Technical Library

ExSil® 50 (EM2-EX050): High Elongation Elastomer – Medical Grade

ExSil® 50 is a two-component ultra high elongation silicone elastomer developed for medical applications.

Features and Benefits:

  • Self-sealing
  • High elongation
  • High recovery
  • Low extractables
  • High tear strength
  • Flowable and moldable
  • High oxygen permeability
  • Long-term thermal stability


  • Diaphragms
  • Microfluidics
  • Vibration damping
  • High performance seals
  • Septa with easy penetration and good resealability
  • Optical and electrical interconnects

Sample before stretching

Sample elongation

The stretched sample exhibits shape recovery

Note: The values below are typical and are not intended for use in preparing specifications. Please contact a Gelest representative when writing specifications.

Cured PropertiesValueUnits
Tensile strength3MPa
Tear strength5-7kN/m
Elongation at tear failure1,000-1,500%
Durometer5Shore A
Specific gravity (Part A)1.06g/mL
Refractive index (nD25)1.41
Volatiles (4 hr/150 °C)≤ 0.1wt%
Critical surface tension23-24mN/m
Contact angle, water100-105°
Volume resistivity2.90 x 1014ohm*cm
ExSil® 50 PartViscosity (cSt)
Base (Part A)500-700
Activator (Part B)800-1,000
Activated Mix500-700
Silicone ElastomerExtractables (w%)
Resin reinforced silicone4.2
Silicone, 100 °C strip3.1
ExSil® 500.5

Stress strain curves of ExSil® 50 compared to resin reinforced silicone

TGA thermograms of ExSil® 50 compared to resin reinforced silicone

Silicone rubber septum with 1 mm core (left) vs ExSil® 50 septum with self-healing 1 mm core (right)

Thoroughly mix Part A and Part B in a 100:1 ratio. Try to avoid introducing bubbles. For critical applications, de-air mix under vacuum. The pot-life is 24 hours at 25 °C. Avoid entrapping air during transfer and casting. Cure at 100 °C for 8 hours or at room temperature for 72 hours. ExSil® 50 can be self-bonded by exposure to oxygen plasma and pressing surfaces together in a dry atmosphere