Volume 11 Issue 4

The objective of this research was to determine the influence of wood species (Fagus sylvatica L. and Populus tremula L.), thickness (4, 6, 10, 18 mm), and degree of densification (0%, 10%, and 20%) on the impact bending strength (IBS) and Brinell hardness (BH) in the radial direction. Three-factor analysis of variance confirmed that the difference in IBS was significantly related to the wood species and wood thickness. Wood densification did not have a significant effect on IBS. In addition, beech wood exhibited higher IBS values than aspen wood. The IBS values increased proportionally with increasing thickness. All factors affecting Brinell hardness were statistically significant, although thickness had the smallest influence overall. The Brinell hardness values were substantially higher in beech wood than aspen wood, and in some cases were more than three times greater. On the other hand, densification exhibited a more positive effect on increasing Brinell hardness for aspen wood than beech wood.

Poly vinylidene chloride-vinyl chloride emulsions (PVDC) were added as a substitute for chlorinated paraffin (CP) in the preparation of ultra-low density fiberboards (ULDFs). The micromorphology and fire performance of ULDFs were investigated using a scanning electron microscope, limiting oxygen index instrument, and cone calorimeter. The results showed that PVDC specimens were coated with a regularly smooth film, while the distribution of CP inside CP specimens was uneven. The limiting oxygen index increased with the dosage of PVDC, then reached a plateau at 50 mL and 28%, slightly higher than CP specimens (27.3%). The peak of heat release rate, mean heat release rate, mean CO, and total smoke release of PVDC specimens was reduced 43.3%, 13.5%, 38.5%, and 51.5% lower than respective CP specimens, and with nearly the same total heat release (only 0.04 MJ/m2 higher). Thus, PVDC exhibited excellent heat-reducing and smoke-suppressing properties and could replace CP in ULDFs.

The artificial neural network (ANN) method was used in comparison with the adaptive neuro-fuzzy inference system (ANFIS) to describe polygalacturonase (PG) production by Bacillus subtilis in submerged fermentation. ANN was evaluated with five neurons in the input layer, one hidden layer with 7 neurons, and one neuron in the output layer. Five fermentation variables (pH, temperature, time, yeast extract concentration, and K2HPO4 concentration) served as the input of the ANN and ANFIS models, and the polygalacturonase activity was the output. Coefficient of determination (R2) and root mean square values (RMSE) were calculated as 0.978 and 0.060, respectively for the best ANFIS structure obtained in this study. The R2 and RMSE values were computed as 1.00 and 0.030, respectively for the best ANN model. The results showed that the ANN and ANFIS models performed similarly in terms of prediction accuracy.

Palm kernel shell (PKS) was incorporated into natural rubber composites at loadings ranging from 0 to 20 phr using a laboratory-size two-roll mill. A soil burial study of the PKS-filled NR composites as a function of filler loading and silane coupling agent incorporation was then conducted over a period of six months. The degraded composites were evaluated by means of tensile testing. To study the degradation of the composites after soil burial, their morphological properties were observed by scanning electron microscopy. Prior to the soil burial tests, as the PKS filler loading increased, the tensile strength and elongation at break of the composites both with and without the silane coupling agent decreased, while the tensile moduli (M100 and M300) increased. At identical filler loading values, the NR/PKS composites with the incorporated silane coupling agent exhibited better tensile properties than the NR/PKS composites without the silane. Following the soil burial tests, the tensile strength, elongation at break, and the tensile moduli (M100 and M300) all decreased because of microbial attacks on the composites. The addition of silane enhanced the retention of the tensile properties of the NR/PKS composites after soil burial because of the improved adhesion at the filler-rubber matrix interface.

Bleached kraft pulp of hardwood was pretreated in a NaOH-thiourea aqueous solution to modify the bulk and softness of the cellulose fibers with minimal reduction in paper strength. The effects of soaking time, fiber concentration, alkali dosage, and freezing time were evaluated through single factor experiments. The optimal conditions were determined to be a soaking time of 15 min, fiber concentration of 15%, alkali dosage of 9%, and freezing time of 75 min. Under the optimal conditions, the bulk and softness of the treated cellulose fibers were increased by 28.7% and 21.6%, respectively, compared with those of untreated cellulose fibers. The tensile and burst indices were only reduced by 1.2% and 5.1%, respectively, under these conditions. Also, there were almost no effects on the polymerization degree, the thermostability, and the structure of the functional groups or crystalline regions.

Commercial talc was modified with phthalimide to produce a composite filler, which was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF), and scanning electron microscope (SEM). It was used as a papermaking filler, and its efficiency was compared with that of plain commercial talc and when mixed with additives (i.e., cationic polyacrylamide and alum-rosin size). The results showed that phthalimide could be linked appropriately to the surface of talc particles through forming ester bonds with the surface hydroxyl groups. The brightness of the composite filler was more than that of the commercial filler due to a reduction in the impurities and removal of the metal compounds. Unlike other treatments, the brightness of the papers filled with modified talc (MT) was enhanced with increases in filler loading. In spite of reducing the paper strength in all treatments, the reduction was significantly less in the MT treatment, which implies the enhancement in particle tendency to develop hydrogen bonds in the fiber network.

The effects of filler content and methacrylate acid (MAA) treated Nypa fruticans husk (NFH) on the mechanical properties, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and morphology of NFH regenerated cellulose (RC) biocomposite films were investigated. Ionic liquid containing 8 wt% of lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) was used to dissolve microcrystalline cellulose (MCC) and NFH to produce NFH RC biocomposite films. Methacrylate acid was used as a modifying agent on the NFH to promote better mechanical and thermal properties for the resulting NFH RC biocomposite films. The results showed that the tensile strength, Young’s modulus, crystallinity index (CrI), moisture content, and thermal stability of the untreated NFH RC biocomposite films increased with increasing NFH content up to 3 wt% and decreased with further increments. The MAA-treated NFH showed improved tensile strength and Young’s modulus compared with the untreated NFH RC biocomposite films. The presence of MAA enhanced the crystallinity index (CrI), moisture resistance, and thermal stability of the NFH RC biocomposite films. Good interfacial interaction between the NFH and RC matrix was proven by scanning electron microscopy (SEM).

Trametes versicolor and Pleurotus ostreatus were used for the biopulping from pineapple leaf fiber (PALF). PALF substrate was subjected to T. versicolor for 2 to 6 weeks and to P. ostreatus for 4 to 8 weeks. The yields, holocellulose and lignin contents, and extractives in ethanol-toluene mixture and in sodium hydroxide (NaOH) solution were evaluated. Fourier transform infrared spectroscopy (FTIR) spectra, thermogravimetric analysis (TGA), and color studies by L*a*b* systems were used for sample analysis. The results showed that the pulp yield was 55% to 70% with P. ostreatus and 35% to 50% with T. versicolor. Longer colonization periods increased the amount of holocellulose and decreased the amount of lignin and extractives in ethanol-toluene and NaOH solution. TGA showed an increase in intensity associated with cellulose, and the observed inflexion was attributed to lignin, which showed a tendency to fade. The FTIR spectrum showed high intensity between 3100 cm-1 and 3600 cm-1 (cellulose) and decreased intensity at 1730 cm-1 (lignin). For both fungi, the pulp color produced an increase in L* color parameter and decreased in yellowness, while little variation was observed in redness. The most appropriate colonization period was 5 weeks for P. ostreatus and 4 weeks for T. versicolor.