Papers by Keyword: Polymer

Abstract: Material abrasion is a critical consideration in product design, manufacturing, and maintenance because it has a high impact on several properties. When it comes to the abrasion of polymer yarns, insight into the behaviour of yarns due to constant abrasion is important for ensuring final product quality, performance, and customer satisfaction. For this study, a group of polymer yarns is selected. The yarns differ in raw material, as well as the yarn type. Within the experiment selected yarns in both single condition and within the fabric structure were conducted to different abrasion tests. The study findings reveal that yarn type, raw material composition, and additional treatments significantly influence abrasion resistance. Recycled polyester yarns demonstrate comparable, if not superior, abrasion resistance to conventional ones, making them viable for various applications.

Abstract: This study theoretically proposes a refractive index (RI) sensor based on a polymer composite with a no-core fiber (NCF) design structure. Sensor designs with diameter variations of 125 µm, 105 µm, and 85 µm are simulated using the Wave Optics Module of COMSOL Multiphysics® software. The sensors are characterized within an analyte range of 1.470 RIU to 1.500 RIU, at intervals of 0.005 RIU. The results demonstrate effective interaction between the structure and the sensing medium. The highest recorded sensitivity is 4×10⁻⁶ (dimensionless) for the 85 µm sensor, followed by 2×10⁻⁶ for the 105 µm sensor, and 1×10⁻⁶ for the 125 µm sensor. This study offers valuable insights, guiding the optimal design of polymer-based RI sensors for future environmental monitoring, chemistry, and biomedicine applications.

Abstract: Lignin is the largest component of biomass and the second most abundant natural polymer. Lignin-based products are commonly applied as binders, and are utilized for polymer applications. The purpose of this study is to use lignin as an admixture in mortar. The lignin dissolved in 1M NaOH solution, and the ratio was 1:5 by weight. The lignin contents utilised in this study were 1%, 2%, 3% by weight of cement and a cement water rasio of 0.4. Lignin as an admixture in mortar increased the flowability value. The flowability value increased as the lignin content rose. the highest compressive strength and flexural strength occured at 1% lignin content. They were 35.71 MPa and it was 5.49 MPa, at the age of 28 days. The longest setting time was obtained at 3% lignin content for initial setting time of 285 minutes, and final setting time of 540 minutes. Based on the results of the setting time test, it has been determined that the more lignin was mixed in, the longer the setting time will be. Therefore lignin as an admixture to the mortar makes changes its characteristics.

Abstract: The present research proposes the comparison of chitosan zinc nanocomposites in the form of membranes and hydrogels. Three concentrations (0.2, 0.4, and 0.6 wt%) of zinc (Zn) nanoparticle inclusion were used to create the chitosan nanocomposites for enhanced biological applications. Statistical analysis was performed with sample size N=16, an alpha error of 0.5, 95% confidence interval (CI), and G-power at 80%, The nanocomposite variations were analyzed for their improved capabilities against chitosan for its antibacterial activity (mm), water uptake (%), and other visual parameters including SEM and FTIR. Independent T-test through SPSS software revealed that both nanocomposites were statistically significant with (p = 0.01, p<0.05) and (p=0.026, (p>0.05)). The current study proposes novel chitosan with zinc nanocomposites with enhanced biological activity and offers a future scope for improved biomedical applications.

Abstract: Electrospinning (ES) is a vital technique for producing ultrafine polymer fibers and is widely used in various applications. However, conventional electrospinning setups with some polymer solutions face challenges like bead formation and inconsistent fiber diameters. Integrating airflow into the system helps stretch the fiber and speed up the evaporation of polymer jets, thereby improving fiber morphology. Despite these benefits, incorporating airflow complicates the setup and makes it less user-friendly, as achieving precise laminar airflow toward the jets is difficult. To address these problems, we developed a novel electrospinning attachment featuring easily adjustable slits incorporating controlled airflow with a pressure regulation system. The design allows for convenient adjustment of airflow direction through replaceable slits and blades. Its simplicity allows for easy blade replacement at different angles to control airflow toward the polymer jet. In our experiments, we tested two different slits angles of 30° and 60° (3D printed) to the setup. The results showed that controlled airflow significantly reduced bead formation and produced more uniform fiber diameters. With a 60° slit angle at 0.1 bar, the average fiber diameter was 647.6 nm, decreasing to 526.4 nm at 0.2 bar. Conversely, fibers spun with a 30° slit angle had an average diameter of 712.6 nm at 0.1 bar, with minimal change at 0.2 bar. These findings indicate that controlled laminar airflow with adjustable slit angles substantially improves the properties of electrospun fiber mats.

Abstract: In the numerous applications of technical polymers, it is a wide practice to compound them with solid lubricants in early steps of fabrication to improve the tribological behavior, considerably reducing friction and wear. Nonetheless, especially in injection molding, the inclusion of these lubricants often poses difficulties as they can significantly alter the viscosity and thermal behavior of the resin inside the screw. This practice is also quite inefficient due to the treatment of the whole bulk of the parts, where only the contact surfaces are affected by these inclusions. So, the aim of this work is to use lubricants with these solid particles in suspension, in order to have them permanently embedded in the working surfaces as they are put into service and then studying the impact that these inclusions have in the tribological behavior of the base polymer.

Abstract: When using the coat hanger die method for co-extrusion, the biggest challenges often involve maintaining the uniformity of the velocity distribution at the outlet of the die and ensuring the stability of the interface plane. This paper investigates the effect of different cross-section of feed channels connected to the coat hanger die on the velocity and pressure distribution of the flow at different parts of the die. Co-extrusion of LLDPE (Linear Low Density Polyethylene) and HDPE (High Density Polyethylene) polymers is simulated using ANSYS software 2020 R2 for coat hanger die design with rectangular and circular cross-sections inlet geometry; the results are compared for Carreau-Yasuda model to observe the result differences between rectangular and circular coextrusion channels connected to coat hanger die. Our results showed that rectangular cross-section feedblock generated higher values for pressure in comparison with the pressure generated by the circular cross-section feedblock. The maximum velocity generated in the circular feedblock is lower than that generated in the rectangular one, nevertheless there is more uniformity in velocity distribution in circular than rectangular cross-section.

Abstract: Multi-material Additive manufacturing (AM) has opened new opportunities for the creation of multifunctional structures that enables value-added structural product designs. Among the multi-material AM techniques, multi-nozzle fused filament fabrication which is a type of material extrusion technique is found to be the more popular choice for multi-material polymer fabrication. One major challenge of multi-material additive manufacturing of polymers is the poor mechanical strength at the interface of the dissimilar materials such as polylactic acid (PLA) and thermoplastic polyurethane (TPU) due to the lack of chemical affinity. Therefore, understanding the mechanical strength at the interface of these dissimilar materials becomes an important topic as it allows product designers to do necessary tweak to the design to compensate for the weaker link in the structural design. In this work, we investigated the tensile strength and the shear strength of different combinations of PLA and TPU and their respective nanocomposites, as well as the fatigue analysis of the bi-layer structures made of these dissimilar materials in a 3-point bending test configuration. Generally, when functional fillers or particles are added to the polymer in composites, they tend to adversely affect the interlaminar adhesion property and fatigue life of the soft-rigid bilayer structure. It was found, that the interlaminar tensile strength and the interlaminar shear strength can reduce as high as 44% and 78%, respectively, compared to the baseline samples with no fillers.

Abstract: Bone tissue engineering has been used in the biomedical field to treat bone defects by implanting scaffolds into bone tissue. However, the currently developed scaffold still needs to be developed to obtain scaffold building materials with good compatible properties and can regenerate damaged bone cells. This study combines PVA/Chitosan polymer with CHA of tuna bone using the porogen leaching method at a calcination temperature of 100°C for 12 hours. The purpose of this study was to determine the physicochemical properties by characterizing XRD, SEM-EDX, FTIR, and the porosity of the scaffold. The results obtained from the results of the PVA/Chitosan/CHA XRD patterns are the formation of the PVA/Chitosan phase at 2θ(°)=19.68, the IR spectrum of the 𝑃𝑂₄³⁻group band and 𝐶𝐻₂ stretching, the ratio mol Ca/P is 1.98, the pore diameter is 1.561 ± 0.07 μm and the porosity is 55.04%. These results indicate that the PVA/Chitosan/CHA scaffold is an amorphous calcium phosphate (ACP) that has the potential for bone tissue engineering.

Abstract: Piezoelectric ceramics possess very high piezoelectric coefficients but lacks the conformability for using them in flexible devices, in high-resolution sensing devices that can be integrated to human skin and other such applications. This problem can be resolved by blending them in appropriate proportion with polymers which are intrinsically light weight, stable and flexible. In this paper polymer composites xPZT– (1-x) PVDF (x= 0, 0.025, 0.05, 0.10, 0.15, 0.20 and 0.25) were prepared by solution casting method and their dielectric and its mechanical properties were studied. Given that PZT has a very high dielectric value, the composite's dielectric constant grew as the filler concentration increased which shows better dipole alignment in the composite. With an increase in filler concentration, the composite loses flexibility and tensile strength. Due to their greater Young's modulus than pure PVDF film, the films with compositions x=0.025 and x=0.05 could have better piezoelectric characteristics.