SILANE MOISTURE CROSSLINKABLE METHODS

There are two method of crosslinking polyethylene by moisture, both involving the use of ethylene vinyl-silane copolymers. These copolymers can either be produced in reactor by polymerizing ethylene with vinyl-Silane, or extruder grafting of polyethylene with vinyl-silane.

1)    Reactor copolymer


This method produce an Ethylene vinyl-Silane copolymer by added Vinyl-Silane copolymer with polyethylene into reactor during a polymerize process.


2)  Silane Grafted Polyethylene

      2.1) The one-step process (monosil)

     


In this process, the grafting generated during the fabrication of the finish product ie. cable. The silane, initiator, polyethylene, catalyst and antioxidant are all added in the same extruder and extruded product begins to cross-linkable. A high L/D ratio extruder has required for this process.

      2.2) The two-step grafting process ( sioplas)


The process is referred to as two-step because two distinct steps are used to obtain the final crosslinked product.
        In the first step, Vinyl Silane was grafts to the polyethylene by a high L/D ratio and high process temperature extruder, and compounds the masterbatch of catalyst and other additives.  
        In the second step, mixes the grafted compound with the catalyst masterbatch and processes it into a finished product. The process is straightforward and allow for high output rates with low scrap on conventional equipments

 

   Advantage  Disadvantage
Monosil

- Low material cost

 

- Less gels and scorch

 

- Ready mixed

 

- Unstable in crosslink level

 

- High L/D ratio extruder required

to finish product processing

 

- High process temperature

 

- Short shelf life

 

 Sioplas

(Chemtech's)

 

 

- Good stability in crosslink level


- Long shelf life

 

- Low material cost

 

- Simple extruder can process

 

- Low process temperature

 

 

 

 

 - Two components

 

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