EEA-CB

In order to understand the phenomena behind resistance variations in the conductive polymer composites (CPCs) due to solvent diffiision. Feller et al. [71] have performed sorption exjjeriments with poly (ethylene-co-ethyl acrylate)-carbon black (EEA-CB) and EEA films in the presence of toluene. One main point here was to determine the influence of CB in the diffiision process. The first results showed that, whichever polymer was used, the diffiision coefificiem increased with toluene activity, which indicated plasticization of the material by the solvent. However, it was interesting to note that the plasticization phenomenon was reduced when fillers were introduced into the polymer matrix. It also appeared that the toluene diflfiisivity was about twofold lower in EEA-CB than in EEA, which was certainly due to a hindrance effect of the carbon black particles. In other words, the decrease in toluene solubility was the result of a tortuosity effect due to the morphology of CPC with a dispersion of CB particles, which acted as barrier components and increased the path for toluene molecules inside the composite. 

Moreover, it seemed that the presence of CB in contact with solvent molecules led to an organizing effect in the CPC, allowing more cohesion in the polymer matrix and suggesting the presence of strong interactions between EEA chains and CB resulting from an adsorption process. 

The miscibility behaviors of poly-D(—)(3-hydroxybutyrate) (PHB)/poly(ethylene oxide) (PEO) and PHB/poly(methyl methacrylate) (PMMA) blends have been studied using a chloroform vapor sorption technique [73]. The addition of PEO, which has been reported to be miscible with both PHB and PMMA, did not enhance the compatibility of PHB and PMMA. Polymer-polymer interaction parameters monitored by using the chloroform vapor sorption technique were found to be negative for PHB/PEO, but positive for PHB/PMMA systems. However, the interaction parameters of both systems were changed significantly depending on their composition. 

The PV properties of homogeneous membranes prepared from a polymer blend of PVA with poly(acrylic acid) (PAA) have been investigated using methanol-toluene and ethanol-toluene liquid mixtures [74]. The PV flux was decreased and selectivity increased gradually for all feed mixtures with different compositions as 

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On irradiation the PTC intensities of the LDPE/ EPDM/CB and LDPE/EEA/CB blends increase by several orders of magnitude (Table 11.34). In the case of the LDPE/EPDM/CB blend, the negative temperature coefficient that is seen in the case of the non-irradiated samples, disappears on irradiation. Jia and Chen [1994] suggest that... 

Table 11.34. Effect of irradiation on PTC values of LDPE/EPDM/CB and LDPE/EEA/CB blends [Jia and Chen, 1974]...

EDPE/EPDM/CB EDPE/EEA 1 RT air y, e-(lMeV) s Positive temperature coefficient, crystallinity 28, 29... 

LDPE (melt index = 2.0), EPDM, EEA (ethylene-ethyl acrylate, melt index = 6.0) and CSF carbon black (CB average size ca. 

LDPE/EPDM/CB Blends Jia and Chen [1994] investigated the effect of irradiation on the positive temperature coefficient (PTC) function of LDPE/EPDM and LDPE/EEA (ethylene-ethyl acrylate) blends containing carbon black. They used LDPE, EPDM, EEA and CSF carbon black (Table 11.9) in the desired ratios and mixed them in a two-roU mill in an internal mixer at 130°C for 5 min. The samples were molded under pressure at 160°C for 10 min. 

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