Bonding Quality of Chemically-Modified Soybean Protein Concentrate-Based Adhesives in Particleboards from Rice Husks

The aim of the present study was to upgrade the bonding quality and water resistance of medium-density particleboards based on rice husks (RH) as a wood substitute and soybean protein concentrate (SPC) as the binder via chemical modification of SPC. Alkali (A), citric acid (CA) and boric acid (BA) were used to modify proteins and the carbohydrate complex in SPC. The effect of chemical treatment performed on SPC was followed by Fourier transform infrared, differential scanning calorimetry, thermo-gravimetric analysis and initial apparent viscosity measurements. Board properties were evaluated in terms of internal bond (IB) and physical properties. Results revealed that boards bonded with SPC treated with boric acid, exhibited the highest IB and the lowest water absorption and thickness swelling at 2 and 24 h, due to cross-linking reactions with exposed OH-groups in the amorphous region of cellulose of RH. Results demonstrate that boric acid-modified–SPC-bonded boards met the requirements of IB recommended by the US Standard ANSI A208.1-2009 for M1, MS, M2 and M3-grade medium-density particleboards but failed to pass the thickness swelling required. This issue of BSPC-RH boards is compensated for by the benefit of being formaldehyde-free which makes them suitable for indoor applications.     

Beam tests of composite steel-concrete members: A three-dimensional finite element model

Modern construction makes frequent use of composite steel-concrete beams for bridge and building applications. This paper describes a three-dimensional finite element model in which all components forming the composite member are modelled by means of solid elements. The proposed approach is developed using the commercial software Abaqus and is able to model the composite response without requiring information from push-out tests commonly performed to define the constitutive relationship for the shear connectors. All materials are assumed to behave in a nonlinear fashion. Contact between the elements is simulated using surface-to-surface and embedment techniques. The adequacy and accuracy of the proposed modelling approach are validated against experimental results available in the literature on simply-supported and continuous beam tests with both solid and composite slabs.     

Kinetics of 4-nitrophenol biodegradation in a sequencing batch reactor

In this paper, the biodegradation process of 4-nitrophenol (4NP) in a sequencing batch reactor has been investigated. Kinetic tests have been carried out on biomass grown on mixed substrate (4NP plus biogenic substrate) both in the presence of a biogenic substrate fraction in the feed and with 4NP as the sole carbon source. Removal kinetics for all tests is well described by the typical substrate inhibition pattern as predicted by the Haldane equation. In both sets, estimated kinetic parameters are very similar: no beneficial effect of the biogenic fraction is observed on the 4NP removal while increasing trend of 4NP maximum removal rate with the 4NP/COD(TOT) ratio in the feed has been observed. This finding has been modelled by estimating the fraction of the total biomass involved in 4NP biodegradation as a function of 4NP concentration in the feed. High removal rates, short acclimation times and good settling characteristics of produced sludge (observed during the whole working period) confirm the suitability of periodic systems in enhancing the bacterial potentialities for biodegradation of xenobiotic compounds.     

Post-yield compressed semicrystalline poly(butylene terephthalate): energy storage and release

Post yield deformation of semicrystalline poly(butylene terephthalate) (PBT) is studied by differential scanning calorimetry (DSC) measurements on compressed specimens after unloading. In particular, the effects of strain level, loading-unloading rate, and deformation temperature are analyzed. DSC traces indicate that a remarkable fraction of the mechanical work of deformation (in the range from 25 up to 62%) is stored in the material after unloading. Final strain dependence of stored energy values for specimens deformed up to 40% follows the general S-shaped trend observed for many amorphous and semicrystalline polymers. The ratio of the stored energy to the mechanical work of deformation (ΔU_ST/W) is decreasing as the final deformation level increases. For a given final strain level, the amount of energy stored in specimens deformed under T_g increases as either loading or unloading rates increase: in particular, both ΔU_ST and ΔU_ST/W values are linearly increasing with the logarithm of loading rate. On the other hand, energy storage for specimens deformed at T_g results to be practically independent from the loading rate. Moreover, as the deformation temperature increases from 25 to 100 °C, ΔU_ST values markedly decrease, while the ratio ΔU_ST/W is almost constant around an average value of about 51%.     

Reactions of cellulose and wood superficial hydroxy groups with organometallic compounds

Various lignocellulosic substrates, including microcrystalline cellulose, pinewood and hemp fibres, were treated with triethylaluminium and triethylboron in suspensions, in non‐swelling media. Chemical and spectroscopic analyses show that coupling surface reactions took place between one or two metal‐to‐carbon (Mt–C) bonds and the OH groups of the natural polymers. The remaining unreacted Mt–C bonds were exploited to graft numerous molecular structures derived from alcohols and amines. The occurrence of the second reaction was proved by Fourier‐transform infrared spectroscopy, elemental analyses, X‐ray photoelectron spectroscopy and contact angle measurements. Copyright © 2004 Society of Chemical Industry     

De‐hairing activity of extracellular proteases produced by keratinolytic bacteria

The depilatory activity of keratinolytic bacteria was investigated. Three keratinolytic bacteria isolated from feather waste were tested for their ability to grow in mineral medium containing bovine hair as sole carbon, nitrogen and energy source. The strains kr2, kr6 and kr10 grew well on bovine hair, producing proteolytic activity as judged by assay with azokeratin as substrate. The proteolytic enzymes from all three strains showed similar pH and temperature optima. Strain kr2 showed mainly serine‐type protease activity, whereas kr6 and kr10 enzymes showed metalloprotease characteristics. The culture supernatants were used as crude enzyme preparations for depilatory studies on bovine pelts. All three strains were efficacious in promoting de‐hairing. Microscopic analysis revealed that the epidermis was completely removed and the absence of hair in follicles was observed. Proteases of keratinolytic bacteria were efficient in promoting depilation of bovine pelts. Enzymatic de‐hairing represents a suitable alternative to the conventional tannery process, with the benefit of avoiding environmental pollution. Copyright © 2003 Society of Chemical Industry     

Recent Catalytic Advances in the Chemistry of Substituted Furans from Carbohydrates and in the Ensuing Polymers

In this review, an overview is given on the last development of catalytic methods for the preparation of substituted furans from carbohydrates and ensuing polymers. The review starts with the recent aspects in the synthesis of some key furan monomers in the presence of solid catalysts. In the second part, selected examples are given of polymerization systems leading to furan-based materials with promising properties, thus constituting a serious alternative to petroleum-based counterparts. Finally, a short examination is given on what could be the future of furan chemistry with the recent development of ionic liquids as solvents.