Volume 14 Issue 3

A green and facile fabrication strategy for synthesis of lignosulfonate-graphene porous hydrogel (LGPH) was designed via incorporation of lignosulfonate (LS) into graphene oxide (GO). This process was achieved by a simple self-assembly method at low temperature, with LS serving as surface functionalization agent. Benefiting from the abundant functional groups of LS and the large surface areas of graphene oxide, the prepared LGPH hydrogel displayed 3D interconnected pores and exhibited an excellent adsorption capacity for Cr(VI) (601.2 mg/g) ions dissolved in water. Importantly, the free-standing LGPH was easily separated from water after the adsorption process, and the adsorption capacities of Cr(VI) onto LGPH maintained 439.1 mg/g after 5 adsorption-desorption cycles. The cost-effectiveness and environmental friendliness of LGPH make it a promising material for removing heavy metals from wastewater.

To ascertain the possibility of using branchwood, trunkwood, and rootwood of Betula platyphylla Roth. in papermaking, this study investigated tissue proportion, fiber features, and major chemical components in whole-tree wood of the tree species. Analysis of variance (ANOVA) indicated that the rootwood had a significantly lower density and vessel proportion, higher ray proportion, wider lumen, and thicker wall of fiber than the trunkwood and branchwood (p <0.05). The branchwood had a significantly shorter fiber and smaller length/width than the trunkwood and rootwood (p <0.05). The trunkwood had significantly longer and narrower fibers with thinner wall and higher cellulose, but lower hemicelluloses than the branchwood and rootwood (p <0.05). The study concluded that the trunkwood of B. platyphylla was suitable for producing good paper, while the branchwood and rootwood met the basic requirements of papermaking and could be used to produce low-grade paper.

Enormous amounts of fiber sludge are generated annually by the pulp industry as a by-product. As a cellulose-rich material, its current usage, mainly as fuel, is inefficient from a material efficiency point of view. This work studied the utilization of fiber sludge from a Finnish and a Swedish pulp mill as a potential feedstock to produce levulinic acid, a valuable platform chemical. The conversion experiments of fiber sludge to levulinic acid were performed in a microwave reactor with a mixture of H2SO4 and Lewis acid as the catalyst. The reaction conditions, which included reaction time and temperature as well as the H2SO4 and Lewis acid concentrations, were studied in detail. The highest levulinic acid yield, 56%, was obtained with Swedish fiber sludge after 60 min at 180 °C with the H2SO4 concentration of 0.3 mol/L and a CrCl3 concentration of 7.5 mmol/L which indicated that the fiber sludge had the potential to be used as feedstock for levulinic acid production.

A cellulose nanocrystal (CNC) based dual-modification was explored as a means to achieve better film properties. Starch was mixed with 0.5 wt% CNC followed by oxidation with NaClO, then esterified with CNC and vinyl acetate. The dual-modified starch showed an increased degree of substitution, disrupted morphology, and decreased crystallinity. A remarkable catalytic effect of CNC was found with 0.3 wt% CNC in esterification, where the degree of substitution was 2.7 times higher than that of dual-modified starch without CNC. The best modifying condition was selected as 0.3 wt% CNC and 7.0 wt% vinyl acetate. The film generated from dual-modified starch, polyvinyl alcohol (PVOH), and glycerol generated a smooth surface and compact structure. Moreover, the films based on dual-modified starch had improved transparency, thermal stability, and tensile strength compared to that of native starch or oxidized starch. The highest tensile strength of film was obtained at 25.7 MPa with 30 wt% PVOH. The film showed the highest water resistance with a contact angle of 113°.

TEMPO-oxidized thermomechanical pulp (TMP) prepared at low-oxidized and highly oxidized levels was compared with untreated TMP to observe the advantage of each pulp on paper properties. While the low oxidized pulp and non-oxidized pulp gave similar properties, highly oxidized TMP significantly increased tensile strength and decreased tear strength. Brightness was negatively affected by oxidation. In order to improve the paper optical properties, the use of a conventional mineral filler retention system was studied, using clay as filler. The high charge induced by the oxidized pulp significantly modified the pulp retention behavior. Moreover, paper made from pulp containing oxidized pulp and clay presented considerably better tensile strength with a loss in tear resistance for the same brightness target, which could be interesting for some paper applications.

Toilet paper is widely used in residences. The low biodegradability of toilet paper’s pulp fibers can cause residence sewer lines to clog, which may be due to some additives or the presence of nonwoven fiber products. In this study, the disintegration rate of toilet paper was compared against various physical factors of the toilet paper sheet. The samples were disintegrated in water at varying pH levels. In the manufacturing of toilet paper, there must be a balance between the desired softness and the necessary wet strength. Twelve commonly used brands of toilet paper were purchased locally. Physical factors of toilet paper samples such as degree of polymerization, thickness, grammage, and softness were determined. The samples were evaluated based on 9 variables using correlation and multivariate linear regression analyses. A strong positive relationship was found between the degree of disintegration of toilet tissue paper and its physical factors. These were the degree of polymerization, the grammage, thickness, and the softness. Additionally, the amount of polymers applied to toilet paper decreased the degree of softness and adversely affected the redispersion of fibers. Thus, this work supports the idea that toilet paper can contribute to clogging of residential sewerage lines.

The pattern of termite infestation was investigated in structural lumber, light Red Meranti (Shorea spp.), using a minimally destructive technique. The relationship between the visual inspection and the pin penetration approach in predicting the basic properties of wood was determined, and a pin penetration distribution value was mapped into a contour map based on the Kriging interpolation technique. Small wood block samples were exposed to reared subterranean termites Coptotermes curvignathus Holmgren (Isoptera: Rhinotermitidae). The characteristics of termite infestation and the changes in the physical-mechanical properties were investigated. The residual surface area of the samples was evaluated using Pilodyn®. The characteristics of the termite galleries found on small wood block samples were as follows: 1) the termite galleries varied in length, or 2) the galleries consisted of long flat tunnels in a longitudinal direction, clean, not decayed, and contained no soil residue. The weight loss percentage from this study exhibited a similar trend with the pin penetration depth, which was directly proportional to the exposure period. The pin penetration result from Pilodyn® generated distribution map that was represented the conditions and basic mechanical properties of the samples. Pilodyn® can be used a complement for visual inspection in in-situ assessment.

Automation offers a promising solution to improve competitiveness for the labor-intensive furniture manufacturing sector in Malaysia. This study evaluated the level of application of automation, the factors driving it, and the readiness of the furniture manufacturers towards Industry 4.0. A questionnaire-based survey was targeted to large and medium-sized furniture manufacturers throughout Malaysia, with responses from 312 manufacturers. The results revealed that the panel-based furniture manufacturers were more responsive towards the adoption of automated technologies than other types of furniture manufacturers. The machining centers and finishing operations within the furniture factories showed the highest application of automated technologies. The factor analysis revealed that the drivers for the application of automated technologies were the desire for higher production capacity, cost involved, product characteristics, and government policy. This study emphasized that in the cost-sensitive furniture manufacturing industry, the economic benefits of applying automation outweigh any other factor in the decision to explore such technologies. The study also revealed that furniture manufacturers are not ready to adopt Industry 4.0, and any efforts by the government to push for such transformation will require the provision of incentives and other tangible economic benefits.

Rubberwood, which can be regarded as a natural polymer composite, presents many difficulties in the process of material modification. In this study, a convenient method was developed to impart superhydrophobicity to the rubberwood surface. SiO2-PS composite film was formed on rubberwood surface by simple short-term impregnation. The obtained superhydrophobic rubberwood exhibited a water contact angle (WCA) of ~155.6° at room temperature. The superhydrophobic coating surface provides the abilities of self-cleaning and anti-bacteria for rubberwood. Combined with a small amount of 3-iodo-2-propyl-butyl carbamate (IPBC), the control effect of the four fungi reached 75% (Botryodiplodia theobromae), 100% (Trichoderma viride), 95% (Penicillium citrinum), and 100% (Aspergillus niger), respectively. The developed method herein features environment-friendly raw materials, facile processing, and large-scale fabrication. It provides a new solution for long- term timber protection processing.

The possibility of making glues of natural origin (pure lignin and lignin-gluoxal (instead of chemical resins for making plywood from poplar layer was investigated. For this purpose, lignin was reacted with glyoxal and the lignin-glyoxal glue was produced. To make the desired plywood, pure lignin (L.100%), lignin-glyoxal 15% (L.85%, G.15%), and lignin-glyoxal 30% (L.70%, G.30%) were used as the adhesive at three different levels. Ammonium chloride (1%) as the hardener and wheat flour (30%) as the filler based on the dry weight of the adhesive were also used. Plates made with urea formaldehyde resin at 160 g/m2 were considered as control samples. After the laboratory boards were produced, the physical and mechanical properties of samples, such as thickness swelling after 2 and 24 h of immersion in water, shear strength, modulus of rupture and modulus of elasticity, were measured. In addition, the groups and bonds in the pure lignin and lignin-gloxal adhesives were identified by Fourier transform infrared (FTIR) spectroscopy. In most tests and compared to the boards made of the adhesives and control boards, the lignin-glyoxal 30% (L.70%, G.30%) glue came closest to the performance of the control glue.