Volume 11 Issue 1

The chemical structures of four alkali lignins isolated from poplar, fir, straw, and bagasse were investigated. To explore the relationship between the structural units and the thermal decomposition behavior, the system was tested by elemental analysis, Fourier transform infrared spectrometry, thermogravimetric analysis (TGA), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results indicated that the carbon content of poplar lignin (PL) was higher than that of others. Fir lignin (FL) exhibited the highest guaiacol units, while the other three lignins were abundant in syringol units. The thermal decomposition characteristics and pyrolysis products of the four lignins were influenced by the material structural and composition. The DTG curves showed that the initial temperatures and major degradation temperatures of woody lignins（FL and PL） with complex inherent structures were shifted to the high temperature zoom compared with that of non-woody （BL and SL）lignins. Py-GC/MS analysis showed that guaiacol-type phenolic compounds were predominant pyrolysis products derived from the four lignins. The yield of guaiacol-type phenols could reach 82.87%. Moreover, the BL had selectively on phenol-type compounds with yield of 27.89%.

Biomimetic hydroxyapatite (HA) growth on mercerized kenaf fiber (KF) was achieved by immersion in a simulated body fluid (SBF) solution with the addition of a chelating agent. An electron micrograph revealed uniform HA layers on the KF within 14 days of immersion with significant vibrational peaks of HA components. The tensile tests showed no significant drops in the unit break of the modified fibers. This new bone-like apatite coating on KF can be useful in the field of bone tissue engineering. The key motivation for this new approach was that it utilizes the abundantly available kenaf plant resource as the biobased template.

Ethanol production strategy was studied using multiple strain microbes from microwave irradiation (MI) pretreated sago waste. Sago waste (SW) was MI-pretreated for reducing sugars production using 2 heating media (water and sulfuric acid) under pretreatment conditions including MI power, pretreatment duration, and solid loading. When water was used, the pretreatment parameters were optimized using Box-Behnken Design (BBD). However, gelatinized starch and charring of SW led to an insignificant quadratic model. To mitigate the gelatinization problem while determining the best MI pretreatment conditions, water was substituted by sulfuric acid using single factor method. The highest reducing sugar yield of 261.5 mg/g SW was achieved at 7.5% solid loading, 6 min pretreatment duration, and 300 W MI power. The effectiveness of the pretreatment was ascertained by field-emission scanning electron microscopy (FESEM) and chemical-composition analysis. When fermenting MI-pretreated SW using ragi tapai, simultaneous saccharification of starch and ethanol production was evidenced from the sugar/ethanol profile. A resulted yield of 7.24 g ethanol/100 g SW confirmed the fermentability of MI-pretreated SW. The ethanol production was well fitted into the modified Gompertz model.

Wood-plastic composites (WPCs) are currently discarded using incineration treatment, which is very expensive. Hence, this study was performed to improve the biodegradation of WPCs, such that they could potentially be buried after use, and to estimate their bending strength. A biodegradation test (determining the ultimate aerobic biodegradability of plastic materials under controlled composting conditions) was performed according to ISO 14855-1. Two groups of specimens were prepared using rice-bran mixture as the bioresource. One group contained rice-bran mixtures of 5, 7.5, and 10 wt.% instead of wood flour contents, and another group contained rice-bran mixtures of 8, 16, and 24 wt.% instead of the talc component. During the 20 days of the biodegradation experiment, the WPC (control) showed 18% biodegradation, and 7.5%-rice-bran-mixture-added specimen showed the highest biodegradation of 32%. Furthermore, the bending strength (MOR) was increased by up to 140% by adding rice-bran mixture as a biodegradable component. Therefore, the rice-bran mixture improved the biodegradation and mechanical properties of WPCs.

Rising interest in using wood in non-residential multi-story building structures opens up new opportunities for utilising low-grade hardwoods. The primary objective of this study was to evaluate the geographic variation in modulus of elasticity (MOE) and modulus of rupture (MOR) of sugar maple and yellow birch wood in relation to stand and tree characteristics for two regions in New Brunswick, Canada. Mixed effects statistical models were developed to test the effects of stand, tree, and wood sample variables. A second objective was to examine geographic variation in heartwood discolouration in relation to stand and tree characteristics. Between-tree differences (trees nested within sites) accounted for 44% and 35% of the total variation in yellow birch (MOE and MOR, respectively) and for 69% and 60% of total variation in sugar maple. The fixed effects explained only a very small part for the variation in MOE and MOR in the sugar maple data (10% for MOE and 5% for MOR). For sugar maple, mechanical properties (MOE and MOR) at 50% of the radius were considerably lower than those close to the bark, but this radial variation was not noteworthy for yellow birch. Discoloured heartwood proportion had no significant effect on wood mechanical properties.

A crucial problem for laminate producers is the dimensional instability of decorative papers during soaking in aqueous solutions, but the source of this dilemma is not completely understood yet. In this study, eight commercial decorative papers of similar fiber composition and sizing were analyzed for their structural, physical, and mechanical properties. These properties were examined for their correlations to the dimensional stability of papers when moistened, as assessed by the wet stretch dynamics. Structure-to-property relationships were evaluated by principal component analysis (PCA). Within the set of parameters examined, PCA revealed that fiber orientation and the content of fillers/pigments influenced the wet expansion of paper web and affected its margins and dimensions in longitudinal and transverse directions of the paper machine. These variables are discussed within the context of decorative paper engineering in order to produce high performance papers with regular wet expansion properties.

Primary refined coarse softwood thermomechanical pulp was treated with alkaline peroxide prior to low-consistency (LC) refining. The effects of the pre-treatments on pulp quality, refinability, and electrical energy consumption were assessed. Four pre-treatments were conducted with alkali charges of 2.5 and 6% and peroxide charges of 3 and 4%. The pulps were refined to specific energies up to 600 kWh/t by multiple passes through an LC refiner at intensities of 90 and 150 kWh/t. It was found that alkaline peroxide treatments increased tear strength and protected the fibre from cutting, especially during high intensity refining below a specific energy of 300 kWh/t. Treatment with 6% NaOH and 4% or 3% H2O2 led to lower brightness gains and scattering coefficients but increased the tensile strength index by 31%, potentially lowering the total electrical energy required to achieve strong pulp. The enhancement of tensile strength caused by the highly alkaline peroxide mostly resulted from increased bonding, which was attributable to acid group generation rather than the promotion of further fibrillation during LC refining.

A new fast-growing wood raw material, willow (Salix matsudana cv. Zhuliu), was subjected to pulping to identify the structure of its lignin. Thus, the black liquor lignin (AL) and enzymatic mild acidolysis lignin (EMAL) were prepared, and their molecular structure and molecular weight of the isolated lignin polymers were comprehensively investigated by Fourier transform infrared spectroscopy (FT-IR), two-dimensional nuclear magnetic resonance (2D-NMR HSQC), 13C nuclear magnetic resonance (13C-NMR), and gel permeation chromatography (GPC). The NMR results showed that syringyl (S) unit was the predominant structural monomeric unit in willow lignin, as opposed to guaiacyl (G) and p-hydroxyphenyl (H) units. The S/G ratio for the EMAL was found to be 2.02, whereas that for the AL was 0.94. The lignin in the black liquor (AL) fraction was modified during pulping, as shown by its reduced molecular weight. The two isolated lignin polymers, EMAL and AL showed low weight-average molecular weight: 4127 g/mol and 3522.5 g/mol, and in addition they exhibited low polydispersity index (Mw/Mn < 2.0).

This work presents a new technique for producing a slow-release fertiliser with bioplastic polymer coating. Poly(lactic acid) (PLA) was blended with granular NPK fertiliser and empty fruit bunch (EFB) fibres using extrusion technique. The polymer coatings were characterised using thermal gravimetric analyser (TGA) and diffraction scanning calorimetry (DSC). The PLA and EFB fibres complemented each other in terms of their thermal stability in the BpF composites. A homogenous BpF blend was observed under a scanning electron microscope (SEM). In biodegradation the percentages of weight loss for PLA/EFB/NPKC1 and PLA/EFB/NPKC2 were higher due to the presence of EFB fibres, which were 64.3% and 76.3%, respectively.

This study aims to evaluate the mechanical properties of rattan/polymer composites prepared by polymerization with methyl methacrylate (MMA). The P. kerrana rattan samples were impregnated in a vacuum system and polymerized in an oven at 60 °C for 8 h, using 0.5 wt.% of azobisisobutyronitrile as a catalyst. The macro-mechanical properties of the treated and untreated samples were analyzed. The bending modulus and strength of the treated rattan increased by 206% and 215%, respectively. Additionally, the compressive modulus and strength increased by 109% and 107%, compared to untreated rattan. Scanning electron microscopy (SEM) images showed that MMA penetrated the cell lumen. Furthermore, Fourier transform infrared spectroscopy (FTIR) analysis revealed that MMA diffused into the parenchyma and vessels, but it was not found in the fiber wall. Thus, it can be inferred that the improvement in the mechanical properties of treated rattan was mainly caused by the strengthened parenchyma and vessels. Modification with MMA was shown to be an effective way to enhance the macro-mechanical properties of P. kerrana.