SPECIAL CHARACTERISTICS :

A silane grafted Crosslinkable polyethylene compound, curable by exposure to moisture, for insulation of power cables and possessing excellent extrudability at high output rate.

PP 409 has been specially developed for cables up to 72 KV. The special formulation and compounding techniques used ensures that the contamination level is kept within the required limits for this voltage grade.

PP 409 has general melt index range of 0.7 – 1.0 which provides firm stability during extrusion, especially for the thick insulations required for high voltage.

DESCRIPTION :

This compound utilizes the system for crosslinking of polyethylenes developed by DOW coming and known as sioplas. It is a two-component system comprising a silylated ethylene polymer known as the graft copolymer PP 409, and a masterbatch PP401 containing a crosslinking catalyst. The two materials normally used in the ratio of 95 parts graft to 5 parts catalyst masterbatch.

Stored separately, these materials are fairly stable but when mixed and exposed to moisture, crosslinking takes place.

This system allows the compound to be extruded as normal thermoplastic which will then attain a high level of crosslinking in the processed form. The finished product has all the properties associated with polyethylene crosslinked by other methods.

TECHNICAL DATASHEET : 

CONTAMINATION :

Contamination is measured by the use of Dyanascope’s micrometer (x 200)

*level of contamination

1. a) no particle > 0.5 mm
    b) max. 5 per 500 gm bet.0.2 to 4.9 mm

2. a) no particle > 0.3 mm
    b) max particle. 5 per 500 gm bet. 0.2 to 0.29 mm


*1> up to 11 kv
*2> for 22 & 33 kv

RECOMMENDED EXTRUSION CONDITIONS :

Extruder

Thermoplastic extruders will process PPIL siplas – type compound particularly if the screw is suitable for polyethylene extrusion. An extruder having L/D ratio of at least 20 and compression of 2.5:1 is recommended.

Extrusion Temperature Conditions

As a guide the following temperature profile is recommended :-

This profile may vary depending on extruder type, design and output.

Screw water temperature: 60șC-70șC 
Screens : 30,100,30 (mesh apertures 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 tubing tools should be used.

CROSSLINKING AND CORE SCREENS :

Compound PP 409/401 may be used in conjuction with deformation resistant thermoplastic semiconducting material PPIL grade P – 10040 – CB for conductor and insulation shield.

CROSSLINKING OR CURE :

Curing can be done in the following ways:
- By immersion in hot water at 70-80șC
- By exposure to low pressure steam ( about 0.15 bar)
Following factors are important for cure,
- The ratio of conductor to insulation thickness
- Barrel diameter of the cable on which the core is cured

For thickness greater than 8 mm a maximum temperature of 80șC(which is below the phase change temperature of PP 409) is recommended, otherwise a set in the shape of the core will occur, preventing the core from lying flat after removal from the drum.

The period required to obtain full cure will depend upon insulation thickness but typical periods in steam atmosphere are:

A significant decrease in cure time is possible through immersion in pressurized water (1.3bar) at a temperature of 100șC.

MASTER BATCH :

It is recommended that the catalyst masterbatch be thoroughly dried before usage at 60șC for 18 hrs. at a depth not greater than 5 cm.

STORAGE :

Store under cold and dry conditions for best results.

FORM AND PACKING :

Form : pellets

Packaging : Moisture resistant high density carboy containing 125 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.

• Silane Grafted Crosslinkable Polyethylene 
  for Low Voltage Power Cable Insulation Grade - PP 408 / 401

• Silane Grafted Crosslinkable Polyethylene Black
  for Low Voltage Power Cable Insulation / Sheath Grade - XL-ABC-01

• Thermoplastic Semiconductive Compound 
  for Conductor / Insulation Shielding of Power Cables

Compounds for Telecom Cables