Filler Modification Research Articles

How Can the Filler-Polymer Interaction in Mixed Matrix Membranes Be Enhanced?

Mixed matrix membranes (MMMs) constitute a type of molecular separation membranes in which a nanomaterial type filler is dispersed in a given polymer to enhance its selective permeation ability. The key issue in MMMs is the establishing of a proper filler-polymer interaction to avoid non-selective transport paths while increasing permeability but also to improve other membrane properties such as aging and plasticization. Along the pass years several strategies have been applied to enhance the physicochemical interaction between the fillers (e. g. silicas, zeolites, porous coordination polymers, carbonaceous materials, etc.) and the membrane polymers: increase of external surface area, priming, use of intrinsically more compatible fillers, in situ synthesis of filler, in situ polymerization, polymer side-chain modification and post-synthetic modification of filler.

Effect of L-arginine and KMnO4 amendment on sulfonamide antibiotics wastewater treatment in an adsorption-biological coupling reactor: Insights from performance and functional genes analysis

The overuse of sulfonamide antibiotics (SAs) has placed considerable treatment pressure on wastewater treatment plants. The adsorption-biological coupling reactor we developed have been demonstrated to be effective in the treatment of SAs wastewater. However, the effect of filler modification on reactor performance and the degradation mechanisms of SAs remains inadequately understood. Herein, the amendment of filler with L-arginine and KMnO4 were investigated. The overall removal efficiency of COD, TP, NH3-N, sulfadiazine (SD), and sulfamethoxazole (SMX) in the reactor with L-arginine-modified coke (A-Coke) as filler were (79.29±15.29)%, (84.81±4.13)%, (92.67±11.25)%, (93.45±4.74)% and (93.60±4.13)%, while in the reactor with KMnO4-modified coke (K-Coke) as filler, the overall removal efficiency of COD, TP, NH3-N, SD and SMX were (90.60±6.68)%, (96.26±2.52)%, (95.14±5.29)%, (92.63±5.78)% and (93.65±6.48)%, respectively. The dominant bacteria in the reactor with A-Coke as filler were Azohydromonas, Propionibacterium, Bdellovibrio, and Sphingomonas, and those in the reactor with K-Coke as filler were Azohydromonas, Lysobacter, Plasticicumulans, and Cupriavidus. The compounds 4-hydroxy-2-aminopyrimidine, 4-hydroxy-2-hydroxy-aminopyrimidine, n-acetamide, 4-benzoquinone, 1,2, 4-trihydroxybenzene, 3-amino-5-methylisoxazole, and TP163 were detected as metabolites of SAs in the reactor filled with A-Coke. In contrast, 4-hydroxy-2-hydroxy-aminopyrimidine, 3-amino-5-methyl isoxazole, and TP163 as metabolites of SAs were detected in the effluent water of the reactor with K-Coke as filler. The results demonstrate that the amendment of L-arginine and KMnO4 could increase the performance of the adsorption-biological coupling reactor, which has potential application prospects in the treatment of SAs wastewater.

Insight into the aminosilane functionalized-montmorillonite/Pebax mixed matrix membranes with selectively fast gas transport channels for CO2 permeation

Mixed matrix membranes (MMMs) hold a great prospect for CO2 separation and capture. To further improve the separation efficiency, surface modification of fillers with organosilanes is an effective way to establish a link between polymers and fillers with respect to optimizing the interfacial morphology. In this study, MMMs were prepared using polyether-block-polyamide (Pebax) as a continuous matrix phase and aminosilane functionalized-montmorillonite (K-MMT) as dispersive fillers. K-MMT plays multiple roles for modifying the structure and improving the performance of resultant MMMs. The introduction of K-MMT disrupts the hydrogen bonding between the hard segments and decreases the crystallinity of MMMs. Furthermore, the inner channels of K-MMT could provide high-speed facilitated gas transport passages, of which the structural metal cations further offer transport carriers so as to substantially increase the CO2 permeability. Moreover, K-MMT can positively capture CO2 in gas mixture on the dependence of the mobility of long-chain amino groups and the reversible reaction between CO2 and amine groups. Additionally, the introduction of 3-aminopropyl triethoxysilane tends to enlarge the structural interlayer spacings of MMT, resulting into the facilitated penetration of CO2 through resultant MMMs. In brief, the MMMs doped with 4 % K-MMT show the optimal gas separation, i.e., CO2 permeability of 196.4 Barrer and CO2/N2 ideal selectivity of 162.4, which is far beyond the proposed 2019 upper bound for CO2/N2 system.

Properties of EPDM Nanocomposites Reinforced with Modified Montmorillonite.

Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to obtain DMMT, which was confirmed by XRD, XPS, FTIR, and TGA. After compounding DMMT gel with the solid EPDM via the gel compounding method, a silane coupling agent, vinyltrimethoxysilane, was introduced to construct covalent interactions between rubber and filler. Compared with the unmodified MMT filler EPDM, the EPDM/DMMT nanocomposite showed much fewer filler aggregates in the matrix. The highest tensile strength of the composites reached 6.5 MPa with 10 phr DMMT, almost 200% higher than that of pure EPDM.

Research progress of highly wear‐resistant and oxidation‐resistant polymer acetabular cup prosthesis

AbstractThe polymer‐based acetabular cup prosthesis, a vital component of hip replacement surgery, significantly contributes to the recovery of patients afflicted with osteoarthritic conditions. Nevertheless, the current clinical usage of polymer acetabular cup prostheses commonly encounters the challenge of balancing wear resistance and oxidation resistance, significantly impacting both their lifespan and patients′ quality of life. Consequently, researchers have persistently enhanced the attributes of polymer acetabular cup prosthetic materials. These enhancements, including irradiation and filler modifications, are intended to concurrently bolster both the wear and oxidation resistance of the prosthesis materials. This comprehensive approach aims to address wear‐associated clinical complications like osteolysis and oxidative brittleness, ultimately extending their in vivo service life. For this reason, this paper retrospectively discusses the progress of research on the modification of polymer acetabular cup prosthesis materials for high wear and oxidation resistance and explores potential design methods for optimising artificial acetabular cup materials, with a view to providing new ideas for extending the service life of artificial joint implants.

Effect of Wettability Modification of Inert Fillers on the Properties of Epoxy Coatings: An Experimental and Theoretical Approach

Effect of Wettability Modification of Inert Fillers on the Properties of Epoxy Coatings: An Experimental and Theoretical Approach

Strongly reinforced mechanical and thermal properties of polyamide 66 by high loading titanium dioxide whiskers

Of large length-to-diameter ratio and specific area, inorganic whiskers were widely applied for polymer reinforcement. As a well-known nanofiller, titanium dioxide (TiO2) has been welcome by polymer engineering, mostly for whitening with spherical shapes favored. To date, there have been no TiO2 whiskers reported for polymer reinforcement. In this work, a rutile type TiO2 whisker was compounded with polyamide 66 (PA66) to prepare nanocomposites with surficial modification being conducted to further improve the compatibility between them. It was found that the rutile-type TiO2 whisker significantly improves the mechanical properties of PA66 at high loadings and the performance went better when surficial modification for it was applied. Under 50 wt% addition of TiO2 whisker either modified or not, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and heat deformation temperature of prepared PA66 composites were respectively increased by 52 %, 279 %, 44 %, 313 %, 20 %, 199 % and 84 %, 279 %, 88 %, 303 %, 114 %, 207 %, comparing with the pristine PA66. The mechanism regarding the overall reinforcement was analyzed, which was attributed to the shape-relevant multiple interactions between TiO2 and PA66. Besides, the improved adhesion due to strong stable chemical bonding by surficial modification of fillers, is also accountable.

Effect of BaTiO3 Filler Modification with Multiwalled Carbon Nanotubes on Electric Properties of Polymer Nanocomposites.

Two ranges of dielectric permittivity (k) increase in polymer composites upon the modification of BaTiO3 filler with multiwalled carbon nanotubes (MWCNTs) are shown for the first time. The first increase in permittivity is observed at low MWCNT content in the composite (approximately 0.07 vol.%) without a considerable increase in dielectric loss tangent and electrical conductivity. This effect is determined by the intensification of filler-polymer interactions caused by the nanotubes, which introduce Brønsted acidic centers on the modified filler surface and thus promote interactions with the cyanoethyl ester of polyvinyl alcohol (CEPVA) polymer binder. Consequently, the structure of the composites becomes more uniform: the permittivity increase is accompanied by a decrease in the lacunarity (nonuniformity) of the structure and an increase in scale invariance, which characterizes the self-similarity of the composite structure. The permittivity of the composites in the first range follows a modified Lichtenecker equation, including the content of Brønsted acidic centers as a parameter. The second permittivity growth range features a drastic increase in the dielectric loss tangent and conductivity corresponding to the percolation effect with the threshold at 0.3 vol.% of MWCNTs.

Acid-mediated strategies designed for stretchable and durable polyacrylamide/sodium alginate dual-network hydrogels toward flexible capacitors and wearable sensors

The utilization of acid as a synthesis assistant provides an effective means to regulate the structure of hydrogels, thereby simplifying the design and preparation process of multifunctional hydrogels. However, there remains a dearth of discourse concerning the utilization of this convenient acid-mediated strategy, which possesses the potential to directly govern molecular interactions within gel networks for rational structure and property design. Herein, we describe the preparation of flexible dual-network conductive hydrogels using polyacrylamide (PAM) and sodium alginate (SA) as substrates, driven by the strategy of acid-mediated (HCI, H2SO4, and H2C2O4) in detail for the first time. Especially, the structure-activity relationship of hydrogels was elucidated through a comparative analysis of molecular dynamics (MD) simulations and empirical properties, thereby enhancing the understanding of this field. Furthermore, extensive investigations have been conducted to explore the distinct impacts of acid ions and concentrations. The acid-mediated method exhibits superior versatility and operability compared to the filler modification method, thereby enabling a more convenient acquisition of conductive and robust hydrogels suitable for flexible capacitors and wearable sensors. Consequently, this study presents a straightforward, efficient, and cost-effective universal strategy for targeted functional hydrogel design.

Optimizing the Microenvironment in Solid Polymer Electrolytes by Anion Vacancy Coupled with Carbon Dots.

The practical application of solid polymer electrolyte is hindered by the small transference number of Li+, low ionic conductivity and poor interfacial stability, which are seriously determined by the microenvironment in polymer electrolyte. The introduction of functional fillers is an effective solution to these problems. In this work, based on density functional theory (DFT) calculations, it is demonstrated that the anion vacancy of filler can anchor anions of lithium salt, thereby significantly increasing the transference number of Li+ in the electrolyte. Therefore, flower-like SnS2-based filler with abundant sulfur vacancies is prepared under the regulation of functionalized carbon dots (CDs). It is worth mentioning that the CDs dotted on the surface of SnS2 have rich organic functional groups, which can serve as the bridging agent to enhance the compatibility of filler and polymer, leading to superior mechanical performance and fast ion transport pathway. Additionally, the in situ formed Li2S/Li3N at the interface of Li metal and electrolyte facilitate the fast Li+ diffusion and uniform Li deposition, effectively mitigating the growth of lithium dendrites. As a result, the assembled lithium metal batteries exhibit excellent cycling stability, reflecting the superiority of the carbon dots derived vacancy-rich inorganic filler modification strategy.

Optimizing the Microenvironment in Solid Polymer Electrolytes by Anion Vacancy Coupled with Carbon Dots

The practical application of solid polymer electrolyte is hindered by the small transference number of Li+, low ionic conductivity and poor interfacial stability, which are seriously determined by the microenvironment in polymer electrolyte. The introduction of functional fillers is an effective solution to these problems. In this work, based on density functional theory (DFT) calculations, it is demonstrated that the anion vacancy of filler can anchor anions of lithium salt, thereby significantly increasing the transference number of Li+ in the electrolyte. Therefore, flower‐like SnS2‐based filler with abundant sulfur vacancies is prepared under the regulation of functionalized carbon dots (CDs). It is worth mentioning that the CDs dotted on the surface of SnS2 have rich organic functional groups, which can serve as the bridging agent to enhance the compatibility of filler and polymer, leading to superior mechanical performance and fast ion transport pathway. Additionally, the in‐situ formed Li2S/Li3N at the interface of Li metal and electrolyte facilitate the fast Li+ diffusion and uniform Li deposition, effectively mitigating the growth of lithium dendrites. As a result, the assembled lithium metal batteries exhibit excellent cycling stability, reflecting the superiority of the carbon dots derived vacancy‐rich inorganic filler modification strategy.

Hydroxyapatite modified with polyhedral oligomeric silsesquioxane as a filler for dental resin-based composites

Hydroxyapatite modified with methacrylate groups-bearing polyhedral oligomeric silsesquioxane was for the first time applied as a filler in the experimental composite for dental applications. As the modifier changed the hydroxyapatite surface from hydrophilic to hydrophobic, it was predicted that the stability of the obtained composites would be improved in comparison with raw hydroxyapatite-filled composites. The stability in the oral imitating environment, basic physicochemical properties, and remineralizing potential understood as the ability to release calcium ions, were examined. The distribution of the fillers in the organic matrix, composites’ degree of conversion, depth of cure, flexural and compressive strengths, sorption, and solubility after 2 and 12 weeks of incubation, and the concentrations of calcium released were examined. The results were subjected to statistical analysis. The filler modification resulted in the improvement of the composites’ mass stability during long-term incubation with simultaneous beneficial more balanced calcium release profiles and comparable physicochemical properties.Graphical abstract

Thermodynamic prediction of filler surface modification by APTES on corrosion resistance of nano-TiO2/waterborne epoxy coatings

Common techniques for creating novel coatings include chemically modifying inorganic fillers and exploring how modifications affect coating service performance. However, it frequently takes a lot of time and tedious attempts to get the ideal alteration degree for fillers. Although the surface energy of the fillers is thought to be a significant thermodynamic parameter, it is still unknown how chemical modification affects surface energy and how the properties of fillers in a coating relate to the quantization difference of thermodynamic parameters. In this study, the impact of chemical modification on the quantization difference of nano-TiO2 surface energy has been uncovered. Creating a “wetting-reagglomeration-adsorption” isogram by utilizing three surface interfacial parameters has also been achieved: the contact angle between the liquid resin and the filler, the driving energy of the filler reagglomeration, and the polymer molecules' diffusion energy at the filler/coating interface. The relationship between the quantitative difference of thermodynamic parameters and the dispersion, compatibility and interfacial strength of the fillers in the waterborne epoxy was predicted by the isocontour map. From the isocontour map, the modified nano-TiO2 fillers with 4.04 APTES molecules/nm2 shows the minimum ∆Wa of 16.17 mJ/m2 and the maximum Ws of 23.15 mJ/m2 in the composite coating, which is predicted to exhibit the best dispersibility and the strongest interfacial strength. The prediction results were successfully verified by the techniques of microscopic morphology observation (TEM and SEM), mechanical properties tests (DMA and tensile tests), and corrosion resistance tests (EIS and salt spray tests). This work has a significant guiding role in the development of the filler modifications for the creation of novel coatings.

Effects of Filler Modification on the Properties of Elastomeric Composites

Effects of Filler Modification on the Properties of Elastomeric Composites

Boosting carbon capture with CO2-Ultrapermeable molecularly imprinted membranes

Mixed matrix membrane (MMM) is one of the most promising candidates for exceeding the gas separation upper bound, while fillers can largely determine their ultimate performance. The molecular imprinting technique was first employed to prepare a layer containing rich CO2 adsorption sites on the UiO-66-NH2 surface for fabricating highly CO2-permeable PIM-1-based MMMs with higher selectivity. Transmission electron microscopy (TEM) and element mapping confirmed the successful formation of the core-shell structure for the imprinted metal-organic frameworks (MOFs). The MMMs prepared with imprinted MOFs present enhanced CO2 permeability and CO2/N2 selectivity, higher compatibility between polymers and fillers, and better mechanical strength compared to the MMMs with the pristine UiO-66-NH2. The MMMs formed with 5 wt% imprinted MOFs showed superior CO2/N2 separation performance beyond the 2019 upper bound with an ultrahigh CO2 permeability of 13,000 barrer (increased twice compared to pristine PIM-1 membrane). Moreover, with a filler content of 13 wt%, the obtained membrane maintains good mechanical properties, which indicates the benefit of the imprinted layer for the improvement of the filler loading inside a PIM-1 matrix. The membranes showed decreased CO2 permeability and CO2/N2 selectivity under the wet conditions, but stable performances over 46 hours of dynamic testing. The results indicate the presented approach for filler modification via molecular imprinting is a promising strategy for the enhancement of the MMM separation performance.

Radiolytic modification of polymer filler for cement compositions

Radiolytic modification of polymer filler for cement compositions

Preparation and Evaluation of Epoxy Based Material for High Performance Electronic Packaging through the Surface Modification of Fillers

The continuous integration and refinement of electronic equipment results in the more stringent requirements for epoxy resin (EP) based materials, such as excellent heat dissipation and low coefficient of thermal expansion (CTE). In order to improve the dispersion of silica powder (SP) in EP and thus expand the application of EP in the field of electronic packaging, our research described in this paper adopted the KH-550 coupling agent to modify the surface of SP (m-SP). The effects of KH-550 coupling agent on the characteristics of the composites were investigated in terms of thermal, rheological, electrical insulation and mechanical properties. The results showed that when the content of KH-550 was 2 wt% of the fillers, the best modification effect was achieved, and the surface properties of the fillers were changed accordingly. In particular, the materials filled with m-SP exhibited lower viscosity end, better mechanical and electrical insulation properties. It was also found that the adding of the KH-550 had different effects on the thermal degradation, dynamic thermo-mechanical properties and the thermal deformation behavior of the materials. According to our study, the thermal conductivity and the CTE of m-SP/EP filled with 70 wt% of modified fillers were 0.787 W/m.K and 28.3 ppm/°C respectively, corresponding to a significant thermal conductivity improvement and low CTE.

Composite Material Based on Polypropylene and Modified Natural Fillers.

The work presents the results of a comprehensive study on obtaining compositions based on polypropylene and natural fillers modified by enzymatic preparations under high-shear forces. The experiment protocol includes determining the modification time and the ratio of water volume to the mass of natural filler (hydro modulus) during modification, which turned out to be different for each type of filler. Physical and mechanical analyses were conducted to evaluate the operational characteristics of the obtained composites, with particular attention given to comparing the modified compositions with their unmodified counterparts. The time and hydro module of the enzymatic modification of the natural fillers under consideration were investigated, which turned out to be different for each type of filler. It was found that surface modification of natural fillers improves mechanical properties; namely, the tensile strength of composites with wood and sunflower fillers increases by 10%, and the impact viscosity of composites also increases by 12% with wood and sunflower fillers. Water absorption decreases in composites, after 2 h boiling, with wood flour by 30% and with rice husk by 10%. After a 14-day test at room temperature, water absorption decreases by more than 30% in composites with rice husk. When determining the free surface energy of composites, it was found that the modification of the filler reduces the polarity of the composites in all samples, which can be interpreted as an improvement in the interaction between the filler and the polymer matrix. The findings of this research have important implications for the development of advanced polymeric materials that can be used in a wide range of applications, including automotive, aerospace, and construction industries. The results underscore the importance of surface modifications to optimize the properties of polymeric composites and provide valuable insights into the role of natural fillers in enhancing the performance of these materials.

Preparation and properties of fluorosilicone composites with thermal conductivity and chemical resistance through modification of filler and matrix

The improvement of heat dissipation and chemical resistance of encapsulating materials can greatly increase the service life of electronic devices. Fluorosilicone rubber exhibits superior chemical resistance compared to silicone rubber when used for encapsulation, enabling it to effectively handle highly complex application scenarios. In this study, a thermally conductive and chemically resistant composite material (i.e., F-Al2O3/F-AlN@F-ALSR) was prepared by introducing fluorine-modified Al2O3 and AlN into fluorine-added liquid silicone rubber matrix from both filler and matrix fluorination modification perspectives. The effects of the properties of fillers before and after modification, different mixing ratios (i.e., the ratio of F-Al2O3 to F-AlN) and different addition amounts (i.e., the amount of F-Al2O3/F-AlN added in F-ALSR) on the thermal conductivity and chemical medium resistance of the composite material were investigated, and the mechanisms of thermal conductivity and chemical medium resistance were explored. The results showed that when the ratio of F-Al2O3 to F-AlN was 3:7 and the total amount of filling was 300 phr, the material had a thermal conductivity of 1.047 W/mK and a thermal diffusivity of 0.652 mm2/s. The rate of change of mass and volume during 72 h of immersion in acid, alkali, toluene and engine oil was low. This further proves that the addition of F-Al2O3/F-AlN in F-ALSR can effectively create a heat conduction path and protect the composite material from environmental effects, resulting in materials with excellent thermal conductivity and chemical resistance. This study provides new ideas for improving the dispersion of fillers in the matrix and rationalizing the preparation of liquid silicone rubbers for thermally conductive, chemically resistant electronic potting.

The enhanced tribological performance of fabric‐reinforced resin composites by biomimetic surface modification of fillers

The poor dispersion of multiwalled carbon nanotubes (MWCNTs) and weak interfacial adhesion of fabric and resin matrix seriously affect the tribological performance of fabric‐reinforcement resin composites. Tannic acid (TA), a plant‐derived compound, which is similar to mussel‐inspired polydopamine, can adhere to various substrates under a weak basic buffer solution. Therefore, in this work, TA‐modified MWCNTs were incorporated into TA functionalized fabric composite to improve the tribological performance of the fabric composite. The results indicate that the MWCNTs and fabric were successfully modified with TA. The wear tests revealed that the TA‐MWCNTs reinforcement TA‐fabric resin composites exhibited the best tribological performance, in which the friction coefficient and volume wear rate decreased by 16.9% and 40%, respectively, compared with pristine fabric composite. The favorable interfacial bonding between fabric and resin is beneficial to the friction force transfer to the load‐bearing fabric, decreasing the stress focus and thus reducing the damage to composite materials. Meanwhile, the good dispersion of MWCNTs contributes to the excellent lubrication performance. This simple and eco‐friendly method of treating fillers with TA provides a new approach to achieve high‐performance tribological materials.