Macromolecular Symposia最新文献

The C─F bond in the structure of Tetra-fluoroethylene propylene (TFEP) determines its good high temperature resistance and chemical stability, which makes this rubber widely used in the petrochemical industry. Compared with other rubbers, TFEP has high molecular chain stability and is not easy to cross-link. So, it suffers from low cross-linking efficiency and poor mechanical properties. The development of suitable cross-linking systems is significant to improve the performance of TFEP. Polyhedral oligomeric silsesquioxane (POSS) is widely used in composites because of its good thermal stability and mechanical properties. POSS-like materials have been widely used as cross-linking agents in the preparation of polymers, but their applications in fluoroelastomers are relatively few. In this paper, the effects of two different reactive functional groups of the R groups of POSS materials on the cross-linking behavior of TFEP are analyzed. We first optimized the formulation by vulcanization and mechanical property tests. Then, the type and dosage of the main crosslinking agent were optimized by vulcanization characteristic test, mechanical property test, and other characterization methods. The structures of the composites were characterized by IR spectroscopy and scanning electron microscope (SEM). Their mechanical and thermal properties were measured by tensile experiment, thermogravimetric analysis (TGA), and Differential Scanning Calorimetry (DSC) Analysis.

This study aims to investigate dynamic mechanical properties of platinum (Pt) catalyst cured vinyl-methyl-polysiloxane (VMQ) phenyl-vinyl-methyl-polysiloxane (PVMQ) elastomers at natural frequency and compare those properties for these two elastomer systems. It is also aimed to show the effect of radiation on dynamic mechanical properties of VMQ and PVMQ elastomers at natural frequency. First, Pt-VMQ and Pt-PVMQ elastomers’ curing conditions were determined using a moving die rheometer. Then, the cured silicone elastomers were irradiated with different doses. To show the effect of absorbed dose on the mechanical properties of both elastomer systems, stress–strain behaviors were examined using universal testing machine, and it was shown that ionizing radiation increases the tensile strength of both elastomer systems while it decreases elongation at the break value of both of them. The crosslink densities of Pt-VMQ and Pt-PVMQ elastomers were calculated to determine the effect of the absorbed dose on the network structure of elastomers. In order to determine the crosslink density of both VMQ and PVMQ elastomers, swelling degree and other relevant parameter were used, and it was shown the effect of ionizing radiation on both VMQ and PVMQ elastomers is an increase in crosslink density. To identify the effect of irradiation on the damping properties of Pt-VMQ and Pt-PVMQ elastomers at the natural frequency, dynamic mechanical properties were investigated using Dynamic Mechanical Yerzley Oscillograph (DMYO-5). As a result of this study, it has been shown that PVMQ elastomers’ dynamic mechanical properties at natural frequency are more stable against radiation than VMQ elastomers.

Nanocluster is an important field of science and technology, which helps to investigate the advancement that subsists among the microscopic and macroscopic framework of materials. The study of transition metallic nanoclusters has drawn considerable attention recently. In the present work, density functional theory (DFT) paradigm is efficaciously applied to examine platinum Pt_n (n = 2–7) nanoclusters. Highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap of Pt_n nanoclusters fluctuate among 0.259–1.275 eV. The data reveals that Pt₂ cluster exhibits maximum ionization potential, HOMO–LUMO energy gap, molecular hardness, and electronegativity, whereas it has minimum softness and electrophilicity index. System Pt₅ displays a minimum value for HOMO–LUMO energy gap and molecular hardness. However, Pt₅ cluster exhibits a maximum value of softness and electrophilicity index. Cluster Pt₇ possesses a minimum value of ionization potential and electronegativity, whereas it displays a maximum value of electron affinity. System Pt₆ exhibits minimum electron affinity and maximum dipole moment. The smaller electrophilicity index of Pt₂ cluster indicates potential for the stable cluster. The linear association among HOMO–LUMO gap and CDFT-based parameters are examined. The HOMO–LUMO gap of the investigated platinum nanoclusters follows an even–odd alteration pattern.

In this study, the sol–gel synthesis technique was used to create the pure nickel ferrite (NiFe₂O₄) nanoparticles. Citric acid is utilized as a stabilizing agent to aid in the creation of nanoparticles and control the size and morphology of the nanoparticles. Nickel sulfate hexahydrate (Ni(SO₄)⋅6H₂O) and iron nitrate nonahydrate (Fe₂ (NO₃)₃⋅9H₂O) are used as precursors. To improve the size and band gap of the resulting nanoparticle sample, ultraviolet (UV) characterization is performed. To create the homogenous solution known as PEG-NiFe₂O₄ nanofluids of 2% concentration and 0.6 g of nanoparticle powder were disseminated into 30 mL of polyethylene glycol (PEG) polymer and agitated for at least 4 h at 70°C. To evaluate the ultrasonic velocity, density, and viscosity at various temperatures (303–333 K), the acquired sample was poured into the ultrasonic interferometer cylinder of ultrasonic wave frequencies 2 and 5 MHz in addition, utilizing practical parameters like ultrasonic velocity, density, and viscosity, the associated ultrasonic parameters like adiabatic compressibility, acoustic impedance, and ultrasonic attenuation were calculated. The obtained results have been discussed in detail.

Carboxylated nitrile butadiene rubber (XNBR) is widely used in glove manufacturing due to its exceptional properties. However, the limited biodegradability of XNBR gloves has raised environmental concerns, driving the need for sustainable material innovations. This study explores the potential of cellulose-based fillers to enhance the biodegradation process. Cellulose nanofibers (CNF) were extracted from oil palm empty fruit bunches (OPEFB) and incorporated as fillers into XNBR latex to evaluate their impact on biodegradation across various crosslinking systems. The latex films were prepared with sulfur crosslinking (XNBR-control) and without sulfur crosslinking, utilizing different formulations (CNF, CNF-ZnO, CNF-ZDEC, and CNF-sulfur). These films were subjected to aging tests and soil burial experiments to assess their performance. Tensile properties and crosslink density were measured to understand the effects of aging, while biodegradation was monitored at intervals of 2, 4, and 8 weeks during soil burial. Analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, mass loss measurements, and surface morphology analysis were employed to characterize the degradation process. The results revealed that incorporating CNF significantly improved the biodegradation rate of XNBR latex films. Notably, films prepared without sulfur crosslinking degraded faster than those with sulfur crosslinking, highlighting the influence of crosslinking chemistry on biodegradability. This study demonstrates that integrating nanocellulose from agricultural waste like OPEFB into XNBR latex provides an effective pathway to enhance environmental sustainability in glove manufacturing.

Bio-based oil is emerging as a promising alternative to replace rubber processing oil from petroleum as a plasticizer in elastomers. Petroleum-based oil is considered environmentally harmful and is derived from nonrenewable resources. This study explores replacing petroleum-based rubber processing oils with bio-based oils in elastomers. The research focuses on ternary rubber blends (NR/BR/SSBR) mixed with petroleum-based oil (RPO), epoxidized palm oil (EPO), coconut oil (CO), soybean oil (SBO), and sunflower oil (SFO), using conventional rubber processing methods. A dual filler system of carbon black and silica was employed to reinforce the rubber. The result shows that among all bio-based oils, EPO improves both tensile strength (0.7% increase) and elongation at break (7% increase) compared to RPO, along with better wear resistance and skid resistance but prolonged the optimum cure time. In the meantime, CO offers good elongation, wear resistance, and dynamic performance similar to RPO, with a slight decrease in tensile strength. Meanwhile, SBO has the lowest rolling resistance among the bio-based oils based on Tan δ at 60°C, but it also decreases tensile strength and wear resistance while greatly increasing flexibility (11.2% increase in elongation). Among the bio-based oils, however, SFO offers a balance with moderate improvements in flexibility and dynamic properties but lower wear resistance.

The goal of this study is to present a thorough comparison of the physicochemical characteristics of potassium permanganate (KMnO₄) and potassium iodide (KI) in deionized water (DD water) at various temperatures. The study highlights how temperature affects the characteristics of these solutions and investigates their possible uses in industrial and medicinal settings. Evaluation of the KI and KMnO₄ solutions’ density, viscosity, and solubility in deionized water is among the factors that go into their physicochemical characterization. Measurements are carried out at different temperatures to capture the temperature-dependent behavior of these mixes and get insight into their application under various environmental situations. Within the medical field, studies look into how well these solutions work for certain uses, such as wound care, antifungal therapies, etc. Their potential in medication delivery systems and pharmaceutical formulations is also investigated. The study examines these solutions’ industrial uses in analytical chemistry, chemical production, and water treatment. The findings of this study further our knowledge of the kinetics and thermodynamics of KI and KMnO₄ solutions in deionized water. Comparative assessments help to choose appropriate applications in the industrial and medical arenas by illuminating the distinctive characteristics of each solution. Ultrasonic velocity will be measured in KI and KMnO₄ mixed with DD water by using an ultrasonic interferometer, and all the other acoustical parameters will also be evaluated. The obtained results will be discussed in detail.