Materials Science Forum Vol. 1140

Abstract: Hydrogels, a type of polymer, can be synthesized from both natural and synthetic sources, including some biopolymers like alginate and chitosan, making them particularly interesting for biomedical applications. The popularity of hydrogels in the medical field is due to their high-water content, flexibility, and biocompatibility. Hydrogels, which can swell in a hydrated state, are capable of controlling the release of active substances in pharmaceutical and biomedical applications. Alginate and chitosan exhibit polyanionic and polycationic properties when dissolved under appropriate conditions, allowing them to interact with each other. This interaction occurs through the carbonyl groups of alginates and the amino groups of chitosan. Alginate also has the advantages of being non-toxic, biodegradable, biocompatible, and non-allergenic. Therefore, these two materials readily form polyelectrolyte complexes. The use of calcium chloride in producing hydrogels is due to its ability to perform ionic cross-linking on polymers such as alginate. Calcium chloride reacts with the carboxylate groups in alginate, forming stable cross-links between polymer chains. This cross-linking process results in a three-dimensional network that provides structure and stability to the hydrogel. The benefits of adding CaCl₂, in addition to facilitating cross-linking, include increasing the viscosity of the alginate solution, which enhances the formation of the alginate matrix. This study demonstrates that the ratio of chitosan to alginate significantly influences the properties of the resulting hydrogel, impacting its swelling ratio, stability, and ultimately, its potential for biomedical applications. Specifically, the optimal ratio of 5A:1C exhibited superior swelling and gel fraction characteristics, suggesting its potential suitability for controlled drug delivery systems. The successful cross-linking confirmed by FTIR analysis further strengthens the viability of this specific composition for biomedical applications.

Abstract: The dyeing ability of the polypropylene (PP) fiber was modified by blending with poly(lactic acid) (PLA). The PP, PLA, and PP/PLA fiber were obtained using the melt-spinning technique in the presence of the polypropylene-graft-maleic anhydride as a coupling. The dyeing ability, mechanical and thermal properties, and crystalline structure of the PP, PLA, and PP/PLA fibers were investigated. The effect of dyeing ability was measured using the CIE L^* a^* b^*. The a* value of the PP of 11.91 increased to 43.48 for PP/PLA90, showing a light pink to red color. The SEM images demonstrated smooth fiber with color coating on the fiber. The mechanical property of the fiber indicates that increasing the PLA decreased the tenacity of the PP fiber. The melting behavior of fiber increased with the PLA. The XRD presented the PP's crystalline and the PLA's amorphous structures.

Abstract: This study explores the synthesis and application of bio-based polyurethane (bio-PU) as a sustainable alternative to synthetic polyurethane (PU) in rubber polyurethane flooring. Bio-PU was synthesized by converting epoxidized palm oil (EPO) to bio-polyols using polysorbate20 at a ratio of 3:1, which was then reacted with polymeric methylene diphenyl diisocyanate (pMDI) to produce bio-PU. The bio-PU was blended with commercial PU and rubber granulate in concentrations of 10%, 20%, and 30%, with the aim of developing eco-friendly flooring materials. Key properties, including hydroxyl value, chemical functional groups (via FT-IR), force reduction, vertical deformation, tensile strength, elongation at break, and UV weathering resistance, were evaluated. The results demonstrated that rubber polyurethane flooring containing 30% bio-PU exhibited comparable or superior mechanical properties to flooring made with synthetic PU, meeting industry standards for force reduction, vertical deformation, and UV resistance. This study concludes that bio-based PU can serve as a viable alternative for the base layer of synthetic flooring, offering both environmental benefits and reliable performance.

Abstract: This study investigates the mechanical and low-velocity impact properties of 3D-printed Polyamide 12 (PA12) composites reinforced with randomly oriented hemp fibers. Hemp fiber was incorporated at varying weight percentages (4%, 6%, 8%, 10%, and 12%) within the PA12 matrix. Compression molding at 185°C and 4000 psi was used to fabricate composite samples. Tensile testing, drop weight impact analysis, hardness measurement, and scanning electron microscopy (SEM) were conducted to characterize the mechanical behavior of the composites. Results demonstrate that the incorporation of hemp fibers significantly enhances the tensile properties of the PA12 matrix. Composites containing 6% hemp exhibited the highest tensile strength compared to neat PA12. Further increasing the hemp fiber content up to 10% maintained comparable tensile properties to the 6% composite.

Abstract: The melt flow behavior of polylactic acid (PLA) composites reinforced with iron fillers at different extrusion temperatures was significantly explored to improve their hot melt extrudability and printability in FFF 3D printing technology. PLA/Fe composites have been developed to produce 3D polymer composite (PMCs) filaments for high-strength and magnetic filament applications. The melt flow properties, including melt flow rate (MFR) and flow behavior index (n), of PLA/Fe composite filaments were measured at 200 °C, 220 °C, and 240 °C. Furthermore, the velocity measurement on the composite filament melt was conducted during the melt flow test. A simulation model of the capillary tube in melt flow indexer was developed to predict the melt flow behavior and properties of the polymer composite using Computational Fluid Dynamics (CFD) simulation. The extrusion velocity of the model was compared with the experimental results. The cell Reynolds numbers of the PMCs melt were determined at the testing temperatures. The extrusion velocity and cell Reynolds numbers of the PMCs tended to increase with increasing testing temperatures, while the average velocity decreased four times with doubling the extruder diameter.

Abstract: This study investigates the influence of carbon black content on the mechanical properties of Nitrile Rubber (NBR), with a focus on applications in rotary shaft seals. NBR blends were prepared with varying levels of carbon black (40, 45 and 50 phr) and characterized to assess changes in hardness, tensile properties, compression set, and abrasion resistance. The results indicate that increasing the carbon black content enhances the hardness, tensile strength, and abrasion resistance of the NBR elastomers, which is beneficial for high-wear applications. However, this improvement in mechanical strength is accompanied by a higher compression set, suggesting a potential reduction in sealing efficiency due to diminished elasticity and recovery after deformation. The study highlights the critical need for optimizing carbon black content to achieve a balance between mechanical durability and effective sealing performance, ensuring the reliability of NBR elastomers in demanding rotary shaft seal applications.

Abstract: Crude palm oil (CPO) is commonly utilised in processed food items, including cooking oil. Cooking oil is made by heating it at high temperatures and refining it with bleaching earth to remove the sap and brown-red hue. As a result, it can remove β-carotene from CPO, which is no longer physiologically beneficial for human metabolism. This study seeks to eliminate sap and contaminants in CPO by assessing optimal degumming operation model with response surface methodology (RSM) to gain degummed red palm oil (DRPO) at high retaining β-carotene content. The results show that the optimal factors are 70°C heating temperature and 0.4% (v/v) of phosphoric acid concentration, with a β-carotene value was 455.892 ppm. After the degumming process, the physicochemical properties of palm oil remained relatively constant. Group bonds were unchanged since the primary triglyceride component contains C-H and C=O group bonds. The predicted degradation β-carotene model was y = 451.94 - 53.8(X) - 10.99(Y) + 3.61(XY) - 17.23(X²) - 18.56(Y²) by lack of fit 3.47%, X is temperature range, and Y volume range. This quadratic model has function for further degummed reactor design, on range operation variable.