AL2CHEM SPECIALTIES AL 121 Silane

AL121 is used as a polymer modifier via grafting reactions. The resulting pendant trimethoxysilyl groups can function as moisture-activated crosslinking sites. The Silane grafted polymer is processed as a thermoplastic and crosslinking occurs after fabrication of the finished article upon exposure to moisture.

Functions: Coupling Agent, Crosslinking Agent

Chemical Family: Silanes

Compatible Polymers & Resins: Polyethylenes (PE)

Processing Methods: Extrusion

End Uses: Cables, Pipes, Shrink Wrap, Tubing

Technical Data Sheet

Knowde Enhanced TDS

Identification & Functionality

Chemical Family
Plastics & Elastomers Functions
Chemical Formula
C5H12O3Si
CAS No.
2768-02-7
EC No.
220-449-8
Technologies

Features & Benefits

Benefits of Crosslinking
  • Higher maximum use temperature
  • Reduced deformation under load (creep)
  • Improved chemical resistance
  • Superior environmental stress crack resistance
  • Increased abrasion resistance
  • Improved impact strength
  • Memory characteristics (shrink film, tubing)
  • Improved impact strength
Advantages of Silane Crosslinking over Radiation or Peroxide
  • Low capital investment
  • Low operating (energy) costs
  • Higher productivity
  • Processing versatility
  • Thick, thin, or variable thicknesses possible
  • Complex shapes possible
  • Wilder processing latitude (control of premature crosslinking)
  • Useful with filled composites
  • Applicable to all polyethylene densities and copolymers.

Applications & Uses

Compatible Polymers & Resins
Plastics & Elastomers End Uses
Plastics & Elastomers Processing Methods
Applications

Polymer Modification:

AL121 is used to modify polyethylene and other polymers by grafting its vinyl group to the polymer backbone using a radical initiator, such as peroxide. This provides a polymer with pendant trimethoxysilyl groups that may be used as moisture-activated crosslinking sites via hydrolysis of the alkoxy groups followed by condensation of the resulting silanols.
 

Crosslinking of Silane-Grafted Polymers:

The reaction of Silane-grafted polyethylene to form a crosslinked or vulcanized polyethylene useswater to form the crosslinks. This technology is widely used around the world for commercial applications in wire and cable insulation, tubing, and other similar uses.

Properties

Physical Form
Appearance
Colorless transparent liquid
Typical Physical Properties
ValueUnitsTest Method / Conditions
Boiling Point (at 760mmHg)122°C
Density (25/25°C)0.960 - 0.970
Molecular Weight148.2
Puritymin. 98.0%
Refractive Index (at 25°C)1.3905 +/- 0.0005

Technical Details & Test Data

Basic Reaction

The basic reaction sequence is as follows: polyethylene is reacted (grafted) with vinyltrimethoxysilane, using a peroxide initiator, in an extruder. The grafted polyethylene is then formed into a finished product, such as cable jacketing, wire insulation, or pipe. The forming step is usually done by a second extrusion, during which a catalyst for the moisture-cure step is added. Finally, the formed article is exposed to moisture or hot water to cause hydrolysis of the Silane and condensation to form crosslinks via Si-O-Si bond formation.