Curing Technique Research Articles

Utilization of Coal Fly ash and ultra fine additives in producing HPC: Influence on early strength, flexural parameters and microstructure

This study investigates the beneficial utilization of Coal Fly ash (Class F) in conjunction with certain ultra-fine additives rich in reactive calcium and silica to produce High Performance Concrete (HPC). High early strength, improvement in flexural parameters including flexural toughness and micro structure modifications are considered as key attributes of resulting HPC. Combinations of mineral admixtures are worked out for optimal quantities by limiting Ordinary Portland Cement (OPC) to 450 kg/m3 in concrete. Conventional method of concrete preparation is adopted to make the process of HPC production more realistic and site friendly without depending on high energy intensive High-speed mixers and special curing techniques. Compressive strength is tracked right after 14th hour of concrete casting and up to 56 days. Certain selected mixes are further tested for Flexure performance, Tensile strength, Shear strength, Water permeability and Micro structural characteristics. The results indicate the possibility of enhancing strength up to a highest of 32 MPa and 51 MPa for 14 h and 24 h of concrete casting respectively in case of optimum mixes. Combinations of selected mineral additives have resulted in Ultimate strength of greater than 100 MPa after 28 days of curing which has further improved to a maximum of 127 MPa as on 56th day. Flexural strength has shown a comparative improvement by 19–26% from reference with considerable improvement in Flexural toughness. For best performing mixes resistance to tensile stresses and shearing stresses is recorded to be enhanced by 29% and 27% respectively. Concrete compactness is analysed by measuring resistance to water ingress under pressure along with Microscopic studies to understand modifications in the concrete microstructure.

Investigating the effect of polypropylene fibre on mortar mechanical properties with the aid of microwave curing

In recent times, there has been increased interest in using various types of fibres in the cement-based materials industry. This work thus aims to investigate the possibility of improving the mechanical properties of mortar samples by using available and cheap polypropylene fibre with the aid of a microwave curing technique. For this purpose, 5×5×5 cm cubes of mortar containing different percentages and lengths of polypropylene fibres were cast and then subjected to various ranges of curing time under microwaves. Compressive strength, direct tensile strength, and density tests were conducted on reference mortar (specimens without fibres) and mortar reinforced with polypropylene fibre specimens at various ages (3, 7, and 28 days) of curing. The results showed a marginal decrease in the compressive strength against an increase in the direct tensile strength as fibre content increased. All mixes showed acceptable values for density against the reference mixes.

Dielectric elastomer film with anisotropic actuation deformation on film plane

ABSTRACTA new dielectric elastomer (DE) film, which was able to show anisotropic large plane deformation actuated by an external electric field, was designed and synthesized. Specifically, an asymmetric di‐vinyl monomer cyclohex‐3‐enylmethyl acrylate (CEA) was incorporated into the middle block of poly(styrene‐b‐butyl acrylate‐b‐styrene) as potential crosslinking points. By widely used UV curing technique through a mask, the DE films could be locally hardened any area one selected. This could break the symmetry of the actuation deformation on the DE film plane, maximizing the deformation in a given direction while the actuation area strain remained unchanged. The actuation strainy/strainx reached 2.3, strain in x direction was 10.3% while in y direction was 23%, when the DE film of S(BA‐ran‐CEA)S with 2.5 mol % CEA incorporated was locally hardened in the form of soft and hard belt of 1 mm width alternatively along y direction. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48795.

Analysis of X ray diffraction spectra of cholesteryl acrylate-Indium Tin Oxide nanoparticle composites

Composites of cholesteryl acrylate with Indiun Tin Oxide (ITO) nanoparticle was made by UV curing technique at various the concentration of ITO nanoparticles. In this research using variation concentration of ITO nanoparticles. Polymer Cho-ITO nanoparticles have succeeded in becoming a composite. Pattern of X Ray Diffraction of Cholesteryl acrylate-Indium Tin Oxide nanoparticle (Cho-ITO) at ITO 10% w/w showed peak for Cholesteryl acrylate in 2θ at 2,6782°; 5,2275°; dan 15,8050° with value of dspacing (001) was 32,96 Å. For ITO in 2θ at 30,6244°; 35,5105°; 45,6814°; 51,0400°; dan 60,6473°. therefore pattern of XRD of Cho-ITO at ITO 20% w/w showed peak for cholesteryl acrylate in 2θ at 2,6372°; 5,2022°; dan 15,7867° that value of d spacing lattice (001) is 40,09 Å. For ITO in 2θ at 30,5685°; 35,4428°; 41,8550°; 50,9846°; 60,6252°. increasing value of d spacing for (001), that d spacing for cholesteryl acrylate 32,60 Å when added was by ITO 10% w/w dspacing increase untuil 32,96 Å. When added ITO 20% w/w value of d spacing until 40,09 Å.

Utilization of CO2 curing to enhance the properties of recycled aggregate and prepared concrete: A review

In recent years, the CO2 curing technique has been developed to enhance the properties of recycled aggregate (RA) and recycled aggregate concrete (RAC), materials that can absorb the CO2 gas and are more sustainable for the construction industry. A body of literature on the CO2 curing of RA and RAC is currently available, but a systematic review is lacking. Therefore, this paper reviewed the published literatures on the use of CO2 curing to enhance the properties of the RA and prepared RAC. The studies on CO2 curing technology, the properties of carbonated recycled aggregate (CRA), and the micro-properties, workability, mechanical properties and durability performance of concrete with CRA are respectively reviewed. The results showed that the RA properties, CO2 concentration and pressure, relative humidity and curing time all had a significant impact on the properties of CRA. Carbonation treatment improved the pore structure of RA and reduced its porosity, and the workability, mechanical properties and durability performance of prepared RAC were also improved. In addition, an outlook on the CO2 curing of RA and prepared concrete was presented, and we expected that this work may inform further investigation of the use of CO2 curing to enhance the properties of concrete and cement products.

Fast-cured UV-LED polymer materials filled with high mineral contents as wear-resistant, antibacterial coatings

Development of ultraviolet (UV) curing technique has greatly expanded the preparation and application of polymer composite coatings due to its unique characteristics of high efficiency curing and controllable operation. However, the inevitable hazards of high pressure mercury lamps, as well as difficulty resulting from large amount of heat release when coating products, greatly limit the practical application and development of such curing coatings. Herein, a series of novel controllable, fast-cured coatings filled with high mineral contents were successfully designed and synthesized based on progressive ultraviolet light emitting diode (UV-LED) technology with ultra-low energy consumption. Due to the addition of a large number of opaque mineral particles, a new polymerization mechanism for the system was proposed and verified. Inorganic particle fillers (μm-level) can produce various degrees of reflective or refractive points, thus effectively reducing the barrier effect of the filling particles and realizing a much deeper solidification. Silver nanoparticles (AgNPs) were then combined with this composite material to fabricate a long-term antibacterial interior wall base-coating without interference with the curing effects. More importantly, the various effects of reactants of polymeric composite coatings with high inorganic mineral content for such UV-LED curing systems (365 nm) were brought to as comprehensive a conclusion as possible. This coating remained stable over a 15-week period against bacteria with the bactericidal coefficient of approximately 99.5% for E. coli and about 97% for S. aureus. We believe that proposed applicable polymerization mechanism will greatly enrich the current UV polymerization system, especially for polymer composite material with high mineral contents, and our designed wear resistance, high-hardness, and long-term antibacterial coating will also have great application prospects in many practical fields.

Preparation of acrylic pressure-sensitive adhesives by UV/UV step curing as a way of lifting the limitations of conventional dual curing techniques

Pressure-sensitive adhesives (PSAs) and UV-curable acrylic systems are widely utilized in different industries, with particular attention currently directed at their use in the production of re-useable modules for smart devices. Herein, we developed a two-step UV/UV curing technique to overcome the limitations of dual curing methods conventionally used for PSA preparation and characterized the thus obtained acrylic adhesives by a range of techniques to determine the uncured marginal portion of the pre-polymer, viscoelastic properties, and adhesive properties (peel and tack). Insufficient primary curing resulted in marked physical property deterioration, while the expression of secondary curing was weak when excessive irradiation energy was supplied. Thus, it was concluded that the physical properties of acrylic PSAs could be controlled by adjustment of primary curing energy.

Facile strategy and mechanism of greatly toughening epoxy resin using polyethersulfone through controlling phase separation with microwave‐assisted thermal curing technique

ABSTRACTToughening has been the essential issue for developing high‐performance thermosetting resins. Herein, starting from polyethersulfone (PES) and bisphenol A epoxy resin (EP), a facile strategy is developed to prepare tough resins through controlling phase structure with microwave‐assisted thermal curing. PES/EP resins cured with the assistance of microwave curing (m‐PES/EP) have two major differences compared with those using traditional heat curing (t‐PES/EP), one is high degree of phase separation, and the other is phase separation mechanism. Initial phase separation of all t‐PES/EP resins follows spinodal decomposition mechanism, while those of m‐PES/EP systems with 8 wt% and 18 wt% of PES follow nucleation and growth mechanism. These differences are derived from the fact that microwave curing has much faster phase separation rate and curing reaction rate than thermal curing owing to the higher thermal effect. Differences in phase structure bring different macro performances, and m‐PES/EP systems have higher impact strengths, fracture toughnesses, and flexural strengths than t‐PES/EP resins. This investigation provides a facial and effective way of developing higher performance thermoplastic/thermosetting resin system through controlling phase structure. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48394.

Novel cement curing technique by using controlled release of carbon dioxide coupled with nanosilica

Nanotechnology has attracted a lot of interest in the modification of building materials involving nanoparticles. Among the nanoparticles available, the incorporation of nano-silica draws intense attention due to the similarity of its chemical composition with cement and its pozzolanic properties. In this work, the potential capability to utilise CO2 in improving cement composites properties through carbonation acceleration mechanism was explored. In this study, various type of nano silica was used as a CO2 carrier and incorporated into cement mortar design with different amount of carbonated silica loading, ranging from 0.55 wt% to 2.42 wt% and cured in water and ambient air condition. The aim of this study is to examine the effects on the compressive strength of nano-silica impregnated with CO2 and incorporated into cement mortar. From the results, it was found that at 1.89% silica loading, the hydrophilic silica mortar (HSAM) samples can achieve the highest compressive strength of 34.1 MPa at 7 days and 40.7 MPa at 28 days, with a percentage gain of +38.06% and +17.29% respectively as compared to blank samples. However, the incorporation of silica for more than 1.89 wt% resulted in a negative effect on the compressive strength gain of HSAM samples. By the incorporation of 2.42 wt%, the samples showed a significant drop in compressive strength of −21.46% at 7 days and −17.29% at 28 days. The results proved that nano-silica coupled with CO2 can accelerate curing of cement mortar by means of carbonation.

A Study of the Temperature Distribution in a Polymer-Composite Rod When Heat-Treated with Microwave Radiation

We propose a method for designing transversely illuminated traveling-wave microwave devices. Devices of this type produce a uniform 3D temperature distribution in a polymer-composite rod. We describe theoretical and experimental results from studies of the 3D temperature distribution in the rod, along with the advantages of microwave curing technology over traditional curing techniques for polymer composites.

Clinical Performance of Composite Using Direct and Indirect Technique

AIM: This study aimed to evaluate and compare clinical performance of composite in regard to colour, marginal staining, surface roughness and chipping in anterior teeth using direct and indirect technique. MATERIAL AND METHODS: 60 anterior teeth were selected for this study and were randomly divided into 2 groups. Facial reduction of 0.75-1 mm was done in both groups. In Group A (n=30), veneer preparation was done directly by incremental layering technique. In Group B (n=30), putty impression was taken, a cast was made and composite build up was performed on the cast. The prepared veneer was placed into visible light cure chamber for uniform curing. It was then loaded with the luting cement and gently seated on labial surface. Veneers were evaluated at baseline, 3, 6 months for colour stability, marginal staining, surface roughness and chipping according to modified USPHS criteria (Ryge’s criteria). Score of Alpha, Bravo and Charlie were assigned, and the results were statistically analysed using Chi square test. RESULT: No statistical difference was found in Group A and B at 0, 3, 6 months in all parameters. CONCLUSION: Clinical performance of direct and indirect technique for composite curing was found similar in the present study.

Application of a pressure-transform tumbling assisted curing technique for improving the tenderness of restructured pork chops

Boneless pork shoulder were injected with marinate and treated with one of the three following curing treatments: (1) injection without tumbling, (2) vacuum tumbling, or (3) pressure-transform tumbling. The effect of pressure-transform tumbling treatment on porcine tissue microstructure, protein denaturation, water-holding capacity and textural properties of restructured pork chops was investigated. Results showed that pressure-transform tumbling with gas composition of CO2: N2 = 1 : 1 resulted in favorable yield of 118.22% of restructured pork chops. Tenderness was improved by 39% and 25% compared to the control group that was injected but not tumbled, and the vacuum tumbled group, respectively. Myofibers remained well-organized an the diameter was reduced by pressure-transform tumbling. FT-IR results showed that pressure-transform tumbling can modify protein conformation by increasing the amount of ɑ-helical and ẞ -sheet structures, but did not alter the secondary structure of proteins. The method has potential to benefit both consumers and manufacturers, by including reduction in processing time, improvement in product quality, and potential cost savings.

Correlative roles of silica as a blowing aid and a Pb(II) adsorbent for natural rubber composite foams

The present work aimed to study two correlative behaviors of rubber composites and rubber composite foams filled with SiO2 that affect the cure characteristics and the adsorption capacity of Pb(II) from an aqueous solution; these behaviors have never been reported before as a conjoint analysis. A two-stage curing technique was used to vulcanize the rubber samples. The effect of NaHCO3 as well as SiO2 content on the cure characteristics, physical properties, and Pb(II) adsorptivity of the rubber compounds was examined. The addition of SiO2 had a more pronounced effect on the cure characteristics and crosslinking density of rubber compounds than that of NaHCO3. Changes in t90, CRI, and crosslinking density as a function of SiO2 loading played an important role in the foaming behavior of the rubber samples. The SiO2 addition in the rubber compounds enhanced the blowing efficiency, which facilitated the adsorption of Pb(II). The adsorption mechanism for the samples containing SiO2 was mainly based on electrostatic attraction, as evidenced by a shifting wavenumber for the silanol functional group and as observed in FTIR results. The experimental results showed promising potential for the utilization of rubber filled with SiO2 for Pb(II) removal beyond its service lifetime.

NIR LEDs and NIR lasers as feasible alternatives to replace oven processes for treatment of thermal-responsive coatings

Near-infrared (NIR) laser sources (800–1000 nm) can potentially reduce the processing time for curing by a fast heating and incorporation of NIR absorbers into the coating. The latter converts NIR laser light absorbed into thermal energy. This curing technique was successfully applied to one-component thermoset coatings based on blocked polyisocyanate/hydroxy-polyester and melamine formaldehyde/hydroxy-acrylate resins with heptamethine cyanines as near-infrared absorbing material. The laser curing was additionally compared with LED sources. In general, the curing time significantly decreases in comparison with traditional heat sources. Furthermore, the photopolymerization of acrylates or epoxides can be induced simultaneously by adding suitable initiators due to photochemical generation of radicals and cations. Curing of the thermoset resin system and the photopolymerization process created interpenetrating networks. Principally, the techniques reported based on photonic NIR sources may help to substitute oven techniques where thermal activation of curing reactions is typically induced by oven or heating with infrared radiators for coating applications.

Photo-crosslinked polymer networks based on graphene-functionalized soybean oil and their properties

The increasing importance of products which are sustainable and eco-friendly drives the scientific community to develop materials derived from bio-based and agricultural feedstock. With the same motivation, we have developed acrylated epoxidized soybean oil (AESO)-based composite with functionalized graphene or graphene oxide using UV curing technique. Graphene and graphene oxide were chemically functionalized with 3-methacryloxypropyltrimethoxysilane and 4,4′-diphenylmethanediisocyanate/hydroxyl ethyl acrylate, respectively, and used as filler in the AESO matrix. Infra-red and X-ray photoelectron spectroscopy confirmed the functionalization of graphene and graphene oxide along with formation of polymer network in composite. Functionalization of graphene and graphene oxide was found to be effective in enhancing homogeneous dispersion into the polymer matrix, which ultimately improved mechanical properties of base polymer (~48% increase in tensile strength with 0.02% addition of functionalized graphene). On the other hand, AESO composite with graphene and graphene oxide without functionalization exhibited lower tensile strengths. The functionalization of graphene and graphene oxide and incorporation of the same in the polymer network using UV curing technique provides a realistic and effective methodology to obtain high performance composite for several applications.

Effect of Different Light Curing Intensities on Cavity Wall Adaptation of Nanofilled Resin Composite Using Transtooth Curing Technique: An In-vitro Study

Aim: to evaluate the cavity wall adaptation of nanofilled resin composite cured with different LED light intensities and with different thickness of buccal wall after thermocycling using environmental scanning electron microscope.Materials and methods: the materials used for this study was nanofilled resin composite material (Filtex Z350XT, 3M, ESPE) shade A3with its corresponding bonding system (single bond universal, 3M, ESPE). A total of 10 sound extracted human maxillary premolar teeth were used in this study. The teeth were divided into 2 main groups of 5 teeth each according to curing light intensities; either standard LED curing mode (800 mW/cm2) for 30 sec or high intensity LED curing mode (1400 mW/cm2) for 10 sec. In each tooth, 2 cavity preparations were performed; moderate cavity preparation width (1/3 intercuspal distance) in the mesial aspect of each tooth and wide cavity preparation (1/2 intercuspal distance) in the distal aspect. All specimens were light cured using transtooth curing technique from the buccal and lingual surfaces. All specimens were subjected to thermocycling protocol. All specimens were subjected to the quantitative margin analysis, examined using environmental scanning electron microscope (ESEM). Two ways analysis of variance (ANOVA) test was used to study the interaction of both variables. The significance level was set at p < 0.05. Results: Two ways ANOVA test revealed that the interaction of both variables was statistically significant (p=0.00). Comparing both intensities, a higher mean value was recorded in high intensity (6.57±1.29), with a significant difference (p=0.00). Comparing 1/2ICD and 1/3ICD, a higher mean value was recorded in 1/3ICD (6.52±2.19), with a significant difference (p=0.00). Conclusions: The wall thickness greatly affects the cavity wall adaptation in transtooth curing technique.Applying High intensity irradiation technique compromise margin quality and marginal seal of resin composite restoration.

A rapid, facile and practical fabrication of robust PDMS@starch coatings for oil-water separation

Abstract PDMS has been widely used to develop oil-water separation materials in the past few decades owing to its strong adhesion, low-surface-energy, and durability. However, traditional curing methods for PDMS suffer from time-consuming and space-limiting, therefore, a rapid and facile fabrication of PDMS based materials should be imperative to be developed for scaled-up production. Inspired by this, we employed PDMS and starch to prepare PDMS@starch composite coatings and hot air gun as a time-saving and cost-effective curing technique was applied. The coatings were effectively used to separate emulsions and oil-water mixtures, as well as exhibited excellent resistance to various water solutions owing to its high hydrophobicity. Moreover, the chemical and mechanical durability of the coatings further show a wide spectrum of envisagement in industrial application of special wetting materials.

A Comparative Study of Light Transmission by Various Dental Restorative Materials and the Tooth Structure.

Light transmission through dental materials and tooth structure has direct clinical implication on such factors as selecting an appropriate curing technique during a restorative process.

Microwave Curing Effect on Internal Sulphate Damage in Nano Alumina Reinforced White Cement

In this study, microstructural investigation was carried out to analyse the internal sulphate damage in the nano-Al2O3 (nAl) reinforced white cement pastes. As white cement is generally used in the production of architectural concrete, 52.5 R type white cement was preferred in the scope of the study. Nano Al2O3 was substituted into the cement paste at 0% and 5% ratios. Three different methods were used for microwave curing. Different microwave curing techniques were performed as 120 minutes of 100 Watt application, 75 minutes of 100 Watt-30 minutes of 150 Watt-15 minutes of 200 Watt application, and 90 minutes of 100 Watt-15 minutes of 150 Watt-15 minutes of 200 Watt. In order to accelerate the formation of DEF damage, Na2SO4 was added to the cement paste at 2%, and 5% ratios. Three different microwave curing methods were used to investigate the occurrence of DEF damage in nano Al2O3 reinforced concrete concretes. In the pastes produced for this purpose, dense ettringite structure was observed. In cement pastes without nAl, the ettringite structure had a low S / Ca ratio (<0.20). More ettringite was formed in methods 2 and 3 used as microwave curing. The heat treatment applied in the microwave curing was the same as in other thermal curing applications, and in case the inner sulphate source was present it led to the formation of ettringite. This process became more evident in the presence of NA by increasing power application

Fully packaged paper heater systems with remote and selective ignition capabilities for nanoscale energetic materials

Development of low-voltage driven multifunctional thermal igniters for nanoscale energetic materials (nEMs) is important for extending the application of nEMs to various thermal engineering fields. In this study, highly flexible heater chips capable of generating a sufficient amount of heat to ignite nEMs at a low voltage are demonstrated by incorporating a patterned aluminum-doped paper (AP) with polymeric substrates. A combination of automatic paper cutting and single-step ultraviolet polymer curing techniques helps in the fabrication of various designs of flexible AP heater chips in a simple and low-cost manner. Based on the AP heater chips, three models of flexible thermal igniters are designed to develop new functions such as selective ignition and sequential ignition in a single chip and successfully operated at low voltages. Two types of compact ignition systems are fabricated by fully integrating the arrayed AP igniters, circuit modules, and portable batteries in a three-dimensional printed single package and on a flexible circuit board. The systems are successfully demonstrated to ignite nEMs wirelessly and selectively with a smartphone.