Cross Linked PE Compounds - Pipe PP 410/401

Special Characteristics:
LLDPE Compound, curable by exposure to moisture, for Heat Shrinkable Tape and Tube used for jointing and repairing of Power and Telecommunication Cables and possessing excellent extrudability and stretchability.
P-80000-BMB is based on high molecular weight polymer and has Melt Flow Index in the range of 5.0-0.8. It has especially developed for heat shrink application.
Description:
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 P-80000-BMB, a tin based cross-linking catalyst masterbatch PP 401 and a masterbatch P-10040-B containing lubricant, UV ingredient and suitable grade of carbon black. The three materials are normally used in the ratio of 90 parts graft, 5 parts catalyst masterbatch and 5 parts special black 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 a normal thermoplastic which will then attain a desirable level of cross linking in the processed form. The finished product has all the properties associated with polyethylene cross linked by other methods.


Technical Characteristics:

Physical & Mechanical Properties

Test Method

Unit

Typical Value

Density

ASTM-D-1505

gm/cm3

0.93

MFI at 190 ᵒC / 2.16 kg

PPIL

gm/10 min

0.67

Unaged Mechanical Properties:

 

 

 

Tensile Strength

IEC 811

Mpa

19

Elongation at Break

IEC 811

%

550

Mechanical Properties after ageing in Air Oven, 168 hr. at 135 ᵒC:

 

 

 

Variation on Tensile Strength

IEC 811

%

+18

Variation on Elongation at break

IEC 811

%

-20

Hot Set Test:
(15 min at 200ᵒ C, 0.2 N/mm2)

 

 

 

Elongation under load

IEC 811

%

240

Permanent Set

IEC 811

%

16

Note: Tensile properties are based on the mixture of 90% of P-80000-BMB, 5% of PP-401 & 5% of P-10040-B extruded and cured at the temperature of 90 ᵒC for a duration of 6 hr.

Electrical Properties:

Electrical Properties

Test Method

Unit

Typical Value

Power Factor at 50Hz at 23ᵒ C

IEC 250

-

0.0004

Dielectric Constant

IEC 250

-

3.0

Volume Resistivity at 20ᵒ C

IEC 502

Ω.cm

2.4 x 1014

Dielectric Strength

IEC 243

Kv/mm

15

 

Recommended Extrusion Conditions

Extruder: Thermoplastic extruder 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 3:1 is recommended.
Extruder Temperature Conditions:
As a guide, the following temperature profile is recommended:

ZONES

1

2

3

4

Head

Die

Temperature

150 ᵒC

160 ᵒC

170 ᵒC

180 ᵒC

190 ᵒC

200 ᵒC

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

Screw Water Temperature: 60 ᵒC - 70 ᵒC
Screens: 30, 80, 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 1.25:1 should be used for Tape and 2:1 for Tube.

Crosslinking or Cure:
Curing can be done in the following ways:

  • by immersion in hot water at 80-90ᵒ C

Following factors are important for Cure:

  • The total volume of material
  • Diameter and packing of roll
  • The material shall cure fully before stretching
  • If required annealing should be done in air oven at 65ᵒ C for max 24 hr. after cure.
  • Proper rest should be given after extrusion & cure to avoid stress.
  • Wrinkle during recovery is due to improper cure.
  • Catalyst percentage may be adjusted to 3% depending on cure characteristics.

Masterbatch:
It is recommended that the catalyst masterbatch and black masterbatch be thoroughly dried before usage at 70ᵒ C for 4 hr. at a depth not greater than 5 cm.

Storage           :           Store under cold and dry conditions for best results.
Form               :           The material is supplied in the form of Pellets.
Packing           :           Moisture resistant aluminium laminated bags of 25 kg.

We believe this information is based on the best currently available data on this subject. It is offered as a possible helpful suggestion in experimentation you may care to undertake along these lines. It is subjected to revision as additional knowledge and experience are gained. PPIL makes no guarantee to results and assumes no obligation or liability whatsoever in connection with this information. This publication is not a license to operate under or intended to suggest infringement of any existing patents.