Recent work has shown that poly(3-hexylthiophene) (P3HT) and the surface-functionalized fullerene 1-(3-methyloxycarbonyl)propyl(1-phenyl[6,6])C(61) (PCBM) are much more miscible than originally thought, and the evidence of this miscibility requires a return to understanding the optimal morphology and structure of organic photovoltaic active layers. This manuscript describes the results of experiments that were designed to provide quantitative thermodynamic information on the miscibility, interdiffusion, and depth profile of P3HT : PCBM thin films that are formed by thermally annealing initial bilayers. It is found that the resultant thin films consist of a 'bulk' layer that is not influenced by the air or substrate surface. The composition of PCBM in this 'bulk' layer increases with increased PCBM loading in the original bilayer until the 'bulk' layer contains 22 vol% PCBM. The introduction of additional PCBM into the sample does not increase the amount of PCBM dispersed in this 'bulk' layer. This observation is interpreted to indicate that the miscibility limit of PCBM in P3HT is 22 vol%, while the precise characterization of the depth profiles in these films shows that the PCBM selectively segregates to the silicon and near air surface. The selective segregation of the PCBM near the air surface is ascribed to an entropic driving force.

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In this research, polypropylene fibers and nonwoven samples were produced with the commercial samples of nanoclay additives in semi-commercial processing machinery. Influence of two different types of nanoclay additives, at different add on levels on processing, structure and morphology of nonwovens is studied. The WAXD and DSC data showed some change in crystallinity and melting behavior indicating changes in the fiber morphology towards improved mechanical properties. Presence and extent of exfoliation of nanoclay in the polymer was verified using transmission electron microscopy (TEM). TEM image reveals intercalated and exfoliated morphology of nanocomposites. About 10 to 20 % increase in tensile strength and modulus in both machine and cross directions is observed. This increase in strength is not accompanied by a decrease in breaking elongation as is the case for most of the fibers. Similarly 10 to 25 % increase in web stiffness and 20 to 80 % increase in web burst strength was observed. Furthermore there is improvement in other performance properties of the spunbond nonwovens. SEM images showed improved thermal bonding in the presence of nanoclay additives. The main advantage of this process is that these fabrics can be produced without any need for change in the processing equipment. This study has shown that by using a suitable compounding method, nanoparticle reinforced fibers and fibrous products with improved performance properties can be produced using conventional production machinery.

The effect of nanoclay additive on the structure, morphology, and mechanical properties of polypropylene meltblown webs is reported here for the first time. Effect of nanoclay on the meltblown processing, resultant fiber web structure, and properties are discussed. Combination of wide-angle x-ray diffraction, differential scanning calorimetry, and transmission electron microscopy were used to determine the nature of clay dispersion in the polypropylene fiber matrix and resultant morphology. Transmission electron microscopy micrographs revealed nanolevel dispersion of the additive in the fiber web. Clay additive did not offer any benefit as far as the mechanical properties of the meltblown web are concerned. Meltblown web samples with nanoclay had higher variability in web structure, high air permeability, high stiffness, and lower mechanical properties.

We report morphology and mechanical properties of natural nanoclay incorporated spunbond polypropylene composite webs. Nanocomposite spunbond webs were produced with up to 5 wt % natural nanoclay additives on Reicofil V R -2 spunbond line. Influence of nanoclay on the resin rheological properties, processibility, and mechanical properties of webs were studied. Wide angle X-ray diffraction and transmission electron microscopy analysis were used to investigate the nanocomposite morphology. Intercalated and flocculated morphology was observed for all the concentrates and for all the spunbond fiber webs. The microstructure and polymer morphology in the presence of additives was characterized using a polarized optical microscope. At higher percentage, excess clay platelets were excluded out of the spherulite boundaries. About 20-30% increase in tear strength was observed for webs with up to 2 wt % nanoclay additives. Compared with the control polypropylene spunbond web, nanoclay reinforced samples showed better dimensional stability. Different failure mode was observed for spunbond webs with additives. Spunbond webs with even as low as 1 wt % clay retain their morphology and integrity in bond point after thermal bonding. Nanoclay incorporated spunbond webs showed significant improvements in the stiffness.