فهرست مطالب

  • Volume:3 Issue:2, 2014
  • تاریخ انتشار: 1393/07/18
  • تعداد عناوین: 6
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  • Natural Fiber-cement Composites in Comparison to Traditional Construction Materials
    F.Mohammadkazemi Pages 108-110
  • Hamid R. Taghiyari, * Afsaneh Kalantari, Amir Ershad, Langroudi Pages 111-118

    Effect of wollastonite nanofibers on biological resistance of historical paper against Aspergillus niger was studied. Specimens from A4 papers were also prepared for comparison purposes. Paper specimens were dipped in aqueous nanowollastonite (NW) with 10, 20, 30, and 40% concentrations and compared with control specimens. In order the nanofibers be fixed on paper specimens, 5% of polyvinyl acetate (PVA) resin was added to all nanosuspensions. Moreover, in order to find out the effect of PVA on fungal growth, a separate set of specimens was prepared dipped in a 5% resin solution, without nanowollastonite content. Results clearly demonstrated the preventing effect of wollastonite nanofibers on the growth of A. niger, resulting in significant decrease in weight loss as NW-content increased. It was concluded that as to the mineral, non-toxic, and non-acidic nature of wollastonite, it can effectively be used for paper preservation and conservation purposes. In this regard, NW-content of 20% is recommended to the industry to both achieve a high level of protection against A. niger, and keep the preservation costs to the minimum level.

    Keywords: Biological resistance, Fungal degradation, Mineral materials, Paper, Wollastonite nanofibers
  • Jia Geng Boon, Rokiah Hashim*, Othman Sulaiman, Wan Noor Aidawati Wan Nadhar, Chow, Yang Lee, Salim Hiziroglu, Tomoko Sugimoto, Masatoshi Sato, Mahamad Hakimi Ibrahim Pages 119-130

    Oil palm trunk particleboard without synthetic adhesive has been introduced as one of the potential green technology products as an alternative to the synthetic resin bonded particleboard. The chemical constituents of the lignocellulosic materials are important in allowing particles to achieve self bonding. The main objective of this study was to evaluate the influence of starch content on the physical and mechanical properties, as well as some biodegradation activities including termite decay and soil burial decay of the particleboard without synthetic adhesive. Internal bonding strength, modulus of rupture, thickness swelling, and soil burial were performed according to British Standard and European Standard. The termite decay on specimen was evaluated with Microtermes gilvus. Addition of starch into specimens resulted in adverse effect on thickness swelling but improved mechanical properties of the samples. However, removing starch containing in particles showed insignificant effect on mechanical properties of the specimens. Weight loss of specimens exposed to termites was not affected by starch content statistically. However, soil buried test samples had significant weight loss.

    Keywords: Particleboard without synthetic adhesive, Oil palm trunk, Starch
  • Savita Dixit*, Smita Nair Pages 131-144

    Lignin is a major component of plant cell walls that is essential to their function. However, the strong bonds that bind the various subunits of lignin, and its cross-linking with other plant cell wall polymers, make it one of the most important factors in the recalcitrance of plant cell walls against polysaccharide utilization. Lignin restricts the degradation of structural polysaccharides by hydrolytic enzymes, thereby limiting the bioconversion of forages and fibrous crops into liquid fuels and other industrial products. Over the past decade it has become apparent that the pretreatment of lignocellulosic materials to remove or modify the lignin, hence altering the metabolic malleability of lignification, provides potential for engineering the troublesome polymer to be more amenable to bioprocessing. The knowledge of the structure of the lignin polymer, including the strong binding between its various subunits, is thus important to develop appropriate pretreatment methods for lignin modification and/or removal. Acylation in lignin subunits provides a valuable distinguishing feature between monocot and dicot plants. A range of acylated monolignols, notably monolignol γ-acetates, γ-hydroxybenzoates, and γ-p-coumarates are known to be lignin precursor ‘monomers’ (monomer conjugates). Generally, in monocots, the monolignols are preacylated by p-coumaric acid (pCA) whereas in dicots the lignins are acylated by p-hydroxybenzoate. However, the Aracacae family shows similarity with many of the dicots in containing p-hydroxy benzoate instead of p-coumarate as the units acylating the lignin. Hence there is differential distribution of lignin acylating groups across monocot families, which is the subject of present study.

    Keywords: lignin, pCA, p, hydroxybenzoates, Monocots, Py, GC, MS, TMAH, HSQC, DFRC
  • Protibha Nath Banerjee Pages 145-154

    The hemicelluloses from sugarcane bagasse were sequentially extracted with steam treatment and alkali. The hemicellulose from steam treatment was found to contain galacto- arabinoxylans while alkali extraction yielded predominantly linear arabinoxylans. The isolated hemicelluloses were found to vary considerably in branching pattern confirmed from different spectroscopic and chemical methods. The hemicellulose from steam treatment was found to be more branched compared to those isolated after alkali treatment. The present study also showed a promising sequential extraction for isolating arabinoxylan hemicelluloses with different degree of branching, molar mass and functional group from sugarcane bagasse. Consequently, products with a high aggregated value could be developed using this xylan-rich fraction as an ingredient for industrial products.

    Keywords: Steam treatment, Sugarcane bagasse, Methylation analysis, degree of branching, alkaline peroxide
  • Yi Yang, * Shiping Jin, Xuenong Duan, Suyi Huang, Haiping Yang Pages 155-168

    During pyrolysis of tobacco rob (TR), the operating parameters such as the temperature, the heating rate, residence time, and particle size affect the process and result of the pyrolysis. Some of these parameters have been closely considered, but the particle size of TR is often ignored. In this study, the size of TR particle was considered as a major factor in determining the mass loss in thermogravimetric analysis (TGA) and product yield and composition at different reactor temperatures in the fixed-bed reactor. The TGA results showed that the conversion rate increased and the activation energy decreased with a decrease in particle size. The experiments demonstrated that fuel gas yield increased with a decrease in particle size, while char and tar yield decreased. Smaller particle sizes resulted in higher H2 and CO contents. Minimizing the size of raw materials is an alternative method to improve the gas quality of TR pyrolysis. The increase of gas yield was attributed to the decomposition of char and tar vapor as temperature increased. Moreover, the performances of the shredder for the breakage of the TR, such as the effect of the rotor velocity and hydraulic pressure on product size distribution was investigated. The results showed that with hydraulic pressure increasing, size distribution of product was finer. When hydraulic pressure was constant, the products size distribution was coarser with increasing rotor velocity.

    Keywords: Pyrolysis, Kinetic, Tobacco rob, Particle size