Resin Suspension Research Articles

Impact of the Curing Temperature on the Manufacturing Process of Multi-Nanoparticle-Reinforced Epoxy Matrix Composites.

This study aims to analyze the effect of the curing temperature of nano-reinforcements during the manufacturing process on the mechanical properties of composites involving graphene (GNP), carbon nanofibers (CNFs), and a hybrid mixture of these two nanoparticles. In this context, the type of nanoparticles, their content, their type of resin, and their hybridization were considered. The results showed that both nanoparticles increased the viscosity of the resin suspension, with an increase of between 16.3% and 38.2% for GNP nanoparticles and 45.4% and 74% for CNFs depending on the type of resin. Shrinkage was also affected by the addition of nanoparticles, as the highest results were obtained with GNP nanoparticles, with a 91% increase compared with the neat resin, and the lowest results were obtained with CNFs, with a decrease of 77% compared with the neat resin. A curing temperature of 5 °C promoted the best bending and hardness performance for all composites regardless of the type of resin and reinforcement used, with improvements of up to 24.8% for GNP nanoparticles and 13.52% for CNFs compared with the neat resin at 20 °C. Hybridization led to further improvements in bending properties and hardness compared with single-reinforcement composites due to a synergistic effect. However, the effectiveness of hybridization depends on the type of resin.

Numerical modeling of suspension impregnation through a fibrous medium: Application to the CRTM process

In this article, a numerical model dedicated to the impregnation modeling of a fibrous medium by a particle-filled resin (suspension) is proposed. It allows to simulate and analyze the mold filling with a particle-filled resin during the Compression Resin Transfer Molding (CRTM) process at a given compression speed and compaction force. As per our knowledge, no such work with this last compression mode has already been reported in the literature. The simulation results of our approach were compared with the analytical as well as experimental results, and found in agreement. With an objective to analyze the effect of the process parameters on the suspension flow, particularly on the final distribution of the particles in the developed composite, a detailed parametric study was done. Finally, a comparison between the injection and compression modes is conducted and discussed. The obtained results demonstrate that the particle volume per mold cavity volume depends on the initial concentration, the distance traveled, and the initial volume fraction of the fiber, while it is independent of parameters values of injection and compression. It was also observed that the imposed pressure injection and the imposed force compression are the most favorable to produce composite parts using CRTM.

Microfluidics-Assisted Fabrication of Dual Stopband Photonic Microcapsules and Their Applications for Anticounterfeiting.

The assembly of two different kinds of colloidal particle-based photonic structures into an individual micro-object can achieve multifunctionality. In this study, core–shell photonic microcapsules with dual structural colors and photonic stop bands were prepared through a standard microfluidic technique. Photocurable resin suspension of silica nanoparticles and an aqueous suspension of nanogels were used as shell and core parts of microcapsules, respectively. The structural colors of shells and cores can be tuned by adjusting the concentrations of silica nanoparticles and soft nanogels in their corresponding suspensions. The individual microcapsules possess two distinct stop bands when the two suspensions are combined appropriately. Remarkably, the color information of the core part cannot be directly viewed at a macroscopic level (such as visual inspection) but can be detected at a microscopic scale (such as optical microscopy observation). The color information hidden enables the capability for information encryption and has potentially critical applications in anti-counterfeiting, display, and other fields.

Mechanical, dynamic-mechanical and wear performance of novel non-crimp glass fabric-reinforced liquid thermoplastic composites filled with cellulose microcrystals

The novel reactive methylmethacrylate (MMA) thermoplastic resin (commercially known as Elium® resin) is the first liquid thermoplastic resin which is curable at room temperature. This resin is a competitive solution against traditional epoxy-based composites. In this work, novel non-crimp (NC) glass fabric/MMA resin composites were manufactured using a vacuum infusion process. Cellulose microcrystals (CMCs) were dispersed in the resin to improve the fibre/matrix interface and the composite properties. CMCs were first dispersed in the resin using an ultrasonication process and then the CMC/MMA resin suspension, mixed with a peroxide initiator, was infused into the reinforcing fabric. The amounts of CMCs dispersed in the resin were 0.5%, 1% and 2% (of the weight of the resin). The influence of CMCs on the interlaminar shear strength (interface), flexural properties, abrasive wear and dynamic-mechanical behaviour was thoroughly investigated. From the mechanical characterisation, it was observed that the addition of 1% CMC to the NC glass/MMA resin composites improved the flexural strength, interlaminar shear strength and wear performance by 30.77%, 38.04% and 22.27%, respectively as compared to the neat glass/MMA resin composite. Above this amount of CMC (i.e., 1 wt%), the properties started to degrade as a result of CMC agglomeration.

Preparation and in vitro/in vivo evaluation of a clonidine hydrochloride drug–resin suspension as a sustained-release formulation

Objective The purpose of the present study was to prepare a clonidine hydrochloride (CH) sustained-release suspension. Methods The processes involved in the drug formulation included drug loading, impregnating, and suspension preparation. Clonidine hydrochloride drug–resin complexes (CH-DRC) were prepared using the bath method and the CH-DRC impregnated before the microencapsulation process. Based on the bottom spray fluidized bed coating method, the CH microencapsulated drug–resin complexes (CH-MC) were also prepared using Surelease® (the suspension of ethyl cellulose aqueous dispersion) as the coating material. The effects of coating (process/formulation) on the in vitro release of coating microcapsule were evaluated via single factor investigation and orthogonal design optimization. The CH-MC with optimized formulation was further dispersed in a suitable medium to obtain a sustained-release suspension. Rats were given commercial CH ordinary tablets and the CH sustained-release suspension via intragastric administration. The plasma concentration–time curve and related pharmacokinetic parameters were investigated using the non-compartment model. Results The T max of the CH sustained-release suspension was delayed from 2 h to 5 h compared with the CH ordinary tablets. Similarly, the C max was reduced from 32.138 µg·mL−1 to 18.150 µg·mL−1 with the concentration–time curve being more gentle compared with the commercially CH ordinary tablets. After oral administration, the relative bioavailability of CH sustained-release suspension (AUC0–24 of 137.703 µg·h·mL−1) to its CH ordinary tablets (AUC0–24 of 123.337 µg·h·mL−1) was 111.65%. Conclusions The findings showed that the CH sustained-release suspension for oral administration was successfully formulated.

Comparison of thermosensitive in situ gels and drug-resin complex for ocular drug delivery: In vitro drug release and in vivo tissue distribution.

Conventional ophthalmic eye drops are limited by their rapid elimination rate and short time of action. Ion exchange resin has been used to achieve sustained ocular drug delivery but the high selectivity of drug molecules restricts its broad application. In situ gel system seems to be a good strategy to address these problems but the influence of in situ gel type on the sustained release behavior and tissue distribution after ocular application is unclear. Therefore, in this study, using betaxolol hydrochloride as a model drug, poloxamer 407 and methylcellulose as the carriers, two thermosensitive in situ gel systems were prepared and characterized. Influence of formulation composition type and concentration on in vitro drug release was studied. Tissue distribution after ocular delivery of two different thermosensitive in situ gels was studied and compared with commercial BH eye drop (Betoptic S®). In vitro studies demonstrated that addition of 4% HPMC 606W in 15% P407 solution and 5% PEG4000 in 2% MC solution obtained gels with appropriate gelation temperature and similar sustained drug release rate. In vivo tissue distribution study indicated that they presented similar drug concentration in cornea, iris-ciliary and aqueous humor irrespective of gel type, with higher drug concentration achieved after 4h compared to the commercial resin suspension eye drops. The AUC and MRT of the two in situ gel eye drops were 2 times higher than that of the commercial resin suspension eye drops in cornea. In conclusion, the two thermosensitive in situ gels have prolonged drug release after ocular drug delivery compared with ion exchange resin eye drops, implying their potential applications in clinic with broad drug adoptability.

Digital light processing-stereolithography three-dimensional printing of yttria-stabilized zirconia

Digital light processing (DLP)-stereolithography three-dimensional (3D) printing is a well known technique for fabricating components with complex geometries. However, the application of DLP 3D printing to functional ceramics such as 8 mol% yttria-stabilized zirconia (8YSZ), which is one of the most extensively used electrolyte materials for solid oxide fuel cells, is still a great challenge. Therefore, the fabrication of fully 8YSZ monoliths via DLP 3D printing was attempted herein, including the preparation of UV-curable ceramic suspensions, shaping of green bodies, and debinding and sintering. The results show that intact green bodies printed using a 30 vol% 8YSZ-photosensitive resin suspension with 0.1 wt% oleic acid as the dispersant under the optimized printing conditions was sufficiently dense without connected pores after vacuum debinding and sintering in air. The successful fabrication of 8YSZ monoliths with design flexibility via 3D printing provides a simple method for preparing functional ceramic components and may expand the application of 3D printing technology to the energy field.

Highly Concentrated Hydroxyapatite Suspension for DLP Printing

Due to the lack of commercially available high-quality hydroxyapatite (HA) powder, it is still rarely reported by the literature concerning the development of UV resin for digital light processing 3D printing. The previous studies still had the problem of delamination and also poor sintering performance led by low solid-load slurry. Here low viscosity and high solid-load hydroxyapatite (HA) UV resin suspensions were developed for digital light processing 3D printing. In this study, the effect of the type of dispersant, the dose levels of dispersant and the solid load of HA powder on the rheology properties were thoroughly investigated to obtain a flowable highly-concentrated HA UV resin suspension. Finally, a 40vol% slurry with viscosity of 3.7Pa·s at a shear rate of 10 s-1 was successfully developed. After 3D printing and sintering, a dense ceramic with relative density of 95.85% can be obtained at a sintering temperature of 1300°C.

Optimization of Curing Behavior of Si3N4 UV Resin for Photopolymerization 3D Printing

Silicon nitride (Si3N4) ceramics are widely used in mechanical and thermal management applications due to their excellent properties. To overcome the difficulties in traditional Si3N4 ceramic forming techniques, it is interesting to see the possibility of making complex-shaped silicon nitride ceramic component with novel 3D printing methods. In this study, we aim to study the effect of photo-initiators on the curing behavior of pre-formulated Si3N4 ceramic UV resin suspension. To elucidate the potential multi-factor interactions, a statistic experiment design was implemented in a sequence of screening and optimization by using Modde software. It was found that the kinds of photo-initiators, total amount of initiators and the mixture ratio between initiators have a great influence on the curing properties of silicon nitride UV ceramic resin. Based on these results, a formula was selected based on the criterion of using least amount photo-initiator while reaching the highest curing thickness.

Photopolymerization of acrylate resin and ceramic suspensions with benzylidene ketones under blue/green LED

Finding novel photoinitiators with photobleaching properties suitable for long-wavelength LED light sources is important for their potential use in the photocuring ceramic suspensions containing acrylate resin. Two D-π-A-π-D conjugated benzylidene ketones with visible light absorption (TPAK and CZK) were synthesized and evaluated as photoinitiators in the photocuring of acrylate resin and ceramic suspension under blue (460 nm)/green (520 nm) LED sources. Results showed that the two photoinitiators have high photoinitiating activity and can effectively produce thick-layer curing in acrylate resin and ceramic suspension due to their quick photobleaching properties under 460 nm and 520 nm LED light sources. The curing depth of the ceramic suspensions was measured as a function of the concentration of TPAK and CZK and the energy level of the LED light source. Jacob's equation was used to determine the critical energy Ec and depth sensitivity Dp of every suspension with different concentrations of benzylidene ketones.

The effect of ceria and zirconia nanoparticles on the corrosion behaviour of cataphoretic epoxy coatings on AA6060 alloy

In this work an attempt was made to produce epoxy coating doped with ceria (CeO2) and/or zirconia (ZrO2) nanoparticles, in single step electrophoretric deposition process. Deposition was carried out on AA6060 cataforetically from epoxy resin suspension containing synthesized stable aqueous colloidal dispersions (sols) of CeO2 and ZrO2. The influence of ceria and zirconia nanoparticles on the physicochemical characteristics of epoxy coatings was evaluated by energy dispersive X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and adhesion measurements, while their corrosion stability during immersion in 0.5 M NaCl solution was monitored by electrochemical impedance spectroscopy. All ceria and/or zirconia containing coatings showed better corrosion stability and adhesion than pure epoxy coating, while between doped epoxy coatings one with CeO2/ZrO2 exhhibited the greatest values of charge-transfer resistance due to synergetic effect of both types of added nanoparticles.

Improving the film-forming ability of BaTiO3/epoxy resin suspension by adjusting the solvent composition for the fabrication of embedded capacitance materials

Embedded capacitance materials (ECMs) are gradually taking the place of traditional discrete capacitors in the fabrication of high-end electronic devices. However, the exploration of suspensions with simple compositions and improved performance remains an important topic for the further development of ECMs. In this work, commonly used auxiliaries are not employed, and ethanol is added to a BaTiO3/epoxy resin ethyl acetate suspension, which improves the film-forming ability. The corresponding ECMs show increased mechanical and electrical performance due to the better dispersion of the BaTiO3 nanoparticles. The fabricated embedded capacitors have low tolerances and can pass reliability tests, which verifies their applicability in printed circuit board manufacturing.

移動電界を印加したカーボンナノチューブ/紫外線硬化性樹脂複合材の電気的特性とカーボンナノチューブの配列シミュレーション

This study sought to align multiwalled carbon nanotubes in uncured ultraviolet ray curing resin suspension by applying traveling electric field in the whole area. The suspension coated on a 18mm × 18mm size cover glass and the coated cover glass were put on the multiple-electrode which was constructed with 24 long and slender electrodes. Rectangular and six-phase voltages were applied to the multiple-electrode. The applied voltage in one electrode had the phase differences of ±60 degrees among the voltages applied to the both side electrodes. The multiwalled carbon nanotubes in the suspension were rotated to the direction perpendicular to the electrodes. After the rotation ceased, UV rays were irradiated to the suspension for resin curing. In this way, aligned carbon nanotubes/ ultraviolet curing resin composites were produced. The electrical resistivities of the composites were measured in parallel and vertical directions to the aligned carbon nanotubes. In the latter half of this paper, the carbon nanotubes alignment was simulated under the experimental condition based on the method proposed by the author. Furthermore, the influence of the relative permittivity of the suspension on the fluctuation of the carbon nanotube orientation was theoretically clarified.

Microfluidization, time-effective and solvent free processing of nanoparticle containing thermosetting matrix resin suspensions for producing composites with enhanced thermal properties

Dispersion of low content (0.1wt.%) of multi walled carbon nanotubes (MWCNTs) in an epoxy resin through microfluidization was brought under spotlight as a case study. For the sake of performance comparison, epoxy resin suspension with the same MWCNT content was also produced through sonication, and the energy consumed to disperse MWCNTs in the epoxy resin remained the same for the both processes. At the equal energy consumption level, preparing the resin suspension through microfluidization was determined to take approximately 4.5min, which is about 9 times lower than it takes for the same suspension to be prepared through sonication. Following cure of the prepared suspensions, thermal and thermo-mechanical properties of the resulting composites were systematically investigated. As a result, glass transition temperature (Tg) of the neat epoxy and its composites produced by sonication and microfluidization were determined to be 78±3, 83±5 and 88±4°C, respectively. Moreover, thermal expansion coefficient (CTE) of the epoxy resin was reduced by 7% when it was blended with MWCNTs through microfluidization, while no significant change was observed in the corresponding CTE value when through sonication. Thermomechanical testing findings implied about 5% and 10% improvement in storage and loss modulus values of the composites produced by microfluidization over by sonication. Transmission electron microscopy (TEM) examination showed that MWCNTs were more homogenously and individually dispersed in the epoxy resin by retaining their initial aspect ratio through microfluidization. Scanning electron microscopy (SEM) examination revealed that composite fracture surface morphology significantly varied, depending to large extent on the type of the process used. Based on the results obtained, it was proposed that microfluidization might pave the way for cost-and-time effective solvent-free processing of nanoparticle modified thermosetting resin suspensions, especially including those that could be promisingly used as matrix constituent for manufacturing fabric reinforced composites with multi-functional properties.

In situ assessment of carbon nanotube flow and filtration monitoring through glass fabric using electrical resistance measurement

Filtration of nanofillers into porous fabric media is still an issue during the preparation of advanced fiber-reinforced composites. The assessment of resin/multiwall carbon nanotube (MWCNT) flow, MWCNT filtration, and the cure monitoring of glass fiber/carbon nanotube-polyester composites by means of the measurement of the electrical resistance was introduced. The vacuum-assisted resin transfer molding technique was used. The electrical resistances measured over the span of a composite were qualitatively correlated with MWCNT flow and the degree of MWCNT filtration. It was found that while the complexity of the fabrics could likely introduce preferential deposition of MWCNTs, their filtration is mainly affected by their dispersion state in the resin suspension. Relationships among critical parameters such as the lengths and diameters of MWCNTs, the inter- and intra-tow dimensions of glass fabrics, the dispersion level of MWCNTs, and the viscosity of nanocomposite samples are discussed and correlated to the filtration, cure, and flow phenomena. We showed that our method can also serve as an early warning to obviate defects in the resulting composite.

Microfiltration of micro-sized suspensions of boron-selective resin with PVDF membranes

In this paper microfiltration (MF) separation of fractionized ion exchange Amberlite IRA743 resin from aqueous solutions using polyvinylidene fluoride membranes with the pore sizes of 0.1, 0.22 and 0.45μm was studies. The effect of membrane pore size, transmembrane pressure, pH and concentration of the resin suspensions, presence of NaCl, MgCl2 and Na2SO4 salts on permeate flux has been evaluated. It was shown that the dominant membrane fouling mechanism during MF of the resin suspensions is formation of a cake layer from deposited resin on the membrane surface. The flux declines with increasing operating pressure and suspension concentration, while it increases with the presence of inorganic salts and feed pH. Changes in zeta potential of resin particles and the membranes as well as agglomeration and electroviscous effects should be considered while analyzing these findings. It was shown that the resin particles after boron sorption can be efficiently regenerated and reused in combined adsorption-microfiltration (AMF) process of boron removal from water, however a sharp drop in membrane flux during MF separation of the resin suspension should be further addressed to develop the efficient AMF procedure.

OS1510 多重電極上に置いた未硬化懸濁物中のCNTの多相電圧印加による一方向配列に関する研究

Multiwalled carbon nanotubes in uncured ultraviolet ray curing resin suspension were aligned by applying the multi-phase voltage. After the alignment, the suspension was cured by irradiating ultraviolet ray. The multiple-electrode used to the experiment was constructed by 24 long and slender electrodes. The cover glass was put on the multiple-electrode, and the suspension was dropped on the cover glass. The multi-phase voltage was applied to the multiple-electrode, and the traveling electric field was applied to the suspension.

Modeling of particle–resin suspension impregnation in compression resin transfer molding of particle-filled, continuous fiber reinforced composites

A particle–resin suspension impregnation model is used for analyzing the mold filling process in compression resin transfer molding (CRTM) of particle-filled, continuous fiber composites. The model is based on Darcy flow coupled with particle filtration and is applicable to two-dimensional impregnation through isotropic/anisotropic fiber preforms. Comparisons with simple analytical solutions and experimental results from the literature were made to validate the numerical solution. Simulations showed that CRTM was advantageous over resin transfer molding (RTM) for smaller non-homogeneity in composite microstructure, when particle filtration was high. Limits on certain process parameters were observed beyond which molding pressures in CRTM became comparable with those in RTM. The preform anisotropy was effective in the particle distribution profile. The choice of inlet gate configuration in CRTM was found influential in the particle distribution homogeneity and molding pressures. The developed modeling tool can be extended to analyze any composite liquid molding process involving particle fillers.

Coupling ion exchange with ultrafiltration for boron removal from geothermal water-investigation of process parameters and recycle tests

A hybrid process was established in a stirred vessel coupling ion exchange with ultrafiltration (UF). Boron selective chelating ion-exchange resins Dowex XUS-43594.00 with an average particle diameter of 20μm were used for boron separation from geothermal water and a submerged hollow fiber type UF membrane module (ZW-1, GE) was used for the filtration of the resin suspension and collecting permeate. Process variables such as the concentration of ion exchange resin in the suspension, replacement rates of fresh and saturated resins in the stirred vessel, and flow rate of permeate were evaluated in order to determine the efficiency of the hybrid process for boron removal from geothermal water. The recycle performance of the hybrid system was monitored following ten sorption–washing–elution–washing–regeneration–washing cycles.

Effect of shear, temperature and pH on the dynamics of salt induced coagulation of wood resin colloids

The effect of pH, temperature and shear on the coagulation dynamics of a wood resin suspension destabilized by salt additions was investigated. Stability of wood resin colloids was measured as a function of time using a photometric dispersion analyser (PDA) upon the step addition of salt solutions. Colloidal stability upon salt addition was found to be a function of pH (directly related to colloidal wood resin charge). This follows the predictions from the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory. In general temperature also affected colloidal stability according to expectations. However, the effects were found to be strongly related to salt type. The effect of shear on the stability of a colloidal suspension was more important than expected. At low shear, the critical coagulation concentration of colloidal wood resins scaled with salt valency to the −6 power. Deviations from the Shultz–Hardy rule become important as shear was increased and a critical coagulation concentration (CCC) proportional to the counter ion charge to the power of 7 (CCC∝z−7) relationship was measured at the highest shear. We suggest a relationship of the form: CCC∝(Ωz)−6τ or CCC∝[z−6τ+Ω] where Ω=f(G) and τ=g(G). An additional term would be required for the systems under orthokinetic conditions usually found in industry.