strength change -13%, elongation change -27%
Flame retardant grade UL94V-0
The above data are typical product performance and are not the factory standards. Formal procurement and batch acceptance should be based on the valid TDS, specification sheet and delivery batch COA confirmed by both parties.


Which application directions is product SH-8660 suitable for?


Application direction Candidate direction Still need verification
Wire and cable Heat-resistant flame-retardant insulation or sheath Flame retardant grade, electrical performance, bending resistance, long-term aging
Automotive parts Heat-resistant flame-retardant seals, gaskets, sheaths Resistant to oil, vibration, temperature cycling, flame retardant grade
Gaskets and seals Heat-resistant flame-retardant static sealing Compression permanent deformation, resilience, medium compatibility
Electrical insulation components Flame-retardant structural components Volume resistivity, dielectric strength, flame retardant grade
Industrial heat-resistant components 250℃ level heat-resistant flame-retardant products Mechanical properties after high-temperature aging retention rate
What are the key differences in product selection between SH-8660 and similar flame-retardant silicone rubber?


Comparison direction Product SH-8660 (heat-resistant flame-retardant solid adhesive) Ordinary silicone rubber Ordinary flame-retardant silicone rubber Fluorine rubber Selection boundary
Flame retardant grade UL94V-0 No Usually V-1 or V-0 General Need to verify according to UL94 standard
Heat resistance After 72 hours of 250℃ aging, performance is relatively good 200℃ level 200℃ level 200℃ level Need to select based on the highest usage temperature
Mechanical properties Hardness 63A, tensile 10.2MPa, elongation 370%, tear 36kN/m Medium Medium Higher Need to select based on sealing or insulation requirements
Molding method 224 peroxide vulcanization, open mill, compression molding Peroxide or addition type Peroxide Peroxide or addition type Need to select based on molding process
Flame retardant system Need to verify the stability of UL94V-0 No Contains flame retardant General Need to select based on flame retardant grade
Oil resistance General Poor General Excellent Select fluorine rubber when in contact with oil-based media
Cost Medium Low Medium High Need to evaluate performance and cost comprehensively
Why is it necessary to conduct complete tests when compatibility with rubber and vulcanization system is still needed?


Aydota's public information states that product SH-8660 is used in wire and cable, automotive parts and gaskets, with excellent heat resistance, mechanical properties and UL94V-0 flame retardant grade. However, when used in actual systems, there may still be:


Batch differences and dispersion uniformity of 224 vulcanizing agent.


Differences in roller temperature, roller distance and mixing time of the open mill.


The influence of storage time and storage temperature on the dead material of the rubber compound.


The matching of one-stage vulcanization and baking conditions with the thickness of the product.


The influence of flame retardant and filler batch differences on the stability of UL94V-0.


The influence of mold design and exhaust procedure on the internal quality of the product.


The influence of contact media and long-term high-temperature aging conditions.


The influence of product thickness on the flame retardant grade and vulcanization degree.


Storage conditions and rubber compound validity period.


Ventilation environment and operator protection.


Which parameters should be confirmed when using product SH-8660?


Parameter category Information to be confirmed
Application direction 电线 cables, automotive parts, gaskets, electrical insulation components
Molding process Open rolling, molding, extrusion or injection
Dosage of Dibutyltin Dioxide (DBTDO) 1.2% recommended value， adjusted according to the product
Open rolling conditions Roll temperature， roll distance， mixing time， feeding sequence
One-stage vulcanization 120℃×10min， adjusted according to the thickness
Baking conditions 120℃×1H， adjusted according to the product requirements
Product thickness Influences the degree of vulcanization and flame retardancy
Operating temperature Long-term temperature, peak temperature, 250℃ aging requirement
Contact medium Oils, solvents, water vapor, acids and alkalis
Storage conditions Cool, dry, ventilated, environmental temperature less than 30℃， shelf life 6 months
Acceptance criteria Hardness, tensile strength, elongation, tear strength， UL94V-0， performance retention rate after 250℃ aging
What should be verified for the product SH-8660?


The plasticity and uniformity of the rubber after open rolling.


The uniformity of DBTDO dispersion and the storage time of the vulcanized rubber.


The hardness， tensile strength， elongation and tear strength after one-stage vulcanization and baking.


The flame retardancy level of UL94V-0， tested according to the thickness of the product.


The changes in hardness， tensile strength and elongation after 250℃×72h aging.


Whether there are air holes， defects and dead materials in the product.


Electrical insulation performance (if applicable).


The volume change and mechanical property retention rate after contact with media.


The consistency of flame retardancy and mechanical properties between batches.


The plasticity and vulcanization activity after storage.


The effectiveness of the ventilation environment and operator protection.


How to design tests before using the product SH-8660?


Establish a benchmark of the current flame-retardant silicone rubber， record the model， batch， DBTDO dosage， open rolling and vulcanization conditions， and failure performance.


Uniform test conditions： open rolling roll temperature， roll distance， mixing time， DBTDO dosage， one-stage vulcanization， baking conditions， product thickness.


Set candidate samples： current rubber， product SH-8660， different DBTDO dosages or vulcanization conditions gradients.


Complete the full process tests： open rolling → vulcanization → molding → one-stage vulcanization → baking → performance test → flame retardancy test → aging test.


Evaluate the actual results： hardness， strength， elongation， tear strength， UL94V-0， performance retention rate after 250℃ aging.


Test items Uniform requirements
Open rolling conditions Keep consistent or set gradients according to the test design
DBTDO dosage Set gradients according to the test design
One-stage vulcanization conditions Set gradients according to the test design
Baking conditions Set gradients according to the test design
Product thickness Set according to the actual product
Measurement methods Hardness， strength， elongation， tear strength， UL94V-0， consistency of aging performance
Under what circumstances should product SH-8660 not be directly used?


DBTDO dosage or open rolling process not confirmed， resulting in insufficient vulcanization or dead materials.


Long storage time of vulcanized rubber or storage temperature exceeding 30℃， causing dead materials.


Large product thickness， one-stage vulcanization or baking conditions not adjusted according to the thickness.


Specific food contact， medical or airworthiness approval required， but corresponding materials have not been obtained.


There is a clear thickness requirement for UL94V-0， but not tested according to the actual thickness.


Only have the product name， but no open rolling， vulcanization and product thickness data.


The customer requests to directly mix into the in-use system， but cannot control the DBTDO dosage and mixing conditions.


When switching from ordinary silicone rubber or other flame-retardant silicone rubber， the DBTDO dosage and vulcanization process have not been re-adjusted.


Storage conditions do not meet the requirements of cool， dry， ventilated， and environmental temperature less than 30℃， the rubber may deteriorate.


Contact with oils， solvents or strong chemical media， without evaluating the media resistance performance.


Working in an environment with poor ventilation can affect the health of operators due to the decomposition products of bis(2-ethylhexyl) terephthalate.


There are strict requirements for the long-term aging performance at 250℃, but no aging verification of more than 72 hours has been conducted.


What kind of selection support can Aijota provide?


As a solution provider for the entire organic silicon industry chain, Aijota can assist in comparing the applicability of heat-resistant and flame-retardant solid silicone rubber in different molding processes, curing conditions and application scenarios for product SH-8660.


For projects that need to balance UL94V-0 flame retardancy, 250℃ heat resistance and mechanical properties, the following information should be provided before selection:


Application direction and product structure.


Molding process and open-molding conditions.


Dosage of bis(2-ethylhexyl) terephthalate and storage time of the vulcanized rubber.


One-stage curing and baking conditions.


Product thickness and flame retardant grade requirements.


Operating temperature, contact medium and aging requirements.


Current rubber compound model, dosage of bis(2-ethylhexyl) terephthalate and failure performance.


Acceptance method and applicable standards.


After receiving complete materials, it can be determined whether to prioritize testing product SH-8660 or choose other flame-retardant silicone rubber or fluorine rubber routes.


Common Misconceptions


The UL94V-0 flame retardant level can cover all thicknesses and structures.
The UL94V-0 needs to be tested according to specific thickness. The thickness, structure and dispersion of the flame retardant affect the flame retardant grade. It cannot be judged solely based on the product description.
The more double diisocyanate is used, the more fully the curing process is.
Excessive double diisocyanate may lead to over-curing, brittle products or bubble formation. It is recommended to use 1.2% as the recommended value and optimize through small-scale tests.
The cured rubber can be stored for a long time.
The rubber with added curing agent should be used within the applicable period. The storage temperature should be less than 30℃.
After one-stage curing, the final performance can be achieved.
The 120℃×1H baking is crucial for performance improvement and volatile substance removal. It should be carried out according to the recommended conditions.
The addition of curing agent can be directly added to the application system if compatible with the rubber.
It is still necessary to confirm the mixing process, the amount of double diisocyanate, the curing conditions and the long-term aging stability.
The performance at 25℃ is the same, and it can be replaced in equal amounts.
Different flame retardant systems, heat resistance and curing characteristics of different flame retardant silicone rubbers are different. Revalidation is required when replacing.
Product SH-8660 can be used for all heat-resistant and flame-retardant seals.
This product is suitable for 250℃ grade heat-resistant and flame-retardant products. For systems with higher temperatures or stronger chemical media requirements, fluororubber or other elastomers may be needed.
Storage for 6 months still allows normal use.
The shelf life is 6 months. After expiration, retesting of plasticity, curing activity and flame retardant performance is required.
Ventilation environment is not important.
The decomposition products of double diisocyanate may affect the health of operators. Work should be carried out in a ventilated environment and personal protective equipment should be worn.
Recommendation for selection steps


Confirm the application direction: electrical wires and cables, automotive parts, gaskets or electrical insulation components.


Confirm the molding process and mixing conditions.


Confirm the amount of double diisocyanate and the storage time of the cured rubber.


Confirm the one-stage curing and baking conditions.


Confirm the thickness of the product and the requirements for UL94V-0 flame retardant grade.


Confirm the operating temperature, contact medium and 250℃ aging requirements.


Choose Product SH-8660 or other flame-retardant silicone rubbers based on the application scenario.


Set up different double diisocyanate amounts and curing conditions for small-scale tests.


Test hardness, strength, elongation, tear strength and UL94V-0.


Perform 250℃×72h aging, medium immersion and electrical performance verification.


Evaluate the internal quality and batch consistency of the products.


Confirm that the storage conditions and ventilation protection are in place.


After multiple batch verifications, determine the final usage plan.