Porous Fillers Research Articles

PEO-based mixed matrix membranes containing N-doped microporous carbon microparticles for enhanced CO2/N2 separation

As a promising strategy to reduce greenhouse gas emissions, carbon dioxide capture from industrial and power plants has been proposed. Due to its advantages of low consumption and a modest environmental impact, membrane technology has been widely used in the gas separation process. Advanced porous fillers can be successfully added into the polymer matrix to create mixed matrix membranes (MMMs) with simple processing and applicable gas separation performance. The high porosity and stability of microporous carbon materials make them desirable for use in the gas separation process. Herein, N-doped microporous carbon microparticles (NMCP) were successfully synthesized and incorporated into UV crosslinked polyethylene oxide (XLPEO) matrix membranes. Fast CO2 transport channels are created in MMMs by rationally constructing NMCP fillers with ultra-micropores (∼0.53 nm), high-content heteroatoms (N, 13.94%), and two-dimensional morphology. The relationship between the structure of the NMCP samples and the gas separation performance of MMMs was discussed. Additionally, tests were conducted on the effects of NMCP loading, operating conditions, and long-term stability of NMCP/XLPEO membranes. NMCP/XLPEO membranes with a 2.5 wt% NMCP loading displayed a CO2 permeability of 606 Barrer and a CO2/N2 selectivity of 56.4, approaching the 2019 upper bound. This work offers a novel perspective to build fast gas transport channels in porous carbon-based MMMs for carbon capture.

Cage-like structured flexible hybrid fiber/SiO2 aerogel composite for noise reduction

The fiber/aerogel material prepared by the traditional method of sol-gel has a serious powder shedding phenomenon, and has serious environmental pollution and health hazards. In this study, an environmentally friendly porous sound absorption material with a cage-like structure, which used flexible ultrafine glass/quartz hybrid fibers (HFs) as the carrier and SiO2 aerogel as the pore filler, was produced using the wet manufacturing process. The addition of aerogel enhanced the internal reflection of sound waves, reduced the propagation speed, increased the acoustic energy loss and improved the sound absorption coefficient (SAC). The noise reduction coefficient (NRC) reaches 0.49 in the range of 250–6300 Hz. The obtained composite presented a low density (73.5 mg/cm3) and heat resistance up to 500 °C.

Innovative Nanostructured Fillers for Dental Resins: Nanoporous Alumina and Titania Nanotubes.

The possibility of improving dental restorative materials is investigated through the addition of two different types of fillers to a polymeric resin. These fillers, consisting of porous alumina and TiO2 nanotubes, are compared based on their common physicochemical properties on the nanometric scale. The aim was to characterize and compare the surface morphological properties of composite resins with different types of fillers using analytical techniques. Moreover, ways to optimize the mechanical, surface, and aesthetic properties of reinforced polymer composites are discussed for applications in dental treatments. Filler-reinforced polymer composites are the most widely used materials in curing dental pathologies, although it remains necessary to optimize properties such as mechanical resistance, surface characteristics, and biocompatibility. Anodized porous alumina nanoparticles prepared by electrochemical anodization offer a route to improve mechanical properties and biocompatibility as well as to allow for the controlled release of bioactive molecules that can promote tissue integration and regeneration. The inclusion of TiO2 nanotubes prepared by hydrothermal treatment in the resin matrix promotes the improvement of mechanical and physical properties such as strength, stiffness, and hardness, as well as aesthetic properties such as color stability and translucency. The surface morphological properties of composite resins with anodized porous alumina and TiO2 nanotube fillers were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and X-ray chemical analysis. In addition, the stress-strain behavior of the two composite resins is examined in comparison with enamel and dentin.

Enhancing dry mix mortar strength with natural fillers and polymers

Dry mix mortars are becoming more and more popular in the world’s building materials market. Therefore, the issue of increasing the technological and mechanical properties of stucco mixes is relevant. The aim of the paper is modification of lightweight dry stucco mixes with fine limestone and perlite as well as with hydroxyethyl methyl cellulose and dispersible polymer. In order to investigate the different mixes, an 18-point experiment was designed. Density, compressive strengths and crack resistance of dry plaster mixes were studied using requirements of standard. Mathematical models were obtained for the compositions as a result of processing the experimental data. The regularities of the fillers’ and additives’ influence on the properties of the mixes were established, depending on their amount and combination. It was observed that methyl hydroxyethyl cellulose improves the crack resistance and compression strength, and contributes to a slight decrease in density. The crack resistance of plaster mortars changes more than 1.5 times, the most crack-resistant compositions have an average amount of porous fillers.

Gas adsorption isotherm, pore size distribution, and free volume fraction of polymer-polymer mixed matrix membranes before and after thermal rearrangement

In this work, CO2 adsorption at 273.15 K and N2 adsorption at 77 K of mixed matrix membranes has been studied, as a method to directly determine their fractional free volume (FFV). These membranes consist of a continuous phase of copoly(o-hydroxyamide)s (HPA) or copoly(o-hydroxyamide-amide)s (PAA) and a relatively highly porous polymer network filler (PPN1). Both the pure copolymers and the mixed matrix membranes (MMMs) have been analyzed before and after a thermal rearrangement (TR) process.The CO2 adsorption results have allowed characterizing the pore size distribution of the studied membranes in the 3–15 Å range, by using the Non-Local Density Functional Theory (NLDFT). Whereas the N2 adsorption has allowed determining the pore size distributions in the range between 20 and 250 Å.The experimental determination of the pore volume and the density allows the direct calculation of the membranes’ free volume fractions, which were in good agreement with the most usual FFV evaluation methods. In addition, part of the pore volume detected by N2 adsorption was associated with defects and poor integration of the membrane components. This correction has allowed us to make a new evaluation of the density of these materials.

Evaluation of Thermal and Rheological Properties of Phase Change Material-Incorporated Asphalt Mastic with Porous Fillers

Incorporating phase change material (PCM) into paving materials can regulate the pavement temperature, improve the pavement durability, and mitigate the heat-island effects. In this research, porous fillers were used as the PCM carrier, and the thermal and rheological behaviors of the asphalt mastic with the PCM were evaluated. Two different carrier materials (diatomite and expanded perlite) and four types of PCMs were used in the study. The candidate filler, PCM, and proper blending ratios were determined based on the results of scanning electron microscope image analysis, the filter paper test, and the temperature sweep test. The thermal and rheological behaviors of the mastics with PCMs were further evaluated with different filler replacement ratios. Thermal analysis through a differential scanning calorimetry test, thermal conductivity and volumetric heat capacity test, and real-time temperature performance test were performed on the asphalt mastics. Rheological tests, including the complex shear modulus test, the bending beam rheometer test, and the linear amplitude sweep test, were also conducted. The modified mastics were found to have high heat capacity with the latent heat storage ability. The rheological analyses showed that with the addition of polyethylene glycol, while the low-temperature performance of the asphalt mastics was improved, the performance at intermediate and high temperatures was not adversely affected by the PCM.

Synergistic tuning mixed matrix membranes by Ag+-doping in UiO-66-NH2/polymers of intrinsic microporosity for remarkable CO2/N2 separation

Novel mixed matrix membranes (MMMs) with superior CO2/N2 separation properties are of great importance for post-combustion CO2 capture from flue gas. Metal-organic frameworks (MOFs) as one of the most attractive porous fillers for MMMs fabrication, are considered to provide a solid molecular sieving mechanism for enhancing CO2/N2 selectivity. However, it causes the reduction in gas permeability and limits its further industrialization. Herein, we proposed a new strategy for filler functionalization by doping silver ions (Ag+) into UiO-66-NH2 nanoparticles through the double-solvent method and used for the preparation of advanced MMMs. The double-solvent method is benefits for the enrichment of Ag+ in the hydrophilic pores of UiO-66-NH2. As a result, the prepared novel MMMs called Ag+@UiO@PIM-1 with the polymers of intrinsic microporosity (PIMs) as polymer matrix, show outstanding CO2 permeability. According to the mixed gases (CO2/N2 = 10:90) permeation experiments under 25 °C and 2 bar, the membrane with 30%Ag+@10%UiO loading achieves more than 65% increase in CO2/N2 selectivity (∼30) and 120% in CO2 permeability (>15,000 Barrer) compared to the pristine PIM-1 membrane. By optimizing the Ag+ doping amount and Ag+@UiO loading content, the separation performance exceeds the 2019 CO2/N2 upper bound. To figure out the separation mechanism, the pore texture properties and CO2 affinity of the functional filler (Ag+@UiO) together with the membrane structure were characterized by XPS, PXRD, SEM, gas sorption, etc. The synergistic mechanisms by combing CO2 facilitated transport and molecular sieving from pore regulation were identified to enable advanced CO2/N2 membrane separation.

Fabrication of high-performance thermally conductive phase change material composites with porous ceramic filler network for efficient thermal management

In this study, a novel erythritol-grafted bisphenol A (ETBPA) phase change material (PCM) was fabricated through esterification, and a porous ceramic filler network consisting of carbonized cellulose nanofiber (CNF) was prepared via freeze-casting and carbonization of CNF. The PCM composites (ETBPA/BNCNF/BN and ETBPA/AlNCNF/AlN) were fabricated using three kinds of methods: melt mixing, hot-pressing, and injection molding. Results revealed that the hot-pressed BN-based composite exhibited an ultra-high thermal conductivity (13.09 W/mK, 2518% enhancement compared to pure ET) along the through-plane direction, 300% increased tensile strength (3.2 MPa), and a latent heat of 98.4 J/g. The fabricated ETBPA/BNCNF/BN composites exhibited efficient thermal management performance via the combination of heat absorption and heat dissipation properties owing to their high thermal conductivity and large latent heat. The results indicate the potential of the fabricated PCM composites to contribute to the research on thermal management systems.

Modelling the Influence of Composition on the Properties of Lightweight Plaster Mortar and Multicriteria Optimisation

The influence of the components of plaster mortars on their properties is considered in a lot of studies at a qualitative level without searching for optimal compositions of these multicomponent composite materials. The purpose of this study was to obtain the experimental-statistical models based on the results of the designed experiment, allowing the influence of light fillers and polymer admixtures on the properties of the mortars to be evaluated and analysed; the compositions complying with specified requirements and compromised optimally by a number of properties should be found. The quantities of fine limestone and perlite as well as of the hydroxyethyl methyl cellulose and dispersible polymer were varied in the experiment. The effective viscosity and thixotropy of the mix, compression, tensile, adhesive strength, frost resistance, and density of hardened mortars were determined for 18 compositions according to the experiment design. The obtained models have allowed the individual and synergetic effects of mix components to be evaluated. The fine perlite has turned out to have the greatest positive effect on the properties. This porous filler increases the strength while decreasing the density of the mortars. It is shown how the composition complying with specified requirements-and the best based on several properties-has been found.

Durability of Asphalt Concrete with Mineral Fillers Made of Non-Carbonate Raw Materials

The decisive influence on the corrosion resistance of asphalt concrete, and, consequently, on its durability is influenced by the presence of structural bonds at the interface between phases "crushed stone - binder". The weakening of these bonds leads to formation of various defects in roadway - cracks, potholes, etc. The article examines influence of mineral fillers made of non-carbonate raw materials on the durability of asphalt concrete. Analysis of group composition of bitumen made it possible to establish a mechanism for slowing down the aging rate of an organic binder when using porous mineral fillers made of natural zeolites and brown coals. It was found that asphalt concrete with natural zeolite and brown coal in their composition have low dependence of deformative properties on ambient temperature compared to asphalt concrete with traditional limestone mineral filler.

Recycling of ash slag of the fuel and energy complex into the production of porous aggregate and its ecological and economic efficiency

Currently, the need to solve the accumulated environmental problems is crucial for the survival of mankind. The article describes a method of processing a large–tonnage secondary resource - ash and slag and waste of the fuel and energy industry. An assessment of the ecological and economic efficiency of this technology was presented. It showed that the use of large-tonnage waste of the fuel and energy industry makes it possible to obtain porous aggregates with improved physical and mechanical properties. It was shown that ash-slag waste can be used as a filler and a burn-out additive in the production of porous fillers based on the liquid-glass composition. The new technology for obtaining a porous filler (RF patent № 2470885) involves the following operations: grinding andmixing, obtaining granules, heat treatment at 250-300 °C, heat trearment at 1000 oC, production of a porous filler M400 with a thermal conductivity of less than 0.25 W / (m °>C). The method of production of porous aggregate allows for the use of large–tonnage waste - ash and slag materials without the use of natural traditional raw materials such as clay, and quartz sand. The study has shown that porosity is little visible. This means that the ash–slag material contributes to the production of closed pores in the porous filler, which increases strength of the products; the optimal amount of ash-slag is 37%. The results of the use of ash and slag are as follows: a) an increase in the volume of production of porous aggregates due to waste recycling; b) increased profit; c) higher waste capacity; d) saving on material resources.

Flow of viscous reacting fluid through a porous filler in a flat channel

The flow and heat transfer of a viscous chemically reacting liquid in a flat channel during the molding of composite products are studied. The main assumptions in the task definition were made on the basis of the high viscosity of the liquid and its low thermal diffusivity. The Brinkman equation is used as a motion equation. The flow is accompanied by a chemical reaction, resulting in a sharp increase in viscosity. The viscosity is considered to depend on the temperature and the degree of conversion. This, in turn, led to the inclusion of the kinetic equation of a chemical reaction in the mathematical model. The energy equation is denoted using a single-temperature model and includes dissipative heat emissions. The problem is solved for temperature first-order boundary conditions. The calculations are given for the Nusselt number distribution and the velocity profile transformation. The task was solved numerically by the finite difference method using iterations.

Investigation of the formation of microstructure and strength characteristics of slag-alkaline arbolite

The creation of the slag-alkaline arbolite's structure is examined in this study, which is based on measurements of the deformation of the mortar component, contact zone, and filler. Composites made of slag and alkaline arbolite are among the lightest building materials available, with excellent sound insulation and low thermal conductivity. Standard measuring equipment and procedures for analyzing the chemical and physico-mechanical properties of slag-alkaline arbolite composites were employed during the experimental tests. All of the test samples were light concrete prisms with a cross section of 150x150 mm and a length of 600 mm. For comparison, one portion of the samples was constructed of slag-alkaline Portland cement, and the other portion was made of slag-alkaline binder with crushed cotton stem fibers as an organic component. The durability and deformability of arbolite were tested under Kazakhstan weather conditions and in standard hardening chambers. The arbolite underwent a compression stress that ranged from (0.3 to 0.75) Rbn of prismatic strength. It was discovered that the organic cellulose filler added to the slag-alkaline binder based on crushed cotton stalk fiber, which makes up to 70 % of the volume, has a major impact on the way structures are formed. The system becomes rigid, the elasticity changes, and the acoustic properties in this case will fix both physical and physico-chemical processes when a porous organic filler is added. The acquired results can be applied to the creation of efficient wall materials for civil buildings, including seismic zones

Performance improvement of waste oyster-shell powder–cement binary system via carbonation curing

The dumping of significant amounts of industrial waste oyster shells causes marine pollution and economic loss. Grinding and processing waste oyster shells into oyster shell powder (OSP) to substitute a portion of cement can potentially reduce marine pollution and greenhouse gas emissions. Herein, 0, 15, and 30% OSP were added to cement and cured by employing different methods with and without CO2. The dilution effect of the OSP reduced the heat of hydration. The compressive strength and electrical resistivity of all the mixtures increased after carbonation curing compared to the seal cured specimens. The CO2 absorption contents and rate of carbonation increased with an increase in the OSP content. During carbonation curing, OSP contributes to the carbonation of the cement material, forming large amounts of carbonation products (calcite, aragonite, and vaterite). The precipitation of carbonation products acts as a pore filler, significantly increasing the mixture's performance more than seal curing. Therefore, OSP has significant potential as a replacement material for cement via carbonation curing, and its promising CO2 capture and storage capacities provide a viable solution for greenhouse gas reduction.

COMPUTER MODELING OF PROPERTIES OF A COMPOSITE MATERIAL WITH POROUS FILLERS

The article is devoted to forecasting of heat-shielding and mechanical properties of composite materials based on porous fillers.Analytical dependencies for determining the thermal conductivity coefficient of materials of homogeneous and heterogeneous structure are given. Based on the finite element method, there has been developed a method for numerical determination of the thermal conductivity coefficient of composite materials with a variotropic structure.The results of computer studies are in line with the dependences obtained on analytical models. The expediency of using multilayer composite materials based on porous fillers in load-bearing and enclosing structures of shell and plate types has been shown.

Porous liquid metal-organic frameworks with selectively high gas solubility

Porous liquid metal–organic frameworks (MOFs) have recently been discovered rather promising for gas absorption and separation in practical chemical industry processes. In this work, we successfully fabricated a kind of MOF-based porous liquid (i.e., UIO-66-PL) by dispersing the hydrophilic porous filler of UIO-66-NH2 nanoparticles into a specific hydrophilic ionic liquid (IL, [HEMIM][DCA]) through the wet-impregnation method. The obtained UIO-66-PL was a kind of stable porous liquid with well-maintained permanent porosity and liquid-like behavior at room temperature. More importantly, this UIO-66-PL has larger gas absorption capacities than its reference IL hindered solvent as the well-preserved permanent porosity could act as free void space for gas accommodation. Also, IL could serve as a selective gate for target gas to the permanent porosity within UIO-66-PL, i.e., the majority of the permanent porosity in UIO-66-PL is inaccessible to nitrogen, but available for carbon dioxide, demonstrating that this UIO-66-PL could function as a type of fluid selective gas sorbent with high target gas solubility.

Structure Formation and Properties of a Porous Fillers Based on Man-Made Waste

Structure Formation and Properties of a Porous Fillers Based on Man-Made Waste

PVA/UiO-66 mixed matrix membranes for n-butanol dehydration via pervaporation and effect of ethanol

In this work, pervaporative mixed matrix membranes (MMMs) composed of porous UiO-66 filler newly-synthesized and poly (vinyl alcohol) (PVA) have been investigated for dewatering n-butanol (BuOH) from BuOH/H2O and BuOH/ethanol/H2O solutions. The influences of the filler loading, feed concentration and feed temperature on the membrane dehydration performance are investigated in detail in terms of pervaporation flux/separation factor, pervaporation separation index and component permeance/selectivity. It is found that with the increase in feed water concentration or temperature, total permeation flux across the MMM substantially rises while the dehydration separation factor decreases considerably. With the increase in feed temperature, pronounced increase in the driving force is resulted, yielding the decline in the partial permeance and water/n-butanol selectivity but increase in the component flux. As the water content increases, the water permeance and water/n-butanol selectivity are reduced while both BuOH flux and permeance increase. Over the filler loading range considered here, the MMM with 15 wt% UiO-66 has reached the largest pervaporation separation index of 2560 kg/m2·h at 70 °C and 10 wt% water in the feed. In the case of using 10 wt% ethanol for BuOH in the feed, the dewatering separation performance has varied substantially as compared to the binary feed, leading to reduced separation factor and elevated permeation flux for the 15 wt% UiO-66 filled MMM. In the meantime, the MMM has maintained excellent separation performance over a testing duration of 240 h. Our results show that pervaporative UiO-66/PVA MMMs have demonstrated great potential in practical BuOH dehydration applications.

A Universal Room-Temperature 3D Printing Approach Towards porous MOF Based Dendrites Inhibition Hybrid Solid-State Electrolytes.

Hybrid solid-state electrolytes (HSSEs) provide new opportunities and inspiration for the realization of safer, higher energy-density metal batteries. The innovative application of 3-dimensional printing in the electrochemical field, especially in solid-state electrolytes, endows energy storage devices with fascinating characteristics. In this paper, effective dendrite-inhibited PEO/MOFs HSSEs is innovatively developed through universal room-temperature 3-dimensional printing (RT-3DP) strategy. The prepared HSSEs display enhanced dendrite inhibition due to the porous MOF filler promoting homogeneity of lithium deposition and the formation of C-OCO3 Li, ROLi, LiF mesophases, which further improve the migration of Li+ in PEO chain and comprehensive performances. This universal strategy realizes the fabrication of different slurry components (PEO with ZIF-67, MOF-74, UIO-66, ZIF-8 fillers) HSSEs at RT environment, providing new inspirations for the exploration of next-generation advanced solid-state batteries.

USE OF 3D-PRINTED FRACTURE MODELS VERSUS SAWBONES FOR SURGICAL RESIDENT TRAINING: A FEASIBILITY STUDY

Conventional fracture courses utilise prefabricated sawbones that are not realistic or patient specific. The aim of this study is to determine the feasibility of creating 3D fracture models and utilising them in fracture courses to teach surgical technique.We selected an AO type 2R3C2 fracture that underwent open reduction internal fixation. De-identified CT scan images were converted to a stereolithography (STL) format. This was then processed using Computer Aided Design (CAD) to create a virtual 3D model. The model was 3D printed using a combination of standard thermoplastic polymer (STP) and a porous filler to create a realistic cortical and cancellous bone. A case-based sawbone workshop was organised for residents, unaccredited registrars, and orthopaedic trainees comparing the fracture model with a prefabricated T-split distal radius fracture. Pre-operative images aided discussion of fixation, and post-operative x-rays allowed comparison between the participants fixation. Participants were provided with identical reduction tools. We created a questionnaire for participants to rate their satisfaction and experience using a Likert scale.The 3D printed fracture model aided understanding and appreciation of the fracture pattern and key fragments amongst residents and unaccredited trainees. Real case-based models provided a superior learning experience and environment to aid teaching. The generic sawbone provided easier drilling and inserting of screws. Preliminary results show that the cost of 3D printing can be comparable to generic sawbones.It is feasible to create a fracture model with a real bone feel. Further research and development is required to determine the optimum material to use for a more realistic feel.The use of 3D printed fracture models is feasible and provides an alternative to generic sawbone fracture models in providing surgical training to residents.