ABSTRACT:The aim of this study deals with the modification of the chrome tanned collagen (leather) by in situ grafting with 2-ethyl hexyl acrylate (2-EHA) and methacrylic acid (MAC) to improve its dyeability using Amecid Floxine 2GN (C.I. Acid Red 1) and Remazol Black B (C.I. Reactive Black 5). The optimum condition of in situ grafting has been evaluated. FTIR spectra of the ungrafted and the in situ grafted chrome tanned collagen showed that the corresponding band of the acrylate carbonyl ester occurs at 1730 -1735 cm Ϫ1 when compared with the ungrafted ones.The colorimetric data of the in situ grafted and dyed samples exhibited improvement in color shade, dye bath exhaustion, wash and light fastness relative to the ungrafted and dyed ones.
ABSTRACT:Although leather has a number of desirable properties such as thermal stability and fire retardancey, in addition to high toughness, it has a few drawbacks such as weight, high water absorption, poor soil and rot resistance, and nonuniformity. If these defects are overcome, leather's usefulness would be further enhanced and its competitive position with respect to synthetics would increase. This study reports the physical and mechanical properties of buffalo leather after chemical graft copolymerization with ethyl acrylate, butyl acrylate, and 2-ethyl hexyl acrylate using benzoyl peroxide as an initiator. The optimum conditions for grafting (e.g., monomer and initiator concentrations, temperature and time of grafting, and solvent leather ratio) were extensively investigated. The study achieved outstanding properties for buffalo leather in reduction of water uptake after grafting, especially on using 2-ethyl hexyl acrylate and butyl acrylate monomers. FT-IR and solid 13 C-NMR for leather before and after grafting confirmed the grafting process.
The purpose of this study was to formulate the new combined system of acrylic and citric acids, which was prepared by free radical polymerization and esterification reaction at the same time to form citric-acrylate CAC oligomer. The presumable chemical structure of this oligomer and the reaction mechanism were investigated by different spectroscopic tools ( 1 H, 13 C-NMR and ATR-IR), GPC and TGA/ DTA. The effect as masking agent of the eco-friendly oligomer (CAC) in the chrome tanning of the collagen and the pickling of the hide was approached by the study of the hydrothermal and mechanical properties of in-situ treated/grafted chrome tanned collagen (hide powder) and pickled hide, respectively. The use of citric acrylate CAC oligomer instead of the traditional strong acids resulted in significant improvement in chrome exhaustion and physical properties of the leather.
This work deals with preparation and characterization of immobilized laccase (Aspergillus sp.) over oxidized multi-walled carbon nanotubes (ox-MWCNTs) via simple mixing technique. The resulting materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscope (TEM) and particle size distribution analysis using dynamic light scattering technique (DLS). The results showed that the TEM images exhibited more separate individual carbon bundles with particle size around of 396 nm after enzyme immobilization rather than the spaghetti-like tubes with size about 180 nm in the case of ox-MWCNTs. Also, the lowering in the zeta potential negative value (-5 mv) proved that the free carboxyl groups at ox-MWCNT surface were decreased after enzyme immobilization. Moreover, the thermal stability was decreased after enzyme immobilization using TGA. These results confirmed that the laccase could be reacted at the side walls of the ox-MWCNTs without structure damage. The biocatalytic effect of the immobilized laccase was investigated after its incubation with silver nitrate solution for 1 and 24 h. It can be concluded that the biocatalytic efficiency of the immobilized laccase could be enhanced after its incubation with silver nitrate solution for 24 h at room temperature relative to the free form. On the other hand, the enzyme stability was improved after immobilization up to 50ºC and at pH 3.0, while no remarkable differences on the activity values were observed for immobilized and free laccases at acidic pH range (4-6).
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