Volume 6 Issue 4

A challenge in producing wood-plastic composites (WPCs) with a high wood content using extrusion processes is the poor processability, which gives rise to inadequate properties of the resulting WPC. Plasticizing the stiff wood cell walls can be a strategic response to this challenge. Two thoughts are addressed herein on improving the plasticity of wood particle cell walls: use of ionic liquids or use of low molecular weight organic thermal conductors. An ionic liquid can dissolve the cell wall surface and therefore reduce the stiffness of cell wall during an extrusion process. Organic thermal conductors can be incorporated into the cell wall (bulking) to improve the thermal conductivity, thereby sufficiently softening the lignin, a native plasticizer embedded in the cell walls. The potential issues that may arise as a result of these approaches are also presented and discussed.

In an attempt to explain variations in delignification behaviors among different hardwood species, the kraft pulping delignification rates of Eucalyptus urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, birch, red alder, cottonwood, and acacia were obtained and correlated with their respective lignin chemical structures. Since H-factor for hardwood is calculated based on the softwood activation energy (Ea) value, a comparison between softwood vs. hardwood activation energy was also performed. Lignin was isolated by a modified isolation protocol, using alkaline pretreatment of the wood prior to isolation. The lignin preparations were analyzed via quantitative 13C NMR spectroscopy. Substantial variations were found among the hardwood species studied. A linear correlation between the kraft delignification rate and the amount of syringyl units was found. Activation energy values obtained for kraft pulping of hardwoods were very similar and almost identical to the value obtained for softwood. Birch was the only species with outlier behavior.

1-octadecanol is known to be a highly effective agglomerating agent for nonimpact-printing toners. However, it was found that some xerographic toners did not agglomerate under alkaline conditions. The effect of alkali on the agglomeration was studied with two different toners, one carrying no surface charge and one carrying a negative charge. The effect of the addition of a cationic surfactant on the agglomeration under neutral and alkaline conditions was then studied using two different cationic surfactants. It was found that both toners agglomerated better under neutral conditions than under alkaline conditions. The toner carrying no surface charge agglomerated much better than the toner carrying a negative charge under either alkaline or neutral conditions. The addition of a cationic surfactant greatly improved the agglomeration of the toner carrying a negative charge but had relatively small effect on that of the toner carrying no surface charge. It is recommended that agglomeration of mixed office waste with 1-octadecanol should be carried out under neutral conditions with the addition of a small amount of a cationic surfactant.

The present study deals with the utilization of a cellulosic material, i.e. fungal biomass of Mucor heimalis, for the removal of cadmium from aqueous solution in a batch system. Effects of various parameters such as pH, biomass dosage, contact time, and initial metal concentrations were investigated. The sorption of cadmium followed pseudo-second-order rate kinetics (R2=0.998). Intraparticle diffusion was found not to be the sole rate-controlling step. Thermodynamic studies revealed that the sorption of cadmium was feasible, spontaneous, and exothermic. Various isotherm models viz. Langmuir, Freundlich, Redlich–Peterson, Dubinin-Radushkevich, and Temkin isotherms were applied. The Langmuir and Redlich–Peterson models were found to be in good agreement with experimental data with high R2, low RMSE, and low χ2 values. The Redlich–Peterson isotherm constant g was found to be unity, which implies a good fit to the Langmuir model. The maximum sorption capacity calculated from the Langmuir isotherm was 85.47 mg/g at optimum conditions of pH 6.0, contact time of 35 min, biomass dosage of 1g/L, and temperature of 25 oC.

In this work the multi-factor, non-linear dependencies between main (tangential) FC (N) and normal (radial) FN (N) cutting forces and eight machining parameters by sawing simulation of wood of Pinus sylvestris L. were evaluated. The relationships are graphically illustrated and discussed. Evidence of several contradictions was found relative to results from available literature.

An inexpensive methodology is proposed to identify and locate a single defect within a wooden beam using free a flexural vibration technique. A similar approach has been introduced in the literature based on free longitudinal vibration, which was selected to be a leading frontier for the present research. The flexural vibration technique was tested for five groups of the absolutely clear specimens while holding a manually drilled hole at 0.1, 0.2, 0.3, 0.4, and 0.5 of their total span. The beams were tested in free flexural vibration with both ends in a free condition before and after drilling, and relative shifts of modal frequencies due to the presence of the defects were measured and compared to their mathematically calculated values in a sinusoidal equation. Using the method of least squares, a coincidence factor was developed based on the differences of the measured and calculated shifts of the four initial resonance frequencies where the minimum district of the coincidence factor curves successfully indicated the defected area. Though the longitudinal vibration approach was promising enough to estimate the position of the defect, its combination with the flexural vibration might increase the degree of confidence in the identifications.

The performance of rice husk powder (RHP) filled polypropylene (PP)/ recycled acrylonitrile butadiene rubber (NBRr) biocomposites with and without coupling agent, γ-aminopropyltrimethoxysilane (APS), were investigated. The composites with different RHP filler loading (0 to 30 phr) were prepared in a Haake internal mixer. Mechanical properties, swelling behavior, and water absorption of PP/NBRr/RHP were studied. Increasing RHP loading in PP/NBRr/RHP biocomposites increased processing torque, tensile modulus, water absorption, and swelling in oil but decreased the tensile strength and elongation at break of the biocomposites. The γ-APS treated RHP composites exhibited higher processing torque, tensile strength, and tensile modulus but lower elongation at break when compared to untreated RHP composites. This is due to strong bonding between γ-APS treated RHP filler and PP/NBRr matrices. These findings were well supported by micrographs from the morphology studies. The γ-APS treatment on RHP improved the adhesion between RHP fiber and PP/NBRr polymer matrices, which led to less water and oil absorption into PP/NBRr/RHP/ biocomposites.

Rapeseed waste from biodiesel production was explored as a biosorbent for the removal of Cu(II) and Cd(II) ions from aqueous solutions under batch conditions. The optimum value of the initial pH for the sorption of both metal ions was found to be 4.5 to 5. The efficiency of Cu(II) and Cd(II) removal from aqueous solutions varied from 49% to 91% and from 61% to 97%, respectively, by increasing the rapeseed waste dose from 5 to 30 g L-1. According to the evaluation using the Langmuir equation, the monolayer sorption capacity of copper (II) and cadmium (II) ions on rapeseed waste was found to be 15.43 mg g-1 and 21.72 mg g-1, respectively at 293 K. The batch sorption systems under study were thermodynamically characterized by means of parameters such as ΔG, ΔH, and ΔS. The kinetic parameters derived from the pseudo-first-order and pseudo-second-order equations were calculated and compared.

Waste tyre dust (WTD)/kenaf fibre (Ke) hybrid filler filled natural rubber (NR) compounds having constant 30 phr loading were prepared with increasing partial replacement of WTD by kenaf fibre at 0, 10, 15, 20, and 30 phr. Curing characteristics, mechanical properties, rubber-fibre interaction, and morphology of the NR compounds were studied after the compounds were obtained. The curing characteristics such as t2 and t90 increased with increment of kenaf fibre loading. For MHR, the increasing partial replacement of WTD by kenaf fibre showed increasing MHR value. For tensile properties, the value of tensile strength and elongation at break value decreased with increasing kenaf fibre loading. The values of M100 and M300 increased but then decreased after the addition of 15 phr of kenaf fibre loading. Besides, fatigue life value also showed a decreasing trend with increasing kenaf fibre loading. For rubber-fibre interaction, the values of Qf/Qg showed a small increment with increasing kenaf fibre loading. The SEM micrographs obtained for fractured surface of WTD/kenaf fibre hybrid filled NR compounds supported the results for the mechanical properties.

Environmentally friendly polyurethane (PU) spray foam insulation was prepared by substituting petrochemical polyol with soy-based polyol. The effects of adding wood fiber and water on the cell morphologies were studied. Cell size increased with the presence of wood fiber, but it decreased with an increase of water (H2O). Still, shorter fiber decreased in foam density but increased in cell size and open cell content.