Carbon polymer matrix effects

Sugawara, A., Nishimura, T., Yamamoto, Y., Inoue, H., Nagasawa, H. and Kato, T. (2006) Self-organization of oriented calcium carbonate/polymer composites effects of a matrix peptide isolated from the exoskeleton of a crayfish. Angewandte Chemie International Edition, 45, 2876-2879. 

Besides zeolites and traditional silica, carbon molecular sieves have been investigated as dispersed phases. Mixed-matrix membranes have been created using carbon molecular sieves dispersed in polyetherimide (Ultem) and Matrimid, separately. These mixed-matrix membranes displayed an increase in both permeability and selectivity over their neat polymer counterparts." The effect of trace amounts of toluene impurity in the feed stream of these carbon-polymer membranes was tested, and the membranes showed promising stability over time against the impurity. Zeolite-carbon mixed-matrix membranes have recently been developed where the carbonized polymer matrix is derived from a pure Matrimid membrane." These mixed-matrix membranes double the CO2/CH4 selectivity of the pure carbonized Matrimid membranes tested but lose over half of their productivity in the process. While these properties are well above Robeson s upper bound, other researchers have achieved better separation properties using only pure carbonized Matrimid membranes. ... 

The mechanism of antioxidant action on the oxidation of carbon-chain polymers is practically the same as that of hydrocarbon oxidation (see Chapters 14 and 15 and monographs [29 10]). The peculiarities lie in the specificity of diffusion and the cage effect in polymers. As described earlier, the reaction of peroxyl radicals with phenol occurs more slowly in the polymer matrix than in the liquid phase. This is due to the influence of the polymeric rigid cage on a bimolecular reaction (see earlier). The values of rate constants of macromolecular peroxyl radicals with phenols are collected in Table 19.7. 

Composite-based PTC thermistors are potentially more economical. These devices are based on a combination of a conductor in a semicrystalline polymer—for example, carbon black in polyethylene. Other fillers include copper, iron, and silver. Important filler parameters in addition to conductivity include particle size, distribution, morphology, surface energy, oxidation state, and thermal expansion coefficient. Important polymer matrix characteristics in addition to conductivity include the glass transition temperature, Tg, and thermal expansion coefficient. Interfacial effects are extremely important in these materials and can influence the ultimate electrical properties of the composite. 

Various investigations have considered the effects of titanate treatments on melt rheology of filled thermoplastics [17,41]. Figure 10, for example, shows that with polypropylene filled with 50% by weight of calcium carbonate, the inclusion of isopropyl triisostearoyl titanate dispersion aid decreases melt viscosity but increases first normal stress difference. This suggests that the shear flow of the polymer is promoted by the presence of titanate treatment, and is consistent with the view that these additives provide ineffective coupling between filler particles and polymer matrix [42]. 

One of the problems encountered in the entrapment of activated charcoal in a polymer matrix is the blinding-off of the pores of the charcoal, thus inactivating it. Because the pores of the carbon are responsible for its ability to adsorb organics, any pores that are filled or coated with a polymer matrix reduce its effectiveness. Conventional treatments involve blending the carbon into an acrylic latex and then applying the slurry to a reticulated foam. Upon drying, a coalescence encapsulates the carbon. 

These polar transformation products and sulfur oxides (SO2, SO3) arising in the ultimate stages of the transformation process are formed in trace amounts in the aged polymer matrix. Volatile products may be sources of undesirable organoleptic problems. This limits the use of organic thiocompounds in odor-sensitive applications. Organic S-proto-nic acids 85, 86 deactivate basic stabilizers (HAS). The peroxidolytic effect of 85, 86 is reduced in the presence of some antiacids or fillers, e.g., calcium carbonate. 

Generally, the thermal stability of the composites was improved by the addition of the CNTs, which may be attributed to the following combined effects (1) the uniformly dispersed carbon nanotubes presumably provided thermo-oxidative stability to the polymers in the vicinity of the tube surfaces (2) the enhanced thermal conductivity of the composite can facilitate heat transport and thus increase its thermal stability (81) (3) it is possible that the formation of compact chars of CNTs and polymer matrix during the thermal degradation is beneficial to the improvement of thermal stability of the composites (82). 

---