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Fourier transform Raman spectroscopy shows considerable promise as a new characterization technique for molecules which contain chromophores which absorb in the visible region, the region where conventional Raman measurements are made. With the use of near-infrared excitation, spectra in the absence of fluorescence and resonance enhancement are obtained. These advantages can be further enhanced if the collection of data using this technique becomes routine, requiring a level of complexity comparable to that of conventional Raman scattering. Toward that end, the implementation of a 90° scattering geometry in our FT-Raman measurements was undertaken, and the results are shown to be at least comparable to those obtained with the use of reflective optics in a 180° geometry. A number of results on both liquids and solids have also been obtained in order to compare FT-Raman with conventional scanning Raman measurements.

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Block copolymers represent a potentially new class of materials for integrated optics. Before these materials can be used as optical waveguide materials, however, their optical waveguiding properties need to be well understood. In this paper, lamellar-forming block copolymer waveguides are treated and modeled as ideal multilayer structures in which the lamellae are oriented parallel to the substrate and superstrate interfaces. A computer program based on an N-layer waveguide formalism is used to calculate the propagation constants and plot the optical field intensity distributions of some sample diblock and triblock copolymer thin-film waveguides. In a block copolymer thin film, individual block copolymer domains can have anisotropic optical properties due to chain stretching, in the case of coil-coil block copolymers, or due to the presence of a liquid crystalline block, in the case of rod-coil block copolymers.As a result, optical anisotropy of the layers is also treated in the waveguide formalism. Theoretical waveguide calculations show that block copolymer films with a domain size smaller than about A/5 behave optically like homogeneous uniaxial films. Consequently, block copolymers represent a convenient way of making waveguides with a controlled birefringence. In contrast, block copolymer films with a domain size larger than about U3 but less than the wavelength of light are found to preferentially segregate the light into the high refractive index domains. When the low-index layer is at the air interface, only the high-order modes are supported and a greater segregation of the light can be achieved. ABC triblock copolymer films, in which the refractive index of the B and C blocks is larger than that of the A block, are found to exhibit even better confinement of the light into the high-index regions. The optical waveguiding properties predicted for large domain size block copolymers are not seen in single slab homopolymer waveguides and may have potential device applications.

Knowledge of the permeability tensor in liquid composite molding is important for process optimization. Unfortunately, experimental determination of permeability is difficult and time consuming. Numerical calculation of permeability from a model reinforcement can circumvent experimentation. However, permeability predictions often rely on a model reinforcement that does not accurately mimic the actual microstructure. A rapid, nondestructive technique called optical coherence tomography (OCT) can image the microstructure of a composite in minutes. Actual microstructural information can be then used to improve the accuracy of the model and therefore the predicted permeability. Additionally, the influence on fiber volume fraction and microstructural variability on permeability can be systematically studied.In this work, binary images were generated from the low contrast OCT data through image de‐noising, contrast enhancement and feature recognition. The resulting data were input to a lattice‐Boltzmann model for permeability prediction. The influence of the fiber volume fraction, tow surface area, average mean free channel path, and variable microstructure are discussed in terms of their individual and synergistic effects on permeability. The calculated axial and transverse permeabilities from the images show very good agreement with the experimental values.

Exterior and interior automotive applications of TPO (thermoplastic polyolefin) resins, which are, often, composed of a paint coating over an injection‐molded TPO, have increased interest in the surface chemistry and physics of TPOs. Specifically, the interface system composed of base‐coat paint/adhesion promoter/TPO is of primary importance in controlling the paint adhesion to the TPO. The major, active component in the adhesion promoter is a chlorinated polypropylene (CPO). A theoretical model based on phase thermodynamics and diffusion kinetics resulted in a prediction that the TPO/CPO interface should have a lower bound thickness of about 11 nm and an upper bound of about 400 nm. A battery of experimental strategies to characterize this interface system was discussed. Techniques used were transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning transmission X‐ray microscopy (STXM). The near‐surface morphology of both unpainted and painted, injection molded TPO plaques exhibited ethylenepropylene rubber particles close to the surface, i.e. within the first 0.1–0.8 micrometer of the TPO surface, and no “overlayer” of transcrystalline polypropylene at the surface of the TPO. Each of these microscopic methods showed that the adhesion promoter/TPO interface was very sharp. The thickness of this interface was measured with respect to the interdiffusion of the CPO and TPO by STXM. The STXM measurements yielded an apparent interface thickness between the adhesion promoter and TPO of 340 ± 80 nm. This was in good agreement with the theoretical predictions.