Improving the adsorption performance and surface roughening of rayon fibers via enzymatic treatment with cellulase

In recent years, expectations have increased for the development of filters for removing air pollutants. Rayon fibers have rough surfaces and excellent adsorption characteristics. Therefore, rayon is a promising material for such filters. By further roughening its surface, its adsorptivity to substances such as volatile organic compounds can likely be improved. The surface of rayon fibers was roughened via wet spinning carried out by adding oleic acid to a raw viscose. As a result, porous fibers containing several pores with a diameter of about 0.5–1.0 µm were obtained. A weight reduction treatment of the porous rayon fibers with cellulase, a cellulose-degrading enzyme, resulted in the appearance of several streaks and asperities on their surfaces. To investigate the adsorption behavior of the rayon fibers after cellulase treatment, dye adsorption was examined using an aqueous methylene blue solution. The porous rayon fibers adsorbed much more dye than the regular fibers. In addition, the fibers absorbed more dye after treatment with cellulase than without treatment in both fibers. The deodorizing function of the rayon fibers was also investigated using ammonia gas. The porous rayon fibers treated with cellulase had a very high deodorizing effect. In the proposed study, rayon fibers (which are porous inside) were treated with cellulase, and their surface was found to be considerably rough.

Interfacial Characterization by Pull-Out Test of Bamboo Fibers Embedded in Poly(lactic acid)

In this work, the apparent shear strength at the interface between a bamboo fiber and the surrounding poly(lactic acid) (PLA) matrix is quantified. A method for processing pull-out test samples within a controlled embedded length is proposed and the details of the test procedure are presented, along with a critical discussion of the results. Two series of samples are considered: untreated and mercerized bamboo fibers from the same batch, embedded in the same polyester matrix. Electron and optical microscopy are used to observe the fiber-matrix interface before and after the test, and to identify the failure mode of each sample, especially as regards the occurrence of fibrillation in the fiber bundles. The values of apparent interfacial shear strength are calculated only for regular fibers successfully pulled out from the matrix, and reported with their statistical variations. Mercerization, whose efficiency was proven by Fourier Transform InfraRed (FTIR) spectroscopy, did not appear though to improve the quality of the interface (τapp = 7.0 ± 3.1 MPa for untreated fibers and τapp = 5.3 ± 2.4 MPa for treated fibers).

Classification and rigidity of totally periodic pseudo-Anosov flows in graph manifolds

In this article we analyze totally periodic pseudo-Anosov flows in graph 3-manifolds. This means that in each Seifert fibered piece of the torus decomposition, the free homotopy class of regular fibers has a finite power which is also a finite power of the free homotopy class of a closed orbit of the flow. We show that each such flow is topologically equivalent to one of the model pseudo-Anosov flows which we previously constructed in Barbot and Fenley (Pseudo-Anosov flows in toroidal manifolds.Geom. Topol. 17(2013), 1877–1954). A model pseudo-Anosov flow is obtained by glueing standard neighborhoods of Birkhoff annuli and perhaps doing Dehn surgery on certain orbits. We also show that two model flows on the same graph manifold are isotopically equivalent (i.e. there is a isotopy of$M$mapping the oriented orbits of the first flow to the oriented orbits of the second flow) if and only if they have the same topological and dynamical data in the collection of standard neighborhoods of the Birkhoff annuli.