Journal of Fibers and Polymer Composites

Tensile Strength of Adhesively Bonded Steel to Hybrid Sisal-Glass Reinforced HDPE Composite Joint for Automobile Side Body Panel Application

Samuel Tesfaye Molla — 2026-02-15

The increasing demand for lightweight, high-performance, and environmentally sustainable materials in the automotive industry has accelerated the adoption of adhesive bonding as an alternative to conventional joining techniques such as welding and mechanical fastening. Reliable prediction of stress distribution and debonding behavior in adhesively bonded composite–metal joints is therefore essential to ensure structural integrity under service loading. This study presents a comprehensive computational and experimental investigation of the tensile stress behavior of adhesively bonded single-side strap joints (ABSSSJ) formed between steel and hybrid sisal–glass reinforced high-density polyethylene (HDPE) composites for automobile side body panel applications. The hybrid composite adherend was modeled as an orthotropic laminate with a ([0°/+45°/90°/–45°/0°]) stacking sequence, while the adhesive layer was characterized using different epoxy systems (Araldite 2020, Araldite 2015, and AV138) with thicknesses ranging from 0.12 to 1.0 mm and elastic moduli between 1.85 and 6 GPa. An analytical variational method was employed to evaluate shear and peel stress distributions, and the results were verified using a cohesive zone model (CZM)-based finite element approach to simulate crack initiation and progressive debonding. Experimental tensile and shear tests were conducted to validate the numerical predictions. The results indicate that an adhesive thickness of approximately 0.75 mm provides an optimal balance between load transfer efficiency and stress reduction at the overlap edges. The numerical and analytical predictions exhibited strong agreement with experimental measurements, with a maximum deviation below 6%. The validated results demonstrate that hybrid sisal–glass reinforced HDPE composites, when combined with appropriate adhesive and joint design, offer a promising, lightweight, and sustainable solution for automotive side body panel structures.

Modified PVA Film from Methanol-Soluble Phenolic Extracts of Spatholobus littoralis Hask as Active Pharmaceutical Packaging

Kadriadi Kadriadi — 2026-02-20

The development of active pharmaceutical packaging based on biodegradable materials is an important strategy to reduce dependence on single-use plastics and their environmental impact. Polyvinyl alcohol (PVA) is a potential biodegradable polymer, but it has limitations in terms of exposure to ultraviolet (UV) radiation and microbial contamination. This study aims to develop a modified PVA film with methanol-soluble phenolic extract of Spatholobus littoralis Hask as active pharmaceutical packaging with UV protection, antioxidant, and antibacterial functions. The phenolic extract was obtained through a maceration method using methanol as a solvent, while the PVA film was fabricated using the solution casting technique. The PVA film was modified with varying concentrations of phenolic extract of 0, 1.25, 2.5, and 5wt% (PPE0, PPE1.25, PPE2.5, and PPE5), then evaluated for its UV protection properties, antioxidant activity, and antibacterial activity. The results showed that the addition of S. littoralis phenolic extract was able to increase the ability of PVA films to block UV radiation completely (100%) in the 200–400 nm wavelength range. Antioxidant activity testing using the DPPH method showed an increase in free radical scavenging ability as the concentration of phenolic extract increased. In addition, the modified PVA film showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli. These findings indicate that S. littoralis Hask phenolic extract has potential as a natural bioactive agent in the development of environmentally friendly and multifunctional active pharmaceutical packaging, with dual protection capabilities against UV degradation and microbial contamination. This research makes an important contribution to the development of sustainable pharmaceutical packaging materials based on renewable natural resources.

Structural Characterization and Tensile Properties of Untreated and Alkali Treated Water Hyacinth Fibre

Augustine Uchechukwu Elinwa — 2026-02-27

Water hyacinth (Eichhornia crassipes) is an abundant aquatic biomass whose utilisation as a reinforcement fibre is limited by high contents of hemicellulose, lignin, waxes, and inorganic deposits. This study evaluates the effect of 10 % NaOH treatment on the structural, chemical, thermal, and mechanical properties of water hyacinth fibres (WHF). Scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA/DTG), and single-fibre tensile testing were employed. Alkali treatment induced extensive defibrillation of compact fibre bundles into individual microfibrils (≈2–7 µm), transformation of cellulose I to cellulose II, and a marked increase in crystallinity from approximately 25 % to 71 %. Potassium and chloride contents were reduced by more than 99 %, and the maximum thermal degradation temperature increased from about 337 °C to 367 °C. Tensile strength and Young’s modulus increased from 18.4 ± 3.1 MPa to 58.1 ± 2.9 MPa and from 1.42 ± 0.18 GPa to 4.83 ± 0.23 GPa, respectively. These results demonstrate that NaOH treatment effectively purifies and structurally optimises WHF, significantly enhancing its thermal resistance and mechanical performance for sustainable composite reinforcement applications.