Volume 14 Issue 4

Modified starch (MS) degraded composites were prepared via a molding method with starch as a substrate and a blending process with crumb rubber (CR) and added plasticizers such as glycerol, urea, and formamide. The mechanical properties and water absorbability of the MS degraded composites were measured. The functional group variations were confirmed by Fourier transform infrared spectroscopy (FT-IR), and the changes of the functional groups were investigated with a stereoscopic microscope to analyze the microstructure of the composites. The results indicated that the addition of CR substantially improved the performances of degradable composites. When the CR content was 50 wt% of the MS, the interfacial properties of the reinforced materials and the dispersing degree of the filler were improved. Compared with the composite without additive, the tensile strength and bending strength of the composites were increased by 107% and 49.5%, respectively. The minimum water absorption ratio was reduced by 78% compared with the composite without the additive.

Ultraviolet varnishes are widely used for production processes in the parquet industry. A large number of chemicals are used in this sector, and each one has different characteristics. In this study, the effects of accelerated aging of ultraviolet varnish (3 and 5 coats) when applied to lemonwood (Citrus limon (L.) Burm.) (grown in Mezitli, Mersin, Turkey) were investigated. The ultraviolet varnish coated samples were subjected to aging processes (144 h, 288 h, and 432 h) by using UV-A 340 nm lamps. Color (L*, a*, b*, and ΔE*) parameters, glossiness (perpendicular (⊥) and parallel (//) at 20°, 60°, and 85°), and surface adhesion strength via the pull-off method for ultraviolet varnish coated samples were quantified before and after weathering. According to the results, the varnish type, aging period, and interaction between all studied variables, i.e. L*, a*, b* color parameters, glossiness (perpendicular (⊥) and parallel (//) at 20°, 60°, and 85°), and adhesion strength were found to alter the surface properties. As a result, the lemon tree can be used in the production of an ultraviolet parquet system.

Starch has potential to be used in new, functional food packaging materials. The attractive factors of starch as a packaging material are its low price and degradable properties. However, brittleness hinders its function as a packaging film. In this study, chitosan nanofillers (CSN) were incorporated into sago starch (SS) formulations to improve the mechanical, physical, and chemical properties of the film. The synthesis of a new formulation from the optimization process resulted in increased mechanical properties; the tensile strength obtained for the sago starch/chitosan nanofillers (SS/CSN) film was 88 MPa compared with 46 MPa for the sago starch film (SSF). In terms of thermogravimetric analysis, the SS/CSN film sustained up to 390 °C with 60% weight loss, whereas SSF experienced a weight loss of 67% at 375 °C. The analyses summarize the concept of using biocomposites to improve the properties of film for the potential purpose in biodegradable packaging plastics.

The biomimetic application was studied for banana leaves (Musa acuminata Colla), which have been commonly used as a traditional cleaning technique for ironing plates. In this study, banana leaf surfaces were subjected to horizontal sliding forces of 5 N, 10 N, 15 N, and 30 N, using a heated plate at 100 °C, 200 °C, 300 °C, and 500 °C. The self-cleaning behavior of the banana leaves was determined by measuring the adhesion force, roughness, and contact angle, which were subsequently correlated with the surface morphology. Based on the results of this study, the adhesion force decreased from 6.39 nN ± 0.42 nN at 100 °C to 0.50 nN ± 0.50 nN at 500 °C with a load of 30 N, whereas the roughness increased from 0.79 µm ± 0.21 µm at 100 °C to 1.12 µm ± 0.30 µm at 500 °C. Furthermore, the contact angle decreased from 124.8° at 100 °C to 104.0° at 500 °C with a load of 30 N. This study established that the morphology of the banana leaves was altered with the temperature during sliding, which correlated with the surface characteristics.

New alternatives to plastic straws are being considered due to consumer demands for sustainability and recent changes in government policies and regulations, such as bans on single-use plastic products. There are concerns regarding paper straw quality and stability over time when in contact with beverages. This study evaluated the performance and properties of commercially available paper straws and their counterpart plastic straws in various intended applications. The physical, mechanical, and compositional characteristics, as well as the liquid interaction properties of the straws, were determined. The paper straws were composed mainly of hardwood fibers that were hard sized with a hydrophobic sizing agent to achieve a contact angle of 102° to 125°. The results indicated that all the evaluated paper straws lost 70% to 90% of their compressive strength after being in contact with the liquid for less than 30 min. Furthermore, the paper straws absorbed liquid at approximately 30% of the straw weight after liquid exposure for 30 min. Increased liquid temperatures caused lower compressive strengths and higher liquid uptake in the paper straws. This report provides directions and methods for testing paper straws and defines current property limitations of paper straws relative to plastic straws.

The aim of this study was to evaluate the effect of the grades of cellulose nanofibril (CNF) on the strength and drainage of security paper made from cotton lint mixed pulp (CLMP). Refined CNF (RE-CNF), enzymatic CNF (EN-CNF), and carboxymethylated CNF (CM-CNF) were prepared, and their characteristics were analyzed. Handsheets were made via the addition of three CNFs into CLMP furnish, and their physical properties were measured. The drainability of the CLMP in the presence of CNFs was also determined depending on the grades and the dosage of the CNFs. The CM-CNF was the most effective at enhancing tensile strength by 50%, folding endurance by 464%, and sheet density by 10% when 5% of CM-CNF was added in the CLMP furnish. Moreover, 5% of EN-CNF improved tensile strength by 30% and folding endurance by 156%, but it was less effective as a paper strength promotor than CM-CNF and RE-CNF. A dramatic drainage reduction by 34% was observed when 5% of CM-CNF was added into the CLMP furnish, and EN-CNF presented the highest drainage rate. A high dosage of CNFs deteriorated the furnish drainage and promoted the strength. Therefore, papermakers should select the proper grade and the dosage of CNF for the manufacture of high-strength security paper.

Screw withdrawal and flexural strength were evaluated for Dendrocalamus asper and Gigantochloa levis bamboo species to explore the possibility of their use as structural material in place of wood. Dry bamboo strips and 4-mm-thick oil palm trunk veneer (OPTV) were processed into thin laminates and hot-pressed using urea formaldehyde resin to produce bamboo-OPTV hybrid biocomposites. Bamboo furniture is far more resistant to damage than traditional hardwoods. Bamboo is even used in cutting boards for this reason. Even though there have been some reports on the mechanical enhancement of the bamboo-based composites, so far there has been no comprehensive study on the screw pulling and flexural strength of bamboo-based hybrid composites. The results revealed a stronger correlation of the bamboo hybrid under screw withdrawal and flexural strength, but there was a weaker correlation in the mechanical properties of the bamboo hybrid due to the random selection of laminate from different bamboo species. Furthermore, test results clearly showed that bamboo-OPTV hybrid biocomposites can be used as an alternative to wood and wood-based composites for furniture applications.

Black poplar (Populus nigra L.) was subjected to thermal modification in superheated steam. The modification was performed at 160 °C, 190 °C, and 220 °C for 2 h. The equilibrium moisture content of the black poplar wood was examined when it was exposed to 76% ± 2% relative humidity at a temperature of 20 °C ± 2 °C. The thermal modification of the poplar wood changed its moisture-exchange-related physical properties to a large extent. The effects of temperature on individual properties (density, mass loss, hygroscopicity, swelling, and water absorption) were diverse, and the intensity of these effects increased with increasing temperature of the thermal treatment process. In most cases, no significant differences were observed between the changes in properties of the sapwood and the heartwood.

Anaerobic digestion of biomass wastes could have a huge impact on renewable energy requirements. Moreover, it reduces biomass wastes and greenhouse gas emissions. To improve the performance of anaerobic digesters, the co-digestion of different biomass wastes, such as waste activated sludge, microalgae, and agriculture wastes including sawdust, wheat straw, and rice straw has been performed in this study. The results showed that sludge and microalgae have low carbon/nitrogen (C/N) ratios. Meanwhile, the addition of agriculture wastes to sludge and microalgae mixture increased the C/N ratio and improved biogas yield by 179%, 209%, and 265% in the cases of adding sawdust, rice straw, and wheat straw, respectively. Co-digestion with wheat straw showed the highest values of C/N for the feedstock (20.6) and biogas production. Moreover, it recorded the highest reduction values for total solids (48.1%), volatile solids (58.2%), and chemical oxygen demand (77.5%) as compared to the other wastes.

Corncob cellulose from residue of saccharified agricultural waste corncob was used as a new resource of cellulose to dissolve in 1-allyl-3-methylimidazolium chloride (AmimCl) and then to regenerate in three different coagulation baths: water, 60 wt% AmimCl aqueous solution, and anhydrous ethanol. The effects of the different coagulation baths on the properties of corncob cellulose aerogels and regenerated films were studied. The results showed that the aerogels had porous network structures, and the regenerated films were relatively transparent with high strengths and good thermal stabilities. When 60 wt% AmimCl was used as the coagulation bath, the network of the obtained aerogel was dense and uniform, and the regenerated film had good thermal stability and a tensile strength superior to the films from the other regeneration baths. The films might have uses in packaging or other fields and aid in comprehensive utilization of agricultural wastes.