University of Leoben

About: University of Leoben is a education organization based out in Leoben, Austria. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 2574 authors who have published 6833 publications receiving 134076 citations. The organization is also known as: Montanuniversitaet Leoben & Montanuniversität Leoben.

Review: current international research into cellulose nanofibres and nanocomposites

Abstract: This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.

Linear optical properties of solids within the full-potential linearized augmented planewave method

Abstract: We present a scheme for the calculation of linear optical properties by the all-electron full-potential linearized augmented planewave (LAPW) method. A summary of the theoretical background for the derivation of the dielectric tensor within the random-phase approximation is provided together with symmetry considerations and the relation between the optical constants. The momentum matrix elements are evaluated in detail for the LAPW basis, and the interband as well as the intraband contributions to the dielectric tensor are given. Results are presented for the metals aluminum and gold, where we crosscheck our results by sumrules. We find that the optical spectra can be extremely sensitive to the Brillouin zone sampling. For gold, the influence of relativistic effects on the dielectic function is investigated. It is shown that the scalar-relativistic effect is much more important than spin-orbit coupling. The interpretability of the Kohn-Sham eigenstates in terms of excited states is discussed.