Volume 8 Issue 1

A new nickel activation process was developed for metalizing the carbon fiber (CF) surface with electroless nickel plating. The oxidation and activation processes were examined using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometry (EDS), and X-ray Diffractometry (XRD). XPS analysis showed that HNO3 oxidation improved the O/C ratio of the CF surface, which resulted in an increase in the amount of oxygen-containing groups. As activation time increased, both Nio cluster and Ni-P deposits increased. More than 50 mg of Nio clusters formed on the surface of 1g CF. SEM observations illustrated that particles and island-like shapes were developed from the Nio cluster, which helped to initiate the electroless nickel-plating on the CF surface. A continuous and compact coating with a thickness of about 2 to 3 μm was obtained. EDS results showed that the nickel and phosphorus content in the deposits was 97.34 wt.% and 2.66 wt.%, respectively. XRD indicated that the Ni-P coating was crystalline and the maximum deposition on 1 g CFs was as high as 9000 mg. As the results of the observations reveal, the activation method is a feasible alternative to Pd activation.

The chemical composition of the lipophilic extractives in the hexane extracts from grey alder bark, knotwood, and cones has been investigated by gas chromatography and gas chromatography-mass spectrometry. The efficiency of two extraction methods was compared. The highest amount of lipophilic extractives (about 9% of o.d. material) was observed in grey alder cone, while the lowest (about 3%) was found in knotwood. The three different morphological parts of alder showed significant differences not only in the content but also in composition of extractives, namely fatty acids, triglycerides, and triterpenes. The main identified compounds were triterpenoids (lupen-3-one, lupeol, betulone, betulinol, and betulinic acid) in bark, and triglycerides in cones. The major group in knotwood was free fatty acids (mainly linoleic acid, 18:2).

Because of its energy and mechanical properties, babassu shell is a promising energy crop for the future. Its production potential in Brazil is estimated at 6.8 million tons of fruits/year. The aim of this study was to evaluate the effects of torrefaction on the main energy and mechanical properties of Orbignya speciosa (Babassu). Three different torrefaction temperatures (220, 250, and 280°C) and two different durations (15 and 30 minutes) were employed. The influence of sample orientation was taken into account. The results showed that the energy properties of babassu are greatly improved during heat treatment. Torrefaction also led to uniform resistance to babassu shell compression. It was found that low temperature treatment was sufficient to envisage grinding and babassu use in pulverulent form.

Bamboo has received increased attention as a biomass material because it is fast growing and has good mechanical properties. But bamboo is very vulnerable to mold fungi, which greatly limits its applications. In this paper, bamboo was firstly hydrothermally treated at 140 °C by three different treatments: with water only, NaOH, and NaAc aqueous solution, then heat treated at relatively mild conditions (180 °C). Subsequently, the mold resistance of bamboo before and after the two-step heat treatment was investigated. The mechanism of mold resistance was analyzed by a bamboo chemical component analysis, FTIR spectroscopy. The results showed that strong degradation of hemicelluloses by heat treatment could inhibit mold growth to some extent. Moreover, the modification of lignin and the creation of phenolic compounds in the bamboo could prevent or slow down fungal growth.

Copper azole type B (CAz-B) preservative and polyphosphatic carbamate (PPC) fire retardants were impregnated in succession into green (97% MC) and kiln-dried (18% MC) Japanese cedar (Cryptomeria japonica (L.f.) D.Don) lumber by the passive impregnation method to prolong the period of lumber use by increasing its resistance to fire and biological degradation. Lumber was dried with a kiln or by air-drying. Total chemical retention, penetration, leaching, decay resistance (JIS K 1571), and fire retardancy (ISO 834-1 standard, 20 minutes) tests were performed according to the mentioned standards. Preservative retention was higher in the green lumber (4.97 kg/m3) compared with the kiln-dried (4.88 kg/m3) lumber. However, fire retardant retention was similar for both lumber types (107 and 111 kg/m3). Leaching was higher in kiln-dried lumber (21.8%) compared to air-dried lumber (14.4%), although there were no significant differences in the decay resistance test between these two lumber types. The fire performance of both lumber types was similar in the fire resistance test. Therefore, the passive impregnation method can be used effectively for impregnation of both preservatives and fire retardants into wood.

The longitudinal compressive and multi-directional bending properties after hydrothermal treatment of juvenile and mature elm wood were analyzed. Wood chemical composition and X-ray diffraction analyses were conducted in order to investigate the different properties of the juvenile and mature wood. Scanning electron microscopy was used to observe the wood’s microstructure during longitudinal compression. The results indicated that both juvenile and mature wood could bend multi-directionally and that their relative cellulose crystallinities increased after hydrothermal treatment. The hydrothermal-treated juvenile wood contained more hemicellulose with unstable net-linked polysaccharide and condensed lignin, higher relative crystallinities degree than did mature wood, and more spaces formed by the extractive separation of mature wood. The longitudinal compressive and bending performances of the juvenile wood were worse than those of mature wood. The relationship between variations of stress and strain was separated into two stages, both of which displayed linear increases. However, the stage after the proportional ultimate stress increased slowly and smoothly, confirming the formation of some folds in the wood cells.

Five soluble polysaccharide fractions were sequentially extracted with water, EDTA, Na2CO3, 4% KOH, and 14% KOH solutions at room temperature for 4 h from cell wall material of rabbiteye blueberry (Vaccinium ashei) fruits, and their physicochemical properties were examined. The sequential treatments yielded a total 36.02% soluble polysaccharides of the dry cell wall material. HPAEC and spectroscopy (FT-IR, NMR) analyses indicated that water-, EDTA-, and Na2CO3-soluble polysaccharide fractions were mainly composed of pectins, followed by lower amounts of arabinogalactans and glucans, while the two KOH-soluble fractions were mainly composed of hemicelluloses. Homogalacturonan was proven to be the predominant component in the isolated blueberry fruit pectic substance. The isolated blueberry fruit hemicelluloses could be defined as a linear β-(1→4)-linked-xylopyranosyl, in which xylose was the predominant neutral sugar (69.98 to 77.16%), followed by lower amounts of galactose, glucose, arabinose, and mannose.

Effects of different resination techniques relative to the mechanical properties of commercially produced thick medium density fiberboard (MDF) were investigated. The amount of urea-formaldehyde resin (11 wt%) applied to the wood fibers was gradually decreased in the blowline (11, 10.5, 10, and 9.5 wt%), while it was gradually increased in the short-retention blender (0, 0.5, 1, and 1.5. wt%). The internal bond strength of the MDF boards considerably improved as the amount of the resin applied to the fibers in the short-retention blender was increased to 1.5 wt%. In particular, the increase in the IB strength was most pronounced as the resin content increased from 1 to 1.5%. The edge and face screw withdrawal resistances increased by 7.7 and 7.9% as the amount of the resin applied to the fibers in the blender was increased. Similar values were also observed for the flexural properties. Overall, the total resin content in the production of thick MDF can be decreased as blender resination, a means of post-dryer resin addition, is incorporated into the blowline resination technique.

Cellolignin, a by-product from the wood processing industry, was studied as a new, eco-friendly adsorbent for the removal of methylene blue cationic dye from aqueous solutions, using a batch adsorption procedure. Experimental data were processed in order to study the equilibrium, thermodynamics, and kinetics of methylene blue adsorption onto cellolignin. Between the two studied isotherm models (Freundlich and Langmuir) the Langmuir model better described the equilibrium adsorption data at temperatures higher than 25 °C; the mean free energy (E) values obtained from the Dubinin-Radushkevich isotherm model show that the sorption of dye occurs via surface electrostatic interactions with the active sites of the cellolignin. The equilibrium data were used to calculate the free energy, enthalpy and entropy changes, and isosteric heat of adsorption (ΔHX). Results confirm the feasibility and the endothermic nature of the adsorption process, suggesting that adsorption is a physico-chemical process. The isosteric heats of adsorption indicated energetic heterogeneity of adsorption sites and possible interactions between the adsorbed dye molecules. Kinetic assessment suggests that the adsorption process followed a pseudo-second order model and the rate-limiting step may be the binding of dye onto the adsorbent surface. The diffusion models show that intraparticle diffusion is not the sole rate-limiting step; the external mass transfer also influences the adsorption process in its initial period.

Cellulosic fibre of oil palm empty fruit bunches (EFB) were used as a raw material for acid hydrolysis using mineral acids (H2SO4 and HCl) to produce reducing sugar at moderate temperature and atmospheric pressure. Experiments were carried out to investigate the effect of the hydrolysis parameters, including acid concentration, temperature, and reaction time, on the total reducing sugar (TRS) yield with the aid of response surface methodology (RSM). The preliminary hydrolysis studies of the EFB fibres showed that the presence of lignin in the fibres significantly affected the TRS yield. The maximum predicted TRS yield using H2SO4 was 30.61% under optimal conditions: acid concentration of 5 N, temperature of 139.65 oC, and reaction time of 4.16 h. For the hydrolysis using HCl, the maximum predicted TRS yield is 39.81% under optimal conditions: acid concentration of 4.63 N, temperature of 133.7 oC, reaction time of 2.05 h.