Optimization of PVC-free materials in cables

1. Introduction

1.1 Scope
1.2 Follow-up Group
1.3 Project Progress

This project has been carried out by DRAKA-NKT in co-operation with NKT Cables for The Danish Environmental Board in the period 1992-1995.

1.1 Scope

The scope of the project has been a further investigation into the possibilities of substituting PVC with Halogen Free Flame Retarded materials based on the results obtained in the previous project: Alternative to PVC in cables and connected building installations.

Special attention has been paid to minimizing those barriers towards increasing the use of the PVC-free materials, which were identified in the previous project i.e. primarily the processing difficulties encountered with these materials as well as their inferior long term properties in differing aggressive environments.

1.2 Follow-up Group

The project has been followed by a group with the following composition:

Jacob Brønnum, Miljøstyrelsen
Erling Bøje, Århus Kommunale Værker
Jørgen Bille Hansen, DSB Elektrotjenesten
Tom Nisted, Dansk Brandteknisk Institut
Svend Bank Andreasen, Telecom A/S
Flemming Hummelshøj Petersen, Københavns Belysningsvæsen

1.3 Project Progress

A large number of Halogen Free Flame Retarded compounds were selected for a thorough investigation of critical properties including long term properties in different environments.

At the same time the necessary computer software and knowledge have been established to simulate the relevant extrusion processes.

Based on the obtained results from the ageing tests three compounds were selected for further testing i.e. characterization of rheological properties, process simulation and later on test runs in the factory. The produced cables were then tested for mechanical properties and fire performance characteristics.

Preliminary tests were made on small optical cables produced on small extruders in order to minimize the material consumption. Experience obtained with these small cables during the simulation and the production processes were then later on used in a larger scale production of power cables.

Conclusions concerning the suitability of the established process conditions for the two cable types have been drawn. The possibilities of substituting PVC with Halogen Free Flame Retarded materials are considered.