Volume 19 Issue 4

Polylactic acid (PLA) is a biodegradable polymer extensively used in packaging; however, its mechanical and barrier properties require enhancement for wider applications. Chitin-derived nanoflakes (CNFL), a two-dimensionally separated nanomaterial derived from α-chitin, possess high strength and toughness, making them ideal additives for improved PLA performance. This study investigated the effect of CNFL on the properties of PLA composite films. Incorporating CNFL significantly enhanced the mechanical properties of PLA, increasing its tensile strength and stiffness while preserving flexibility. This enhancement was attributed to the nucleating effect of CNFL, which increases crystallinity. Additionally, CNFL improved the thermal stability of the composite films by mitigating thermal deformation. Notably, the oxygen barrier properties of CNFL-filled PLA composites were also enhanced, demonstrating a significant reduction in oxygen permeability at optimal CNFL concentrations due to increased tortuosity of the oxygen diffusion path. Overall, CNFL-filled PLA composites exhibit great potential as renewable packaging materials, particularly for protecting sensitive products, such as food and pharmaceuticals, from oxidative degradation, thereby extending shelf life and maintaining quality. These findings suggest that CNFL-filled PLA composites are promising materials for advanced applications, offering a combination of enhanced mechanical performance, improved thermal stability, and superior oxygen barrier properties.

This study aimed to develop new composites and evaluate the physico-mechanical properties and formaldehyde content of flat-pressed three-layer particleboard (FPTP) made of bamboo (as a face material) and rubberwood (as a core material) residue bonded with urea-formaldehyde adhesive. Different ratios of core and face material were adopted to investigate the effects of these ratios on the properties of the particleboards. The results indicate that increasing the proportion of rubberwood particles enhanced mechanical properties. All particleboards complied with the maximum permissible thickness swelling percentage (12%) specified in IS 3087 (2005) for Grade 2 category boards. While the moduli of rupture and elasticity values increased with higher rubberwood content, the particleboards did not satisfy the IS 3087 (2005) standard overall. However, the internal bonding strength of T4 (0.5 N/mm²) met the minimum requirement. Nail and screw withdrawal resistance of the particleboards indicated significantly higher resistance with increased rubberwood proportion. Only T4 particleboards met the minimum requirement stipulated by IS 3087 (2005) regarding screw withdrawal resistance for both Grade 1 and Grade 2 category boards. All boards met the criteria for the E₂ classification (formaldehyde content ≤ 30 mg/100 g for oven-dried boards).

The effects of liquid organic fertilizer (LOF) made from anaerobic digestion on some physiological factors and volatile components of arugula plants that were grown in salty conditions were investigated. The experiment was conducted in three different stages. In the first two stages, seeds were grown in petri dishes and pots for seven days. The third stage involved growing seedlings in pots for 60 days. Salinity inhibited the germination of 7-day arugula seedlings in petri dishes and their emergence in pots. In these stages, LOF pretreatment failed to eliminate stress-induced inhibition. Some physiological parameters were analyzed in 60-day seedlings in the third stage. Salt-induced inhibition showed significant negative effects on all parameters. In contrast to previous stages, LOF (1% and 5%) and NPK had positive effects in all groups at the third stage, eliminating salt stress in all parameters except water content. Contrary to expectations, volatile components showed no significant change but had fluctuating values due to salt stress or fertilizer treatments.

Cotton cultivation in the United States is relevant globally, with the nation ranking among the top producers and exporters. This study examines conservation practice adoption trends and technological advancements in U.S. cotton production, focusing on sustainability and productivity. Efforts to improve cotton farming practices have reduced its environmental impacts, including decreased soil loss, water usage, and greenhouse gas emissions. Precision agriculture technologies have been instrumental in enhancing efficiency and reducing input costs, albeit with varying degrees of success. To gain deeper insights into cotton grower challenges and needs, a Natural Resource Survey was conducted in 2023 with 753 respondents. As a follow-up to the 2008 and 2015 surveys, the insights from this survey provide valuable data on grower practices and priorities, highlighting the increasing influence of climate change on cotton production. The findings underscore the importance of conservation agriculture and ongoing research to address grower concerns while improving production efficiency. Particularly noteworthy are the outcomes indicating an increase in cover crop adoption and a decrease in tillage practices, reflecting the industry’s commitment to sustainability. This study contributes to understanding the dynamics shaping the U.S. cotton industry and offers insights into the challenges and opportunities for continual improvement in U.S. cotton cultivation.

Changes of microstructure, crystallization, chemical composition, and equilibrium moisture content (EMC) of heat-treated wood (HTW) were investigated to explore the effects of heating media (saturated steam, superheated steam, air) and heat treatment (HT) temperature on HTWs. The results showed that the saturated steam induced more severe cell wall destruction than the other two media. Although the porosity slightly increased with the increasing HT temperature, superheated steam and air HT still decreased the porosity compared to that of control, whereas saturated steam HT increased the porosity. The HT increased both relative crystallinity and crystal size of HTWs. The increasing HT temperature slightly increased the relative crystallinity but decreased the crystal size. The highest crystallinity (55.0%) was observed after saturated steam HT. Leaching led to the increase of crystal size of HTW treated in saturated steam (about 0.15 nm), while those treated in unsaturated steam and air decreased. The increase in relative amount of lignin and cellulose due to the hemicellulose degradation were the main chemical changes of HTWs. Further lignin condensation reaction only occurred after saturated steam HT. Although saturated steam HT induced increased porosity, its lowest EMC (5.91%) indicated the decrease of hydroxyl groups.

Air-dried density, weight loss (WL), impact bending strength (IBS), Shore-D hardness, and thermal conductivity values were determined for heat-treated poplar (Populus nigra L.) and beech (Fagus orientalis Lipsky) wood and compared with those for untreated samples. The test samples were heat-treated at 140, 160, 180, and 200 °C for 2 h. The results showed that density decreased and WL increased with increasing temperature for all temperatures. Additionally, during the heat treatment, the IBS increased in beech wood samples at 140 °C, but at higher temperatures, these values gradually decreased in both wood species. The highest decline in IBS values, found at a temperature of 200 °C, was 66.5% for beech and 55.7% for poplar. The Shore-D hardness of both wood species increased after heat treatment and regarding beech wood, the hardness increasing rate at temperature at 140 °C, 160 °C, 180 °C and 200 °C, 8.94%, 14.19%, 8.27% and 11.7%, respectively according to control samples. Regarding poplar wood, hardness increasing rates were 6.20% at 140 °C, 4.41% at 160°C, 5.88% at 180°C and 5.31% at 200°C according to control samples. The thermal conductivity of poplar and beech wood samples decreased after heat treatment, except for samples heat treated at 160 °C.

Hydroxyethyl cellulose/nanolignin composite films were prepared and characterized. The composite films were produced via casting of synthesized nanolignin added to hydroxyethyl cellulose at different concentrations (2.5%, 5%, 10%, and 20% by mass). A control film without nanolignin was also prepared for comparison. The thermal properties of the composite films were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), while the mechanical properties were determined by tensile testing and the surface properties were determined by water contact angle measurements. In addition, the morphologies of the samples were examined by scanning electron microscopy (SEM). It was observed that with the addition of nano lignin, the glass transition temperature of the composite films increased from 109 °C to 262 °C; the elongation at break increased from 19% to 51%; and the contact angles increased from 53 °C to 73 °C. The results showed that the presence of nanolignin produced materials being more flexible and more hydrophobic with higher glass transition temperatures.

For a hygiene paper such as tissue and towel, strength, softness, and absorbency are known as attributes that a user is looking for. It is proposed here that purchasing decisions are likely to be influenced by in-use experiences, which may be quite different from the physical properties measured with current standardized tests. There have been continuous efforts on developing physical test methods to replace subjective in-use tests because the benefits of the former are too significant to be overlooked. This paper considered some in-use test methods for paper towel products that can be carried out by panel members quickly in the course of sensory panel testing. In addition, laboratory tests were developed in an attempt to quantify such input. The sensory panel testing showed that (wet) strength and absorbency were the key contributions to the performance of paper towels. Softness did not show any significant contribution to it. Wet strength showed a high correlation with absorbency. The (wet) ball burst strength had the highest correlation with the in-use strength. Although both the tensile strength and the ball burst strength had a high correlation with preference, the ball burst tester is preferred because more reproducible and simpler to operate.

This article describes an innovative Future Work 4S project and provides comprehensive feedback on a free Massive Open Online Course (MOOC) focused on environmental skills. Feedback was collected from two main target groups: educators (including university professors, teachers, and trainers) and student adult learners from Bulgaria, Greece, the Czech Republic, and Italy. The purpose of this survey is to provide an in-depth analysis of the feedback received on the Green Skills course and to highlight the main strengths identified by both educators and students. The findings reveal a high appreciation for the course’s interactive and experiential learning approach by both the students and the educators. Specifically, 93% of participants agreed that the course was interesting, engaging, relevant, accessible, and developmental. The course’s interactive exercises and gamification elements were particularly praised, enhancing learning and motivation. However, suggestions were made for including more practical examples and improving the uniformity of the text.

Bark plastic composite is a composite wood board consisting of a plastic matrix and bark in the form of powder or fibers as a filler. This research aimed to determine the influence of ratio and particle size on the characteristics of the composite made of Gmelina bark mixed with recycled polypropylene. Bark plastic composites were made with variations in powder: plastic ratio, namely 40:60% (P60), 30:70% (P70), 20:80% (P80), and 0:100% (P100), as well as variations in filler particle size, namely 40 to 60 mesh (M40), 60 to 80 mesh (M60), and 80 to 100 mesh (M80). Maleic anhydride (MAH) as a compatibilizer was added at 5% of the matrix’s weight. The reference testing standards were JIS A 5908:2003 and SNI 03-2105-2006. In the physical property testing, including density, moisture content, water absorption, and thickness swelling, all boards with different treatments met the standards. In the modulus of elasticity (MOE) testing, none of the boards with different treatments met the standards, while in the internal bond testing, all boards with different treatments met the standards. As for the modulus of rupture (MOR) testing, hardness, and screw-holding power, some samples met both standards. The M40P80 treatment produced the best bark plastic composite.