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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Abstract:
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
Polymer
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
Macromolecules
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
PREPARATION
OF LOW-DENSITY POLYETHYLENE COMPOSITES BY UV IRRADIATION
FELISBERTI MI, GIESSE R, DEPAOLI MA
POLYMER BULLETIN
13 (2): 163-169 1985