Overview: history of the research group (DILAB)

Since its inception the group has been involved in applied research activities in the field of Physics Dielectric Materials from the viewpoint of their electrical properties, sometimes as an isolated group and others in coordinated action with other groups.

In collaboration with the Universidad Pública de Valencia (UPV) and Universitat Pública de Catalunya (UPC), in 1982, we approved a project by the CAICYT entitled: Study of transitions and relaxations in polymers by electric and calorimetric methods (Pr. No.734) (Head Investigator: Prof. Ricardo Diaz Calleja, duration: 1982-1985). In this project work will center on the study of relaxations of PET-a by TSDC. From this stage arise several works among which include "The Glass Transition Temperature of PET-a by TSDC”, which correlates glass transition temperature with the peak α maximum temperature for TSDC, as the first time.

Then we started another project "Study of physical aging of polymers of different microstructure by thermal analysis" (Q. No 395) (Researcher: Prof. S. Montserrat, duration: 86-89). The project started the study of the behaviour of relaxation during the cold crystallization (Thermal stimulation by steps method). Moreover, in PET, we make the first physical aging studies using the TSDC technique.

After that the group of Electrical Properties of Insulating Materials was created, currently known as Laboratory of Dielectric Materials Physics (DILAB). This group started with the polarization windows method. DILAB also performed the work ‘Study of the polar and free charge peaks of amorphous PET’ that was chosen as oral work to expose at the ISE 8 (Berlin). This study continued in collaboration with the group of Dr M. Latour (Chair of Condensed Matter at the University of Montpellier) and the work ‘Storage time effect on free charge relaxation of PET’ was published.

We took part in the genesis of the group ARPEGE (Applications and researches on polymers in electrical engineering: correlations between structures and electronic proprieties), in 1993, with the collaboration of Prof. Tourille (Univ. Montpellier II). ARPEGE was established as such in the 1994. The EU funded the group, under the Human Capital and Mobility program (Head Investigator: Prof. J. Belana). The work was mainly focused on the study of polyetherimides (PEI 1000 and PEI 5000) and in PP and PEN. In this stage, we made several works, three of them were published in a special edition of the journal Polymer International (May 1998). This works compared the results obtained by TSDC with other techniques (TMDA, DSC, DEA), relating the aging with the injection and rupture.

In 1998, we made two contracts with BICC General Cable and initiated a study of XLPE cables by TSDC subjected to different treatments (Head Investigator: J. Belana). We participated in the program ATYCA requested by the company BICC General (M112/1998). In 1999, the group was equipped with an FEDER (2FD 1997-0722 Mat) to perform the ‘Experimental study of the influence of manufacturing parameters and the degree of aging of medium voltage cables with XLPE insulation in the ability to trap space charge’. This project ended in June 2001 (Responsible J. Belana).

Our group performed a project entitled ‘Characterization and evaluation of electrical aging of medium voltage cables by dielectric spectroscopy techniques’ (MAT 2001-2338-C02-01 ) in collaboration with the team of Dr Fruits of the University of Seville, under the National Plan for I+D+I (2000-2003). This project was accompanied by an agreement with General Cable company, the company provided us the materials needed to carry it out. The project was conducted under the responsibility of the J.BelanaUPC and F.Frutos in Seville. The project posed the study of XLPE cable under two strands: one theoretical and one of application. We worked with cables by different orders of degradation, and basically, it tried to find an indicator to keep the aging process of the cable.

We studied the role of its interfaces in the project "Study of the insulator-semiconductor interface in aged power cables using the technique of the thermo-stimulated currents and electroacoustic pulse. Semiconductor behavior "(PTR1995-0742-OP, PETRI, Head Investigator: JADiego), following the research line of cables. The Ministry of Science and Technology funded us from 2003 to 2005. This study was supported simultaneously through an agreement with General Cable Company (GC).

We have finished the project PETRI (REF: PET 2007-0060, Head Investigator: J.Belana) which was awarded in 2008 under the title "Insulation of XLPE cables in medium and high voltage of new technology, electrical characterization and study of conductive processes based on the existence of a virtual electrode", and funded by the McyT. This project has continued in the line of the study of electrical properties of insulating materials used in cables. It analyzes the behavior of the conductivity as a function of various heat treatments and justifies this by changes in the density of traps and due to diffusion processes. We try to assign the results to associated industries, with the collaboration of General Cable (GC).

Since 1995 to 2004, our group DILAB jointly with the research group Nonlinear Dynamics, Nonlinear Optics and Laser (DONLL) (Responsible teachers: R.Vilaseca and J.Garcia Ojalvo) have been recognized by the Interdepartmental Commission and Technological Innovation of the Generalitat, as the Competitive Group, Consolidated and Quality of the Community of Catalonia.