The basic polyolefin polymers ( polyethyene, polypropylene ) used for the production of Softlon foams are composed of long chains of carbon (C) and hydrogen (H) molecules.
As an example, a short molecular chain of polyethylene looks as:
In the case of PE polymers, the hydrogen colecule is party replaced by a CH3 group. For ease of explanation, the chemical structure is simplified in the following graphs to a ‘string’, representing the polymer chain.
In normal, non-crosslinked polyethylene materials ( either foams or non-foams) the polymer ‘stings’ are not linked to each other.
This is why non-crosslinked materials have a sharp and defined melting point (MP) where the polymer chains separate.
As plastification takes place at this temperature they are also called ‘thermoplastics’.
In crosslinked materials the polymer chains of the polymer are chemically linked to each other at certain crosslinkin points there by foaming a 3-dimensional network.
More precisely, crosslinking is accomplished by removal of a hydrogen molecule from the C – C backbone.
Active sites on adjacent chains then react to form a crosslink.
Depending on the number of links between the polymer chains ( narrow or wide-meshed ), the degree of crosslinking varies.
Due to crosslinking, the typical and sharp melting point of non-crosslinked materials becomes a softening range.
Because of this property, crosslinked materials are also called ‘thermo-elastic’. The degree of crosslinking gives the number/density of crosslinking points.
In the case of 100% crosslinking, the material looses almost all its thermo-elaxtic properties and becomes a ‘duroplast’
Irradiation cross inked
The removal of the hydrogen molecule from the C – C backbone of the polymer is accomplished by a high energy electron beam scanning the foamable polymer sheet.
Softlon® is an irradiation cross-linked Polyethylene Foam that may be expanded from 3 to 50 times and has a closed cell structure. Compared with other foams, Softlon® has better characteristics in mechanical properties, dimensional stability, lightweight properties, heat insulation properties, heat resistance, chemical resistance and fabricability with many unique properties and a wide range of applications.
Softlon® is therefore a very versatile and popular material used extensively in the fields of packing, building and construction, sundry goods, etc., that are very easy to work with such as Slitting, Slicing, Laminating, Embossing, Vacuum foaming and so on can all undertaken easily.
That are all designing for value and proven to perform, SOFTLON® products offer out standing thermal insulation properties, wide working temperature range, CFC and HCFC free, and offer a high degree of fire and smoke protection.