Journal of Research Updates in Polymer Science

Shear Strengthening of Deep Beams Using Polymer-Based CFRP Bars via the Near-Surface Mounting (NSM) Technique

2026-01-19T10:23:33+00:00

Near-surface-mounted strengthening with polymer-based carbon fiber-reinforced polymer (CFRP) bars has been proved as one of the efficient techniques in enhancing the shear capacity of reinforced concrete RC deep beams. This paper presents an experimental investigation on the shear behavior of RC deep beams strengthened with NSM CFRP bars. Five identical RC deep beam specimens with the same geometry and internal steel reinforcement were tested under two-point loading. One specimen was left un-strengthened as a control beam; while four specimens have been strengthened by CFRP bars embedded in the shear zone with two orientations, 0°/90° and 45°/135°, and two spacing configurations, 100 and 150 mm. Response parameters of prime interest included first shear cracking load, ultimate shear capacity, crack pattern, and mid-span deflection. The findings of the experiment demonstrated that NSM CFRP strengthening improved the shear performance of deep beams; depending on the orientation and spacing of the CFRP bars, shear capacity augmentation ranged from about 14% to 47% in comparison to the control specimen. Additionally, at similar load levels, strengthened beams demonstrated a 10% to 40% decrease in mid-span deflections and fracture widths. The test results demonstrate how well polymer-based CFRP bars inserted using the NSM technology improve the stiffness and shear strength of RC deep beams.

Structural behavior and Thermal Stress Response of Steel Members under Thermo-Environmental Loading for Polymer Reinforced Structural Systems

2026-01-19T10:20:39+00:00

The structural behavior and thermally induced stresses of steel members play an important role in the safety, serviceability and long-term performance of civil engineering structures exposed to high temperatures and high humidity. Variations in stiffness, thermal deformation and stress redistribution directly affect the bearing capacity, deflection limit and durability of structural components, especially when polymer-based coatings and hybrid polymer-metal systems are used for environmental protection. In this study, a numerical investigation is performed to measure the thermomechanical response of commonly used structural steels (AISI 304, 316, 1020 and 1045) subjected to coupled thermal and humid conditions. Key structural parameters including elastic stiffness degradation, thermal deflection and thermal stress development are evaluated to support rational material selection and performance-based structural design. The results show that increasing temperature gives a significant increase in deflection for all steel grades due to a reduction in Young's modulus, while the thermally induced stress decreases as a result of hardness softening. Carbon steels (1020 and 1045) exhibit low thermal deflection and high structural stiffness, while stainless steels (304 and 316) exhibit superior resistance to moisture-induced corrosion and environmental degradation, which is essential for durability-oriented structural applications. These findings highlight the inherent trade-off between structural stiffness, thermal compatibility and environmental resistance when choosing a steel substrate.

Mechanical and Morphological Analysis of 3D-Printed Polylactic Acid-Polybutylene Adipate Terephthalate Composite

2026-02-04T14:02:57+00:00

In this research paper, a detailed examination of the mechanical properties and morphologies of PLA and PBAT polymer blend materials which were produced through 3D printing techniques was conducted. The examination was completed using a PLA/PBAT/Joncryl blended material with a composition ratio of 77/20/3 wt% and manufactured through FDM techniques and an experimental design technique known as the Taguchi method to evaluate the effects of various manufacturing parameters on the mechanical characteristics of the material. This study investigates the mechanical and morphological performance of FDM-printed PLA/PBAT/Joncryl blend specimens using a Taguchi L9 design. A PLA/PBAT/Joncryl blend (77/20/3 wt%) was fabricated and printed by varying layer height (0.16–0.24 mm), printing temperature (190–210 °C), and infill density (50–100%). The optimal condition (0.16 mm, 210 °C, 100% infill) produced a maximum tensile strength of 41.20 N/mm² and elongation of 12.42%. ANOVA results confirmed infill density as the most significant parameter contributing 81.35% of the variance (P = 0.009). SEM revealed reduced voids and improved interlayer fusion at higher infill levels, while DMA showed higher storage modulus (~2200 MPa) for 100% infill specimens. The findings provide a process–structure–property relationship for optimizing biodegradable PLA/PBAT components for high-strength applications. This study illustrates that the infill % is the primary parameter that should be adjusted, while the layer height and printing temperature contribute but to a lesser extent to the improved performance of biodegradable PLA/PBAT/Joncryl blends.