SPECIAL CHARACTERISTICS
:
A silane grafted crosslinkable polyethylene compound, curable by exposure to moisture, for insulation of power cables and possessing excellent extrudability at high out put rate.
PP 408 is based on a high molecular weight polymer and has melt index in the range of 0.5 to 0.8. It has especially developed for low voltage cable insulation and for sheathing purpose.
DESCRIPTION :
This compound utilizes the system for cross – linking of polyethylene developed by DOW Corning and known as Sioplas. It is a two component system comprising a silylated ethylene polymer known as the graft copolymer PP 408 , and a master batch PP 401 containing a cross – linking catalyst. The two materials normally used in the ratio of 95 parts graft to 5 parts catalyst master batch.
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.
TECHNICAL DATASHEET :
Property |
Test
Method |
Unit |
Typical
value |
Density |
ASTM-D-1505 |
gm / cm3 |
0.925 |
|
MFI at 190°
C / 2.16 Kg. |
PPIL |
G / 10 |
0.5 |
|
Unaged
mechanical properties: |
|
|
|
Tensile
Strength at Break |
IEC811 |
MPa |
18 |
|
Elongation
at Break |
IEC811 |
% |
550 |
|
Mechanical
Properties after ageing in Air oven, 168 hr. at 135° C : |
|
|
|
|
Variation on
tensile strength |
IEC811 |
% |
+10 |
|
Variation on
elongation at break |
IEC811 |
% |
-15 |
|
Hot set
test, 15 min. at 200° C, 0.2 N / mm2 : |
|
|
|
|
Elongation
under load |
IEC811 |
% |
100 |
|
Permanent
Elongation after Cooling |
IEC811 |
% |
5 |
Electrical
Properties : |
|
|
|
|
Power factor
at 50 Hz at 23° C |
IEC250 |
Nil |
0.0004 |
| Dielectric
constant |
IEC250 |
|
2.3 |
| Volume
Resistivity at 20° C |
IEC502 |
Ohm.cm |
2.4*106 |
| Dielectric
Strength |
IEC243 |
Kv
/ mm |
25 |
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 atleast 20 and compression of 3:0:1 is recommended.
Extrusion Temperature conditions :
As a guide the following temperature profile is recommended:-
| Zone 1
|
Zone
2
|
Zone
3
|
Zone
4
|
Head
|
Die
|
| 160°
C |
170°
C |
180°
C |
190°
C |
200°
C |
210°
C |
This profile may vary depending on extruder type, design and output
Screw water temperature : 60ºC – 70ºC
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 in the case of tubing tools, it is generally recommended that a draw down ratio not greater than 3:5:1 should be used both for sector and round shaped conductor. PPIL engineers would be glad to provide comprehensive details of recommended tool design for both round and sector shaped conductor.
CROSS-LINKING OR CURE :
Curing can be done in the following ways:
Following factors are important for
cure
MASTER BATCH :
It is recommended that the catalyst masterbatch be thoroughly dried before usage at 60ºC 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.
