Volume 14 Issue 1

The Fundamental Research Committee (FRC), founded in 1956 to organize regular symposia among pulp and paper scientists, has been aiming to widen access to their archival published proceedings.  The FRC decided that it would be best to make their published work freely available on the web rather than continuing to offer CD versions for sale.  They wanted to work together with an entity having experience with open access publishing.  The FRC has selected BioResources as that entity, based on our 13-year record of open access service to the same branch of science and technology.  BioResources is honored to take on this role and accordingly will henceforth prominently list the “Fundamental Research Symposia Archives” on our web page with links to the FRC content.

As a widely distributed and fast growing graminaceous plant, bamboo has emerged as an important raw material for pulping and papermaking to mitigate the shortage of wood resources, at least in the East Asia region. New technologies such as silicon removal have been developed to overcome the disadvantage of bamboo as a pulping raw material, as well as to improve the quality of bamboo pulp products. The bamboo pulping capacity in China is continuing to increase in the near future.

Forest residues are a potentially important source of renewable energy. They are generated as a byproduct of timber harvesting around the world. To optimize the utilization of such biomass, one must know its physical and chemical properties. This paper presents an analysis of comminuted forest residues from Pinus sylvestris L. They were classified into four size fractions for which three density parameters were established pursuant to relevant standards. The mean bulk density of the fractions amounted to 110 to 190 kg/m3, apparent density 725 to 908 kg/m3, and specific density 1111 to 1350 kg/m3. The findings were compared to the results of previous research on other forms of forest biomass. The measured apparent-to-specific density conversion coefficient was β = 0.64. The elementary composition of forest residues measured in this work differed from that of other biomass types described in literature. In terms of carbon, nitrogen, sulfur, oxygen, and ash content, statistical analysis showed that the two compared types of biomass (forest residues and energy wood chips) formed two separate homogeneous groups, while both of these materials constituted one homogeneous group in the case of hydrogen content. The calorific value of the forest residues was 15.78 ± 0.39 MJ/kg.

Xylitol production from the hemicelluloses of prehydrolysis liquor (PHL) is of practical interest from both economic and environmental standpoints. The removal of the inhibitors, e.g., lignin, acetic acid, and furfural, is the key to improving the conversion of xylose to xylitol when Candida tropicalis fermentation is used. For this purpose, a full chain process involving activated carbon adsorption, ion exchange resin treatment, acidolysis, and fermentation was considered in this work. The results showed that 72.6% of lignin and 67.1% of furfural were removed using an activated carbon dosage of 20 mg/g PHL. Additionally, 61.2% of acetic acid was also removed at a resin dosage of 100 mg/g PHL. Subsequently, acidolysis using sulfuric acid and pH adjustment with lime was performed on the treated PHL to convert the oligosaccharides into monosaccharides; a yield of 0.40 g xylitol/g xylose was achieved via treating the PHL with Candida tropicalis fermentation at 30 °C, 200 rpm, and 96 h. In addition, a material balance was determined for the full chain process.

Currently, polyurethane (PU) production is completely dependent upon fossil oil, as the two primary reagents necessary for PU production, polyol and isocyanate, are derived from fossil fuels. Eucalyptus branches are waste products for most forest management companies. In this work, polyols obtained by the liquefaction of eucalyptus branches were used for foam production. The influence of the isocyanate, catalyst, surfactant, and blowing agent contents on the foam properties was studied. Overall the amount of each chemical used in the production of PU foams had a noticeable effect on the density and compressive properties. The amount of water (blowing agent) had the strongest effect and decreased the density and compressive properties because of higher foam expansion. The other chemicals increased or decreased the density and compressive stress depending on the amount used. The density of the produced foams ranged from 36 kg/m3 to 108 kg/m3, the compressive stress ranged from 15 kPa to 149 kPa, and the Young’s modulus ranged from 64 kPa to 2100 kPa. The results showed that it is possible to convert these forest residues into PU foams with properties somewhat similar to those of commercial foams, although with a lower compressive strength.

The catalytic acetylation of bamboo (Phyllostachys pubescens) was compared with acetylation using concentrated sulfuric acid, acetic acid, potassium acetate, and noncatalytic acetylation at 120 °C for 3 h. The weight percentage gain, dimensional stability, color difference, and wettability of bamboo after the acetylation was comprehensively measured. Also, the chemical and thermal properties of the resultant bamboo were characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. The results showed that the potassium acetate-catalyzed acetylation of bamboo greatly accelerated the reaction degree, had little effect on color change, extraordinarily decreased wettability, and had little irregular impact on the dimensional stability. The catalytic activity was followed by potassium acetate, sulfuric acid, noncatalytic acid, and acetic acid. The FTIR analysis showed that the functional groups in the acetylated bamboo were mainly affected by different catalysts. The thermal stability of acetylated bamboo was higher than the untreated bamboo. In particular, potassium acetate-catalytic acetylation greatly reacted with -OH groups and increased thermal decomposition.

The application of rice husk fibers (RHFs) to reinforce wood plastic composites has received appreciable attention. However, good interfacial adhesion is important for actual applications. Pretreatment methods can reduce the hydroxyl groups in plant fibers in order for them to bond with the plastic matrix. In this research, RHFs were pretreated by four methods: hydrothermal treatment (HT), microwave treatment (MT), alkali treatment (AT), and benzoylation treatment (BT). The effects of the four pretreatment methods on aging behavior of RHFs/polyvinyl chloride (PVC) composites was studied with simulated soil-accelerated aging conditions. Accelerated-soil aging caused the physical and mechanical properties of the composites to deteriorate. The ultimate performance of the composites was improved by the pretreated RHFs. The effectiveness ranking of the pretreatment methods was: benzoylation-treated RHFs reinforced PVC (BRRP) > alkali-treated RHFs reinforced PVC (ARRP) > hydrothermal-treated RHFs reinforced PVC (HRRP) > microwave-treated RHFs reinforced PVC (MRRP) > untreated RHFs reinforced PVC (URRP).

Arabinoxylan (AX) was extracted from sugarcane bagasse and modified through crosslinking with glutaraldehyde (GA). The effects of crosslinking degree on the rheological and coating properties of glutaraldehyde crosslinked arabinoxylan (GAX) were investigated. To better evaluate the degree of crosslinking, the crosslink index was used to represent the degree of crosslinking for the GAX in this study. The viscosity of the GAX solution increased when the degree of crosslinking increased, and the solution demonstrated non-Newtonian flow behavior. A high degree of crosslinking was detrimental to the film and coating properties of the GAX. At an optimum degree of crosslinking, the tensile strength of the GAX films increased by approximately 170% and 60% compared with that of the AX and GAX with the highest degree of crosslinking, respectively; the tensile strength of the GAX-coated paper increased by approximately 15% compared with that of the GAX with the highest degree of crosslinking. When calcium carbonate was mixed with the paper coating adhesives, the GAX showed comparable coating properties to that of polyvinyl alcohol, demonstrating its potential to substitute petroleum-based paper coating adhesives.

The combustion of biomass fuels has been a significant source of global energy, and about 10 million tons of straw are used annually, yielding at least 0.5 million tons of straw ash. However, the ash from rice straw has rarely been reused, thereby contributing to environmental pollution. A new approach is reported for preparing mesoporous silica aerogels using straw ash-based biosilica via a sol-gel process and vacuum freeze-drying. The mesoporous structure, porosity, pore volume, and specific surface area of this straw ash-based aerogel had satisfactory values. Effects of pH on the synthesis of silica aerogel were investigated to better understand the most important factors influencing the gelation, final structure, physicochemical properties, morphology, and thermostability of the samples.

Cellulose nanofiber (CNF) was successfully isolated from kenaf bark by microfluidization at 20,000 psi for 40 passes. The combination of hydrothermal process and xylanase treatment prior to CNF isolation led to effective cellulose purification. The fiber used for enzymatic pretreatment for CNF isolation had an 85.9% whiteness index and 85.1% cellulose content. The crystallinity of the cellulose extracted from the kenaf bark continued to increase with successive treatments, as indicated by X-ray diffraction analysis. In addition, the enzyme-treated fiber showed increased thermal stability, as shown by thermogravimetric analysis. After CNF isolation, morphological characterization of the CNF was performed via field emission-scanning electron microscopy and transmission electron microscopy. The CNF had an average diameter that ranged from 5 to 10 nm and no undesired elemental contamination, as evidenced by energy dispersive X-ray spectroscopy. The mechano-enzymatic treatments used in this work to obtain CNF were judged to be a promising technique for the fabrication of biomedical and other high-value materials.