Volume 8 Issue 3

The concept of dry surface treatment for paper coating applications has been available for more than ten years. Different from conventional coating methods such as extrusion coating and suspension coating, dry surface treatment involves a combined process of non-contact deposition of coating materials and surface smoothening of the coated paper. Pronounced features of this concept include avoidance of the need for paper drying and elimination of various negative consequences related to rewetting of the paper with water, etc. However, to date the concept has not been commercialized. Some significant challenges remain. Commercializable technologies for production of size-controllable coating particles and their electrostatic deposition onto paper are the key. Reconsidering this interesting concept may at a minimum shed light on the technological advancement in the area of pulp and paper.

Wheat straw pulp can be considered to be one of most important raw materials for specialty and functional paper products. Bleaching sequences involving laccase and xylanase were applied to bleach wheat straw pulp. The bleached pulp properties after a sequence of xylanase (X), laccase (L), and extraction (E), i.e. XLE, were compared with those of LE and LEX sequences. It was found that the XLE bleaching sequence was the most suitable sequence for laccase and xylanase synergetic biobleaching. The bleaching results of OXLEQP and OQP beaching sequences (where O stands of an oxygen stage, Q indicates a chelation stage, and P means peroxide) were compared. For a specific target brightness level of over 80% ISO, XL pretreatment was found to save 28.6% of the H2O2 requirement and increase the viscosity by 6.7% compared with the OQP bleaching sequence. It was also found that synergetic biobleaching could decrease the consumption of refining energy. There were no detectable adsorbable organic halides found in the biobleaching effluents.

The aim of the present study was to determine the surface roughness of heat-treated Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis L.), Uludağ fir (Abies bornmülleriana Mattf.), and sessile oak (Quercus petraea L.) wood material samples following planing by the cutters of a horizontal milling machine. The samples that were heat-treated at 140 ºC or 160 ºC for 3, 5, or 7 hours were then processed by star blades or razor blades, which are the most frequently used blade types in a milling machine. The surface roughness of the samples was determined by a touch (spined) scan device (TIME TR200), as indicated by the ISO 4287 principle. The results of the study indicate that heat treatment decreases the surface roughness value of the wood material and a significant difference in surface roughness cannot be detected between planing using the razor blade or the star blade.

Xylan, the major component of hemicellulose in hardwoods and various grasses, has great potential for bio-refinery applications such as the production of energy and high value-added chemicals. A convenient and environment-friendly catalytic process for the conversion of xylan into furfural in ultrapure water using chromium-loaded perovskite-type oxides as the solid catalyst has been investigated. The crystalline and morphologies of the catalysts were studied by X-ray diffraction analysis (XRD) and scanning electron microscope analysis (SEM), and the reactions were optimized by varying different parameters. It was found that LaCo0.8Cu0.2O3 modified with 1.5wt% chromium had the highest catalytic activity in the transformation of xylan to furfural at a temperature of 433 K in a 1:600 weight ratio of xylan to hyperpure water for 10 h; the corresponding yield was 21.2% for furfural. Furthermore, a possible mechanism for the dehydration of xylan to furfural using Cr-LaCo0.8Cu0.2O3 as a catalyst is proposed.

Specific Edge Load (SEL) and Specific Energy Consumption (SEC) are nowadays the most popular parameters for defining the intensity of pulp refining. As a result, these factors are widely used in industrial practice. The purpose of this research was to determine limitations connected with use of these parameters during bleached kraft pulp refining. Performed tests showed that, despite keeping the SEL and SEC at constant level, changes of pulp refiner consistency always modified the character of the refining process. Obtained results showed that neither SEL nor SEC are fully reliable parameters to describe and to control the refining process.

This work explores the use of mechanical (MP), thermomechanical (TMP), and chemi-thermomechanical (CTMP) pulps from orange tree pruning fibers (OPF) as reinforcing elements of polypropylene (PP) composites. Due to the nature of the natural fibers, the use of a coupling agent is needed to attain a good interface and to prevent fiber slippage from the matrix. The main objective of the present work was to investigate the orientation factor, the interfacial shear strength, and the intrinsic strength of the OPF. Coupled and non-coupled composites were formulated and tested, optimizing the coupling agent content with the objective of maximizing the tensile strength of the composites. Hirsch and Kelly-Tyson models and the Bowyer-Bader methodology were used to compute the micromechanic properties. The contribution of subcritical, supercritical fibers, and matrix were also calculated.

A simple one-step method was developed for rapid separation and quantification of the linear xylo-oligosaccharides (XOS) and cello-oligosaccharides (COS) mixtures by using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). By exploiting small ion-exchange behavioral differences of various oligosaccharide components on the CarboPac PA200 column, a two-stage binary gradient elution program of NaOAc-NaOH solution was established. Subsequently, nine linear oligomers were separated simultaneously and readily within 30 min, in the order of: xylobiose, cellobiose, xylotriose, xylotetraose, cellotriose, xylopentaose, cellotetraose, xylohexaose, and cellopentaose. The method was applied successfully in the analysis and determination of different lignocellulosics processing products. The system provides a convenient and powerful analytical tool for technical research and development on polysaccharide components bioconversion in lignocellulosic biomass processing.

The effect of filler modification using methacrylic acid (MAA) on polypropylene (PP)/cocoa pod husk (CPH) composites was studied. The performances of unmodified and modified PP/CPH composites were analyzed for torque development, tensile properties, and thermal properties. The presence of MAA increased the stabilization torque of the PP/CPH composites. The tensile strength and modulus of the modified PP/CPH composites were improved compared to unmodified PP/CPH composites, but the elongation at break was reduced. The crystallinity and thermal stability of the PP/CPH composites increased after modification with MAA. All the composite property changes were due to the improvement in filler-matrix adhesion and this was confirmed by scanning electron microscopy (SEM).

Bio-fibers have been used for some time to reinforce thermoplastic composites; such structures are being used in a variety of commercial applications. In this study, wood fiber and flax fiber were used to reinforce high-density polyethylene (HDPE) formed by extrusion. The flexural, tensile, and impact resistance properties of the resulting flax fiber/wood fiber/HDPE (F/W/HDPE) composites were measured and modeled as a function of the volume fraction of flax fiber. Finally, the correctness of the modified model was verified. Based on the measurement data, the volume fraction of flax fiber was shown to play an important role in determining the mechanical properties of these composites. With increasing flax fiber volume fraction, the flexural strength, tensile strength, tensile modulus of elasticity, and impact resistance of the composites generally increased. However, the flexural modulus decreased. Based on the rule of mixtures (ROM) model, two coefficients were introduced and a new curve-fitting model was established based on measurements of macrostructure. Compared with the traditional ROM model, the new model developed in the present study could describe the flexural strength, tensile modulus, and impact strength of F/W/HDPE composites more accurately.

Loofah sponge was activated by thermochemical esterification between the carboxyl groups of citric acid and hydroxyl groups of cellulose to introduce free carboxyl groups, which were further reacted with lipase amino groups with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as the condensing reagent. This resulted in loofah sponge–immobilized lipase. Under the optimized immobilization conditions, the highest activity of immobilized lipase per gram of dry carrier was found to be 45.8 U/g. The immobilized lipase exhibited maximum activity at 40 °C, pH 8.0, while the optimal temperature and pH for the free lipase were 37 oC and 7.5, respectively. The immobilized lipase showed better thermal stability, storage stability, and reusability than free lipase.