Monomer Blends Research Articles

Tuning the Organic Electrochemical Transistor (OECT) Threshold Voltage with Monomer Blends

Tuning the Organic Electrochemical Transistor (OECT) Threshold Voltage with Monomer Blends

Supraparticles from Cubic Iron Oxide Nanoparticles: Synthesis, Polymer Encapsulation, Functionalization, and Magnetic Properties.

Supraparticles (SPs) consisting of superparamagnetic iron oxide nanoparticles (SPIONs) are of great interest for biomedical applications and magnetic separation. To enable their functionalization with biomolecules and to improve their stability in aqueous dispersion, polymer shells are grown on the SPs' surface. Robust polymer encapsulation and functionalization is achieved via atom transfer radical polymerization (ATRP), improving the reaction control compared to free radical polymerizations. This study presents the emulsion-based assembly of differently sized cubic SPIONs (12-30 nm) into SPs with diameters ranging from ∼200 to ∼400 nm using dodecyltrimethylammonium bromide (DTAB) as the surfactant. The successful formation of well-defined spherical SPs depends upon the method used for mixing the SPION dispersion with the surfactant solution and requires the precise adjustment of the surfactant concentration. After purification, the SPs are encapsulated by growing surface-grafted polystyrene shells via activators generated by electron transfer (AGET) ATRP. The polymer shell can be decorated with functional groups (azide and carboxylate) using monomer blends for the polymerization reaction. When the amount of the monomer is varied, the shell thickness as well as the interparticle distances between the encapsulated SPIONs can be tuned with nanometer-scale precision. Small-angle X-ray scattering (SAXS) reveals that cubic SPIONs form less ordered assemblies within the SPs than spherical SPIONs. As shown by vibrating sample magnetometer measurements, the encapsulated SPs feature the same superparamagnetic behavior as their SPION building blocks. The saturation magnetization ranges between 10 and 30 emu/g and depends upon the nanocubes' size and phase composition.

Constituent compatibility and physical properties of bio‐based EUG/EPDM blends

AbstractEucommia ulmoides gum (EUG)/ethylene propylene diene monomer (EPDM) blends were prepared using EUG with high and low molecular weight, respectively, and their physical properties and constituents compatibility were investigated. The blend exhibited superior physical properties and constituents compatibility when EUG with high molecular weight occupied 10 wt%. When its content increased further, the physical properties deteriorated gradually，the results of SEM, DSC, and DMA diagrams indicated poorer constituents compatibility. The blends prepared from EUG with low molecular weight can achieve better compatibility in a comprehensive range of blending ratio. When the EUG content was 20 wt%, the maximum tensile strength of the blend was observed, which was 49.9% higher than that of pure EPDM, its rebound resilience ascended by 5%, and the wear resistance remained nearly unchanged.

Flexural strength of dental adhesives with different photoinitiator systems.

The aim of this study was to investigate the flexural strength of dental adhesives containing different combinations of photoinitiators systems. The organic matrix of the experimental adhesives was created using a blend of monomers: 50% by weight bisphenol-A glycidyl methacrylate (BisGMA) and 50% triethylene glycol dimethacrylate (TEGDMA). The photoinitiators utilized were camphorquinone (CQ) and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), with diphenyliodonium hexafluorophosphate (DPIHFP) and 2-(Dimethylamino)ethyl methacrylate (DMAEMA) as co-initiators. These photoinitiators and co-initiators were integrated into the organic matrix at a concentration of 0.5% by mass, resulting in the formation of 6 groups (n=12): CQ/DMAEMA (control); CQ/DMAEMA/DPIHFP; BAPO; BAPO/DMAEMA; BAPO/DPIHFP and BAPO/DMAEMA/DPIHFP. Samples measuring 7 mm in length, 2 mm in width, and 1 mm in height were prepared and subjected to a three-point flexural test. Data were analyzed using one-way ANOVA with Tukey's post-hoc test (α=0.05). Results indicated that groups incorporating BAPO and DPIHFP exhibited higher flexural strength compared to those with CQ and DMAEMA. The BAPO/DPIHFP group achieved the highest mean flexural strength values (p<0.001). These findings suggest that using adhesive systems with alternative photoinitiators and co-initiators can lead to superior flexural strength compared to conventional systems. Key words:Photoinitiators, Dentin-bonding agents, Light-curing.

Synthesis and evaluation of fluorescent resins with europium-β-diketonate complex for orthodontic use.

No effective technique exists for removing adhesive remnants following bracket debonding. We propose that fluorescence imaging using europium ions (Eu3+) offers an effective solution for minimizing iatrogenic enamel damage. This study aimed to assess the impact of different mixing ratios of monomer mixtures on the photoluminescence and flexural properties of a newly developed fluorescent adhesive. Four monomer blends with varying urethane dimethacrylate (UDMA) to triethylene glycol dimethacrylate (TEGDMA) ratios were prepared and polymerized. The blends contained 0.1 wt% of tris(1,3-diphenyl-1,3-propanedionato)(1,10-phenanthroline) Eu(III), [Eu(DBM)3Phen], as the phosphor. Optical measurements and flexural tests were conducted for each resin specimen. The emission spectra exhibited narrow bands corresponding to the 4f-4f transitions of the Eu3+ ions. The photoluminescence properties remained unaffected by the mixing ratio, whereas the mechanical properties tended to improve with higher UDMA content. We conclude that the Eu(DBM)3Phen-containing resin shows promise as a fluorescent orthodontic adhesive that contributes to preserving enamel health.

Achieving property enhancements in dental resin composites via reduced concentrations of camphorquinone within a ternary initiator system

ObjectivesThe study aimed to assess the impact of diphenyliodonium hexafluorophosphate (DPI) on the physicochemical properties of experimental resin composites (ECRs) featuring reduced concentrations of camphorquinone (CQ)/amine. MethodsFive concentrations of CQ (0.125, 0.25, 0.5, 0.75, and 1 mol%) with dimethylaminoethyl amine benzoate (EDAB) in a 1:2 mol% ratio (CQ:EDAB) were incorporated into a 50:50 mass% monomer blend of bisphenol glycidyl methacrylate (BisGMA) and triethyleneglycol dimethacrylate (TEGDMA). An additional 5 groups with the same CQ:EDAB concentrations had 0.5 mol% DPI added. Each resin group contained 60 wt% of 0.7 µm barium-alumino-silicate glass. Light transmission (n = 3), real-time degree of polymerization (n = 3), temperature change during polymerization (n = 5), polymerization shrinkage strain (n = 3), flexural strength, and modulus (n = 12), as well as water sorption and solubility (n = 5), were evaluated. Data were analyzed using two-way ANOVA and Tukey's post-hoc test (α = 0.05). ResultsLight transmission was reduced in groups containing 0.125 and 0.25 mol% of CQ without DPI. DPI increased temperature, degree and rate of polymerization, despite the reduction in CQ/amine concentration. Additionally, there was an increase in polymerization shrinkage strain, flexural strength and modulus, and a reduction in water sorption and solubility in ECRs with DPI, even with lower concentrations of CQ/EDAB. SignificanceDPI improved the assessed properties of composites across various concentrations of CQ/EDAB, showing the benefit of reducing the quantity of CQ used without compromising the properties and curing of the resin composites.

Optimizing mechanical performance in 3D printing through a benzoxazine monomer blend photosensitive resin formulation

AbstractThe objective of this study was to enhance the mechanical properties of 3D printed specimens in commercial photosensitive resin (PS‐resin) through blend‐thermosets using a benzoxazine monomer based on bisphenol A and a commercially available resin. Specifically, a benzoxazine‐based bisphenol A compound, 6,6‐(propane‐2,2‐diyl)bis(3‐cyclohexyl‐3,4‐dihydro‐2H‐benzo[e][1,3]oxazine), was successfully synthesized via the Mannich reaction. The synthesis involved paraformaldehyde, bisphenol A, and cyclohexylamine in a molar ratio of 4:1:2, respectively. To prepare the blend‐thermosets, a stereolithography 3D printer (SLA) was utilized, combining the PS‐resin with varying amounts of the benzoxazine (ranging from 0 to 8 parts per hundred of resin, phr). The printed specimens were then subjected to a polymerization process by heating them at various temperatures ranging from 120 to 160°C in a hot air oven for 2 h, allowing the benzoxazine to undergo ring‐opening reaction and form the thermoset structure. Characterization of all the materials obtained, including the PS‐resin, benzoxazine, and the blend‐thermosets before and after heating, was conducted using techniques such as FT‐IR and DSC. This work also showcased a sample technique for verifying the ring‐opening of the benzoxazine ring. Additionally, the mechanical properties of the blend‐thermosets were evaluated through tests for tensile strength, elongation at break, modulus, and hardness. The addition of merely 2 phr of benzoxazine monomers and subsequent curing at 120°C resulted in a notable improvement in the mechanical properties.

Kinetic mathematical model with induction and reversion for the vulcanization of natural rubber and ethylene propylene diene monomer blend

The complexity inherent in modeling and optimizing rubber cure processes stems from the intricate interplay between “induction” and “reversion” phenomena. During the vulcanization process, rubber compounds undergo a gradual initial decrease in torque in an “induction” phase. Following this, the primary vulcanization reaction triggers a swift surge in cross-link density. Interestingly, the density may peak and subsequently decline, leading to compromised mechanical properties with prolonged curing times. This “reversion” phenomenon is extensively documented in sulfur-cured rubbers at elevated vulcanization temperatures, typically exceeding 140 °C. Moreover, the cure conditions can influence the final structure, mechanical performance, and thermal stability of the network.This paper introduces a kinetic mathematical model that is able to predict the optimal time and temperature for a blend of natural rubber and ethylene propylene diene monomer. This model incorporates considerations for both the induction and reversion phases of the vulcanization process. These considerations prove particularly critical, especially in scenarios involving large rubber items or when the rheometer curves of the rubber exhibit a slow pace with significant reversion towards the end. Additionally, the study proposes a novel approach for determining the kinetic variables that concurrently consider all vulcanization temperatures using a standard genetic algorithm.

Insights on the chlorine resistance of polyester composite nanofiltration membranes

The use of chlorine as a pretreatment of water treatment and desalination processes causes a loss in performance and lifespan of the membranes usually employed in these processes. Polyester (PE) membranes have been proposed as an alternative due to the absence of amidic hydrogen; however, fabricating PE composite membranes with equivalent performance and high tolerance towards chlorine has proven challenging. In this work, we evaluate the effects of monomer concentration and blends, proton scavenger, surfactant concentration, reaction time and temperature on interfacial polymerization (IP) of trimesoyl chloride and resorcinol. Reaction temperature was the most crucial factor to achieve a PE coating film with high crosslinking degree (XD), high divalent rejection and excellent chlorine tolerance. The resorcinol membrane showed a Na2SO4 rejection of >90 % before and after 6000 ppmh-Cl2 at pH 7. XPS analysis showed that chlorination of PE membranes resulted in loss of CC bonds and increase in C–C and C–O bonds. At high crosslinking degrees, the changes caused by chlorine were minimal. Based on the characterization and the performance of the chlorinated membranes, ring chlorination followed by ring hydrolysis is the proposed mechanism for degradation of lower XD membranes.

Reaction-induced morphological transitions in a blend of diblock copolymers and reactive monomers: dissipative particle dynamics simulation.

The dissipative particle dynamics (DPD) method is applied to the morphological transitions of microphase-separated domains in a mixture of symmetric AB-diblock copolymers and reactive C-monomers, where polymerization and cross-linking reactions take place among C-monomers. The initial structure for the DPD simulation is an equilibrated cylindrical domain structure prepared by the density-biased Monte Carlo method with density profiles obtained from the self-consistent field theory. By introducing a cross-linking reaction among reactive C-monomers, we confirmed that the DPD simulation reproduces the morphological transitions observed in experiments, where the domain morphology changes due to segregation between A-blocks of diblock copolymers and cross-linking networks of C-monomers. When the cross-linking reaction of C-monomers is sufficiently fast compared to the deformation of the domains, the initial cylindrical domains are preserved, while the distance between the domains increases. On the other hand, when the formation of the cross-linking network is slow, the domains can deform and reconnect with each other in the developing cross-linking network. In this case, we observe morphological transitions from the initial domain morphology with a large-curvature interface to another domain morphology with a smaller-curvature interface, such as the transition from the cylindrical phase to the lamellar phase. We calculated the spatial correlations in the microphase-separated domains and found that such correlations are affected by the speed of the formation of the cross-linking network depending on whether the bridging between microphase-separated domains occurs in a nucleation and growth process or in a spinodal decomposition process.

Construct the relationship of the interface structure-properties for TPV via micromechanical method based on cohesive zone model

It is well accepted that thermoplastic vulcanizate (TPV) combine the appealing recyclability of thermoplastics with the mechanical robustness when compared to traditional rubbers. However, the compatibility between heterogeneous materials has a significant impact on the high-performance TPV. This work demonstrates a novel representative volume element (RVE) model via the cohesive zone model for TPV based on polypropylene (PP)/ethylene propylene diene monomer (EPDM) blends. Considering the material characteristics, both the elastic and elastic-plastic interface types have been employed to establish this RVE model. The model indicates that the elastic-plastic interface model could provide a better description for the mechanical behavior of this TPV. Finally, a bivariate partial dependence plot for TPV has been obtained via the simulation result, illustrating the influence mechanism between the interface structure-properties for TPV. Moreover, the universality of this impact mechanism was validated in a PA6/EPDM-based TPV system. This work could provide a theoretical foundation for optimizing interface compatibility and implementing controllable performance for TPV.

Development of a Boron Nitride-Filled Dental Adhesive System.

There is a dearth of adhesive systems capable of forming stable bonds between restorative materials and tooth surfaces. To address the concern, this study determined the effects of using methacrylate-functionalized boron nitride nanosheets (BNNSs) in a polymeric dental adhesive system. The bisphenol A glycidyl dimethacrylate (BisGMA):2 hydroxyethyl methacrylate (HEMA) (60:40) adhesive monomer blend with a photoinitiator was filled with 0 wt% (control), 0.1 wt%, and 1 wt% BNNSs and light cured. Fourier transform infrared spectroscopy was performed to determine the conversion degree of monomer double bonds (DoC). Water absorption and solubility were measured. Flexural strength and Youngs's modulus were evaluated to determine the mechanical properties of the composite adhesive system. Finally, dentin bond strength degradation and fracture mode were quantified with a microtensile bond test to confirm the bonding ability of the developed adhesive system. Results showed that the incorporation of BNNSs increased DoC (9.8% and 5.4% for 0.1 and 1 wt%, respectively), but it did not affect water sorption (101.9-119.72 (µg/mm3)), solubility (2.62-5.54 (µg/mm3)), Young's modulus (529.1-1716.1 MPa), or microtensile bond strength (46.66-54.72 MPa). Further studies are needed with varying BNNS loading percentages from 0.1 wt% to 1 wt% in order to more comprehensively determine the effect of BNNSs on dental adhesives.

Prediction of the optimal vulcanization of a fiber‐reinforced elastomeric isolator made of natural rubber‐ethylene propylene diene monomer blend

AbstractTo seismically isolate a structure, it is possible to interpose a rubber device between the foundation and superstructure that increases the period of the superstructure, a feature that allows the structure to be “transparent” to the seismic excitation. A package of several rubber pads typically constitutes a seismic isolator; they are 10–20 mm thick vertically interspersed with either steel laminas or fiber‐reinforced polymer dry textiles suitably treated. So, the rubber has a primary role and must be vulcanized correctly to create the polymer cross‐linking properly. All rubber mechanical properties are strongly affected by curing temperature and curing time. Under vulcanization is a typical production error that suppliers make in large‐scale productions, especially when the size of the devices is considerable. It is common to deal with elastomeric isolators where rubber pads have been treated at a largely suboptimal temperature. This article proposes a numerical model for predicting the cross‐linking degree of rubber pads used in seismic isolation and made by a natural rubber‐ethylene propylene diene monomer rubber compound. The aim is to correctly define the optimal curing temperature and exposition time for producing a rubber quadruple shear test specimen and a fiber reinforced elastomeric isolator (FREI). The model is a kinetic one and takes into consideration the induction time. An experimental investigation has been conducted to validate the model with visible inspections and hardness measurements taken on the rubber pads (quadruple shear specimens) and the rubber devices. The results have shown the reliability of the new numerical model proposed, with a homogeneous mechanical properties distribution obtained within the rubber pads and the FREI.

Fabrication of Triblock Elastomer Foams for Oil Absorption Applications: Effects of Crosslinking, Composition, and Rheology Factors

Oil spill accidents and oil-contaminated wastewater release from industries cause severe environmental pollution, resource waste, and economic loss. Thus, there is a dire need for an efficient oil/water separation approach to mitigate the challenge. Among the various oil/water separation technologies, employing oil-absorbing materials is one of the most effective strategies. In this work, a highly effective elastomer foam based on styrene–ethylene–butylene–styrene (SEBS) and ethylene propylene diene monomer (EPDM) blend was developed. Dicumyl peroxide was employed as a radical initiator for the crosslinking of the elastomer blend. The crosslinking of the blend significantly increased the melt strength of the SEBS/EPDM blend and therefore allowed them to expand extensively (up to 1200 vol %) with substantial volume increase (expansion ratio 12.8–13.1) and created pores with well-defined structures. As a result, the material exhibited outstanding oil absorption (up to 1030 wt %) due to an enlarged surface area and blend constituents. The incorporation of EPDM and radical-mediated crosslinking prevented the dissolution of SEBS in the oil and maintained the structural integrity of the foam in the oil, paving the way for recyclability. Also, the inherent hydrophobicity of employed polymers led to poor interaction with water and, thus, outstanding oil/water separation ability of the developed elastomer foams. Additionally, the foaming of triblock polymers, including SEBS, remained largely unexplored. This study has elucidated the impact of crosslinking and rheological factors on the successful foaming of SEBS.

Monomer blended electrochemical polymerization in chiral liquid crystals to produce electro-optically active copolymer

Electro-optically active low-bandgap conjugated copolymers were obtained by electrochemical polymerization (EP) in cholesteric liquid crystal (CLC). We prepared CLC electrolyte mixture blends of monomers, and electrochemically polymerized for obtaining conjugated copolymer with optical activity, in which the structure of the CLC is transferred, from achiral monomers on a CLC template. In addition, this copolymer showed a narrow bandgap and a significant red shift of the absorption band compared to the homopolymer. The optical rotatory dispersion (ORD) indicates that the polymer is chiroptically active and that the optical rotation can be tuned via redox. The guest monomers used for the EP in liquid crystal (LC) require solubility in the host LC and a rod-like structure, limiting their structural design. This technique has the advantage that complex synthesis of monomers is no required, and simple composition of monomers can be used to prepare copolymer films in a convenient manner by blending various monomers. This method expands the design range of optically active electrochromic devices based on conjugated polymers with pleochroic properties.

Development of propylene butene copolymer/ethylene propylene diene monomer blend foam and the effect of network structure on its reprocessing properties

AbstractThermoplastic materials have received extensive attention for their excellent mechanical properties and reproducibility, and have been emerging in lightweight accessories. However, for the traditional thermoplastic vulcanized (TPV) rubber, the dynamic vulcanization process makes it difficult to achieve low density and good compression performance. Herein, lightweight propylene butene copolymer/ethylene propylene diene monomer (PPB/EPDM) blend foam was prepared by static vulcanization of PPB and EPDM blend and supercritical nitrogen (sc‐N2) foaming technology. The minimum density and compression set of the PPB/EPDM blend foam were 0.065 g/cm3 and 13.6% respectively, a significant improvement was obtained compared with TPV. In addition, the PPB/EPDM blends retained the mechanical properties after seven times reprocessing, and the blend foam had similar cell structures to that of dynamic vulcanized TPV foam because of the phase transition of PPB/EPDM blend during reprocessing. This work provided an idea for the preparation of high‐performance, lightweight, and recyclable thermoplastic materials.

Development of thermoplastic vulcanizates based on polypropylene/ethylene propylene diene monomer for prototyping by Fused Filament Fabrication

This article demonstrates how thermoplastic vulcanizates (TPVs) can be 3D printed by modifying their formulation and the Fused Filament Fabrication (FFF) process. Novel FFF filaments based on polypropylene (PP)/ethylene propylene diene monomer (EPDM) blends were printed and characterized. The development of these TPV filaments allows a broad range of properties by varying the grades of the thermoplastic/rubber phases.Thermoplastic vulcanizates are widely used in the automotive industry, amongst others, and a printable filament could have applications in both prototyping and production of bespoke parts. Given the increasing prominence of TPVs, as replacement for thermoset rubbers, FFF of these materials is considered industrially beneficial. The newly prepared TPVs possessed tensile strength of ∼20–30 MPa and elongation at break ∼700–1100% when measured in the direction of printing. Tensile properties (at 0° and 90° to the printing direction), interlayer adhesion, and Micro-CT were measured and compared with neat PP and PLA.

Characterization of Natural Rubber, Styrene Butadiene Rubber, and Nitrile Butadiene Rubber Monomer Blend Composites Loaded with Zinc Stearate to Be Used in the Solid Tire Industry

Vulcanization is an important step in the manufacture of solid tires in which the crosslinking process occurs. In vulcanization, the materials commonly used as activators and coactivators are ZnO and stearic acid, respectively. In this research, ZnO and stearic acid were replaced with zinc stearate to improve the characteristics of vulcanized rubber. Zinc stearate was applied in four formulas with a composition of 5 to 9 phr. A formula that is often used in the rubber industry was used as a comparison, and ZnO and stearic acid of 5 phr and 2.5 phr, respectively, were applied. The rubber compound for solid tire production was developed using an open mill at a compounding temperature of 45 °C ± 5 °C. The vulcanization process of developing the rubber compound into vulcanized rubber was carried out at 150 °C for 20 min. Rubber compound test results showed that the use of zinc stearate at a ratio of 8 phr accelerated the curing time (t90) between 58.3% and 69%, the scorch time (ts2) between 22.4% and 95.5%, and the torque delta (Δs) between 17.67 and 24.21 kg-cm. In addition, the vulcanized rubber mechanical properties test results for the compression set parameter increased between 28.6% and 57.1%. Scan results with SEM–EDS showed that using ZS could improve the homogeneous distribution of the material in the vulcanized matrix of solid tire rubber.

Influence of aviation hydraulic oil swelling on the mechanical properties of HNBR/EPDM vulcanizates reinforced by carbon black

AbstractThe study on swelling behaviors of rubber products in liquid media is of great value for life prediction and practical application guidance. In this work, changes in the mechanical properties of hydrogenated nitrile rubber/ethylene propylene diene monomer (HNBR/EPDM) blends caused by swelling in aviation hydraulic oil YH‐15 were studied. Effects of two kinds of carbon black, N220, and N990, on the tensile properties of HNBR/EPDM blends at both unswollen and swollen states were investigated. The results turned out that N220 exhibited better reinforcing effects than N990 on HNBR/EPDM blends. The tensile properties of unfilled and filled HNBR/EPDM blends decreased rapidly at first and then tended to stabilize with the extension of swelling time in YH‐15, while the modulus at 100% declined firstly and then increased. After swelling for 72 h, the tensile strength of HNBR/EPDM blends filled with N220 decreased by more than 35%, and by comparison, it decreased by about 20% for the N990‐filled HNBR/EPDM blends. The cross‐sections of the tensile samples after swelling changed greatly compared with the unswollen samples. In addition, the effect of swelling on the hardness of the HNBR/EPDM blends was not obvious.

Preparation and properties of rubber nanocomposites based on natural rubber/ ethylene propylene diene monomer reinforced with nanosilica, carbon black and barium sulfate

In this work, rubber nanocomposites based on natural rubber/ethylene propylene diene monomer (NR/EPDM) blends and reinforced with nanosilica (NS) in combination with carbon black (CB) and barium sulfate (BS) were prepared by melt blending method in a Brabender internal mixer. The appropriate contents of NS and CB for reinforcing the rubber nanocomposites based on NR/EPDM are 10 and 30 phr (parts per hundred rubber), respectively. The NR/EPDM nanocomposites material reinforced with 10 phr NS and 30 phr CB has the best mechanical properties that with the enhancement of tensile strength over 117% and 40 % compared to that of the NR/EPDM nanocomposite material unreinforced and reinforced with only 10 phr NS, respectively. The appropriate content of BS for replacement of CB in the NR/EPDM blend is 6 phr. The rubber nanocomposite based on NR/EPDM (60/40) blend reinforced with 10 phr NS, 24 phr CB and 6 phr BS has a tight structure, high mechanical properties, and especially, high alkali resistance and heat resistance, abrasion resistance and low endogenous heat due to rotation and friction. This material may be used to manufacture technical rubber products that require heat resistance and stability in alkaline environments, such as conveyor belts used in the cement industry.