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MINERAL FILLERS AND POLYMER MATRIX COMPATIBILISATION FOR PERFECTING MATERIALS USED AS INSULATION AND SHEATH OF ELECTRICAL CABLES

Objective


It is shown that low cost halogen free materials for wires and cables applications can be developed.

Two fillers are selected HYDROFY N 2,5 um and HYDROFY 1P/N 1,5 um.

Several types of polymers are tested such as EPR or EPDM, EBA or EMA, LLDPE or VLDPE, and EVA; Ethylene Vinyl Acetate (EVA), Linear Low and Very Low Density Polyethylene (LLDPE, VLDPE) are selected for industrial trials.

Several kinds of commercial compatibilizers are tested in laboratory, the best ones being chosen for industrial productions.

First industrial trials are produced with silane coupling agents; despite a good surface aspect and good initial mechanical characteristics, these compatibilizers are forsaken because of a decreasing of the elongation at break after ageing, and because of the price compared to the objective.

Other industrial trials are produced with a commercial maleic anhydride grafted polymer as compatibilizer, VA 1801 from EXXON. Two compounds are produced with HYDROFY 1P/N 1,5 um and a third one with HYDROFY N 2,5 um, and all together fulfil the requirements with a price a 1,1 ECU/1.

Compatibilizers from LIEGE are produced by a industrial partner, IVEA EMMAILLAGE, and are tested in compounds. The extrusions give a very good aspect surface. We can notice the very high elongation at break, between 400 and 500% on cable. All the other characteristics are fulfilled except the tensile strength at break which is low on cable compared to the measurements on moulded plates.

This lower tensile strength at break measured on cable is due to the evaporation during the extrusion of the remaining solvent contained in the compatibilizer. This evaporation induces porosity in the cable and decreases the mechanical characteristics, specially the tensile strength at break. A better drying of the compatibilizer with stronger evaporation of the solvent during the synthesis should increase the tensile strength at break.

These new compatibilizing agents synthesised by the University of Liege are very promising but their development and the elaboration would require more time in order to improve the conditions of synthesis for a better drying to evacuate all the solvent; this should increase the tensile strength at break up to the required compound.
The research is directed at developing new types of polymeric compounds for the insulated cables industry.

Major objective : a sheathing type compound which incorporate at least 250 pcr of mineral fillers while complying with the future needs for low voltage rigid cables sheathing (e.g. mechanical properties, recyclability and environmental cleaniless).

Minor objective : an insulating type compounds, derived from the sheathing compound, fitting the needs of low voltage insulation, while containing a large amount of fillers.

The research will focus on the problem of mineral filler/polymer compatibilization - it will range from the synthesis of specific molecules (w fonctionalized polymers, block polymers twice functionalized grafted polymers) to the development of adequate coating system, compounding process and extrusion technique.

Successful completion should yield, within 2 years time, to the replacement of the present PVC sheath by the newly developed material, containing less polymer and more mineral fillers (made in Europe) thus leading Europe to an higher technical level, and an improved independance from oil based materials.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

ALCATEL
Address
170 Avenue Jean-jaures
69344 Lyon
France

Participants (2)

Nuova Sima Srl
Italy
Address
Frazione Valtreara 83
60040 Genga An
UNIV LIEGE
Belgium
Address
Sar Tilman B6
4000 Liege