Material Selection Guide: Silicone vs LSR for Medical Grade Gaskets

Problem Statement: Silicone Compression Set Failure in Autoclave Sterilization

Medical gaskets require 1,000+ autoclave cycles at 134°C with steam exposure. Conventional VMQ silicone develops >40% compression set after 500 cycles, leading to seal failure.

Material Science Analysis

Standard VMQ silicone crosslinks degrade under cyclic steam exposure. Liquid Silicone Rubber (LSR) uses platinum-catalyzed curing for:

• Higher crosslink density (3.2x vs VMQ)
• Lower extractables (<0.5% per ISO 10993-5)
• Superior hydrophobicity (110° water contact angle)

Technical Specifications

• Material: Medical Grade LSR (USP Class VI)
• Shore A Hardness: 40±2
• Tensile Strength: 8.5 MPa (ASTM D412)
• Elongation at Break: 600%
• Temperature Range: -60°C to 200°C continuous

Property	LSR (Platinum Cure)	VMQ (Peroxide Cure)	EPDM
Compression Set (500 cycles @ 134°C)	12%	43%	65%
Steam Resistance (hours to failure)	1,200+	400	150
Extractables (ISO 10993-5)	0.3%	1.2%	2.8%
Tear Strength (kN/m)	35	25	18

Standard Compliance

RubberQ’s IATF 16949 system controls:

• Lot traceability with 100% material certification
• Cleanroom molding (ISO Class 7 per ISO 14644-1)
• Post-cure validation per ISO 13022

For custom material compound development or IATF 16949 documentation, consult RubberQ’s engineering department.