Centrifugally spun poly(ethylene oxide) fibers rival the properties of electrospun fibers

Centrifugal force spinning (CFS), also known as centrifugal spinning, forcespinning, or rotary jet spinning, provides considerably higher production rates than electrospinning (ES), but the more widespread use of CFS as an alternative depends on the ability to produce fibers with robust thermal and mechanical properties. Here, we report the CFS of poly(ethylene oxide) (PEO) fibers made using a spinning dope formulated with acetonitrile (AcN) as the volatile solvent, and we describe the thermal and mechanical properties of the centrifugally-spun fibers. Even though the formation, diameter, and morphology of electrospun and centrifugally-spun PEO fibers are relatively well-studied, the article presents three crucial contributions: the pioneering use of PEO solutions in AcN as spinning dope, characterization of crystallinity and mechanical properties of the centrifugally-spun PEO fibers, and a comparison with the corresponding properties of electrospun fibers. We find that fiber formation occurrs for the chosen CFS conditions if polymer concentration exceeds the entanglement concentration, determined from the measured specific viscosity. Most significantly, the centrifugally spun PEO fibers display crystallinity, modulus, elongation-at-break, and fiber diameter that rival the properties of electrospun PEO fibers reported in the literature.     

Coherence effects in scattering systems of two interacting dipoles at resonance

Coherence effects in the backward-scattering direction, such as enhanced backscattering (EBS) and the appearance of a negative polarization branch (NPB), are investigated for a simple scattering system composed of two dipolelike particles separated by a fixed distance. The influence on these effects of coupling resonances between the particles is analyzed. The appearance of these coherent phenomena (EBS and NPB) and their relationship as a function of the optical properties of the particles (polarizability) and particle separation are also studied.     

Electromagnetic wave scattering from two interacting small spherical particles. Influence of their optical constants, ε and μ

In this research, the influence of the optical constants ε and μ on the scattering patterns of a system consisting of two interacting Rayleigh particles is analyzed. We study specific scattering configurations in which the particles are separated by a fixed distance and where the connecting axis has fixed orientations with respect to the incident electromagnetic field. Multiple scattering effects and how they are affected by the optical properties of the particles are considered.