Research Articles

In the present communication, the effect of positional density on the DC electrical conductivity of bamboo fibres was studied. A comparative study was made between the DC conductivity behavior of bamboo fibres taken from upper and lower portions of bamboo. Four samples from each portion going from centre to periphery were taken. Bamboo fibers taken from the upper portion were less dense, hence showing lower values of DC conductivity. In spite of the lower portion of bamboo being more dense, it showed higher values of DC conductivity, which is attributed to moisture content. Bamboo fibres from centre to periphery were taken from the strips cut at 2 mm distance from centre. The DC conductivity increased from centre to periphery. A theoretical model was developed and verified with the experimental results. It was also found that experimentally determined σdc values of bamboo fibres taken from different radial locations from center to periphery were in agreement with those values obtained from the proposed equation.

In order to obtain the adhesion force of fiber in a paper sheet easily, the relationships between internal bonding strength (IBS) and surface lignin content of masson pine CTMP treated with peracetic acid (PAA) have been investigated with XPS technique, and the surface morphology of fibers was also imaged by AFM. The results showed that the extent of lignin covered on the fiber surface was two times as high as that of whole pulp lignin, and the IBS was inversely proportional to surface lignin. The relationship between IBS and lignin coverage was formulated based on the experimental data. The mutual adhesion forces, cellulose-to-cellulose and lignin-to-lignin, were calculated using these equations, and the results were 28.69 mN/m and 2.487mN/m, respectively.

A chemo-mechanical method was used to prepare cellulose nanofibrils dispersed uniformly in an organic solvent. Poly(ethylene glycol) (PEG 1000) was added to the matrix as a compatibilizer to improve the interfacial interaction between the hydrophobic poly(lactic acid) (PLA) and the hydrophilic cellulose nanofibrils. obtained by solvent casting methods from N,N-Dimethylacetamide (DMAc) were characterized by tensile testing machine, atomic force microscope (AFM), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). The tensile test results indicated that, by adding PEG to the PLA and the cellulose nanofibrils matrix, the tensile strength and the elongation rate increased by 56.7% and 60%, respectively, compared with the PLA/cellulose nanofibrils composites. The FT-IR analysis successfully showed that PEG improved the intermolecular interaction, which is based on the existence of inter-molecular hydrogen bonding among PLA, PEG, and cellulose nanofibrils.

In this study, the effect of pine cone ratio on wettability and surface roughness of particleboards was examined. Contact angles of water on the produced samples were measured with a goniometer. The surface roughness of the samples was determined with a fine stylus tracing technique. Particleboards made from 100% wood particle had the lowest average contact angle (95.6°), but the highest was for the particleboards containing 50% pine cone (116.3°). Average surface roughness was higher for samples containing a higher amount of pine cone in the mixture. The smoothest surface (9.77 μm Ra) was observed when panels were produced using 100% wood particles. On the other hand, the roughest surface (15.50 μm Ra) was found for the samples containing 50% cone particles in the mixture. Rmax and Rz parameters had similar trends to the Ra values. Increasing the pine cone ratio in the mixture negatively affected the contact angle and surface roughness parameters of the particleboard.

A series of 4- alkyoxybenzoyloxypropyl cellulose (ABPC-n) samples was synthesized via the esterification of hydroxypropyl cellulose (HPC) with 4-alkoxybenzoic acid bearing different numbers of carbon atoms. The molecular structure of the ABPC-n was confirmed by Fourier transform infrared (FT-IR) spectroscopy and 1H NMR spectroscopy. The liquid crystalline (LC) phases and transitions behaviors were investigated using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and refractometry. It was found that the glass transition (Tg) and clearing (Tc) temperatures decrease with increase of the alkoxy chain length. It was observed that the derivatives with an odd number of carbon atoms are non-mesomorphic. This series of ABPC-n polymers exhibit characteristic features of cholesteric LC phases between their glass transition and isotropization temperatures.

A study has been carried out to evaluate physical and flexural properties of composites made by areca fibers with a randomly distributed orientation of fibers. The extracted areca fibers from the areca husk were alkali treated with potassium hydroxide (KOH) to get better interfacial bonding between fiber and matrix. Then composites were developed by means of a compression molding technique with varying process parameters, such as fiber condition (untreated and alkali treated), and fiber loading percentages (50% and 60% by weight). The developed areca fiber reinforced composites were then characterized by physical and flexural tests. The results show that flexural strength increases with increase in the fiber loading percentage. Compared to untreated fiber, significant change in flexural strength has been observed for treated areca fiber reinforcement.

The objective of this research was to investigate the utilization of olive mill sludge (OMS) as an alternative to wood in the manufacture of the medium density fiberboard (MDF). The MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from various mixtures of hardwood fiber/dried OMS flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (by weight) percents, respectively. With increasing OMS flour content, the flexural properties of the panels, modulus of rupture and modulus of elasticity, decreased by 31.0% and 29.2% as compared to panels without OMS flour, respectively. However, the water resistance was improved by the addition of the OMS flour up to 20 wt % content. For example, the thickness swelling and water absorption values of the panels containing 20% OMS flour were 17.3% and 59.5%, while they were found for the panels without OMS flour as 21.5% and 75.6%, respectively. The findings obtained in the study showed that the OMS was capable of serving as lignocellulosic raw material in the manufacture of the MDF.

Experimental laminated veneer lumbers (LVLs) from rotary peeled I-214 (Populus x Euramericana) and two Populus deltoides I-77/51andS.307-26 fast growing hybrid poplar clones were manufactured with a melamine urea formaldehyde (MUF) adhesive successfully. Two Populus deltoides clones that are grown in Turkey were used for the first time in LVLs manufacturing. The results showed that clone types affected physical and mechanical properties of LVLs. Populus deltoides clones had better physical and mechanical properties compared to Populus x Euramericana clonedue to their higher density and fiber length values. S.307-26 clone had the highest and I-214 had the lowest properties among three hybrid poplar clones. The physical and mechanical properties of LVLs were higher than those of solid woods. This increase may be due to compaction factor (densification), manufacturing techniques, and the use of adhesives. The degree of contribution of solid wood properties to the LVLs’ properties was explained by using a contribution factor. Two Populus deltoides clones were found to be more suitable for LVLs manufacturing compared to Populus x Euramericana clone.

In the present study, classical statistical tool Response Surface Methodology (RSM) was adopted for the optimization of process variables in the bioconversion of pretreated sugarcane bagasse into ethanol by cellulase and Candida wickerhamii MTCC 3013 based on Central Composite Design (CCD) experiments. A 23 five level CCD with central and axial points was used to develop a statistical model for the optimization of process variables such as incubation temperature (25 – 45°) X1, pH (5.0 – 7.0) X2,and fermentation time (24 – 120 h) X3. Data obtained from RSM on ethanol production were subjected to analysis of variance (ANOVA) and analyzed using a second-order polynomial equation, and isoresponse contour plots were used to study the interactions among three relevant variables. Maximum response for ethanol production was obtained when applying the optimum values for temperature (33°C), pH (5.7), and fermentation time (104 h). Maximum ethanol concentration (4.28 g/l) was obtained from 50 g/l pretreated sugarcane bagasse at the optimized process conditions in aerobic batch fermentation. Various kinetic models such as Modified Logistic model, Modified Logistic incorporated Leudeking – Piret model, and Modified Logistic incorporated Modified Leudeking – Piret model were evaluated and the constants were predicted.

Sodium titanate nanobelt was synthesized by treating titanium dioxide hydrothermally in concentrated sodium hydroxide solution. The product was characterized by SEM analysis and zeta potential measurement. It served as a microparticle to constitute a microparticle retention system with cationic polyacrylamide (CPAM), while the microparticle system was employed to induce the flocculation of kaolin clay. The flocculation behavior of kaolin clay in such a system was investigated by using a photometric dispersion analyzer connected with a dynamic drainage jar. It was found that the sodium titanate nanobelt carried negative charges and had a lower zeta potential at higher pH. It gave a large synergistic flocculation effect with CPAM at a very low dosage, and showed higher flocculation effect with CPAM under neutral and weak alkaline conditions. A suitably high shear level was helpful for the re-flocculation of clay by sodium titanate nanobelt. The clay flocculation induced by CPAM/titanate nanobelt system demonstrated high shear resistance and also generated dense flocs.