Volume 9 Issue 2

The pressure and temperature at the same location in the middle cross section of Sugi wood were measured simultaneously during radio-frequency/vacuum (RF/V) drying. The distribution and variation of pressure and temperature in the wood cross section were investigated in different drying stages. The pressure behavior during the drying process was due to the pressure reduction rate and water vapor generation rate in wood. The temperature was higher in the center and was low from the center to surface layer. Pressure and temperature did not present symmetrical distributions along the vertical direction in the cross section. The pressure was irregular during the timber heating stage and became higher in the central zones than in the intermediate and surface layer zones during the drying process. Pressure curves exhibited three stages (irregular, rapid decreasing, and slow decreasing), in combination with an initial heating stage and a constant temperature stage. Above the fiber saturation point (FSP), the pressure (P) was greater than or equal to the saturated vapor pressure (Ps), corresponding to the temperature at the same location; below the FSP the pressure was maintained by superheated vapor and was smaller than Ps.

H2O2 is both bactericidal and the main oxidant responsible for lignin degradation reaction catalyzed by manganese peroxidase (MnP) and lignin peroxidase (LiP). Thus, H2O2 treatment of corn stalk and the implementation of solid-substrate fermentation (SSF) is possible to increase the removal rate of lignin from stalk in the process of SSF and after SSF, while avoiding the need to sterilize the raw materials. To demonstrate this approach, SSF was initially carried out using corn stalk pretreated with different concentrations of H2O2 as a substrate. A. oryzae was found to grow well in the 3% H2O2-pretreated corn stalk. H2O2-pretreated corn stalk showed increased MnP and LiP synthesis and disintegration of lignin, but inhibited cellulase synthesis and cellulose degradation. Production of the SSF (200 g) on the 10th day was hydrolyzed in the presence of additional 600 mL different concentration of H2O2 aqueous solution. The total removal of lignin (73.15%) of hydrolysis for 10 h at 3% H2O2 solution was highest and far higher than that at the 12th day, as achieved by conventional SSF. Applying this strategy in practice may shorten the time of lignin degradation, increase the removal of lignin, and decrease the loss of cellulose. Thus, this study has provided a foundation for further study saccharification of corn stalk.

The surface free energy and dynamic wettability of wood are important to the performance of its adhesive bonding strength. In this work, the surface free energy of poplar wood samples machined with different processes were calculated by the OWRK (geometric mean) and vOCG (acid-base) methods, and the dynamic wettability of adhesives on wood samples was studied using the S-D wetting model. The results indicate that the contact angles of reference liquids on rotary wood samples were greater than those on planed or sawn wood, and the rotary wood samples were more hydrophobic. The effect of surface roughness on contact angle was insignificant compared with surface structure morphology. The total surface free energy was almost the same for the planed and sawn wood, as calculated by the OWRK and vOCG methods, and the surface free energy of rotary wood samples was lower than that of planed or sawn wood samples. The initial and equilibrium contact angle increased as the viscosity of adhesive increased for all the wood samples, and the contact angles of rotary wood samples were greater than those of planed or sawn wood; however, the K-value was lower. The wettability of the loose side was higher than that of the tight side. Contact angles decreased when surface free energy increased, while the K-value increased.

Ammonium polyphosphate (APP) was synthesized by heating a mixture of phosphoric acid and urea, and APP/diatomite composite flame-retardant fillers were prepared by two methods: mixing and in situ polymerization. Flame-retardant paper was made by adding the prepared composite fillers to paper. The APP and APP/diatomite composite fillers were characterized by XRD, 31PNMR, SEM, FTIR, and TG. The flame retardation of paper containing these composite fillers was determined. Results showed that the prepared APP had a minimum solubility when the molar ratio of phosphoric acid to urea was 1:1.8. Under these conditions, its degree of polymerization was 91.21. After mixing and in situ polymerization, a large amount of APP was adsorbed into the surface of the diatomite. These two APP/diatomite composite fillers had similar thermal stabilities, butthe flame retardation of paper containing in situ polymerized composite filler was better than that of paper containing the composite filler obtained by mixing.

In this study, four engineered proteins containing two family 1 and/or family 3 carbohydrate binding modules (CBMs) were constructed and expressed as soluble forms in Escherichia coli. Their binding performances and effect on paper’s mechanical properties were comprehensively studied with the aim to design suitably engineered CBMs as novel biomaterials for use in the production of new cellulose materials. The recombinant engineered double CBMs exhibited obvious differences in their adsorption to different cellulosic substrates. The CBM3-GS-CBM3 was the most effective in enhancing paper mechanical properties in terms of folding endurance (27.4%) and tensile strength (15.5%) among the four engineered double CBMs, but it gave rise to only a slight increase in bursting strength (3.1%). On the other hand, CBM1-NL-CBM1 achieved a significant simultaneous increase in tensile strength (12.6%) and burst strength (8.8%), as well as folding endurance (16.7%). Unexpectedly, CBM3-GS-CBM1 and CBM3-NL-CBM1 had the lowest effective paper property improvement. The differences in types of CBMs and linker peptides in engineered double CBMs may contribute to the considerable differences in their cellulose binding and paper property modification. Our data suggested that CBM1-NL-CBM1 may provide a better upgrade of the secondary pulp, which makes it very suitable for fiber recycling. Meanwhile, CBM3-GS-CBM3 may have particular potential for paper manufacture requiring high folding endurance.

Two field trials were conducted with untreated coconut wood (“cocowood”) of varying densities against the subterranean termites Coptotermes acinaciformis (Froggatt) and Mastotermes darwiniensis Froggatt in northern Queensland, Australia. Both trials ran for 16 weeks during the summer months. Cocowood densities ranged from 256 kg/m3 to 1003 kg/m3, and the test specimens were equally divided between the two termite trial sites. Termite pressure was high at both sites where mean mass losses in the Scots pine sapwood feeder specimens were: 100% for C. acinaciformis and 74.7% for M. darwiniensis. Termite species and cocowood density effects were significant. Container and position effects were not significant. Mastotermes darwiniensis fed more on the cocowood than did C. acinaciformis despite consuming less of the Scots pine than did C. acinaciformis. Overall the susceptibility of cocowood to C. acinaciformis and M. darwiniensis decreases with increasing density, but all densities (apart from a few at the high end of the density range) could be considered susceptible, particularly to M. darwiniensis. Some deviations from this general trend are discussed as well as implications for the utilisation of cocowood as a building resource.

The present research is focused on the manufacturing and analysis of the thermal and electrical properties of advanced ceramics from alumina (Al2O3) with carbon nanofiller (CNF) from oil palm ash (OPA). The oil palm ash was used to produce carbon black nanofillers with a size of 50 to 100 nm via a ball milling process after undergoing pyrolysis in a furnace at 1000 °C. CNFs were added to the alumina at varying weight fractions and sintered at 1400 °C for the production of CNF ceramic composites. The coefficient of thermal expansion (CTE), electrical conductivity (EC), and electrostatic discharge (ESD) of the ceramic composites were measured. The CTE did not increase with increasing CNF weight and behaved like an alumina matrix. The EC (I-V) showed positive results with increasing CNF weight. The ESD measurement gave predictable results on the dissipative characteristics of ceramic composites due to the insulating nature of alumina with the addition of CNF. Thus, the addition of OPA to alumina may present a suitable route for improving the electrical properties of advanced ceramics.

Fruit nursery paper is a protective technical paper that is used in agriculture to improve the percentage of the fruit that meets quality standards and the fruit’s exterior qualities, such as the smooth surface finish and fruit color. In this work, a more efficient and environmentally friendly method, i.e., the printing method, was proposed in order to minimize environmental pollution, reduce the loss of carbon black, and lower the high production cost caused by the traditional method of directly adding carbon black. The effects of printing pressure and inking amount on the properties of the fruit nursery paper were investigated. The durability and safety of the fruit nursery paper produced by the printing method were also studied. The optimal inking amount and printing pressure under laboratory conditions were 1 mL and 350 N, respectively. The amount of ink transferred to the paper surface increased with increasing printing pressure, which led to better opacity but slightly decreased porosity and softness. A more important finding was that the fruit nursery paper produced by the printing method had excellent durability, and the properties can satisfy the requirements of the end use and safety standards of 94/62/EC stipulated by the Europeon Parliament and Councile directive. Based on these low-cost, environmentally friendly characteristics, the development of this new fruit nursery paper could be beneficial.

The research aimed at optimizing the conditions of pretreatment of wheat straw and of enzymatic hydrolysis of the cellulose (ethanol pulp). The ethanol pretreatment process involving acid-catalytic and enzymatic hydrolysis were evaluated for bioconversion of wheat straw to glucose. The influence of the independent process variables on cellulose yields, cellulose contents, lignin contents, and the rate of lignin removed were analyzed over a broad range by the response surface methodology (RSM). The results of the factorial experiment showed that the significant external factors affecting acid-catalytic ethanol pretreatment of wheat straw were ethanol concentration, maximum temperature, acid dosage, and time at maximum temperature. By analyzing the response surface plots, the optimum process parameters for pretreatment were obtained as follows: ethanol concentration 65%, maximum temperature 180 ºC, acid dosage 1.2%, and time at maximum temperature 60 min. Pulps with residual klason lignin ranging from 9.27% to 13.56% (w/w) were prepared from wheat straw using the acid-catalytic ethanol pretreatment process and were evaluated for bioconversion using enzymatic hydrolysis of the cellulose fraction to glucose. The effects of temperature, pH value, time of enzymolysis, and cellulase dosage on the hydrolysis yield of cellulose were separately examined.

The differences in the physical and mechanical properties and chemical composition of Bambusa rigida bamboo before and after accelerated aging tests were comparatively investigated. The results revealed that the aged specimens had lower physical and mechanical properties than the controls. The differences in chemical composition provided evidence that the reduction in physical and mechanical properties was related to the loss of low-molecular weight substances, such as extracts and inorganic matter, and the depolymerization of the carbohydrates cellulose and hemicellulose. Lignin caused the main resistance to the accelerated aging test because the aged specimens had relatively high Klason lignin content. Significant differences (p<0.05) in surface color between the control and aged specimens were observed, and variations in bamboo properties among culm heights were also evaluated in this study. The results showed that basic density and mechanical properties for both the control and aged specimens increased with increasing culm height, while the volume shrinkage showed an inverse trend.