Polypyrrole/PVC blends

Comparing an injected polypyrrole/PVC blend with a granular magnetic material tuned at the same frequency (Figure 8.36), we have measured the reflection coefficient on 2 mm thick samples, and observed a bandwidth of the same order of magnitude. But the surfacic mass of 2.6 kg/m obtained in the case of the blend, reaches 5 kg/m for the granular magnetic material. 

The most studied systems have been polypyrrole/ PVC blends [372-5]. The electrochemical polymerization of pyrrole on a platinum electrode covered with a film of PVC produces a dark-brown, ductile and flexible composite polymer film with an electrical conductivity comparable to polypyrrole (5-50 S cm ), and mechanical properties very similar to PVC. Bargon et al. [373] have observed that the mechanical properties of these PPy/PVC blends can be further improved by the addition of poly(chloroprene) rubber as a plasticizer. 

Jousse, F. Hourquebie, P. Deleuze C. Olmedo, L., "Synthesis and Microwave Characterization of Polypyrrole-PVC Blends", p. 705 in Chiang, L.Y. Garito, A.F. Sandman, D.J. (Eds.), Mat. Res. Soc. Symp. Proc., Vol. 247 Electrical, Optical, and Magnetic Properties of Organic Solid State Materials, Materials Research Society, Pittsburgh, Pennsylvania, USA (1992). 

At the same time, the study of the water content effect in the medium has been performed [127] on a 10% weight polypyrrole in PVC blend. The influence of ferric chloride nature (anhydrous, hexahydrous and anhydrous -F water in the medium) on conductivity has been studied. 

The Bjorklund works [169] lead us to develop a synthesis route in which the polypyrrole grows in the insulating matrix. Different solutions (PVC, polycarbonate, polyphenylene oxide,. ..) or emulsions (PTFE) of insulating polymer have been tested. In the case of PTFE-polypyrrole blend we used a classical oxidising coupling process by FeCl3 [104,127]. Comparative experiments have been performed on granular materials obtained by polypyrrole powder dispersion in an elastomer or an epoxyde resin [127]. 

The PVC/polypyrrole blends have been realised by in situ growth of the polypyrrole in a PVC solution in an organic solvent (nitrobenzene, THF, or cyclopenta-... 

It was not until 1984 and 1985 that we succeeded in comminuting polypyrrol and polyaniline in the melt by means of ultrasound and dispersing them in special polymer blends. Only two years later we were able to report to the world conference on Organic Metals in Kyoto (Japan) that dispersed conductive polymers displayed a conductivity breakthrough at a concentration of less than ten percent by volume in a thermoplastic polymer matrix—for example a polyvinylchloride (PVC), polyester or polyurethane—and could be processed in the form of such blends. 

V. Mano and his coworkers studied the conductivity, thermal, mechanical, and electrochemical properties of PVC/polypyrrole blends. The blends were prepared by oxidative chemical polymerization of pyrrole in the vapor phase in PVC films impregnated with FeCl3. l.R. reflectance spectra snggested that the polymerization occnrred preferentially on the matrix snrface prodncing sandwich type structures. DMA studies suggested a certain degree of miscibility among the polymeric components of the blends (88. Mano et al., 1996). 

A very recent publication by Rinaldi et al. (Rinaldi, 2006) showed that the solid phase photopolymerization of pyrrole in PVC matrix results in the formation of electrically conductive films. The blend obtained has low conductivity and rather poor electroactivity due to the loss of conjugation length of polypyrrole (PPy) provoked by hologenation. Micrographs of ciyofractured surfaces suggested two distinct phases and thermogravimetiic analysis revealed a low thermal stability of the blend. 

A general problem in the synthesis of those composites is the appearance of conductivity gradients in their thickness direction, which are caused by inhomogeneities in the polypyrrole structure, as a result of difficulties in diffusion of the electrolyte across the host polymer. A method for overcoming these problems has been developed by Wang et al. [375]. PPy/PVC composites can significantly improve uniformity in electrical conductivity and resistance to mechanical delamination when a certain amount of electrolyte is mixed with PVC prior to the electrochemical reaction. After electropolymerization of pyrrole in the presence of electrolyte blended PVC for 20 minutes, the conductivity across the film thickness showed more than ten orders of magnitude difference with respect to film obtained from unblended PVC. 

Figure 18.1. Stress-strain curves for pure PVC (solid line), polypyrrole (long dash), and a PVC/polypyrrole blend (short dash) (Reprinted with permission from ref. 19).

Mano, V., Felisberti, M.I., Matencio, T., De Paoh, M.A. Thermal, mechanical and electrochemical behavior of poly(vinyl chloride)/polypyrrole blends (PVC/PPy). Polymer 37, 5165-5170 (1996)... 

FTIR spectroscopy has been applied in the study of polymer blends including Neoprene rubber, chlorosulfonated PE, nitrile rubber, polyvinyl chloride (PVC) containing carbon black and other fillers [86], Nylon 6 inorganic [87], polyhydroxyether sulfone/poly(N-vinyl pyrrolidone) [88], graphite-based low-density polyethylene [89], caprolactone/Nafion blends [90], polybutylene terephthalate/polyamide [91], polyphenylene sulfide/acrylonitrile - butadiene - styrene [92], PMMA/polypyrrol [93], and lower or high performance liquid chromatography (LDPE/HDPE) [94]. 

Some specific recent applications of the GC-MS technique to various types of polymers include the following PE [49,50], poly(l-octene) [51], poly(l-decene) [51], poly(l-dodecene) [51], 1-octene-l-decene-l-dodecene terpolymer [51], chlorinated polyethylene [52], polyolefins [53, 54], acrylic acid methacrylic acid copolymers [55], polyacrylates [56], styrene-butadiene and other rubbers [57-59], nitrile rubber [60], natural rubbers [61, 62], chlorinated natural rubber [63, 64], polychloroprene [65], PVC [66-68], silicones [69, 70], polycarbonates [71], styrene-isoprene copolymers [72], substituted PS [73], polypropylene carbonate [74], ethylene-vinyl acetate copolymers [75], Nylon [76], polyisopropenyl cyclohexane a-methyl styrene copolymers [77], m-cresol-novolac epoxy resins [78], polymeric flame retardants [79], poly(4-N-alkyl styrenes) [80], polyvinyl pyrrolidone [81], vinyl pyrrolidone-methyl acryloxysilicone copolymers [82], polybutylcyanoacrylate [83], polysulfide copolymers [84], poly(diethyl-2-methacryloxy)ethyl phosphate [85], ethane-carbon monoxide copolymers [86], polyetherimide [87], bisphenol A [88], ethyl styrene [89], styrene-isoprene block copolymer [89], polyvinyl alcohol-co-vinyl acetate [90], epoxide thiol [91], maleic acid-propylene copolymer [92], P-hydroxy butyrate-P-hydroxy valerate copolymer [93], polycaprolactams [39,94], PS [95,96], polypyrrole [95,96], polyhydroxy alkanoates [97], poly(p-chloromethyl) styrene [81], polybenzooxazines and siloxy substituted polyoxadisila-pentanylenes [98,99] poly benzyl methacrylates [100], polyolefin blends after ageing in soil [101] and polystyrene peroxide [43]. 

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