Volume 5 Issue 2

Malaysia, especially the Borneo Island state of Sarawak, has a large variety of tropical wood species. In this study, selected raw tropical wood species namely Artocarpus Elasticus, Artocarpus Rigidus, Xylopia spp., Koompassia Malaccensis, and Eugenia spp. were chemically treated with sodium metaperiodate to convert them into plasticized wood (PW). Manufactured plasticized wood samples were characterized using, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing (modulus of elasticity (MOE), modulus of rupture (MOR), static Young’s modulus (Es), decay resistance, and water absorption). MOE and MOR were calculated using a three-point bending test. Es and decay resistance were calculated using the compression parallel to grain test and the natural laboratory decay test, respectively. The manufactured PW yielded higher MOE, MOR, and Es. PW had a lower water content compared to the untreated wood and had high resistance to decay exposure, with Eugenia spp. having the highest resistance compared to the others.

The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose, and glucose. The effects of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study, and the ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid.

The present study deals with the surface modification of Agave americana L. fiber through graft copolymerization of methyl methacrylate under pressure in the presence of ceric ammonium nitrate as redox initiator. The various reaction parameters such as reaction time, pressure, concentration of nitric acid, initiator, and monomer, etc. were optimized to have the maximum graft yield of 13.6%. The grafted fibers were then subjected to the evaluation of different physico-chemical properties such as swelling behavior, solubility, moisture absorption under different humidity levels, resistance to acids and bases, etc. It was observed that swelling behavior, solubility behavior, and moisture absorbance decreased with increase in grafting, whereas resistance to acids and bases increased with grafting. The fibers grafted under the optimized conditions were then characterized by Fourier transform infra-red spectroscopy, scanning electron microscopy, thermogravimetric analysis, and x-ray diffraction techniques.

The objective of this study is to evaluate the effect of décor paper and resin type on physical properties, mechanic properties, and surface quality properties of particleboards coated with décor papers impregnated by using different resin. White oak, New wenge and common maple pattern decor papers impregnated with urea formaldehyde (UF), melamine formaldehyde (MF) and urea-melamine formaldehyde (UF+MF) were used as coating materials. Particleboard surface was laminated with these coating materials by hydraulic press. As a result, specimens coated with MF-impregnated papers showed better performance than those coated with UF and UF+MF-impregnated papers. Resin type and paper pattern affected the physical, mechanical (with exception of tension strength), and surface properties (especially cigarette burn and abrasion) of coated particleboards. Physical and mechanical properties of coated particleboard were significantly improved compared to non-laminated particleboards. It was found that paper pattern affected the surface properties, such as impact, scratch, and abrasion, resistance to staining and cigarette burn. However, it did not change the cracking and steaming properties of the coated samples. After the coating process, it was determined that cigarette burn, abrasion, impact, and scratch performances were among 1 to 3 grade, lp:10-35, Fp:210-340/100-150, and 2 to 5 grade, respectively.

Coastal Bermuda grass (CBG) has been shown to have potential as a biomass feedstock for sugar production. In this study, the effectiveness of ozone pretreatment for CBG to improve the sugar recovery via enzyme hydrolysis was investigated. Raw CBG and autohydrolysis-treated CBG were pretreated with ozone at ozone consumption of 1.8 to 26.4 % (w/w) at room temperature. Lignin degradation and hemicellulose solubilization increased with increased ozone consumption. At 26.4% ozone consumption by weight on CBG the amount of lignin in the CBG was reduced by 34%. Autohydrolysis of CBG increased the reactivity of cellulose, hemicellulose, and lignin with ozone. The maximum total sugar recovery after enzymatic hydrolysis was 32% for a 14.0% consumption of ozone on raw CBG. For CBG samples pretreated with autohydrolysis followed by a 3.1% ozone consumption pretreatment the maximum total sugar recovery after enzyme hydrolysis was 40.1%. Autohydrolysis pretreatment followed by enzyme hydrolysis yielded a 36.4% sugar recovery, indicating that the application and benefits of ozone after autohydrolysis with the conditions studied herein are marginally better than autohydrolysis alone.

Considering the mild degradation strength and the fact that it may be an organic matter reserve for the soil, in the past years lignocellulosic materials have been used as fibrous raw materials in the manufacture of biodegradable nutritive pots for the seedling in vegetable containerized production. This paper analyses the behavior of the nutritive pots madefrom biodegradable composites for the vegetable seedling production process, focusing on their mechanical strength properties and biodegradability. It was found that the biodegradability of composite materials obtained from a mixture of secondary cellulosic fibers, peat, and additives, is strongly influenced by the presence or absence of the rhizosphere effect and the synergistic relations set in the culture substrate between the plant roots and microorganisms, which develop permanently the recycling and solubilization of mineral nutrients. The results showed that the presence in the substrate of some complex populations made by heterotrophic bacteria favors full degradation of the pulp and lignin contained in the substrate and pots composition. Therefore, unlike the reference sample (plant-free), cultivated versions exhibited an intense biodegradation on the account of rhizosphere effect.

Cellulose hydrogels with quaternary ammonium (QA) groups were prepared via the etherification and cross-linking reaction. The structure of the functional hydrogels with QA groups was confirmed with FT-IR. Differential scanning calorimeter (DSC) analysis indicated that there was a large amount of free water in the hydrogels. The hydrogels showed salt-sensitivity behavior, and they also exhibited a strong antibacterial activity toward Escherichia coli.

The durability of Scots pine heartwood has previously been shown to be affected by the industrial drying process of sawn lumber. The durability of heartwood from boards dried at temperatures between 20°C-110°C was studied by measuring the mass loss in a decay test with a brown rot fungus (Coniophora puteana), and the concentration of total phenolics was measured according to the Folin-Ciocalteu (FC) assay. The relation between mass loss and phenolics in dried heartwood showed a weaker negative correlation at lower levels of phenolics as compared to the strong relationship found in a study on heartwood from standing Scots pine trees. Mass loss in dried heartwood showed a weak negative correlation to density. Heating of extractives-rich green sawdust under moist conditions resulted in a reduction of phenolics with temperature up to 180 oC and with increasing time. The concentration of phenolics in heated, green sawdust was higher in extractives-rich pine heartwood than in heartwood with a normal extractives content.

Lignocellulosic fibers from green coconut fruit were treated with alkaline solution (NaOH 10%m/v) and then bleached with sodium chlorite (NaClO2) and acetic acid (CH3COOH). Alkali-treated and bleached fibers were mixed with high impact polystyrene (HIPS) and placed in an injector chamber in order to obtain specimens for tensile tests. Specimens of HIPS/alkali-treated and bleached coconut fiber composites were tested in tensile mode, and the fracture surfaces of the composites were analyzed by scanning electron microscopy. Untreated, alkali-treated, and bleached coconut fibers were analyzed by scanning electron microscopy and X-ray diffraction. Alkaline treatment was effective for removing the extractives and increasing the roughness of surfaces, while the bleaching treatment intensified the effect of alkaline treatment, while increasing the crystallinity index and surface energy of fibers. Results of tensile tests showed that the addition of 30% alkali-treated and bleached fibers reinforcing the HIPS matrix provided considerable changes in the mechanical properties of composites in comparison with the pure HIPS. On the other hand, chemical treatments were not totally effective for improving the adhesion between the fiber and matrix, as was observed in the analysis of the fracture surfaces of composites materials.

Oxygen delignification can be considered to be the most important part of TCF and ECF bleaching sequences because it allows for cleaner production of pulp. During the process, oxygen gets one electron from lignin in the alkaline condition to form some active oxygen species (AOS), including a superoxide anion radical (O2-•), which is crucial for lignin degradation without damage of carbohydrates. The reaction of O2-• on cellulolytic enzymatic lignin (CEL) from Masson pine was studied. The change in active hydroxyl content after reaction with O2-• was investigated using 31P-NMR. After reaction, the aliphatic hydroxyl and uncondensed type phenol hydroxyl contents decreased, but the content of carboxylic group increased in Masson pine lignin. Through the analysis with HSQC-2D13C-H technology, β-O-4 linkages could be cleaved by O2-•, but β-β and β-5 linkages were observed to be more stable; benzaldehyde and cinnamic aldehyde structures could be oxidized to carboxylic acids by O2-•. Guaiacyl units in lignin were more easily degraded than p-hydroxybenzene units.