Base Polymer (Part A): Shore Hardness Range 10-80 A

Component Specifications

Definition

Base Polymer (Part A) serves as the foundational reactive component in two-part Liquid Silicone Rubber (LSR) formulations. It consists of vinyl-terminated or vinyl-functional polydimethylsiloxane (PDMS) polymers with a platinum-based catalyst (typically a Karstedt's or Speier's catalyst). This component initiates the hydrosilylation reaction when mixed with Part B (cross-linker containing Si-H groups), leading to cross-linking and curing into solid elastomeric silicone rubber. It is engineered for high purity, low viscosity, and controlled reactivity to ensure consistent processing in injection molding, extrusion, or coating applications.

Working Principle

The working principle involves hydrosilylation, where the platinum catalyst in Part A activates the reaction between vinyl groups (C=C) on the PDMS backbone and Si-H groups from Part B. This results in covalent cross-linking, forming a three-dimensional network that cures into a durable, heat-resistant, and flexible silicone rubber without by-products.

Materials

Vinyl-functional polydimethylsiloxane (PDMS), platinum catalyst (e.g., platinum-divinyltetramethyldisiloxane complex), inhibitors (e.g., acetylene alcohols), fillers (optional, such as silica for reinforcement), and pigments or additives for specific properties.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Pot Life	4-8 hours at 25°C
Viscosity	500-5000 mPa·s at 25°C
Vinyl Content	0.1-1.0 mol%
Cure Temperature	100-200°C
Platinum Content	5-50 ppm
Specific Gravity	1.10-1.20 g/cm³
Storage Temperature	-20 to 25°C
Shore Hardness Range	10-80 A

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 10993, ISO 1629, ASTM D1418, DIN 53504, FDA 21 CFR 177.2600

Parent Products

This component is used in the following industrial products

Liquid Silicone Rubber

A two-part, platinum-catalyzed silicone elastomer that cures at elevated temperatures to form durable, flexible rubber parts.

View Product Details

Engineering Analysis

Risks & Mitigation

Catalyst poisoning from sulfur, tin, or amine contaminants
Premature curing due to heat exposure
Inconsistent viscosity affecting mixing ratios
Shelf life degradation leading to reduced reactivity

FMEA Triads

Trigger: Contamination with catalyst poisons (e.g., sulfur compounds)
Failure: Incomplete or delayed curing, resulting in weak or tacky rubber
Mitigation: Implement strict material handling protocols, use dedicated equipment, and conduct pre-use contamination tests.

Trigger: Inaccurate mixing ratio with Part B
Failure: Poor mechanical properties, such as low tear strength or excessive shrinkage
Mitigation: Use precision metering and mixing systems, regularly calibrate equipment, and verify ratios with quality checks.

Trigger: Exposure to high temperatures during storage
Failure: Reduced pot life and premature gelation, causing processing issues
Mitigation: Monitor storage conditions, use temperature-controlled environments, and adhere to shelf-life guidelines.

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Mixing ratio tolerance of ±1% by weight, viscosity variation within ±10% of specified range

Test Method

ISO 11357 for thermal analysis, ASTM D412 for tensile properties, ISO 10993 for biocompatibility, and in-house rheometry for viscosity and cure kinetics

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Base Polymer (Part A)

Manufacturer profiles associated with Base Polymer (Part A).

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Mold Release Coating

Specialized coating applied to molds to facilitate easy release of silicone seal rings during manufacturing.

Silicone Polymer Base

Silicone polymer base is a high-temperature resistant polymer material used as the foundational component in silicone rubber compounds for industrial applications.

Frequently Asked Questions

What is the role of Base Polymer (Part A) in LSR systems?

Base Polymer (Part A) provides the vinyl-functionalized silicone polymer and platinum catalyst necessary to initiate the cross-linking reaction with Part B, forming cured silicone rubber with desired mechanical and thermal properties.

How should Base Polymer (Part A) be stored to maintain stability?

Store in a cool, dry place at -20 to 25°C, away from moisture, heat, and contaminants. Use sealed containers to prevent catalyst deactivation and extend shelf life, typically 6-12 months.

Can Base Polymer (Part A) be used with different Part B formulations?

No, it is formulated for specific Part B counterparts to ensure optimal reactivity and final properties. Incompatible mixing can lead to incomplete curing or poor performance.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Base Polymer (Part A)