1989 - 1994


Electrochemical Study of Poly(Vinyl Chloride) Polypyrrole Blends
Matencio T, Mano V, Felisberti MI, De Paoli MA
Electrochimica Acta

39 (10): 1393-1400 Jul 1994

Blends were obtained by impregnation of an insulating polymer matrix, poly(vinyl chloride), with an oxidant, FeCl3, followed by exposure to pyrrole vapor. The redox properties of films of the blends obtained by this method were studied by cyclic voltammetry and impedance spectroscopy. The results show that thin films (20 mum) are more electroactive than thick films (100 mum) although the proportion of polypyrrole is the same for both (ca. 38%). This electroactive behavior is in agreement with morphology observations, which show different phase separation mechanisms as a function of the film thickness: a spinodal mechanism for the thin film and a binodal mechanism for the thick film.



Chemical Preparation of Conductive Elastomeric Blends - Polypyrrole EPDM .1. Oxidant Particle-Size Effect
Zoppi RA, Felisberti MI, De Paoli MA
Journal Of Polymer Science Part A-Polymer Chemistry

32 (6): 1001-1008 Apr 30 1994

This work describes the preparation of polypyrrole and EPDM rubber blends, PPy/EPDM, by the sorption of pyrrole (vapor phase) in an EPDM matrix containing CuCl2. We investigated the effect of the oxidant particle-size on the sorption and polymerization equilibrium, electrical conductivity, and mechanical properties of the blends. Independently of the CuCl2 concentration and polymerization time, the polypyrrole weight fraction in the blend, X(PPy), increases when the oxidant particle-size is changed from 150 250 mum to smaller than 106 mum. For blends containing 50 phr of CuCl2, obtained following 72 h of exposure to pyrrole, an increase in the Young's Modulus (from 2.2 +/- 0.2 to 3.9 +/- 0.6 MPa) and an increase in the electrical conductivity (from 10(-9) to 10(-7) S cm-1) was observed when the oxidant particle-size was decreased. Infrared spectroscopy, thermogravimetric analysis, scanning differential calorimetry, and scanning electron microscopy were used in sample characterization.



Chemical and Electrochemical Preparation of Conductive Polymeric Composites
De Paoli MA, Felisberti MI, Zoppi RA, Duek EAR, Mano V, Tassi EL
Journal De Chimie Physique Et De Physico-Chimie Biologique

89 (5): 1185-1192 May 1992

The electrochemical preparation of a graft copolymer of aniline and nitrilic rubber is described, together with the preparation of a composite of poly(3-methyl-thiophene) and nitrilic rubber. These retain the electrochemical properties of the conductive polymer and acquire the mechanical properties of the insulator. The Pani/NR copolymer shows electrochromic properties comparable to pure poly(aniline). A chemical preparation method is used to obtain homogeneous blends of poly(thiophene) and poly(pyrrole) with PVC using FeCl3 as oxidant. The Tg, conductivity and morphology of the composites depend on the synthesis temperature. Conductivities are in the 10(-4) to 10(-1) S. cm-1 range.



Hydrophilic Membranes Based on Poly(Vinyl Methyl Ether-Cross-Linked-Polystyrene) Semiinterpenetrating Networks
Felisberti MI, Stadler R
Makromolekulare Chemie-Macromolecular Symposia

44: 75-83 May 1991

Microporous membranes were prepared from poly(vinyl methyl ether - crosslinked-polystyrene) (PVME-cross-PS) semi-IPN's by extraction of poly(vinyl methyl ether) (PVME) with water. Membrane morphology and properties are fixed during the process of swelling, phase separation, PVME extraction and vitrification which occurs upon immersing the samples in water. The membranes are characterized by swelling (water uptake), the relative amounts of free and bound water, and their permselectivity towards KCl solution.



Phase-Behavior of Poly(Vinyl Methyl Ether)-Cross-Polystyrene Semiinterpenetrating Networks
Felisberti MI, Krieger V, Stadler R
Makromolekulare Chemie-Macromolecular Symposia

40: 223-235 Dec 1990

Semi-interpenetrating polymer networks of varying composition are prepared by crosslinking polystyrene containing a small number of maleic anhydride groups (4.8 mol% of MA units) with hexamethylenediamine (HMDA) in the presence of linear poly(vinyl methyl ether) (PVME). Lightly crosslinked samples are homogeneous at room temperature and show a phase behaviour similar to uncrosslinked blends, i.e. lower critical solution temperature (LCST) behaviour. The influence of crosslinking on the phase behaviour has been studied by small angle light scattering (SALS) and turbidity measurements. The cloud point strongly depends on the heating rate. The presence of the network reduces the stable single phase region in agreement to theory. In systems showing spinodal decomposition, it is expected that some concentration fluctuations will grow more rapidly than others resulting in a separated phase system which shows high degree of connectivity with characteristic dimensions. Using temperature jump experiments, SALS can be used to estimate parameters of the phase separation kinetics and the characteristic dimensions of the phases. In temperature jump experiments into the spinodal region a maximum in the scattered light intensity is observed with time at a certain scattering vector. However, the semi-IPN's develop no scattering maximum. This is explained by a damping of the thermodynamical dominant wavelength in spinodal decomposition in the network.



Mechanical Relaxation in Miscible Polymer Systems - The Glass-Transition Regime in Poly(Vinylmethylether) (PVME) Cross-Polystyrene (PS) Semiinterpenetrating Networks
Felisberti MI, Freitas LLD, Stadler R

31 (8): 1441-1448 Aug 1990


Controlled Mechanical Damping in (Partially) Miscible PVME-Cross-PS-Semi-IPNS
Felisberti MI, Muller G, Stadler R
Abstracts Of Papers Of The American Chemical Society

199: 152-Pmse Part 2 Apr 22 1990


Bicontinuous Microfoams by Water-Induced Phase-Separation in Polyvinyl Methyl Ether)-Cross-Polystyrene Semiinterpenetrating Networks
Felisberti MI, Stadler R

22 (10): 4128-4130 Oct 1989


Polyvinylmethylether-Cross-Polystyrene-Semi-Interpenetrating Networks - Synthesis, Orientation Behavior, Phase-Behavior and Water Permeability
Felisberti MI, Abetz V, Krieger V, Stadler R, Cantow HJ
Abstracts Of Papers Of The American Chemical Society

197: 16-Poly Apr 9 1989



13 (2): 163-169 1985