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In this study, the contributions of light scattering and extra-loss mechanisms to the total losses and to the differential mode attenuation of the guided modes are quantified for three different few-mode fibers. The tested fibers have the same modal content but different refractive index profiles, namely step, trapezoidal and parabolic. It is demonstrated that a trapezoidal index profile is a good compromise between low attenuation, low differential mode attenuation while maintaining large effective index differences between modes so as to reduce mode coupling. [ABSTRACT FROM AUTHOR]

ABSTRACT The mechanism of reducing light scattering in isotactic polypropylene ( i-PP), through the addition of so-called clarifying agents, is studied with small-angle light scattering (SALS) and scanning electron microscopy (SEM). The clarifying agents used in this study depict monotectic phase behavior with i-PP, crystallizing in a relatively narrow concentration range in a nanofibrillar network, providing an ultrahigh nucleation density in the i-PP melt. It is found that the clarifying effect, a dramatically increased transparency and reduced haze, that occurs within the aforementioned additive concentration range, coincides with a change in morphology from strongly scattering spherulites to shish-kebab-like crystalline structures, as evidenced by in situ SALS measurements and confirmed by SEM images. A simple scaling law, relating the diameter of the shish-kebab structures to the fibril diameter and volume fraction of the clarifying agent is proposed, suggesting that the performance of a (fibril-forming) clarifying agent will improve by reducing the fibril diameter and/or increasing the volume concentration of the clarifying agent. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 865-874 [ABSTRACT FROM AUTHOR]

While it is known that the aorta stiffens with location and age, little is known about the underlying mechanisms that govern these alterations. The purpose of this study was to investigate the relationship between the anisotropic biomechanical behavior and extracellular matrix microstructure of the human aorta and quantify how each changes with location and age. A total of 207 specimens were harvested from 5 locations (ascending n = 33, arch n = 38, descending n = 54, suprarenal n = 52, and abdominal n = 30) of 31 autopsy donor aortas (aged 3 days to 93 years). Each specimen underwent planar biaxial testing in order to derive quantitative biomechanical endpoints of anisotropic stiffness and compliance. Quantitative measures of fiber alignment and degree of fiber alignment were also generated on the same samples using a small-angle light scattering (SALS) technique. Circumferential and axial stiffening occurred with age and increased from the proximal to distal aorta, and the abdominal region was found to be more stiff than all others ( p ≤ 0.006). Specimens from donors aged 61 and above were drastically more stiff than younger specimens ( p < 0.001) and demonstrated greater circumferential compliance and axial stiffening ( p < 0.001). Fiber direction for all ages and locations was predominantly circumferential ( p < 0.001), and the degree of fiber alignment was found to increase with age ( p < 0.001). Our results demonstrate that the aorta becomes more biomechanically and structurally anisotropic after age 60; with significant changes occurring preferentially in the abdominal aorta, these changes may play an important role in the predisposition of disease formation (e.g., aneurysm) in this region with age. [ABSTRACT FROM AUTHOR]

The blends of poly(butylene terephthalate) (PBT) with thermoplastic elastomer (TPE) at a blending composition of 10-30 wt.% TPE were prepared with an objective to enhance impact toughness of PBT. Two different grades of PBT were selected based on carboxyl end group and viscosity. Melting behavior, mechanical properties, morphology, and rheology of the blends were studied. At all levels of TPE, PBT showed negligible changes in its melting and crystallization temperature; however, percentage crystallinity decreased with an increase in the amount of thermoplastic elastomer. The notched as well as unnotched Izod impact strength of PBT increased with the incorporation of TPE, the increase being about 47% (unnotched) and 54% (notched) with low molecular weight PBT and 18% (unnotched) and 70% (notched) with high molecular weight PBT at 10% TPE level. The tensile strength and tensile modulus of the blends decreased steadily as the weight percent of TPE increased. Analysis of the tensile data using predicted theories indicated that at TPE levels of 30 wt.%, the blends cannot take excessive stress because the interfacial adhesion is lowered. Small angle light scattering (SALS) studies of the samples indicated the decreased rate of crystallization and, hence, an increase in spherulitic radius in the presence of TPE. The increasing incorporation of TPE in PBT/TPE blends increased the shear thinning behavior and hence eased processability. [ABSTRACT FROM AUTHOR]

The effect of nanoCaCO3 on crystallisation behaviour of linear low density polyethylene (LLDPE) was investigated through time resolved small angle light scattering (SALS). The results indicate that the spherulite size of LLDPE is influenced in the presence of nanoCaCO3. In case the LLDPE and composites were crystallised at room temperature, the spherulite size of LLDPE composites is smaller than that of LLDPE. Also, the contents of the nanoCaCO3 (20·0–30·0 wt-%) could influence the structure of spherulite. The spherulite size of LLDPE is also influenced by the crystallisation temperature. When the crystallisation temperature is increased to 85°C, the spherulite size of LLDPE is remarkably affected by the contents of nanoCaCO3. At isothermal crystallisation temperature of 85°C, the crystallisation induction time of LLDPE is greatly shortened in the presence of nanoCaCO3. Furthermore, there is an orientation fluctuation emerging in the early stage of crystallisation in LLDPE containing 2·0 wt-% nanoCaCO3. [ABSTRACT FROM AUTHOR]

In attempt to pursue easy understanding about 1) wide angle X‐ray diffraction (WAXD), 2) small angle X‐ray scattering (SAXS) and 3) small angle light scattering (SALS) under polarization, teaching methods in this manuscript are focused on the concept that quantitative analysis above three phenomena are developed from a unified fundamental equation EE* (E: scattering amplitude, E*: the conjugate complex). The graduate students studying material science can understand the approach based on mathematical knowledge within undergraduate educational curriculum. This approach refers to two important points associated with the different developments. The first is the different wave lengths between X‐ray and visible light associated with different photon energy. When an incident X‐ray beam is entered in the polymer material, electrons in atoms behave as free electrons because of high photon energy. On the other hand, when visible light with low photon energy is entered, electrons of atom cause vibration on bottom of the potential box. These different electron behaviors emphasize to provide the different scattering modes of X‐ray and visible light. The second is the commentary about branching point about the mathematical treatments concerning X‐ray diffraction and scattering amplitude in spite of a unified equation represented by Equation (II‐1). This is explained in terms of focusing element scales. The diffraction and scattering in most of the textbooks have been written individually by different authors and then the descriptions have been never focused on the branching point. [ABSTRACT FROM AUTHOR]

In the recent studies on chitosan hydrogels, it was found that understanding both rheological and structural properties plays an important role in their application. Therefore, a combination of two independent techniques was applied to investigate micro- and macroscopic properties of chitosan colloidal system. Studies on viscous properties, as well as the sol-gel phase transition process, were performed using rheological methods coupled with the small angle light scattering (SALS) technique. Based on the anisotropy of scattering patterns obtained during rotational shear tests, it was found that the chitosan solution reveals two different behaviors delimited by the critical value of the shear rate. Below a critical value, chitosan clusters are deformed without breaking up aggregates, whereas after exceeding a critical value, chitosan clusters apart from deformation also breakup into smaller aggregates. The values of the radius of gyration determined by applying the Debye function allow one to state that with an increase of chitosan concentration, molecule size decreases. An analysis of the light scattering data from the temperature ramp test showed that with an increase of temperature, the level of polymer coil swelling increases. Simultaneously, the supply of thermal energy leads to a neutralization of the charge of chitosan chains. As a consequence, the formation of intermolecular links occurs and a gel structure is formed. [ABSTRACT FROM AUTHOR]