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Under elevated loading conditions, the aggregation of fillers emerges as a pivotal factor driving the degradation of separation performance in mixed matrix membranes. The two-dimensional (2D) modification of fillers, aimed at enhancing interfacial contact with polymers, has been recognized as an effective strategy to improve interphase compatibility and increase filler loading capacity. However, it is worth noting that the BET surface area of 2D fillers is typically relatively low. In this study, a two-step approach was developed. First, a “diffusion-mediated” process was combined with a solvent optimization strategy based on first-principles (DFT) calculations, achieving a 20-fold suppression in ZIF-67 nucleation-crystallization rate. This enabled the successful synthesis of a 2D amorphous nanoflower structure. Subsequently, the processing parameters were fine-tuned to enhance the specific surface area of ZIF-67 to 403 m[sup.2]/g while preserving its 2D structural integrity. Ultimately, the as-prepared 2D ZIF-67 was incorporated into a hydrogenated styrene-butadiene block copolymer (SEBS) matrix to fabricate a mixed matrix membrane. Remarkably, at a filler loading of 20 wt%, the CH[sub.4] permeability coefficient increased significantly from 11.7 barrer to 35.3 barrer, while the CH[sub.4]/N[sub.2] selectivity was maintained at 3.21, indicating minimal interfacial defects and demonstrating the feasibility and effectiveness of the proposed methodology.

Cobalt(II) chloride (CoCl[sub.2]) being in the vicinity of polyimide chains entails modifications in terms of the molecular dynamics, which are mainly governed by the possible presence of amic acid residual groups, by the transition-metal-type characteristics of cobalt and by the CoCl[sub.2] content. Polyimide was synthesized using poly(amic acid) according to the reaction of 2,2′-bis(3,4-dicarboxylphenyl)hexafluoropropane dianhydride (6FDA) with 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MMDA) in N,N-dimethylacetamide. CoCl[sub.2] was added before the thermal imidization of the poly(amic acid). An experimental approach was designed to establish the interaction between the polyimide and CoCl[sub.2] and whether the interaction depends on the quantity of the salt. Evidence for the existence of residual amic acid groups was obtained using second derivative Fourier Transform Infrared Spectroscopy (FTIR) and with the help of 2D correlation spectroscopy (2D-COS). Moreover, FTIR, along with X-ray photoelectron spectroscopy (XPS), revealed the interaction between the polymer and CoCl[sub.2], primarily in the form of Co(II)-N coordinated bonds. Nevertheless, the coordination of cobalt with suitable atoms from the amic acid groups is not precluded. The results of dynamic mechanical analysis (DMA) featured a specific relaxation assigned to the presence of CoCl[sub.2] in the polymeric film and demonstrated that its (non)reinforcing effect depends on its content in the polyimide.

The goal of this paper is to analyze the aging behavior and the mechanism evolution of nano-Al[sub.2]O[sub.3] (NA)-reinforced styrene-butadiene-styrene (SBS) asphalt under different thermal-oxidative aging conditions. First, NA/SBS-modified asphalt and SBS-modified asphalt with different aging levels were prepared. Second, the viscosity and high temperature rheological performance of the specimens were tested and the property-related aging indexes were calculated and compared. Third, a Fourier transform infrared (FTIR) test of the specimen was conducted and the chemical group-related aging indexes were calculated and analyzed. Fourth, gel permeation chromatography (GPC) was used to analyze the molecular weight of the specimens under different aging levels. Then, an atomic force microscope (AFM) was adopted to analyze the microsurface morphology of different specimens. Finally, correlation analysis between property-related indexes and chemical group indexes was conducted. The results show that NA can enhance the thermal-oxidative aging resistance of SBS asphalt. NA can inhibit the increase in sulfoxide groups and the degradation of the SBS polymer with the increase in aging. NA can slow down the formation of large molecule during the aging process. The degree of change in both the bee structures and micromorphological roughness of NA/SBS asphalt is lower than that of SBS asphalt under different aging levels.

The coordination polymerization of 1,3-butadiene with half-metallocenes/MAO catalysts is a versatile route to polybutadiene, yet the kinetic impact of catalyst preparation remains poorly understood. This work compares CpTiCl[sub.3]/MAO systems prepared either in situ or by aging as a function of [MAO]/[Ti], temperature, and the presence of residual trimethylaluminum (TMA) in MAO. Aged catalysts display markedly higher activity than in-situ systems, achieving up to 99% conversion at [MAO]/[Ti] = 250 (vs. 34% in situ) while maintaining similar molecular weights and cis-1,4 microstructure (76–77%). Because the in-situ and aged systems were evaluated at different titanium concentrations, this activity difference should be interpreted as arising from both catalyst pre-conditioning and differences in effective Ti concentration. Time-resolved GPC coupled with chromatogram deconvolution reveals two coexisting macromolecular populations, associated with kinetically distinct chain-growth contributions. For aged systems, the corresponding apparent propagation rate constants remain of the same order of magnitude throughout the reaction, consistent with persistent catalytic heterogeneity rather than progressive site deactivation. The role of residual trimethylaluminum (TMA) in commercial MAO is clarified: TMA accelerates initial activation and enhances chain transfer processes, lowering molecular weight and broadening dispersity, but does not measurably affect cis-1,4 selectivity, which is governed by the ligand environment of CpTiCl[sub.3]. Overall, thermal aging and MAO conditioning emerge as effective tools to tune the kinetic behavior of CpTiCl[sub.3]/MAO catalysts without compromising microstructural control in polybutadiene synthesis.

Heterogeneous hydrogenation is an effective way to improve the performance of unsaturated polymers, but the preparation of supported catalysts with high metal dispersion and stability remains challenging. Herein, we synthesize a SiO.sub.2-based support wrapping with carbon nitride on the surface (CN.sub.x@SiO.sub.2) via the thermal polycondensation of melamine, on which Pd nanoclusters with highly exposed active sites are formed and stably anchored via the strong interaction between N and Pd. The thermal temperature affects the properties of CN.sub.x, which further modulates the electronic and structural state of Pd nanoclusters. The Pd/CN.sub.x @SiO.sub.2-500 catalyst, prepared at 500 °C with an optimal CN.sub.x structure (g-C.sub.3N.sub.4) and high nitrogen content, features highly dispersed and electron-rich Pd nanoclusters (1.3 nm). This catalyst exhibits a hydrogenation activity of 98.0% for nitrile rubber, with a selectivity of 100% for C=C bonds. This work provides a facile method to prepare Pd catalysts with high activity and stability, paving the way for the upgrading of unsaturated polymers via hydrogenation.

Fused deposition modeling (FDM) technology works with specialized 3D printers and production-grade thermoplastics to build robust, durable, and dimensionally stable parts with the best accuracy and repeatability of any other available 3D printing technology. FDM is one of the highly used additive manufacturing technology due to its ability to manufacture very complex geometries. However, the critical problems with this technology have been to balance the ability to produce esthetically appealing products with functionality and properties at the lowest cost possible. In this study, three major process parameters such as layer height, raster angle, and infill density have been considered to study their effects on mechanical properties of acrylonitrile butadiene styrene (ABS) as this material is widely used industrial thermoplastic in FDM technology. The test results show a clear demonstration of the considered factors over the mechanical variables measured. Response surface methodology is used for the validation of the experimental data and the future prediction of the test results. It was found that the optimum parameters for 3D printing using ABS are 80% infill percentage, 0.5 mm layer thickness, and 65° raster angle. The achieved experimental ultimate tensile strength, elastic modulus, yield strength, fracture strain, and toughness (energy absorption) are 31.57 MPa, 774.50 MPa, 19.95 MPa, 0.094 mm/mm, and 2.28 Jm −3 , respectively. Mathematical equation has been developed using surface response methodology which can be used to predict the ABS tensile properties numerically and also to predict the optimum parameter for ultimate properties.

In a high-pressure hydrogen environment, the sealing rubber material is swelled by hydrogen, and the mechanical and tribological properties are reduced, causing various problems in the sealing performance. The focus of this study was the effect of the filler type and content on the tribological characteristics of rubber after exposure to high-pressure hydrogen. Acrylonitrile butadiene rubber specimens were exposed to high-pressure hydrogen at 96.6 MPa, and the change in the amount of wear with time after exposure was observed. The wear test was performed using a pin-on-disc ball tip to measure the amount of wear before and after hydrogen exposure of the materials under fixed revolutions per minute and normal load. Scanning electron microscopy was used to observe the wear track and cross section of the specimen to examine the changes in the wear mechanism after hydrogen exposure and to analyze the wear mechanism for each filler. The results of this study are expected to contribute to the evaluation of the tribological properties of the sealing materials used in hydrogen environments.

In this study, a thermoresponsive shape memory polymer based on various compositions of melt blended of polylactic acid (PLA) and styrene-butadiene-styrene (SBS) copolymer was prepared. Dynamic rheological behavior was measured using a parallel plate rheometer over a range of 0.1-100 rad.sup.- 1 and was correlated with the shape memory, thermal and tensile properties of the blends. The blend with 70%PLA (70PLA/30SBS) that possessed intermediate storage and loss moduli showed the best shape memory performance in terms of shape fixity ratio (R.sub.f) and shape recovery ratio (R.sub.r). The tensile strength and modulus increased while elongation at break reduced with increasing PLA with significant changes found at 50PLA/50SBS due to the formation of co-continuous morphology. The SBS content did not significantly affect the glass transition temperature of the PLA but the crystallinity slightly increased with increasing SBS. The sea-island morphology of 70PLA/30SBS where SBS formed droplets in the PLA continuous phase provides optimum tensile and shape memory properties.

In this paper, the MgO-SiO.sub.2 catalyst was prepared with the deposition-precipitation method, which was used to catalyse the conversion of ethanol to 1,3-butadiene through a two-step process. The carbon deposition deactivation of the catalyst was mainly caused by that the carbon species occupied the acid-basic active sites on the catalyst surface. The carbon deposition mainly includes chain alkanes and aromatic compounds from outer to inner layers, and its site was mainly MgSiO.sub.3, followed by MgO, while SiO.sub.2 showed weak carbon deposition ability.

ABS is an engineering plastic that has butadiene part uniformly distributed over the acrylonitrile-styrene matrix. It possesses excellent toughness, good dimensional stability, easy processing ability, chemical resistance, and cheapness. However, it suffers from inherent shortcomings in terms of mechanical strength and vulnerability to environmental conditions. Furthermore, it is non-conducting and easily fretted. Plating on ABS can serve to enhance the strength and structural integrity as well as to improve durability and thermal resistance resulting in metallic properties on the ABS material. ABS is described as the most suitable candidate for plating because it is possible to deposit an adherent metal coating on it by only the use of chemical pretreatment process and without the use of any mechanical abrasion. This article aims to review the history of ABS plastics, properties of ABS, processes and mechanisms of plating, and studies of plating on ABS involving mainly eco-friendly methods of plating by discussing the literature published in recent years. The details of electroplating of ABS carried out in the authors’ laboratory are also presented.