Polycarbonate nanocomposites

Crack toughness behavior of MWCNT/polycarbonate nanocomposites was also reported (Xiao et al., 2004 Foster et al., 2005). When 2 wt.% MWCNTs was added into the composites, the resistance to crack propagation was markedly increased compared to pure Polycarbonate. At 4 wt.% MWCNTs, a tough-to-brittle transition has been observed. The attack of crack initiation needs shorter time for nanocomposites with 4 wt.% MWCNT compared to the composites with 2 wt.% MWCNTs, which supports that a tough-to-brittle transition exists in these nanocomposites. 

Satapathy BK, Weidisch R, Potschke P, Janke A (2005). Crack toughness behaviour of multi-walled carbon nanotube (MWNT)/polycarbonate nanocomposites. Macromol. Rapid Commun. 26 1246-1252. 

Figure 2.2. Schematic of synthesis of CNT polycarbonate nanocomposites by solution mixing approach. Reproduced from reference 19 with permission from American Chemical Society.

Eitan et al. (1) reported the synthesis of polycarbonate nanocomposites with untreated (as received) and epoxide treated nanocomposites. A 70% increase in the tensile modulus in the nanocomposites as compared to pure polymer with 5 wt% of the untreated nanotubes was observed as shown in Figure 2.12. However, this increase was increased to 95%, when same amount of epoxide treated nanotubes were used thus indicating the significance of interfacial interactions on the composite properties. 

Figure 2.12. Enhancement of the tensile modulus of the polycarbonate nanocomposites as a function of nanotube content in the composites, while using as received (AR) and epoxide treated (EP) multi walled nanotubes. Reproduced from reference 1 with permission from Elsevier.

Figure 2.15. Electrical conductivity of polycarbonate nanocomposites by using different fractions of either unmodified nanotubes or H202 treated nanotubes. Reproduced from reference 54 with permission from Elsevier.

P. J. Yoon, D. L. Hunter, and D. R. Paul, Polycarbonate nanocomposites. Part 1. Effect of organoclay structure on morphology and properties. Polymer, 44 (2003), 5323-39. 

W. S. Chow and S. S. Neoh, Dynamic mechanical, thermal, and morphological properties of silane-treated montmorillonite reinforced polycarbonate nanocomposites. Journal of Applied Polymer Science, 114 (2009), 3967-75. 

Yoonessi, M., Gaier, J.R., 2010. Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites. AcsNano4, 7211—7220. 

Polycarbonate nanocomposites were prepared by melt compounding and the effect of organoclay structure on color formation was examined. Darker colored nanocomposites were obtained for samples containing the organoclay with double bonds in the hydrocarbon tail, compared to those with saturated organic modifiers. The presence of both hydroxy-ethyl groups and tallow tails led to the most important color changes [19]. 

Yoon PJ, Hunter DL, Paul DR. Polycarbonate nanocomposites Part 2. Degradation and color formation. Polymer 2003 44 5341-5354. 

Patterson, P.H., Sloan, J.M., Hsieh, A.J. Photo degradation mechanisms of layered silicate/polycarbonate nanocomposites. In Annual Technical Conference of the Society of Plastics Engineering, p. 3936 (2002)... 

Sloan, J.M., Patterson, P., Hsieh, A. Mechanisms of photo degradation for layered silicate-polycarbonate nanocomposites. Polym. Mater. Sci. Eng. 88, 354-355 (2003)... 

Wang Z, Ciselli P, Peijs T (2007) The extraordinary reinforcing efficiency of single-walled carbon nanotubes in oriented poly (vinyl alcohol) tapes. Nanotechnology 18 455709 Abbasi S, Carreau PJ, Derdouri A (2010) Flow induced orientation of multiwalled carbon nanotubes in polycarbonate nanocomposites rheology, conductivity and mechanical properties. Polymer 51 922... 

The nanotubes were first oxidized in nitric acid before dispersion as the acidic groups on the sidewalls of the nanotubes can interact with the carbonate groups in the polycarbonate chains. To achieve nanocomposites, the oxidized nanotubes were dispersed in THF and were added to a separate solution of polycarbonate in THF. The suspension was then precipitated in methanol and the precipitated nanocomposite material was recovered by filtration. From the scanning electron microscopy investigation of the fracture surface of nanotubes, the authors observed a uniform distribution of the nanotubes in the polycarbonate matrix as shown in Figure 2.3 (19). 

In Polymer-Functionalized Nanoparticles and Nanocomposites. EFTEM was used to evaluate me covalent bonding of polymer coating on nanoparticles and the nanoparticle dispersion, as in a polycarbonate/alumina nanocomposite [120]. 

Polymeric nanocomposites are a class of relatively new materials with ample potential applications. Products with commercial applications appeared during the last decade [1], and much industrial and academic interest has been created. Reports on the manufacture of nanocomposites include those made with polyamides [2-5], polyolefins [6-9], polystyrene (PS) and PS copolymers [10, 11], ethylene vinyl alcohol [12-15], acrylics [16-18], polyesters [19, 20], polycarbonate [21, 22], liquid crystalline polymers [8, 23-25], fluoropolymers [26-28], thermoset resins [29-31], polyurethanes [32-37], ethylene-propylene oxide [38], vinyl carbazole [39, 40], polydiacethylene [41], and polyimides (Pis) [42], among others. 

To modify polycarbonates and derivatives of polymethyl methacrylate dichloroethane and dichloromethane media are used. To modify pol5winyl chloride compositions and compositions based on phenolformaldehyde and phenolrubber polymers alcohol or acetone-based media are applied. The FS of metal/carbon nanocomposites are produced using the above media for specific compositions. In IR spectra of all studied suspensions the significant change in the absorption intensity, especially in the regions of wave numbers close to the corresponding nanocomposite oscillations, is observed. At the same time, it is found that the effects of nanocomposite influence on liquid media (FS) decreases with time and the activity of the corresponding suspensions drops. 

Thus, to modify compositions with finely dispersed suspensions it is necessary for the latter to be active enough that should be controlled with IR speetroseopy. A number of results of material modification with finely dispersed suspensions of metal/carbon nanocomposites are given, as well as the examples of changes in the properties of modified materials based on concrete compositions, epoxy and phenol resins, polyvinyl chloride, polycarbonate, and current-conducting polymeric materials. 

Polycarbonate modification with supersmall quantities of Cu/C nanocomposite is possible using FS of this nanocomposite which contributes to uniform distribution of nanoparticles in polycarbonate solution. Polycarbonate Actual was used as the modified polycarbonate. The FS of copper/carbon nanocomposite was prepared combining 1.0, 0.1,0.01, and 0.001% of nanocomposite in polycarbonate solution in ethylene dichloride. The suspensions underwent ultrasonic processing. 

To compare the optical density of nanocomposite suspension in polycarbonate solution in ethylene dichloride, as well as polycarbonate and polycarbonate samples modified with nanocomposites, spectrophotometer KFK-3-Ola was used. Samples in the form of modified and non-modified films for studying IR spectra were prepared precipitating them Ifom suspension or solution under vacuum. The obtained films about 100 mcm thick were examined on Fourier-spectrometer FSM 1201.To investigate the crystallization and stmctures formed the high-resolution microscope (up to 10 mcm) was used. 

FIGURE 8.31 Curves of optical density of suspension based on ethylene dichloride diluted with polycarbonate and Cu/C nanocomposite in the concentration to polycarbonate 0.001% (1) and ethylene dichloride (2). 

Comparison of optical density of suspension containing 0.001% of nanocomposite and optical density polycarbonate sample modified with 0.01 % of nanocomposite indicates the proximity of curves character. Thus, the correlation of optical properties of suspensions of nanocomposites and film materials modified with the same nanocomposites is quite possible. 

Examination of curves of sample optical density demonstrated that when the NS concentration was 1% from polycarbonate mass, the visible-light spectrum was absorbed by about 4.2 per cent more when compared with the reference sample. When the nanocomposite concentration was 0.1 percent, the absorption decreased by 0.7 per cent. When the concentration was 0.01 per cent, the absorption decreased in the region 540-600 nm by 2.3 per cent, and in the region 640-960 nm - by 0.5 per cent. 

During the microscopic investigation of the samples the schematic picture of the structures formed was obtained at 20-mcm magnification. The results are given in Figure 8.33. From the schematic pictures it is seen that volumetric structures of regular shape surrounded by micellae were formed in polycarbonate modified with 0.01% Cu/C nanocomposite. When 0.1% of nanocomposite was introduced, the linear structures distorted in space and surrounded by micellae were formed. When Cu/C... 

FIGURE 8.33 schematic picture of structure formation in polycarbonate modified with Cu/C nanocomposites in concentrations 1%, 0.1%, 0.01% (From left to the right), 20-mcm magnification. 

Apparently, the decrease in nanocomposite concentration in polycarbonate can result in the formation of self-organizing stmctures of bigger size. In Ref [3], there is an hypothesis on the transfer of nanocomposite oscillations onto the molecules of polymeric composition, and the intensity of bands in IR spectra which sharply increases even after the introduction of supersmall quantities of nanocomposites. In our case, this hypothesis was checked on modified and non-modified samples of polycarbonate films. 

In Figure 8.34, the IR spectra of polycarbonate and polycarbonate modified with 0.001% of Cu/C nanocomposite can be observed. 

FIGURE 8.34 ir spectra of reference sample (upper) and polycarbonate modified with Cu/C nanocomposites in concentration 0.001% (Lower). 

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