Research Articles

Cellulose foams are potential sustainable alternatives for packaging, thermal insulation, and acoustic applications due to their porous structure and renewable origin. Besides good mechanical properties and moisture control, antimicrobial performance is essential for applications involving contact with moisture and organic matter, such as food packaging and medical materials. This study investigates the antibacterial, antifungal, and soil biodegradation behavior of cellulose foams coated with a thin layer (approximately 5 g/m²) of xylan hemicellulose and its modified derivatives, including acetylated and AKD (alkylketene dimer) modified xylan. The results showed that foams treated with acetylated xylan exhibited the highest antibacterial activity, with about 58% inhibition of Bacillus sp species after 24 h at 27 °C. A slight antifungal effect was also observed, with delayed growth of Aspergillus and Penicillium species. Both coating composition and xylan modification significantly affected the degradation kinetics.

Surface roughness plays a critical role in determining the performance and quality of paper products; however, its accurate determination depends strongly on the geometry of the stylus used in contact profilometry. Herein, the effect of stylus-tip size on surface roughness characterization was evaluated along with the suitability of fractal dimension (FD) analysis as a supplementary metric. Styluses with tip radii ranging from 0.25 to 1.75 mm were examined, and a 0.5-mm stylus tip (0.5R) yielded the most stable and reliable surface roughness measurements under a constant contact force of 5 gf. Coating considerably reduced surface roughness fluctuations, with the roughness mean absolute deviation (RMAD) decreasing by 78%. A comparison between a 0.5R conical stylus and a pyramidal stylus showed strong agreement in the R_a and RMAD values, confirming that the conical design maintained minimal contact area. High-resolution profilometry (0.1-μm spacing distance and 200,000 data points per scan) enabled the computation of FD via power spectral density analysis. FD values approached 2 for coated paper, reflecting a transition from line-dominated to more areal surface structures. These findings indicate that stylus selection critically affects surface roughness characterizations and that FD serves as a useful complementary descriptor for surface roughness changes.

Mechanical, microstructural, and hygrothermal behaviours were studied for hybrid epoxy composites reinforced with Borassus flabellifer fruit fiber (BFF), snake grass fiber (SGF), and gum Arabic. Six composites were fabricated with varying BFF-SGF ratios while maintaining constant epoxy (60%) and gum Arabic (10%) content. The composites were evaluated for tensile, flexural, impact, hardness, interlaminar shear strength (ILSS), density, water absorption, thickness swelling, and microstructural morphology using scanning electron microscopy (SEM). Hybridization significantly improved the overall structural performance of the composites. Among all compositions, the C3 composite (15% BFF / 15% SGF / 10% gum Arabic) exhibited the highest tensile strength (72 MPa), flexural strength (89 MPa), impact strength (28 kJ/m²), hardness (79 Shore D), ILSS (42 MPa), and density (1.21 g/cm³), and the lowest water absorption (6.1%) and minimum thickness swelling (1.53%) after 72 h. SEM analysis revealed improved fiber-matrix interfacial bonding, reduced void content, and uniform gum dispersion in the hybrid composites, which contributed to their superior performance. In contrast, single-fiber and gum-free composites demonstrated lower mechanical and hygrothermal performance due to weaker interfacial adhesion and non-uniform stress transfer. These findings indicate that BFF-SGF hybrid composites are promising materials for lightweight structural and semi-structural applications.

The goal of this project was to examine the bamboo craft activities at Sentra Industri’s “Bambu Kencana” center and to suggest technological know-how for creating composite bamboo panels. The employees of the Mechanical Engineering Department at the Faculty of Engineering at Universitas Muhammadiyah Yogyakarta (UMY) Indonesia got the opportunity to visit the center in order to carry this out. Wulung (Gigantochloa atroviolacea), apus (Gigantochloa apus), petung (Dendrocalamus asper), ampel (Bambusa vulgaris ssp.), and tutul (Bambusa maculata) were among the species found on the bamboo plantation at Jangkang Kidul, Sentolo. Apus is the species utilized for webbing. Day beds, chairs, and sofa settees are the center’s primary focus. The entire production process is based only on the old-fashioned way of nailing and tying rattan furniture. A bamboo composite panel is manufactured and brought to the center. The Purwanto people in Jangkang Kidul, Sentolo, received instruction on how to make a bamboo composite. In an attempt to revive the bamboo craft activity, UMY created a prototype using the bamboo composite. By giving a discussion on the process of creating a bamboo composite, the community was introduced to a value-added technology.