Research Articles

A composite of themoplastic polyurethane (TPU) reinforced with short kenaf (Hibiscus Cannabinus L.) fiber (KF) was prepared by a melt-mixing method. Mixing was followed by compression molding to produce sheets for specimen cutting. Five samples were cut from the composite sheet. A mean value was taken for each sample according to ASTM standards. The aims of this study were to optimize the processing parameters and fiber size of TPU/KF composite. The method used to develop this composite consisted of two main steps. First, the influence of processing parameters such as temperature, time, and speed on tensile properties was studied. Second, effects of different fiber size on tensile properties, flexural properties, and impact strength were tested. The optimum blending parameters were 190°C, 11 min, and 40 rpm for temperature, time and speed, respectively. TPU/KF composites with different fiber sizes were prepared, namely, <125, 125-300, and 300-425 µm. Tensile and flexural strength and modulus were best for fiber size range between 125 and 300 µm. Impact strength showed a slight increasing trend with an increase in fiber size.

The effect on morphological, spectroscopic, and thermal properties of oil palm empty fruit bunch fibers (OPEFB fibers) and oil palm frond fibers (OPF fibers) following treatment and modification with sodium hydroxide and succinic anhydride, respectively, were investigated. The evidence of treatment was observed by weight gain and FT-IR. The effect of the treatment upon the fiber surfaces was examined using scanning electron microscopy (SEM), which indicated that succinic anhydride treatment led to smoother surfaces as compared to the sodium hydroxide. The thermal degradation was carried out by thermal gravimetric analysis, which exhibited a different degree of mass loss due to different treatments.

Solution behaviors and adsorption characteristics of sodium lignosulfonate (NaLS) were studied under different pH conditions. The changes of Mw and particle size of NaSL with solution pH were detected by laser light scattering (LLS). Film thickness was determined with a spectroscopic ellipsometer, and surface roughness was measured by atomic force microscopy (AFMaSL was changed from compact to loose. When the NaSL with loose structure and low degree of aggregation was adsorbed on a solid substrate, the adsorption thickness and the surface roughness decreased correspondingly.

The objective of this research was to evaluate the influence of steam-heat treatment on the decay resistance of Chinese white poplar and Chinese fir wood against the wood-rotting fungi Gloeophyllum trabeum (Pers.:Fr.) Murrill. The Chinese white poplar and Chinese fir specimens were obtained from Shandong and Hunan provinces, respectively. They were steam-heat-treated at 170, 185, 200, 215, or 230 oC with time duration of 1, 2, 3, 4, and 5 hrs in an air-tight chamber that comprised less than 2 per cent oxygen. According to the standard GB/T 13942.1-92, the decay resistance experiments were completed with the wood-rotting fungi G. trabeum on an agar block test with 12-week incubation. The results of steam-heat treatment indicated that, compared to a weight loss of 56% for untreated samples, a weight loss of 45% decreased to just 2% for Chinese white poplar with an increase in temperature from 170 to 230℃. No weight loss was observed in the steam-heat-treated China-fir heartwood, sapwood, and untreated sapwood specimens, while only a weight loss of 4.739% in untreated China-fir heartwood specimens was found.

Fractionation using concentrated phosphoric acid is a cost-effective pretreatment approach due to production of highly reactive amorphous cellulose under modest reaction conditions. Chinese white poplar biomass was used as feedstock. The effects of pretreating temperature and liquid/solid ratio of H3PO4/poplar (v/w, ml/g) on poplar fractionation, enzymatic hydrolysis efficiency (EHE), and supramolecular structural change were investigated. Only 31% (w/w, g/g) cellulose was retained in the solid phase at the higher liquid/solid ratio of 10:1 for 60 min, while 38 % cellulose was retained at 8:1. Temperature played an important role in lignin removal, xylan hydrolysis, and enzymatic hydrolysis, which may eventually influence cellulose conversion. More than 40% lignin could be removed after 60 min pretreatment at above 50 oC. A majority of the xylan hydrolysis could be detected in mixed rinsing liquid after 80 min pretreatment at 50 oC and liquid/solid ratio of 10:1. Up to 96.37% EHE could be obtained after 24 h enzymatic hydrolysis at 50 oC. The optimal pretreatment condition was 50 oC, liquid/solid ratio 8:1 (v/w), and 60 min. After pretreatment the CrI index decreased from 39.9 % to 27.7 %, suggesting a decrease of crystalline area percentage. Pyrolysis-GC-MS results of precipitated lignin indicated that nearly 48% of the lignin was phenolic, such that it can be used as a natural antioxidative material.

Plantation-grown wood species are becoming more important. Their anatomical, physical, and mechanical properties are different and generally more variable than wood grown in natural stands. The objective of this study was to investigate the wettability and surface roughness (SR) of natural and plantation-grown narrow-leaved ash (Fraxinus angustifolia Vahl.) wood. The logs were cut from a natural stand versus three different spacings of plantation-grown narrow-leaved ash wood stands. Plantation spacings were 3 x 2 m, 3 x 2.5 m, and 4 x 4 m. The wetting behavior of the wood samples was characterized by the contact angle (CA) method (goniometer technique). A stylus type profilometer was used for the SR measurement according to the DIN 4768 (1990) standard. The SR and CA measurements were done on both the radial and tangential surfaces of the samples. Individual values of both SR and CA of ash wood showed statistically significant differences. Based on the findings, it appears that the natural-grown ash wood have higher (less favorable) SR and lower (more favorable) CA values compared to all the plantation-grown ash wood on both radial and tangential surfaces. Tangential surfaces had lower SR values and higher CA values than the radial surfaces for all groups. In conclusion, plantation-grown narrow-leaved ash wood can be utilized for bonded wood products such as plywood, laminated veneer lumber, and glulam.

This paper reports a simple innovative method to align magnetic cellulose fibers by using a simple permanent magnet to fabricate unidirectional magnetic papers. Magnetic cellulose fibers were made by in situ synthesis of magnetite nanoparticles on alpha cellulose pulp extracted from American southern pine. Scanning electron microscope micrographs and energy dispersive X-ray spectroscopy maps indicated that magnetite nanoparticles completely covered the cellulose fibers. Suspensions of magnetic cellulose fibers were prepared at three levels of concentration (0.02, 0.04, and 0.08 g/L) and poured into the designed magnetic forming machine. Flow rate of suspension into the forming column was adjusted at 0, 0.3, 0.5, and 1 cm/s. The strength of the applied external magnetic field was the same in all cases and lower than 0.18 T. Orientation analysis indicated that the designed magnetic forming machine has a high performance to be used for aligning magnetic cellulose fibers and fabricating unidirectional magnetic cellulose papers. Observed anisotropic magnetic and mechanical properties confirmed the unidirectional structure.

Enzymatic hydrolysis of sludge from a bleached tissue mill generates glucose that can be sold as a product or sent to an ethanol plant. Hydrolysis rates using enzymes from two sources are reported, and a configuration for the industrial conversion of sludge to glucose is proposed. The system combines a set of stirred tank reactors with ash removal and membrane filtration to give a glucose concentrate. The economics of the conversion are attractive.

Wood pyrolysis oil consists of hundreds of complex compounds, many of which are phenolic-based and exhibit hydrophobic properties. Southern yellow pine was impregnated with a pyrolysis oil-based penetrant using both a high pressure and vacuum impregnation systems, with no significant differences in retention levels. Penetrant concentrations ranging from 5-50% pyrolysis oil/methanol on a volume basis were used to determine the threshold concentration for significant physical property improvement. Wood impregnated with penetrant concentration of at least 10% exhibited significant reduction in both moisture sorption and tangential swelling when exposed to a 90% relative humidity and 21°C environment. When exposed to liquid water in a 24-hour soak test, analysis revealed a negative linear relationship between penetrant concentration and both moisture sorption and tangential swell. However, during the course of the 24-hour soak test, a significant linear relationship between penetrant concentration and leachate was determined.

The aims of this study were to investigate the physicochemical changes and microbial population during co-composting of 1 ton oil palm frond (OPF) with 1,000 L palm oil mill effluent (POME) anaerobic sludge. In the first 30 days of composting, the temperature of the composting piles was observed in the thermophilic phase, within a range of 50 - 56oC. Meanwhile, the oxygen level, moisture content, and pH profiles of the compost were maintained at 2.0 to 12%, 60 to 70%, and 7.9 to 8.5, respectively, throughout the composting process. The total bacteria count was estimated to be about 55 x 1010 CFU/mL in the mesophilic phase, and then it increased up to 66 x 1010 CFU/mL in the thermophilic phase, and finally decreased to 9.0x1010 CFU/mL in the curing phase. The initial C/N ratio, 64, decreased to 18 after 60 days of composting process, indicating the maturity of compost product from OPF-POME anaerobic sludge. The diversity of the bacterial community was investigated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results suggested that the co-composting process of OPF with POME anaerobic sludge was dominated by Pseudomonas sp.