Volume 7 Issue 2

Tea (Camellia sinensis L.) fruit peel, the main byproduct during the manufacture of tea seed oil, was used as raw material for the recovery of phenolic antioxidants. The effect of ethanol concentration, extraction time, and extraction temperature on total phenolic content (TPC) and ferric-reducing antioxidant power (FRAP) of the extracts from tea fruit peel was investigated. The maximum predicted TPC (47.5 mg GAE/g dry peel) was obtained under the optimum recovery conditions (43% ethanol, 60°C, and 33 min) given by using response surface methodology (RSM). A high correlation (R2 = 0.929, p < 0.01) between TPC and FRAP value was identified by linear regression analysis. Furthermore, gallocatechin (GC) and epigallocatechin (EGC) were found to be the major individual catechins in the extracts from tea fruit peel. Ethanol/aqueous extraction has been presented as an effective method for the recovery of phenolic antioxidants from tea fruit peel.

Under certain conditions involving uneven exposure to weather, stains related to the extractives can reduce the aesthetic appeal of western red cedar in exterior applications such as fence boards, siding, and sidewall shingles. Selected chemical treatments were evaluated for their ability to inhibit the formation of extractives stain. DDACarbonate, alkyl amine oxide, and combinations thereof delayed extractives stain formation in an accelerated field test, with higher loadings having greater effect.

Changbai larch (Larix olgensis Henry) is one of the main plantation species in the northern part of China, but so far its utilization has been limited to solid wood, pulping, and paper products. As part of a national initiative, the objective of this work was to develop a good understanding concerning how stand management practices affect larch wood and veneer properties. To cope with the variation of initial and final stand density, the term “relative thinning intensity (RTI)” was introduced to describe the effect of stand thinning on the resulting wood and veneer properties. Nine representative sample trees each from four stands were harvested, then trimmed and bucked. Six 1.25 m long bolts along the entire tree stem were systematically cut to peel 2.6 mm thick veneers. Clear wood specimens were also sawn from matched bolts for mechanical testing for the purpose of comparison and validation. The correlation between the main tree variables and properties of clear wood and veneer was analyzed, and the influence of RTI on key wood and veneer properties was examined and compared. A good correlation was found in density and modulus of elasticity (MOE) between larch clear wood and veneer, giving an R2 of 0.75 and 0.71, respectively. This indicates that veneering can be potentially used to characterize this larch species. The stand with the lowest RTI had the shortest rotation but yielded the best properties of both clear wood and veneer, which highlights the importance of stand management in terms of thinning.

A woody (eucalyptus (Eu)) and two herbaceous materials (sweet sorghum bagasse (SSB) and sugarcane bagasse (SCB)) were used to evaluate the effect of liquid hot water (LHW) pretreatment on enzymatic hydrolysis of various lignocelluloses. The results showed that enzymatic hydrolysis efficiency of pretreated materials was SCB>SSB>Eu at 5% solids loading, while SSB>SCB>Eu was at 10% and 20% solids loadings. This indicated the enzymatic hydrolysis efficiency of SCB could be influenced by solids concentration. The differences in surface morphology, crystalline structure, and functional groups of pretreated samples were also examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. SEM photographs and crystallinity indexes (CrI) showed that the structural compactness was Eu>SSB>SCB for both of untreated and treated materials. FTIR spectra showed that the conspicuousness of physicochemical changes was SCB>SSB>Eu. The differences in enzymatic hydrolysis efficiency of pretreated materials can be ascribed mainly to the structural differences.

This study investigates the bonding behaviour of Norway spruce wood strands to a surrounding cement matrix. Effects of wood swelling and shrinking during cement curing were studied by using strands of various thicknesses. The deformation of the spruce wood strands and the surrounding cement matrix, as well as the interface between the wood and the cement were examined using Electronic Laser Speckle Interferometry (ESPI) while applying a pull-out load. Sample deformation was transformed to shear strain maps, showing which side of the strand was tightly bonded to the cement matrix. The analysis of the strain maps proved that all strands were tightly bonded to the cement matrix on only one side. No shear deformation was observed on the loosely bonded side, meaning that there was no adhesion on that side between the wood strand and the cement matrix. Manufacturing of strands results in different surface characteristics and surface roughness. Bringing together the ESPI results with the roughness measurements, it was shown that only the comparably rougher surface adheres to the cement matrix. In a cement bonded composite (CBC) made of lignocellulosics to a greater or lesser extent, only half of the contact area is therefore able to transfer load.

Strand board can be manufactured from sawmill residues, branches, and crown wood left in the forest. The thickness swelling of these residues is quite different from that of mature wood and can have a negative effect on the physical and strength properties of strand board. A mixture of these materials and pressing conditions can be optimized by assessing thickness swelling of wood strands after pressing. Individual wood strands conditioned to 12% moisture content were hot-pressed at 105 °C to 50% of their original thickness and conditioned at 20 °C and 33%, 100%, and 0% relative humidity for 72 hours to determine their thickness swelling. A mechanical model consisting of springs and dashpots was superimposed on a stress relaxation curve to determine strain components with a view to predict thickness swelling. The data were interpreted by analysis of variance in conjunction with Fisher’s protected least significant difference method. The results showed a good agreement between measured and predicted thickness swelling of both juvenile and mature wood.

This review describes the state-of-the-art of material derived from the forest sector with respect to its potential for use in the packaging industry. Some innovative approaches are highlighted. The aim is to cover recent developments and key challenges for successful introduction of renewable materials in the packaging market. The covered subjects are renewable fibers and bio-based polymers for use in bioplastics or as coatings for paper-based packaging materials. Current market sizes and forecasts are also presented. Competitive mechanical, thermal, and barrier properties along with material availability and ease of processing are identified as fundamental issues for sustainable utilization of renewable materials.

Several recent series of investigations were conducted on corrugated board performance in the areas of: loaded container endurance in cyclic humidity, predictive models for edge compression strength (ECT), effects of lightweight facings, measurement of transverse shear rigidity, effects of adhesive level, and out-of-plane crushing on ECT. The course of this program prompted exploration and review of several aspects of ECT testing methods: specimen height, test duration, and fixture-clamping effects. In this review, ECT values are shown to be influenced by the combination of the selected testing technique with the specific structural and strength characteristics of the board being tested. The effect of specimen height on selected single wall C-, E-, F-, and N-flute boards is measured and rationalized using a simplified beam-theory approach. Apparent loss of ECT in a C-flute crushed board is explored to determine whether mitigation is possible by selection or modification of testing method. Investigations of platen speed effects on C-flute substantiate previous work. Lightweight facings on A- and C-flute corrugated boards are observed to display localized buckling, which affects the ECT value. An analytical model that combines the measured bending stiffness of the facings and the compression strengths of the fluting and facings provides an improved predictive accuracy and is applied to a series of laboratory and commercial corrugated boards.

The efficiency of optical brightening agents (OBAs), also known as fluorescent whitening agents (FWAs), has long been of interest in the production of uncoated fine paper, particularly in uncoated fine paper grades containing high-yield pulp (HYP). The increasing levels of whiteness and also the increasing HYP substitution in fine papers has made OBA efficiency an important issue. This paper summarizes recent research findings in understanding and enhancing OBA efficiency in fine papers containing HYP, with focus on the main factors affecting OBA efficiency in both wet end and size press application. These factors include the base sheet brightness and whiteness of the pulp, UV competitors, OBA retention, quenching effects, and OBA migration at the size press. Some new technologies to improve OBA efficiency are discussed.

Dyes used in the coloration of textiles, paper, and other products are highly visible, sometimes toxic, and sometimes resistant to biological breakdown; thus it is important to minimize their release into aqueous environments. This review article considers how biosorption of dyes onto cellulose-related materials has the potential to address such concerns. Numerous publications have described how a variety of biomass-derived substrates can be used to absorb different classes of dyestuff from dilute aqueous solutions. Progress also has been achieved in understanding the thermodynamics, kinetics, and chemical factors that control the uptake of dyes. Important questions remain to be more fully investigated, such as those involving the full life-cycle of cellulosic substrates that are used for the collection of dyes. Also, more work needs to be done in order to establish whether biosorption should be implemented as a separate unit operation, or whether it ought to be integrated with other water treatment technologies, including the enzymatic breakdown of chromophores.