This compound utilizes the system for cross linking of polyethylene developed by DOW Corning and known as Sioplas. It is a three component system comprising a silylated ethylene polymer known as the graft copolymer PP 408, a tin based cross-linking catalyst master batch PP 401 and also a master batch P-10040-B containing lubricant, UV ingredient and suitable grade of carbon black. These three material are normally used in the ratio of 90 parts graft, 5 parts catalyst master batch and 5 parts special black masterbatches. Stored separately, these materials are fairly stable but when mixed and exposed to moisture, cross linking takes place. This system allows the compound to be extruded as a normal thermoplastic which will then attain a high level of cross linking in the processed from. The finished product has all the properties associated with polyethylene cross linked by other methods.Silane grafted black cross linkable polythylene for over head cables.
Special Characteristics :
A silane grafted crosslinkable polyethylene compound, curable by exposure to moisture, for over head cables and possessing excellent extrudability and stretchability. PP 408 is based on a high molecular weight polymer and has melt index in the range of 0.8 to 1.2. It has been specially developed for over head cables.
|Properties- Physical & Mechanical||Typical value||Unit||Test Method|
|Density||0.93||gm/cm3||ASTM – D- 1505|
|MFI at 190°C/5 Kg.||1.1||G / 10Min.||PPIL|
Unaged mechanical properties :
|Tensile Strength at Break||19||MPa||IEC811|
|Elongation at Break||550||%||IEC811|
Mechanical Properties after ageing in Air oven, 168 hr. at 135° C :
|Variation in tensile strength||+10||%||IEC811|
|Variation on elongation at break||-10||%||IEC811|
Hot set test, 15 min. at 200°C, 0.2 N / mm2 :
|Elongation under lord||100||%||IEC811|
|Electrical Properties :||Typical value||Unit||Test Method|
|Power factor at 50 Hz at 23°C||0.0004||Nil||IEC25|
|Volume Resistivity at 23°C||2.4*1015||Ohm.cm||IEC502|
Recommended Extrusion Conditions :Extruder :
Thermoplastic extruders will process PPIL Sioplas – type compound particularly if the screw is suitable for polyethylene extrusion. An extruder having L/D ratio of at least 20 and compression of 3 : 1 is recommended.Extrusion temperature conditions : As a guide the following temperature profile is recommended :
Screw water temperature :60°C – 70°C
30,80, 30 (mesh aperture per linear inch)
Head And Tool Design :
The head and tools should be so designed to allow streamline flow without the possibility of stagnation of material. To obtain optimum physical properties in the case of tubing tools, it is generally recommended that a draw down ration not greater than 3:1 should be used .
Crosslinking Or Cure :Curing can be done in the following ways :
- By immersion in hot water 90-95°C
Following factors are important for cure :
• Total Volume of the material.
• Diameter and packing of roll.
• Catalyst percentage may be adjusted 3.5% depending on cure characteristics.
Master Batch :
It is recommended that the catalyst master batch and black master batch be thoroughly dried before usage at 70°C for 4 hrs. at a depth not greater than 5 cm. ( Base of try should have perforation ) or dehumidified dryer should be used.Storage :
Store under cold and dry conditions for best results.
Moisture resistant high density carboy containing 25 kg
This information is to the best of our knowledge. The values of different parameters and operating conditions listed above are guidance only and should not be used for drawing specifications. The results & operating conditions may vary depending on methods of test and manufacturing / testing equipments.