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A cost-effective stereolithography for medium-scale components is developed to fabricate 3D components with high build speed and resolution from photo-curable resin. The developed SLA utilizes a focused light beam of wavelength range (300 nm–700 nm) coming from the DLP projector and passes through the objective lens and finally imposed on the platform containing a layer of photo-curable resin. After focusing the light beam on the liquid resin layer, the photo-polymerization reaction occurs and the liquid resin becomes solid. Thus, the 3D object is fabricated layer by layer curing of liquid resin. The photopolymer used in this experimentation is polyethylene glycol di-acrylate and Irgacure 784 as photo-initiator. The Creo 3.0 software is used for modelling of 3D objects. A special MATLAB code is developed for slicing of the 3D model and displaying the sliced image one by one through DLP projector. The Arduino microcontroller with stepper motor and ball screw is used to control the motion of Z-stage platform. The Creation workshop software is also used to control motion of the Z-stage and period to display the sliced images through DLP projector. The medium-scale 3D objects with rectangular, square, and circular cross-sections are obtained by curing the aforementioned photo-curable resin. It is observed that the 3D objects are best cured for two seconds curing time with 0.1 mm curing depth along Z-axis.

Biomass-derived dynamic covalent thermoset has been considered as a promising solution to the high dependence on fossil resources and the difficulty in recyclability after curing of conventional bisphenol A epoxy resins. However, the design and preparation of a dynamic covalent biobased epoxy thermoset with both comparable thermal and mechanical performances to bisphenol A epoxy resins and reprocessibility remains a significant challenge. Herein, based on imine chemistry, a novel Schiff base-containing dynamic covalent epoxy thermoset was facilely fabricated from biobased protocatechualdehyde and synthetic siloxane diamine. Due to the more reactive epoxides in the epoxy monomer than in bisphenol A epoxy oligomer, the thermoset exhibited a high cross-linking density, resulting in high thermal stability and glass transition temperature. The rigid aromatic Schiff base moieties endowed the thermoset with excellent mechanical properties: thanks to the plasticization of the flexible siloxane, the thermoset displayed high impact strength. Meanwhile, owing to the high segmental mobility, the fast exchange of imine bonds was guaranteed; and the thermoset was able to be recycled through reprocessing. Taking these features, this work provided great potential for designing and preparing sustainable substitutes for bisphenol A epoxy resins in the high-performance applications.

The purpose of this study was to determine the effect of partial replacement of cement with diatomaceous earth (DE) on the compressive strength and absorption of mortar. The cement volume was replaced by different contents of replacement levels of 0%, 10%, 20%, 30% and 40% DE. Ordinary Portland Cement (OPC) and Portland Composite Cement (PCC) were used while the binder and sand were mixed at 1: 2 and 1: 4 vol ratios. Moreover, 5 × 5 × 5 cm3 cubes were used as the test specimens and their compressive strength was determined at 1, 3, 7, and 28 days while the absorption was evaluated at the curing age of 28 days. The results showed that the compressive strength of mortar with OPC for both 1: 2 and 1: 4 ratios decreased with the increment in the content of the DE. However, at 40% cement replacement, the mortar with OPC was categorized as type M according to SNI 6882:2014 or ASTM C270-10 with 28 days compressive strength observed to be greater than 17.2 MPa. Meanwhile, the mortar with PCC for 1: 2 was observed to have the highest compressive strength of 36.63 MPa at 20% cement replacement and 25.39 MPa at 10% cement replacement for 1:4. Furthermore, the absorption of mortar with DE was observed to be greater than for mortar with cement only.

Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution, which satisfies the needs of sustainable social development. In this study, a bio-based epoxy thermoset precursor (MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process. And the fully bio-based epoxy thermoset (MGOL-EP-SC) was obtained by self-curing without adding any other hardener. MGOL-EP-SC revealed an extremely high glass-transition temperature (Tg) of 265 °C and char yield of 53.2% (in N2), which were at the highest level among the fully bio-based epoxy thermosets reported so far. In addition, when the MGOL-EP was cured with 4,4′-methylenedianiline (DDM), Tg of the MGOL-EP/DDM was decreased by 61 °C and the other comprehensive performance had also been decreased, which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents. Moreover, the MGOL-EP-SC presented certain killing rate (48.4%) to Staphylococcus aureus. These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.

Carbon fibers reinforced SiCN ceramic matrix composites (C/SiCN) were prepared by PIP with homemade polysilazanes (PSN-T03). The PSN-T03 had a viscosity of less than 500 mPa·s and favorable good chemical stability at 80 ℃, which made it quite applicable for PIP process. PSN-T03’ curing reactions happened at temperatures ranging from 149℃ to 205℃, and conversion to amorphous SiCN ceramics could be finished at temperatures above 700℃ with a 70+ wt% ceramic yield. Tensile strength of C/SiCN composites were 230 MPa and 350 MPa respectively at room and high temperature (1400℃), and bending strength reached 380 MPa and 530 MPa. SiCN ceramics began to lose weight at 1400℃ due to the carbothermic reduction of the silicon nitride phase under inert atmosphere, which results in collapse of the mechanical properties of C/SiCN composites above 1400℃.

Molecular self-assembly is the most important strategy for the development of chiral aggregates and chiral functional materials. In this study, we rationally designed and synthesized chiral fluorescent heteroclusters that were self-assembled into microscale cubosomes with a three-dimensional (3D) bicontinuous cubic phase nanostructure. The cubosomes exhibited chirality, indicating that chirality is transferred from the molecules to the 3D nanostructure. Therefore, we confirmed the formation of a chiral bicontinuous cubic phase nanostructure for the first time. We also showed that this chirality originates from the continuous change in the saddle-splay distortion of the molecules within the curved bilayer. At the same time, transparent films of chiral composites were prepared by mixing the chiral cubosomes with an epoxy resin and then curing the mixture. Therefore, we demonstrated an effective method for preparing chiral composites.

The primary objective of this study is to demonstrate the possibility of developing silica, alumina, and zircon-based photocurable ceramic suspensions that can be used for visible light photopolymerization (> 450 nm) and to optimise the binder formulations for the purpose of LCD-based ceramic 3D printing applications. Reference ceramic components for this work are ceramic cores employed in the investment casting of high-pressure turbine blades and vanes. Arguably, one of the most critical steps in photoinduced ceramic 3D printing is developing suitable ceramic suspensions, having high ceramic loading, low viscosity, and short curing times. Ceramic suspensions with four different novel binder formulations and commercial ceramic powders used in core manufacturing (SiO2, Al2O3 and ZrSiO4) were investigated to achieve the best trade-off between: (1) their curing performance (cure depth and curing speed), (2) rheological properties of the binder mixtures at the solid loadings of 60 vol.% for SiO2, 55 vol.% for ZrSiO4, and 45 vol.% for Al2O3; and (3) the green body mechanical properties of the mixtures after printing. The effect of ceramic particles on the selected binders was examined individually, and the correlation between cure depth (Cd), volumetric loading, and curing speed are evaluated. The results show all binders designed in this study provide an adequate cure depth, even at high ceramic loadings. When the curing behaviour of all unloaded binder mixtures from the previous study [ 1 ] compared with the 10 vol.% SiO2 loaded mixtures, the cure depth of all formulated binder mixtures increased 50–55 % and the curing thickness of 60 vol.% SiO2 loaded suspensions were still slightly higher than their unloaded counterparts. The rheology outcomes indicate that lower viscosity binders always result in lower viscosity of the ceramic loaded inks, even without taking the effect of dispersants into account. Besides, the addition of N-Vinyl-2-Pyrrolidone (NVP) monofunctional monomer to the binder mixtures significantly reduces the viscosity and changes the normally linear relationship of the mix viscosity and its silica loading content. Among the binder formulations loaded with 60 vol.% of SiO2, the formulation providing the lowest viscosity and highest mechanical property consists of 5 wt.% of NVP, 45 wt.% of HDDA and 50 wt.% of Photocentric 34 resin. Although this binder mixture showed the highest green flexural strength when loaded by 55 vol.% ZrSiO4, all other mixtures loaded with zircon flour also demonstrated a near-fluid behaviour, below 200 s−1. In Al2O3 loaded mixtures, the HDDA di-functional binder formulations present lowest viscosity and the di- and multifunctional monomer blends (HDDA-Photocentric27) showed the highest mechanical properties when used in a 50/50 ratio. This work summarises the best binder choices for silica, alumina and zircon based ceramic suspensions used in core printing for investment casting applications through LCD screen printing.

The possibility of printing conductive ink on textiles is progressively researched due to its potential benefits in manufacturing functional wearable electronics and improving wearing comfort. However, few studies have reported the effect of conductive ink formulation on electrodes directly screen-printed on flexible substrates, especially printing UV curable conductive ink on common textiles. In this work, a novel UV curable nano-silver ink with short-time curing and low temperature features was developed to manufacture the fully flexible and washable textile-based electrodes by screen printing. The aim of this study was to determine the influence of ink formulation on UV-curing speed, degree of conversion, morphology and electrical properties of printed electrodes. Besides, the application demonstration was highlighted. The curing speed and adhesion of ink was found depending dominantly on the type of prepolymer and the functionality of monomer, and the type of photoinitiator had a decisive effect on the curing speed, degree of double bond conversion and morphology of printed patterns. The nano-silver content is key to guarantee the suitable screen-printability of conductive ink and therefore the uniformity and high conductivity of textile-based electrodes. Optimally, an ink formulation with 60 wt% nano-silver meets the potential application requirements. The electrode with 1.0 mm width showed significantly high electrical conductivity of 2.47 × 106 S/m, outstanding mechanical durability and satisfactory washability. The high-performance of electrodes screen-printed on different fabrics proved the feasibility and utility of UV curable nano-silver ink. In addition, the application potential of the conductive ink in fabricating electronic textiles (e-textiles) was confirmed by using the textile-based electrodes as the cathodes of silver-zinc batteries. We anticipate the developed UV curable conductive ink for screen-printing on textiles can provide a novel design opportunity for flexible and wearable e-textile applications.

Material Jetting (MJ), also known as poly-jet printing, is one type of additive manufacturing (AM) process that involves selectively curing materials using UV light and drops over a selected area. The material can be either jetted when required or continuously depending upon the type of object to be created. In this article, an attempt is made to describe the fundamentals of the material jetting process. The characteristics of the parts printed using material jetting, such as dimensional accuracy, surface quality, and other mechanical properties, are discussed thoroughly. Furthermore, the factors which affect the mechanical properties of the parts created by the material jetting process are highlighted in this study. Also, various applications of the material jetting process in modern times are explored briefly as material jetting is a unique additive manufacturing process that can be used to print multi-colored parts.

Red mud (RM) is an industrial by-product created during the production of alumina/aluminium that has engendered severe environmental concerns arising from its improper disposal. To mitigate the negative environmental impact of RM waste and produce a sustainable material having high mechanical performance (particularly ductility) for a variety of applications, this study developed an alkali-activated fiber reinforced composite (AAFRC) using RM, ground granulated blast-furnace slag (or slag), and silica fume as the precursors. The effects of two different curing conditions (ambient-curing and heat-curing) on the mechanical properties and microscopic characteristics of the material were systematically investigated. The heat-cured RM-derived AAFRC exhibited excellent tensile strain capacity (or ductility) of up to 5.6%, which was significantly higher than that of its counterpart that was cured under ambient condition. Despite the reduction in strength caused by heat-curing, AAFRC retained adequate tensile and compressive strengths of 4.0 and 75 MPa, respectively. The results of three-point bending, single crack tensile, and single fiber pullout tests provided reasonable explanations for the tensile behaviors of the studied material. Scanning electron microscopy revealed that a less compacted matrix was formed in the RM composite due to heat-curing. The combined results from energy dispersive spectroscopy and nanoindentation tests indicated that adding red mud did not alter the types of reaction products for the material, which were similar in composition to conventional alkali-activated slag while also including C-A-S-H and N-A-S-H gels in addition to a type of layered double hydroxide. These findings can serve as theoretical guidelines for the future design and application of eco-friendly, high-ductile cementless composites prepared from RM waste.

Ceramic mask stereolithography additive manufacturing technology has the abilities of fast and accurate printing complex and personalized ceramic parts. However, since the ultraviolet light is strongly blocked by the ceramic particles in the slurry during exposure, the slurry with high refractive index ceramic particles has low cure depth, and serious light scattering. This investigation developed a curable silicon nitride slurry with a high refractive index liquid phase, which significantly reduced the refractive index difference between the liquid phase and the silicon nitride ceramic particles. The high refractive index acrylate monomer and solvent were chosen to increase the cure depth while ensuring the curing accuracy. Compared with the slurry whose liquid phase was pure HDDA, the addition of OPPEA and ACMO in the liquid phase showed a better refractive index increasing effect and the strongest cure depth and dimensional accuracy improvement. POE was verified as a suitable non-reactive high refractive solvent. The composition of 20 wt% OPPEA, 10 wt% ACMO, 40 wt% HDDA, and 30 wt% POE were optimized as the high refractive index liquid phase for 40 vol% solid phase silicon nitride slurry. A finite element analysis model of silicon nitride slurry was established, and the distribution of ultraviolet light intensity in silicon nitride slurry with high refractive index liquid phase was numerically simulated.

Worldwide, precast concrete elements are becoming the primary construction materials, and there have been conducted numbers of studies on their manufacturing process, mechanical properties and curing regime. However, the energy consumption of the precast concrete manufacturing process and specifically the curing process is ignored by researchers. In this study, a thermal model of a curing unit, including three main sections: a curing room, a steam transfer system and a boiler, is developed. Besides, based on the mathematical formulation of heat transfer, a MATLAB code is prepared to determine the heat transfer, the mass of steam, the mass of fuel and the annual fuel cost. By the MATLAB code, the effect of different parameters on the curing process energy consumption and the fuel cost is investigated. Eventually, a smart control system that is based on the condition of the curing unit in every moment is suggested. This system leads to a reduction of 30% of energy consumption and the annual fuel cost.

The main objective of this work is to develop a new polymer based composite material having different reinforcement angle orientations and studies its tensile behavior. For fiber reinforced polymer matrix composites E-2 glass fiber reinforcement and epoxy resin for matrix is used. E-2 g1ass fiber has high strength, chemical resistance and good insulating properties. Epoxy being less viscous allows good adhesion to fibers used in laminate preparation, without misalignment of fibers. Hand layup technique has been adopted for preparation of laminate. Glass fibers are laid, mixture of epoxy resin and hardener is smeared on it alternately, until laminate of desired thickness is achieved, and is left to atmosphere for curing. 2.5 mm laminate is prepared by placing glass fibers of 0.25 mm thickness one above the other. The prepared laminate is then taken for cutting according to ASTM standards (D3039) of 3 sets of rectangular specimens. For first set comprises of 90° angle-oriented specimen, second and third sets for 45° and 30° respectively. These specimens are subjected to tensile test in Lloyd UTM and load being applied gradually at the rate of 2 mm/min is continued until the material fails. The computer simulation plots the graph during the entire testing process and stops when the material fails.

The research carries out the simulation of the growth of the polyurethane foam inside a mold, in order to optimize the resources. The aim finds the accurate option within a production process both in the incorporation of a new product as in improving an existing one. Using the Moldex3D program, the project obtains a mathematical model to calculate parameters such as the viscosity of the material, pressure, volume, temperature, curing, foaming, heat capacity, thermal conductivity and mechanical properties of the material. The density obtained for the material analyzed experimentally is 59.09 kg·m−3 with a uniform watering at the base with a 10 degrees mold inclination with 1740 g of material and air outlets that help to obtain better conditions of mold, seeking to reduce the time used by 25% and reduce manufacturing costs.

In recent decades, natural fibers have emerged as a rising trend in materials research as a reinforcement for polymer matrix materials and as a replacement for non-biodegradable, non-renewable, and high-density synthetic fabrics. The main objective of this research is to examine the mechanical characteristics of hemp and flax-based hybrid composites reinforced with epoxy resin at cryogenic and room temperatures. The composites were made using a hand lay-up approach, with both fibers being prepared with a NaOH solution for 4 h to improve interfacial adhesion. It is apparent from this research that cryogenic temperature has a significant impact on the flexural, tensile and impact characteristics of polymer composites, and that these qualities vary depending on the amount of cryogenic treatment. After being submerged in liquid nitrogen for 15, 30, and 45 min, the specimens are tested for tensile, flexural, and impact characteristics. An untreated specimen has the highest tensile strength of 27.89 MPa, a flexural strength of 58.95 MPa, and impact strength of 10.94 kJ/m2, with the value decreasing as the curing period rises.

Lignosulfonate (LS) was successfully introduced into the epoxy resin matrix with the aid of ethylene glycol (EG) dissolution. Both the rigid LS and soft EG segments were linked into the cross-linked network structure of epoxy resin via esterification of hydroxyl groups in LS and EG molecules with anhydride. The ultimate properties of cured samples were adjusted effectively by changing the proportion of LS and EG components. Curing reaction and kinetics were analyzed, by which the optimal curing process parameters were determined. Although thermal stability of LS itself was relatively lower than that of neat epoxy, the thermal performance was significantly enhanced for the modified sample of epoxy/LS0.5-EG0.5. At the same time, the flexural strength, flexural modulus and impact strength were found to be increased by 23.1, 35.7 and 15.1% respectively compared with the neat epoxy. In addition, the excellent shape memory behavior and improved mechanical stability with LS addition were exhibited by the cured LS-EG modified specimens. This work reveals that lignin can be used as an efficient functional additive to regulate thermal, mechanical and shape memory properties of epoxy resin.

The sustainable utilization of demolition wastes in the production of building materials is regarded as an eco-efficient approach for conserving naturally-occurring resources accompanied by resolving the environmental problems caused by these wastes. Accordingly, the motivation behind this work is evaluating the single and combined effect of nano-waste ceramic (NWC) and nano silica (NS) on the performance of Portland cement concrete. Portland cement was individually replaced by different contents of NWC (2-10 wt. %) and NS (1-4 wt. %). Another mixture was designed to evaluate the synergetic impact of NS and NWC mixture (3 and 6 wt. %) on the performance of concrete. The mechanical (flexural, splitting tensile and compressive strengths) and nondestructive tests (Ultrasonic Pulse Velocity ‘UPV’) were carried on the control and nano-modified hardened concrete. The results showed that the increase of NWC content up to 6wt. % has resulted in a noticeable increment in strengths at all curing ages, followed by a reduction in strengths when NWC content reaches 10 wt. %. However, the usage of 10% NWC illustrates a slight enhancement in strengths compared to control sample. All over the mixtures, the nano-silica modified samples demonstrate a slight enhancement in the mechanical properties compared to NWC. The highest mechanical properties accompanied by the shortest transmitted waves were achieved by the hardened samples having the mixture of 3 wt. % NS and 6 wt. % NWC. This means that the sustainable utilization of NWC not only improves the performance of concrete but also resolves the environmental problems caused by this waste. The sustainable utilization of demolition wastes in the production of building materials is regarded as an eco-efficient approach for conserving naturally-occurring resources accompanied by resolving the environmental problems caused by these wastes. Accordingly, the motivation behind this work is evaluating the single and combined effect of nano-waste ceramic (NWC) and nano silica (NS) on the performance of Portland cement concrete. Portland cement was individually replaced by different contents of NWC (2-10 wt. %) and NS (1-4 wt. %). Another mixture was designed to evaluate the synergetic impact of NS and NWC mixture (3 and 6 wt. %) on the performance of concrete. The mechanical (flexural, splitting tensile and compressive strengths) and nondestructive tests (Ultrasonic Pulse Velocity ‘UPV’) were carried on the control and nano-modified hardened concrete. The results showed that the increase of NWC content up to 6wt. % has resulted in a noticeable increment in strengths at all curing ages, followed by a reduction in strengths when NWC content reaches 10 wt. %. However, the usage of 10% NWC illustrates a slight enhancement in strengths compared to control sample. All over the mixtures, the nano-silica modified samples demonstrate a slight enhancement in the mechanical properties compared to NWC. The highest mechanical properties accompanied by the shortest transmitted waves were achieved by the hardened samples having the mixture of 3 wt. % NS and 6 wt. % NWC. This means that the sustainable utilization of NWC not only improves the performance of concrete but also resolves the environmental problems caused by this waste.

The present study aims to apply an electrostatic dry powder coating process to coat aspirin tablets with polymer blends to produce a single-layer coating film, which potentially allows an advantageous delayed sustained drug release profile. The coating formulations containing polymer blends of enteric polymer (hydroxypropyl methylcellulose phthalate or hydroxypropyl methyl cellulose acetate-succinate) and insoluble polymer (Eudragit® RL) were successfully developed and optimized. Results of scanning electron microscopy and acid resistance test demonstrated that curing conditions had a significant impact on the qualities of the produced film. Drug dissolution experiments revealed that changes in the coating level and the coating formulation with different ratios of the enteric polymer to the insoluble polymer achieved an altered and adjustable drug release profile. All of the results suggested that electrostatic powder coating technology is capable to produce a satisfactory coating film with polymer blends, allowing an advantageous functionality of delayed sustained drug release.

High–temperature proton exchange membrane fuel cells (HT–PEMFCs) are pursued worldwide as efficient energy conversion devices. Great efforts have been made in the area of designing and developing phosphoric acid (PA)–based proton exchange membrane (PEM) of HT–PEMFCs. This review focuses on recent advances in the limitations of acid–based PEM (acid leaching, oxidative degradation, and mechanical degradation) and the approaches mitigating the membrane degradation. Preparing multilayer or polymers with continuous network, adding hygroscopic inorganic materials, and introducing PA doping sites or covalent interactions with PA can effectively reduce acid leaching. Membrane oxidative degradation can be alleviated by synthesizing crosslinked or branched polymers, and introducing antioxidative groups or highly oxidative stable materials. Crosslinking to get a compact structure, blending with stable polymers and inorganic materials, preparing polymer with high molecular weight, and fabricating the polymer with PA doping sites away from backbones, are recommended to improve the membrane mechanical strength. Also, by comparing the running hours and decay rate, three current approaches, 1. crosslinking via thermally curing or polymeric crosslinker, 2. incorporating hygroscopic inorganic materials, 3. increasing membrane layers or introducing strong basic groups and electron–withdrawing groups, have been concluded to be promising approaches to improve the durability of HT–PEMFCs. The overall aim of this review is to explore the existing degradation challenges and opportunities to serve as a solid basis for the deployment in the fuel cell market.

Curtains with light-to-heat conversion capacity can warm up a room under solar radiation and improve the thermal energy efficiency of buildings, thereby reducing energy consumption during winter. Herein, a photothermal silk fibroin aerogel is synthesized by freeze-drying and curing method, using silk fibroin (SF) as template and scaffold, copper sulfide nanoparticles (CuS NPs) as photothermal conversion material, polyethylene glycol (PEG) as plasticizer, and polydimethylsiloxane (PDMS) as the package agent. The results reveal that SF as the template may guide the growth of CuS NPs, and the introduction of PEG improves the flexibility of the prepared CuS@SF aerogel. The composite CuS@SF-PEG/PDMS aerogel not only preserves the initial characteristics of SF aerogel but also integrates hydrophobic, rapid antibacterial ability, high-performance photothermal conversion efficiency, and stable switching effect. The lightweight, self-heating SF-based aerogel can be applied to the preparation of home textiles such as smart curtains. Additionally, it can be used as absorbent for cleaning up viscous oil from water, which could expand the applications of SF-based biomaterials toward meeting the requirements of sustainable developments.

Digital light processing (DLP)-based ceramic stereolithography has attracted significant attentions due to the high printing speed and high dimensional accuracy of DLP printers. However, undesired dropping of unfinished ceramic parts during printing, owing to inadequate adhesion between the first cured layer and the substrate of the building platform, still remains a challenge. In this study, the relationship between the adhesion properties of ultraviolet (UV)-curable alumina (α-Al2O3) suspensions and the functionalities and structures of UV-curable acrylate monomers was investigated. With an increase in the proportions of monofunctional monomers, the adhesion abilities of UV-curable alumina suspensions enhanced because of reduced volume shrinkage, however, inferior curing performances were observed due to a decrease in the double bond densities. Furthermore, the large-volume branched chain structures in monofunctional monomers and ethyoxyl groups in polyfunctional monomers effectively decreased the volume contraction, improving the adhesion performances of UV-curable alumina suspensions and facilitating the conversion of double bonds to provide excellent curing properties, further guaranteeing strong adhesion of these suspensions to the substrate.

Soilcrete properties modified with two types of polymer up to 0.20 % (% wt. dry weight of cement) were tested and quantified. The stress–strain curve of modified soilcrete with polymers was examined for curing periods up to 28 days and modeled using two different mathematical models. The flowability of the soilcerte was maintained within the range of 105 to 110% as recommended by ASTM standard. Polymers decreased the water/cement ratio ( w / c ) by 14.5 to 25.5%, based on the type and amount of polymers. The compressive strength and modulus of elasticity of soilcrete increased by 72% to 153% and by 55% to 195%, respectively, when the soilcrete was modified with 0.20% of polymers. The nonlinear Vipulanandan p-q equation was employed to predict the stress–strain behavior of the modified soilcrete with polymers and was compared with the β model prediction. Based on the statistical evaluation tools, the Vipulanandan p-q model predicted the stress–strain relationships better than β model. Linear (LM) and nonlinear relationships (NLM) were also used to predict the compressive strength, modulus of elasticity, and toughness of the soilcrete as a function of w/c, curing time, and polymer contents.

Purpose: To verify the color change and contrast ratio of resin composites after curing and after 30 days of storage in water. Methods: Dentin A2 shades of different light-cured dental resin composites (Vittra APS, FGM, Brazil; Z350 XT, 3M ESPE, EUA; Tetric N-Ceram, Ivoclar Vivadent, Liechtenstein, and Charisma Diamond, Heraeus Kulzer, Germany) were tested. Ten rounded specimens (8 mm × 2 mm) were prepared for each material. Reflectance for all samples was obtained using a spectrophotometer (Minolta CM 3700d, Konica Minolta, Japan) before curing, immediately after curing, and after 30 days of storage in water. The color change (ΔE*lab) and contrast ratio (CR) data were analyzed using a one-way analysis of variance with Tukey's and paired t-tests (α = 1%). Results: For all materials tested, significant color changes were noticeable after curing and after 30 days in water (p 0.01). Conclusion: The CR values and color changes after curing and 30 days of storage in water varied depending on the material tested. This study corroborates the clinical practice of curing a small amount of unpolymerized resin composite on the tooth surface to select the desired shade before undertaking esthetic restorative procedures.

Stereolithography is one of the most widely used additive manufacturing techniques for preparing high precision and complex ceramic components. Due to the high optical absorbance and refractive index of SiC powder, the rapid stereolithography of SiC ceramics components has become a key challenge. Here, we innovatively use graded silica to improve the curing thickness, rheological and settling performance of the slurry. And we presented a preparation method of SiC ceramic slurry for stereolithography with high solid content, low viscosity, low sedimentation rate and high curing thickness. The printable precision of the slurry is more than 75 μm, the dynamic viscosity is less than 2 Pa·s, and the 24 h sedimentation height is less than 5%. This strategy demonstrates a tantalizing possibility and promising prospect to rapid stereolithography of large size SiC ceramic green body.

Porous ceramics with porosity up to 92.5 % have been successfully fabricated by freeze casting of polycarbosilane (PCS) solution. The effect of PCS concentration and thermal oxidation curing on the pore structure and compressive properties was investigated. Curing mechanism and thermodynamics were illuminated through analyzing the molecular structure, curing activation energy, and curing degree. Porous ceramics, mainly composed of SiC and a small amount of SiO2, have dendritic pore structure which well replicates the solidification morphology of camphene solvent. Results of FT-IR and Gaussian computation of PCS electron density show that Si–H and Si–CH3 bonds play a dominant role in thermal oxidation curing reaction. Both curing degree and ceramic yield increase with the increase in curing temperature and time. The curing degree of Si–H bond is close to 52 % and the corresponding ceramic yield is about 83 % when the porous PCS was cured at 200 °C for 90 min. Both polymer concentration and curing time have influences on the compressive strength of porous ceramics.

A process technology for the processing of the continuous carbon fibre reinforced ZrB2 (Cf – ZrB2) ultra high temperature ceramic matrix composite (UHTCMC) has been developed. The processing steps are slurry infiltration followed by curing and pyrolysis. The composite was then subjected to high temperature pressureless sintering. The microstrcutural and mechanical properties of Cf – ZrB2 UHTCMC were characterized at the completion of each processing step. The de-lamination between the carbon fibre and the ZrB2 matrix layer in 2D Cf – ZrB2 composite after pressureless sintering was found. However, the problem of de-lamination after sintering was not detected in the 2.5D Cf – ZrB2 composite by stitching the infiltrated layers in the Z-direction. Significant improvements in the sintered density, Young's modulus and flexural strength were achieved through 2.5D Cf – ZrB2 composite.

In the present study, exfoliated graphite nanoplatelets (EGN) were chemically modified with carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN) liquid rubber via carboxylation, acylation, and subsequently esterification. Multiple characterizations by means of attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction spectroscopy, thermogravimetric analysis, and scanning electron microscopy demonstrated the chemical modification. For comparison, neat vinyl ester resin (VE), EGN/VE and CTBN-EGN/VE composites were prepared by using a free-standing Teflon mold to avoid pressure during curing. The amounts of EGN and CTBN-grafted EGN containing in EGN/VE and CTBN-EGN/VE composites were 1, 3, and 5 wt%, respectively. The impact strength of EGN/VE and CTBN-EGN/VE composites was strongly dependent upon the CTBN-grafted EGN concentration incorporated into neat VE. It was remarkably enhanced up to 220–240% even with low contents (5 wt%) of CTBN-grafted EGN in comparison to neat VE and unmodified EGN/VE. The result revealed that a small amount of EGN chemically modified with liquid rubber CTBN played an important role in increasing the impact toughness of thermosetting resin.

This work focuses on the controllable fabrication of polymorphic nanostructured carbons consisting of hierarchical pores via “One-for-All” strategy from a single precursor-crude oil. Five kinds of tuned carbons with tremella-, honeycomb-, waxberry-, nanorod- and nanocube-like structures were obtained from crude oil, by employing a facile room temperature curing with structural regulation methods followed by thermal treatment. All the five nanostructured carbons have high specific surface area and large pore volume with hierarchical pores. In short, this study provides an efficient and novel strategy to fabricate controllably porous carbons with desired and multifarious microstructures from a single precursor-crude oil.

The increase of high demand of technological innovation in building construction have increasingly the need materials that have special structural characteristics. Notably, the use of self-compacting concrete (SCC) has been described by many researchers and engineers as a major revolution in concrete technology due to its fluidity and viscosity characteristics, besides providing energy savings during its construction. Tire waste rubber (TWR) is one of the most important residues that cause serious environmental issues. Recycling TWR in the form of aggregates as supplementary construction material is advantageous in many building fronts. To obtain an optimal SCC manufacturing parameters, this research was based on the application of design of experiments. Several mixtures, or designs, were prepared with different TRW proportions (10%, 30% and 50%). In addition, the effect of the rubber grain size was also considered in the model in two different levels. The specimens were submitted to quasi-static and dynamic tests in order to evaluate their structural performance. The considered responses were the natural frequency, damping factor, compression strength and elastic modulus for different curing periods (7 and 28 days). Statistical results showed the significance of the rubber, grain and curing time for the responses, especially for the strength and elastic modulus. The results of this paper could be a guideline for engineers using SCC in building field.

Nanocomposites have received much attention as construction materials, adhesives, and sealants because of the strong interfacial interactions between nano-sized fillers and matrix. However, dispersing the nano-sized fillers in the polymer matrix is challenging because of their tendency to agglomerate. In this study, a glycidyl terminated polysiloxane (g-PDMS) was synthesized and used to disperse fumed silica (nano-sized silica aggregates) in a BPADG/D230 system. The kinetic parameters of the g-PDMS/BPADG/D230 curing were obtained through non-isothermal DSC analysis. The apparent activation energy and reaction order of the epoxy resin/D230 system were calculated to be 51.82 kJ/mol and 0.91, respectively. Next, the effect of fumed silica on the properties of the nanocomposites was investigated. Compared to neat epoxy, the maximum strength, Young's modulus, fracture toughness and fracture energy of the nanocomposite with 5 phr (parts per hundred parts of epoxy resin) fumed silica were increased by 27%, 61%, 76% and 79%, respectively. Lastly, the fracture toughening mechanisms of the nanocomposites were examined using SEM images of the fractured surfaces of single-edge notched specimens after a three-point bending test.

Steam is used to provide heating and moisture in the curing process for the production of precast concrete (PC) construction elements. The generation of steam requires large amounts of fossil fuels. This study considers the incorporation of solar thermal energy into the steam curing of PC construction elements for reducing the need for fossil fuels and associated CO2 emissions. For this purpose, the board made of composite phase change material covers the inner surface of the main sun-facing wall in the heating & curing building. The PCM board is heated by sun rays and accumulates thermal energy during the PCM's phase transition, and this energy then is released to the indoor environment of the building, reducing the amount of steam required to maintain a certain level of temperature during the curing process. The energy consumption simulation software, EnergyPlus, and two physical models (built on the scale of 1:3) were used to study the effects of two different PCMs on the thermal performance of such new type of heating & curing buildings. Composite PCMs considered were GH-33 and GH-37 with 33 and 37 °C melting temperatures developed by the research team. The theoretical and experimental results are in good agreement and demonstrate that, compared to the GH-33, GH-37 PCM increases the temperature of the inner surface of the main sun-facing wall and the upper surface temperature of the PC construction element by 3.4 and 1.4 °C, respectively. The heat accumulation and discharge rates also were greater by 62%. For the investigated design of the building and given location in China, the deployment of studied PCM wall panels results in a reduction in the annual energy consumption and CO2 emissions by 58.6 GJ and 5 tons, respectively. The method developed for applying solar energy and selecting PCMs for augmenting steam curing of PC construction elements can be deployed in different geographical regions.

A digital light processing (DLP) technology has been developed for 3D printing lead-free barium titanate (BTO) piezoelectric ceramics. By comparing the curing and rheological properties of slurries with different photosensitive monomer, a high refractive index monomer acryloyl morpholine (ACMO) was chosen, and a design and preparation method of BTO slurry with high solid content, low viscosity and high curing ability was proposed. By further selecting the printing parameters, the single-layer exposure time was reduced and the forming efficiency has been greatly improved. Sintered specimens were obtained after a nitrogen-air double-step debinding and furnace sintering process, and the BTO ceramics fabricated with 80 wt% slurry shows the highest relative density (95.32 %) and piezoelectric constant (168.1 pC/N). Furthermore, complex-structured BTO ceramics were prepared, impregnated by epoxy resin and finally assembly made into hydrophones, which has significance for the future design and manufacture of piezoelectric ceramic-based composites that used in functional devices.

Improving magnetic-dielectric properties of polymer materials, through filler of functional ceramics, provides feasibility to develop high-frequency flexible electronics. Poly-dimethylsiloxane (PDMS), an inert silicone with low elasticity modulus and high transparency, has been considered a promising candidate for flexible electronics. Current PDMS matrix used in high-frequency devices suffers from unsatisfactory properties due to very low dielectric constant. In this study, using ultrasonic stirring and vacuum-pumping process, we prepare a series of xCo2Z/PDMS (x = 2; 4; 6; 8; 10) composite films, which are consisted of PDMS matrix and different quantity of micro-sized ferrite particles. XRD pattern indicates that the obtained ferrite particles include Co2Z main phase and BaM second phase. We demonstrate that 4Co2Z/PDMS film has improved magnetic-dielectric properties at 800 MHz (μ' = 1.49; e' = 4.54 tanδμ = 0.058; tanδe = 0.008). Also, the film has high saturation magnetization (σs = 17.51 emu/g). Furthermore, SEM micrographs show that using ultrasonic stirring and fast curing, the micro-sized ferrite particles are well dispersed in PDMS matrix. Our study, which provides a simple method to improve high-frequency magnetic and dielectric properties of PDMS matrix, could pave the way for development of high-frequency flexible electronics.

Over the years, stereolithography has been successfully used to prepare complex, strong silicon carbide (SiC) structures. However, most raw materials are dark in color and therefore have broad-spectrum absorbing properties, making the curing steps during stereolithography highly inefficient. Here, diamond powders were mixed with a light-curing resin, yielding a slurry with excellent curability. The slurry was then used to prepare SiC-based composites with complex morphologies using pyrolysis and reaction melt infiltration (RMI) process. The influence of the diamond volume fraction in the slurry on each process stage was investigated. The infiltration of molten Si into diamond body during RMI was greatly enhanced compared to traditional carbon bodies. SiC ceramic-based composites with complex morphologies and a maximum strength of ∼460 MPa was prepared rapidly and efficiently. This study demonstrates the great potential of the slurry for efficiently manufacturing SiC-based composites in mechanical parts where high strength and complex structures are needed.

Ceramic matrix composites are being investigated as new material of choice for aeronautic and aerospace applications, because of their higher thermal resistance. Among the different ways to manufacture these materials, the polymer infiltration pyrolysis (PIP) is the most versatile. This route uses preceramic resins that present the benefit to be processed like thermosets. However, there is a lack of information available regarding the curing kinetics of preceramic resins and their detailed chemical composition. This limits the possibility for the end user to freely operate the resin, with sufficient accuracy to manufacture components. Dynamic Differential Scanning Calorimetry (DSC) were carried out at 1, 3, 5, 10, 15 and 20°C/min, to plot a Time-Temperature-Transformation (TTT) diagram for a commercial polysiloxane resin, the SPR-688. The activation energy and kinetic parameters were estimated using Kinetics Neo. The glass transition temperature of SPR-688 was modelled using the Di Benedetto's equation. The gelation point was investigated by chemorheology using a Dynamic Mechanical Analysis (DMA) apparatus, by plotting tan δ vs time. The degree of cure was thereafter estimated. The curing mechanism was shown to be a single step reaction (A→B). The cure kinetic was successfully described by numerical optimization, which is based on the analytical Friedman method. The proposed model showed a good agreement between predicted and experimental data. This suggests that the curing kinetics of preceramic resins can be approximated using models that are well accepted for thermosetting polymers. This general strategy is key to manufacturing prepregs made of preceramic resins.

Para-aramid fibers (Kolon) are high performance polymeric fibers characterized by their high tenacity and impact resistance. They are used for the soft body armor structures in ballistics. In this study, the testing specimens were made from multilayered Kolon fabrics impregnated with epoxy resin where silicon carbide (SiC) microparticles or SiC nanofibers were added as reinforcement. The laminated composite samples were fabricated by hot compression and curing of epoxy resin. The tensile and impact strengths of the untreated specimens were compared with the ones that underwent water absorption in duration of 72 h (immersion or humidity) followed by desorption. The immersion of the specimens in water and exposure to high humidity (70%) were performed according to the ISO 62 standard while the tensile test was carried out in accordance with the ASTM D 3039 standard. In the end, the tensile test simulation of the laminated composite by using software Abaqus® was accomplished.

This study presents an incremental variational formulation (IVF) for the thermo-mechanical problem of resin products subjected to curing, for which a dual dissipation potential (DDP) for the cure state is originally derived in conjunction with that for viscoelasticity. Following the thermodynamically consistent formulation for the time evolution equation of the degree of cure (DOC) of a thermosetting resin and the linear viscoelastic law, we derive these DDPs by way of Legendre-Fenchel transformations with respect to characteristic dissipations. The evolution of DOC is then casted into the flow rule in mathematical theory of plasticity with the introduction of the curing multiplier as a new internal state variable in an analogous fashion to Perzyna’s viscoplastic regularization theory. Then, the pseudo stress is introduced as a new internal state variable to parameterize the derived flow rule of DOC. By virtue of this pseudo stress, we naturally define an incremental variational problem constrained by the parameterized flow rule in order to construct a semi-implicit scheme for the variational constitutive update. The finite element discretization is applied to the governing equations that satisfy the stationary conditions so that we could perform thermo-mechanical analyses of a thermosetting resin subjected to curing with the strong coupling procedure. The verification analysis is conducted to confirm the validity of the numerical result obtained by the proposed method in comparison with that of the conventional framework and followed by a demonstrative numerical example to simulate the stress development and relaxation in a virtual device subjected to different thermal histories.

The combination of yttria-zirconia (3Y–ZrO2) and stereolithography (SLA) is essential for forming alternative bioceramics for complex, custom-designed dental implants. In addition, suitable bioceramic suspensions are preconditions for such fabrication using SLA technology. In this study, 3Y–ZrO2 and 3Y–ZrO2/graphene oxide (GO) powders dispersed in ultraviolet curable acrylic-based resins are developed. A sedimentation experiment is performed to evaluate various ratios of monomers and dispersants to ensure good stability and dispersion of the suspensions. The hydrophobic structures of KH560 are introduced on the surfaces of ceramic powders, representing better wettability performances with 40 vol% NPG2PODA and 60 vol% Di-TMPTA. Moreover, the effects of premixed solvents and solid contents on the rheological behaviors of suspensions are investigated to confirm shear thinning and pseudo plasticity, with the experimental results fitting the Krieger–Dougherty curves. Further, the cure depth and width of the ceramic suspensions are studied, the results of which show that the penetration depth and critical exposure of the 3Y–ZrO2 (3Y–ZrO2/GO) pastes are 17.2 ± 0.50 μm and 4.80 ± 0.62 mJ/cm2 (11.8 ± 1.20 μm and 22.80 ± 9.34 mJ/cm2), respectively. The addition of GO results in a sharp increase in critical exposure, which intensifies the light scattering and hinders the curing of the ceramic paste. The research is expected to serve as a technical guide for the fabrication of ceramic suspensions for dental implants using SLA technology.

In this work, the physicochemical properties of palm oil fuel ash (POFA) based geopolymers with the addition of graphene oxide (GO) were investigated. Geopolymer composites were prepared by mixing the treated POFA, sand, NaOH, Na2SiO3, and GO. The mixtures were then cast in mortar molds to form the geopolymer composites, with different GO proportions and curing temperatures applied to the composites. Compressive strength, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses, as well as density functional theory (DFT) calculations, have been performed. The compressive test results showed that the compressive strength increased proportionally with the increase of GO content and decreased when there was an excess of GO. The excessive GO and the limited amount of NaOH activator solution inhibited the formation of reduced graphene oxide (rGO) via an in-situ reduction mechanism. The FTIR and SEM analyses revealed that the excess GO tended to promote the formation of epoxy groups on the GO, which eventually confined the formation of dense agglomeration and led to a decrease in compressive strength. The DFT calculations confirmed the significance of the epoxy group stretching. Overall, the ratio of NaOH to GO is a crucial factor in determining the mechanical properties of geopolymers-GO composites.

In order to improve interface effect, PEEK was successfully modified by a direct sulfonation method. As a result, PEEK ultilized 80 wt% H2SO4 solution as sulfonation would display much higher degree of sulfonation, which was increased with the reaction time. Al2O3 particles with different crystal forms were prepared by sintering Al(OH)3 particles as curing agents for phosphates. The influence of sintering temperature on structures of Al2O3 particles was evaluated by XRD and shear strength testing. Furthermore, Al2O3-phosphate/sulfonated PEEK (S-PEEK) hybrid composites were prepared by ultrasonic dispersion and molding at 360 °C. Mechanical properties were also measured by the shear, flexural and compressive strength testing. The phosphate ultilized α-Al2O3 particles as the curing agent could perform much better mechanical properties. In paticular, the compressive strength of α-Al2O3 phosphate/S-PEEK hybrid composites would reach 334.58 MPa. These composites would have many potential applications in aerospace, mechanics and medicines.

The isothermal curing kinetics of carbon nanotube loaded epoxy was investigated using rheometry and differential scanning calorimetry (DSC) at a range of temperatures. Rheo-kinetics was used to observe time-dependent rheological changes in elastic (G′) and viscous (G″) moduli, and complex viscosities of epoxy-CNT samples during isothermal curing. DSC measurements were also performed to monitor the curing reaction, in order to compare against the rheo-kinetic parameters. The Kamal-Sourour kinetic model describes the curing of the epoxy-CNT system for rheo-kinetics and DSC well. The activation energies of the curing reaction were found to be ∼36 kJ/mol and ∼33 kJ/mol using rheo-kinetics analysis and DSC, respectively. In addition, radio-frequency (RF) electromagnetic fields were used to heat and cure the epoxy-CNT sample; such heating techniques are valuable in a number of epoxy processing technologies. G′, G″, and complex viscosities of RF heated samples were measured to monitor RF-aided curing. This allows us to monitor the curing kinetics inside samples being heated by RF fields; the data indicate that RF-aiding curing is faster than curing rates for samples undergoing curing inside a measurement device such as a rheometer or DSC, because the heat generated is immediate and volumetric.

Objective The core-shell chlorhexidine/amorphous calcium phosphate (CHX/ACP) nanoparticles were synthesized and used to modify the dental resin composite, aiming to improve its remineralized and antibacterial properties. Methods The core-shell CHX/ACP nanoparticles were synthesized by vesicle-templating technology and characterized, and their sustained release and antibacterial properties were also evaluated. Subsequently, the synthesized nanoparticles were incorporated into the dental resin composite at 1 wt.%, 5 wt.% or 10 wt.% to obtain different experimental groups. The physical properties, including curing depth, double bond conversion rate, water absorption and solubility, the sustained-release effects, and mechanical properties of the modified resin composite were evaluated. The remineralization ability was also measured by SEM. The antibacterial experiment of the modified resin composite with fresh preparation or aging in water for 28 days was carried out by a plate count method. Results The physical and chemical characterizations showed that the synthesized nanoparticles presented a core-shell structure, and their diameter was about 98.5 nm. The shell was composed of ACP with the core full of CHX. These nanoparticles had a release effect on calcium, phosphate ions, and CHX. The nanoparticles could effectively inhibit the growth of S. mutan at a lower concentration (≥50 μg/mL). The curing depth, the double bond conversion, the water absorption, the solubility, the flexural strength, the flexural modulus, and the compressive strength of the modified resin composite were 3.86-4.88 mm, 62.32-73.61%, 1.47-2.84%, 0.21-0.48%, 45.83-109.46 MPa, 2.57-4.91 GPa, and 66.43-160.38 MPa, respectively. The modified resin composite containing 5 wt.% and above CHX/ACP nanoparticles could effectively inhibit the growth of S. mutans regardless of aging in water, with immediate and aging antibacterial rate of more than 92%. In addition, the modified resin composite had a certain remineralization property in the SBF solution verified by SEM. Significance The core-shell CHX/ACP nanoparticles were successfully prepared and used to modify the resin composite. The modified dental resin composite with 5 wt.% CHX/ACP nanoparticles had excellent mechanical, antibacterial, and remineralization properties. It is expected to be an ideal restorative filling material for clinical application.

Due to high absorbance of UV light and low solid loading, the stereolithography-based additive manufacturing of gray-colored and dense Si3N4 ceramic is of significant difficulty and challenge. The effects of geometric properties of ceramic powders on the curing performance were investigated by studying the absorption difference of the Si3N4 ceramic particles with different colors and particle sizes and ultraviolet light. The results show that the transmission of ultraviolet light and curing performance of the darker Si3N4 ceramic slurry are much poor. Under the same particle size, the Si3N4 ceramic slurry using lighter particles presents the smaller scattering coefficient. The scattering coefficient (∼202) of the gray powder with ∼0.8 μm average particle size is the smallest. Under the same color, the larger the particle size, the smaller the scattering coefficient. The smallest scattering coefficient of the white powder with ∼2.0 μm average particle size is ∼110.

Sodium silicate based ceramic coatings were prepared on the surface of carbon fiber reinforced epoxy resin matrix composite. The coatings were obtained by curing the mixture of silicate adhesive, SiO2 or Na2SiF6 as curing agent, and YSZ and Al2O3 as filler. The effects of adhesive modulus, curing agent, curing temperature and time on curing behavior of the coatings were investigated. The results indicated that the coating obtained from 2.7 modulus of silicate adhesive was dense, cohesiveness, uniform and continuous. As curing agent, SiO2 could promote curing better than Na2SiF6, achieving complete curing of the coating. And the coating containing SiO2 as curing agent was dense, flat and well adhered to the substrate. The curing behavior of coatings was significantly affected by curing temperature and time. The coatings could be cured completely with the increase of curing temperature. The best curing result was obtained at 100 °C curing temperature. Also the experimental results showed that the characteristics of coatings were improved to a certain extent by prolonging the curing time.

Ultra-high performance fibre reinforced concrete (UHPFRC) specimens were cast and cured at temperatures of 10, 20, 30, and 90 °C for periods of up to 360 days to investigate the long-term strength development. The influence of the three lower curing temperatures on the compressive and flexural tensile strengths and behaviour of UHPFRC was studied and compared to the results of 90 °C cured specimens. The results indicated compressive and flexural tensile strengths development at an early age were highly dependent on the curing temperature. The 90 °C cured specimens reached maximum compressive and flexural strengths within 7 days of casting. Specimens from the lower curing temperatures reached feasible striking compressive strengths (greater than 45 MPa) within 3 days of casting and achieved similar strengths to the 90 °C specimens after 90 days. Furthermore, various models such as the Vipulanandan model are developed to predict and correlate various mechanical properties of UHPFRC for any curing temperature, age and steel fibre content.

Objectives The aim of this in vitro study was to incorporate two anti-caries agents, Apigenin and tt-Farnesol, to resin composite and resin cement to reduce the virulence of Streptococcus mutans around dental restorations. Methods Apigenin (Api, 5 mM) and tt-Farnesol (Far, 5 mM) were added alone, together, and combined with fluoride (F). Biofilm of S. mutans was grown on composite discs, and the dry-weight, bacterial viability, and the polysaccharides (alkali-soluble, intracellular and water-soluble) were quantified. CLSM images of the S. mutans biofilm were obtained after three years of water-storage. The effect of the additions on the physicochemical properties and the composite colorimetric parameters were also analyzed. Results The additions did not affect bacterial viability. Api alone and combined with Far or combined with Far and F decreased the bacterial dry-weight, alkali-soluble and intracellular polysaccharides. After three years, the composites containing the additions presented a greater EPS matrix on the top of biofilm. Statistical difference was obtained for the degree of conversion; however, the maximum polymerization rate and curing kinetics were unaffected by the additions. No difference was observed for the water-soluble polysaccharides, flexural strength, and elastic modulus. Api increased the yellowness of the composites. Significance Api, alone and combined, reduced the expression of virulence of S. mutans without jeopardizing the physicochemical properties of the composites.

Reactive Powder Concrete is a type of ultra-high-performance concrete. Improvement of microstructure, elimination of coarse aggregate, particle packing, and toughness enhancement are the main principles of RPC development. To achieve these principles, RPC is characterized by the inclusion of high cement content and pozzolanic materials that make in the other hand its production highly cost and non-environmentally friendly. This work reviewed the principals of developing RPC, the constituent materials, curing techniques and the constituent percentages that affect the compressive strength. The improvement of concrete microstructure, particle packing and toughness properties of RPC are briefly outlined along with the incorporated constituent materials. Curing techniques and the mixture design of RPC are also clearly highlighted. In this study, the impact of using different percentages of the constituent materials of RPC and their available alternatives on compressive strength under different curing regimes are presented. It was showed that curing of RPC considered to be very important aspect in its development as it significantly affects the reactivity of its constituent. It was noticed that applying autoclave curing and using low cement dosage can achieve higher compressive strength results than applying steam curing. It was concluded also that the enhancement percentage in compressive strength can reaches 33% when using fly ash with 40% cement replacement under autoclave curing. It was observed that the enhancement percentage in compressive strength can reaches 45% when using rice husk ash with 30% silica fume replacement under steam curing Volumetric changes are considered the main problematic properties that prevent the wide use of RPC. Verifications are required to clarify mixing different quartz powder to quartz sand and its impact on RPC compressive strength by studying its microstructure.

To reproduce the multicycle precursor impregnation and pyrolysis (PIP) process used in fabricating ceramic matrix composites, three sub-models of PIP were first proposed in this paper: thermochemical, flow, and stress models. The main equations and parameters required were obtained through theoretical derivation and experiments, covering sixteen states of semi-products after every curing or pyrolysis. Then a convenient and efficient finite element (FE) model was explored to realize the three sub-models. Through the FE model, temperature or pyrolysis degree, porosity, matrix volume fraction, and residual stress can be gained expediently. Finally, the FE model was verified through an example of plates. The effects of process factors such as thickness, cycles, temperature-pressure system, and stacking were analysed and the results agreed well with actual conditions; suggestions for optimizing the process are highlighted to control residual stress and prevent possible defects during PIP.

Water-mixable oil (WMO) paints are a relatively new addition to the artists’ palette that have increased in usage and popularity over the past few decades. Understanding the composition and properties of WMO paint is essential for the artists who use them and for the people who work with WMO paintings—particularly art conservators. However, the formulations that make WMO paints possible remain undisclosed by paint manufacturers. In this research, fresh paint and naturally-aged paint-outs from Winsor & Newton’s Artisan WMO products were used to study the chemistry of WMO paints. The development of a unique high-pressure liquid chromatography mass spectrometry (HPLC-MS) method enabled the separation and detection of the non-ionic surfactants in the Artisan WMO paints. A data visualization strategy using contour plots was applied for interpretation of results, affording, for the first time, complete structural identifications of surfactant molecules in a WMO paint. The paints were found to contain a complex mixture of ethoxylated molecules, including polyoxyethylene (POE) fatty acid esters derived from the fatty acid mixture of linseed oil. An exudate that formed from the cured paints was also analyzed. More-saturated fatty acid esters, POE oleate and POE stearate, were detected; however, more-reactive POE fatty acid esters were found absent, providing insight relating to the stability of surfactants in the Artisan WMO paints as well as potential curing reactions. HPLC-MS studies were contextualized with physical observations and surface measurements that were performed on the cured samples. Tacky surfaces observed on the cured paint films showed significantly higher surface gloss and surface hydrophilicity; these observations were quantified using glossimetry and droplet contact angle measurements. These results provide insight into the unique chemistry present in WMO paints and provide a basis for future studies for art conservators and conservation scientists working with this new media.