Improvement In Various Properties Research Articles

Two-step modification strategy enhances carbon fiber/old corrugated container fiber flexible conductive film

Carbon fiber (CF) possesses inherent properties of low density, high strength, and environmental stability. Its high aspect ratio and knittability enable the formation of flexible conductive networks. Old corrugated container (OCC) is rich in cellulose and hemicellulose, rendering them flexible and exhibiting a low coefficient of thermal expansion. In this paper, CF/OCC/PVA flexible conductive films were prepared using polyvinyl alcohol (PVA) as the matrix, CF as the conductive filler and OCC as the flexible support material. Firstly, the coupling agent was grafted on the surface of CF to enhance their surface activity, improve the dispersion of CF in solution and the chemical bonding of CF to the matrix. Subsequently, sizing nanoparticles were applied to increase the roughness of the CF surface. This served to increase the volume of the conductive network and enhance the mechanical interlocking between CF and PVA. The results show that the two-step combined modification strategy have a significant positive impact on the interfacial chemical activity, contact angle, and roughness of CF. Moreover, it leads to notable improvements in various properties of the conductive film materials. This finding is relevant for the preparation of CF reinforced other matrix materials as well as for expanding the special properties and application value of CF conductive thin film materials.

Enhanced thermal conductivity and mechanical property via improvement of hydrogen bonding between hexagonal boron nitride and aramid copolymer

This study focuses on enhancing thermal properties of aramid copolymer nanocomposites by integrating hexagonal boron nitride (hBN). Pristine hBN (P-hBN) is first subjected to oxidative heat treatment at 900 °C, producing thermally treated hBN (T-hBN), which significantly improves thermal conductivity while also increasing the tensile properties of composites. The study further explores the effect of different diamine co-monomers, 3,4′- and 4,4′-oxydianiline (ODA), on the nanocomposite properties. Both types of ODA-based composite films show improvement in various properties containing T-hBN. With 20 wt% of T-hBN, the 3,4′-ODA and 4,4′-ODA-based films exhibit 33.2 % and 290 % increase in tensile strength and thermal conductivity, respectively. The functionalization of hBN by heat treatment enhances the interaction between aramid copolymer and hBN and prevents the aggregation of hBN. The rough interface was shown in fractured images for films with T-hBN, suggesting that the composite films with T-hBN withstand higher external forces. In addition, it was observed that T-hBN exhibits better dispersion compared to P-hBN. This is supported by molecular dynamics (MD) simulation, and, in addition, it also provides the underlying mechanism for the property differences between both types of co-monomers.

Study on the modification of HMX/TPU composites with metal‐phenolic network

AbstractRapid and facile self‐assembly coatings play a crucial role in surface functionalization of materials. In this study, a safe, fast, and environmentally friendly method is proposed to form a metal‐phenolic network (MPN) through the assembly of gallic acid (GA) and iron ions (Fe3+), which is used for the in situ polymerization coating of 1,3,5,7‐tetranitro‐1,3,5‐7‐tetrazacyclooctane (HMX). The surface of the modified HMX crystals become visibly roughened. Thermoplastic polyurethane (TPU) was coated on the surface of modified HMX by water suspension method to form HMX@MPN@TPU double‐layer core‐shell energetic composite material. Compared with the raw material HMX, the β‐δ phase transition temperature of the double‐layer core‐shell structure composite increased by 12.36°C, the impact sensitivity and friction sensitivity decreased, and the compressive strength increased by 38%, which effectively improved its mechanical properties.Highlights It has been demonstrated that metal‐phenolic networks can self‐assemble on the surface of crystals. A water suspension method was employed to prepare energetic material powder into a polymer‐bonded explosive (PBX). The modified PBX showed significant improvements in various properties, indicating that metal‐phenolic networks can serve as excellent modifying materials.

Early mechanical performance of glass fibre-reinforced manufactured sand concrete

The use of manufactured sand as fine aggregate in concrete has been widely adopted in engineering to alleviate the shortage of natural river sand supply. However, there are many factors that affect the properties of manufactured sand concrete (such as the early shrinkage cracking phenomenon is more common than that in natural-sand concrete). In this study, glass fibre was added to manufactured sand concrete to improve its mechanical properties and determine the optimum content of manufactured sand and glass fibre. This study investigated the effects of the replacement rate of manufactured sand and glass fibre dosage on the compressive strength, flexural strength, and shrinkage of concrete. The results show that the optimal replacement ratio of the manufactured sand and ideal glass fibre dosage ranged 60%–80 % and 0.2%–0.3 %, respectively. Concrete exhibited significant improvements in various properties, including 22.97 %, 42.6 %, 7.1 %, and 34.7 % increase in the maximum compressive strength, peak strain, elastic modulus, and flexural strength, respectively. Concrete shrinkage was reduced by 16.1 %. Moreover, a reliable compressive constitutive model for concrete was established, demonstrating high accuracy in predicting the stress-strain relationship of glass-fibre concrete with manufactured sand. The combined utilization of manufactured sand and glass fibres proved to be effective in enhancing the mechanical strength and crack resistance of concrete.

INVESTIGATION OF CRYOGENIC TREATED DRILL BIT

We look into brief introduction of cryogenic treatment. Our focus throughout the report is more on cryogenic treatment of tool steel and high speed steel. In metal forming industry tools are exposed to very complex and rough surface conditions, which are the result of different effects (mechanical, thermal and chemical) and thus require well defined mechanical properties. Different approaches are followed to increase the surface properties of tool steels. The surface hardening treatments of steel has shown significant improvement of various properties including wear and fatigue resistance. Cryogenic treatment is yet another approach acknowledged by some to extend the tool life of many cutting tools. We will describe the complete procedure and investigate the effects on the metallurgical changes in the tool steel. However real mechanisms behind the better performance of tools are still in doubt. Studies in the given references on cryogenically treated tool steel shows micro structural changes in material that can influence the tool life. However little is gained from the experimental results showing involvement of carbide precipitations. Cryogenic treatments of carbides has yet to be extensively studied. In this paper drill bits are treated with cryogenic method and to predict the hardness, wear strength and other results are analysing.

Synergistic effect of PTB emulsion, CaCO3 whisker and Nano-SiO2 on the properties of cement-based materials

With the rapid development of the civil engineering industry, performance requirements for building materials are also increasing rapidly. It is particularly critical to improve the performance of cement-based materials using admixtures. In this study, the synergistic effect of PTB (COMPAKTUNA.PRO) emulsion, calcium carbonate whisker (CaCO3 whisker) and nano-silica (nano-SiO2) on material properties was analyzed. Macroscopic properties such as rheology, compressive strength, flexural strength, durability, bond strength, and permeable pressure were tested. Microstructures were analyzed using the porosity, hydration heat, X-ray diffraction, and scanning electron microscopy methods. The results revealed that the PTB emulsion, CaCO3 whiskers, and nano-SiO2 increased the plastic viscosity and yield stress of the cement. When the nano-SiO2 content was high, the fluidity of the slurry decreased significantly. Overall, PTB emulsion, CaCO3 whisker and nano-SiO2 can improve the strength, durability, bond strength, and permeability of composite materials. PTB emulsions can prolong the hydration process, resulting in low early strength and reduced compressive strength. However, they play a key role in terms of improving durability, bond strength, and permeability pressure. CaCO3 whiskers yield slight improvements in various properties. Nano-SiO2 can promote the hydration rate and hydration effect, thereby improving the strength, compactness, and properties of composite materials. Performance can be optimized by leveraging these synergistic effects and each material has its own unique advantages and limitations. In engineering applications, critical properties should be considered when selecting appropriate admixture contents. This study aimed to improve various properties and to develop materials that are suitable for the complex environment of underground engineering.

Physico‐mechanical and thermo‐mechanical analysis of zinc borate filled glass fiber reinforced polymer composites

AbstractThe potential benefits of using zinc borate powder as filler material in the production of glass fiber‐reinforced composites were explored in this study. The epoxy matrix was filled with zinc borate powder at 5%, 10%, and 15% by weight, as part of the hand lay‐up approach followed by a compression molding process. Ultrasonication was used to mix the epoxy resin with zinc borate fillers. Both the elemental composition and morphological characteristics were studied using a scanning electron microscope and energy‐dispersive X‐ray analysis. The composite's density, tensile behavior, flexural behavior, impact resistance, and hardness were all measured experimentally. The potential incorporation of zinc borate particles resulted in a modest reduction in the void contents, in addition to enhancing the interfacial bonding in glass fiber‐reinforced composites as also a significant improvement in both the mechanical and thermal properties of the hybrid composites produced. The 10 wt.% zinc borate‐ filled glass fiber‐reinforced composites exhibited a significant rise in both ultimate tensile strength (227 MPa), ultimate compressive strength (239 MPa), and ultimate flexural strength (406 MPa) compared to the unfilled counterpart. The performance of the laminated composites was greatly improved by adding zinc borate powder particles to the matrix.Highlights In the present work glass fiber was reinforced with zinc borate to explore the morphological, mechanical, and thermal properties. Ultrasonication was used to mix the epoxy resin and zinc borate fillers and the composites were manufactured by compression molding process. The addition of zinc borate resulted in an increase in tensile strength, flexural strength, and compressive strength. The thermal stability of the composites was increased by the addition of zinc borate to the glass matrix. The good bonding between the matrix and fiber resulted in improvements in various properties.

Xanthoceras sorbifolia Husk Extract Incorporation for the Improvement in Physical and Antioxidant Properties of Soy Protein Isolate Films.

With the increasing awareness of ecological and environmental protection, the research on eco-friendly materials has experienced a considerable increase. The objective of our study was to explore a novel soy protein isolate (SPI) film functionalized with antioxidants extracted from Xanthoceras sorbifolia husk (XSHE) as bio-based active packaging films. The films were evaluated in light of their structure, physical machinery, and antioxidant performance using advanced characterization techniques. The FTIR and microscopy results revealed the hydrogen-bond interaction between the SPI and XSHE and their good compatibility, which contributed to the improvement in various properties of the composite films, such as tensile strength (TS), UV blocking, and the water barrier property. As the XSHE content increased to 5%, the TS of the films dramatically increased up to 7.37 MPa with 47.7% and the water vapor permeability decreased to 1.13 × 10-10 g m m-2 s-1 Pa-1 with 22.1%. Meanwhile, the introduction of XSHE caused further improvement in the antioxidant capacity of films, and the release of active agents from films was faster and higher in 10% ethanol than it was in a 50% ethanol food simulant. Overall, SPI-based films functionalized with XSHE demonstrated promising potential applications in food packaging.

In vitro tribological behavior and corrosion resistance of SiO2/TiO2/ZrO2 coatings formed on the tantalum substrate using plasma electrolytic oxidation for orthopedic implant applications

Tantalum (Ta) is widely used in orthopedic and dental implants due to its remarkable stability, biocompatibility, and mechanical properties. However, in physiological environments, even stable and noble metals can form harmful complexes. This study aimed to enhance the surface mechanical, topographical features, and biocompatibility of Ta by applying a coating of ZrO2, SiO2, and TiO2 nanoparticles using the plasma electrolytic oxidation (PEO) technique. A composite layer was formed on the Ta substrate through PEO at a constant voltage of 500 V with duty cycles of 20% and 40% for 10 min. Evaluation of the coated samples revealed significant improvements in various properties. The nanohardness of the Ta surface at a 40% duty cycle was found to be 6.7 times higher than that of the uncoated Ta sample. The stiffness of the coated Ta at a 40% duty cycle was 2.4 times higher than the uncoated Ta. However, the surface roughness of the 40% duty cycle-coated Ta was higher compared to other samples. The coated Ta at a 40% duty cycle exhibited a higher surface roughness and wettability, which can potentially enhance cell adhesion and proliferation. The surface morphology properties were analyzed using FESEM, which revealed the presence of a composite layer composed of ZrO2, SiO2, and TiO2 nanoparticles on the Ta substrate. Additionally, the contact angle test demonstrated that the coated Ta samples had decreased contact angles from 86° to 9°, indicating increased hydrophilicity compared to the uncoated Ta. Corrosion resistance was assessed through potentiodynamic polarization test and electrochemical impedance spectroscopy. The corrosion resistance of the coated Ta at 20% and 40% duty cycles increased from 0.78 × 103 Ω cm2 to 8.85 × 103 and 9.4 × 103 Ω cm2, respectively, indicating the formation of a nobler layer on the Ta surface. Biocompatibility studies using MG-63 cells showed enhanced cell adhesion and viability on the surface of the 40% duty cycle-coated Ta, attributed to its higher surface roughness and hydrophilicity. The cell viability for the coated samples (Ta-20 and Ta-40) after 3 days of culture was 95% and 98%, respectively, compared to 89% for the uncoated Ta sample. These findings demonstrate that the SiO2/TiO2/ZrO2 ceramic coatings significantly improve the mechanical properties, corrosion resistance, surface morphology, and hydrophilicity of Ta implants. Such enhancements have the potential to extend the lifetime of Ta implants in dental and orthopedic applications.

Polydopamine modified polymeric carbon nitride nanosheet based ABS nanocomposites for better thermal, frictional and mechanical performance

The synthesis and modification of polymeric carbon nitride nanosheets (NPCN) and their exploration toward enhanced thermal and mechanical properties of acrylonitrile butadiene styrene (ABS) nanocomposites are described. Polymeric carbon nitride was synthesized by the thermal treatment method and subsequently modified using polydopamine (PDA) through a simple chemical treatment. Both raw and modified fillers (NPCN and PDA@NPCN) were characterized using detailed spectroscopic analyses. The modified filler was then used to fabricate composites with an ABS polymer matrix, targeting the improvement of various properties of the resulting nanocomposites. Although NPCN has been used to modify various polymer matrices, NPCN modified with polydopamine via. non-covalent interactions has not been reported to date for modifying the properties of polymers. Here, the non-covalent interaction developed via a promising eco-friendly bioinspired method has a positive impact on improving the performances of the ABS matrix. The major objective of the current study is to investigate the interfacial interaction between polydopamine modified polymeric carbon nitride nanosheets and the ABS matrix, and to determine its influence on the thermal, frictional and mechanical performance of the developed nanocomposite. Preliminary analyses indicated the successful incorporation and interaction between PDA@NPCN and ABS. The mechanical studies of the nanocomposites revealed that the tensile strength and frictional behavior improved up to 29 and 51%, respectively, with the lower addition of PDA@NPCN content. Pyrolysis-combustion flow calorimetric studies showed that NPCN had no negative effect on the flammability of ABS. This approach finds potential applications in enhancing the bearing nature of the polymer system without affecting its thermal stability and flammability.

Hot deformation behavior and microstructure of Ni-Cu rich Al-Si AA4032 alloy

The Al-Si alloy family is among the most widely used nonferrous alloys, in both cast and wrought products. The alloys have undergone a continuous progress toward improvement of various properties. The present research investigated the hot deformation behavior of AA4032 alloy, modified with addition of 3.5 %wt of Ni and 3%wt of Cu. The study was carried out using constitutive equations at the temperature range of 693–823 K (420–550 °C) alongside the strain rates of 0.001–1 s−1. The processing maps were determined by superimposing the instability maps on power dissipation maps. Moreover, the effect of extra copper and nickel on the microstructure and phase formation was studied via optical microscopy, SEM and TEM. The hot deformation activation energy of the Ni-Cu rich alloy is also calculated to be 338 KJ/mol (at ε = 0.1) which is notably higher than that of the self-diffusion of pure Al. It is found that the best hot working condition is the temperature range of 720–780 K with a strain rate of 0.001–0.03 s−1. The microstructure of the alloy at the calculated safe zone was uniform, while it showed cracking at the unsafe region of deformation parameters.

A review of recent advances on the properties of polypropylene - carbon nanotubes composites

Polypropylene (PP) has a wide range of engineering applications in automobile, biomedical, energy, machine parts, electronic packaging etc. However, PP lacks some desired engineering properties such as good thermal properties and mechanical strength. For instance, PP is known for its low melting temperature, high flammability and low heat resistance. This has resulted in continuous improvement in various properties of PP via modification of its matrix. One of the ways this has been achieved is by incorporation of foreign bodies in form of reinforcements in the PP matrix. The recent discovery of carbon nanotubes (CNTs) has further paved the ways for advancing the properties of PP via the development of PP-CNTs composites. Such composites have not only shown improved engineering properties but retain the lightweight and flexibility of PP. The advanced engineering properties recorded by various studies using PP-CNTs composites are due to the good properties of PP in conjunction with the excellent properties of CNTs such as high thermal conductivity, strength, electron mobility and formation of conductivity networks in the PP matrix. Although the development of PP-CNTs composites faces challenges of high agglomeration and incompatibility of CNTs in the matrix, the moves towards addressing the hurdles and achievements recorded so far are encouraging. Therefore, this review investigated the contribution of CNTs on various advanced engineering properties of PP-CNTs composites. Various results drawn from previously published literature within the decade were tabulated for future academic references and industrial purposes. Current hurdles faced by PP-CNTs composites, future prospect and their advanced engineering applications were discussed.

Enhancement of thermal shock and slag corrosion resistance of MgO–ZrO2 ceramics by doping CeO2

The purpose of this paper was to develop ceramics materials with high thermal shock resistance and corrosion resistance for preparing gas blowing components. In this paper, MgO-rich MgO–ZrO2 ceramics were obtained by using MgO powder and ZrO2 powder as starting materials and CeO2 as an additive. Changes in the properties in terms of thermal shock resistance, mechanical properties, and slag corrosion-resistance with chemical compositions were examined correlated to microstructure and phase changes. Especially, the effect of doping CeO2 on phase transition of zirconia in MgO-rich system was discussed. The results showed that doping amount of CeO2 significantly improved properties of MgO–ZrO2 ceramics. Especially when doping amount of CeO2 was 2 wt%, residual strength ratio was enhanced over 100% after thermal shock testing. In samples doped with CeO2, ZrO2 was stable in cubic or tetragonal form due to complete solution of CeO2, which was important reason for the improvement of various properties of MgO–ZrO2 ceramics.

Nanostructured AlCoCrCu0.5FeNi high entropy oxide (HEO) thin films fabricated using reactive magnetron sputtering

High entropy alloys (HEAs) are considered as advanced materials with excellent properties, such as superior oxidation and corrosion resistance, high hardness and hydrophobicity and excellent thermal stability. The fabrication of thin films of non-metallic compounds such as oxides and nitrides has demonstrated further improvements in various properties of these high entropy-based materials. In this study, AlCoCrCu0.5FeNi high entropy oxide (HEO) thin films were deposited by radio frequency (RF) reactive magnetron sputtering from a custom-made target using three different oxygen flow fractions (RN) of 12.5, 25 and 50%. The microstructure, composition and physical properties of the HEO films were measured using a wide range of characterization methods. X-ray diffraction (XRD) detected a phase transformation from FCC to spinel structure with an increase in RN from 12.5 to 25%, while a further increase in RN from 25 to 50% retained a weak spinel phase as confirmed by transmission electron microscopy (TEM) analysis. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measured a decrease in both the average agglomerated grain size from 88 to 30 nm and the surface roughness from 6.81 to 1.16 nm with the increase in oxygen fraction from 12.5 to 50%. The film deposited at the highest RN of 50%, had the highest oxygen concentration of 42.7% as determined by energy dispersive spectroscopy (EDS) and 38.4% as determined by X-ray photoelectron spectroscopy (XPS). XPS measurements also indicated a significant presence of surface protective oxides of Al2O3 and Cr2O3 for all the HEO thin films. The film deposited at RN of 25% achieved the highest hardness of 11 GPa, while the film deposited at RN of 50% displayed the highest water contact angle (WCA) of 111°.

Effect of Cereclor as Rejuvenator to Enhance the Aging Resistance of Reclaimed Asphalt Pavement Binder.

Asphalt is the most commonly used material for pavement construction around the world, and therefore, it is vital to acquaint a practice that restores the reclaimed asphalt pavement (RAP) binder properties to the required level of performance by adding proper rejuvenators. However, a rejuvenator may perform better in the early stages of its application but may not necessarily perform better in the long run. The aim of this study is to assess the rejuvenation effect on the aging resistance of RAP binder in long-life performance through applying artificial aging. In this study, base virgin binder of pen grade 60/70 and RAP binder rejuvenated with Cereclor were subjected to artificial aging to simulate the short- and long-term aging effects. Penetration, softening point, ductility, and viscosity; saturates, aromatics, resins, and asphaltene (SARA) fractionation; and Fourier-transform infrared (FTIR) spectroscopy, bending beam rheometer (BBR), and dynamic shear rheometer (DSR) tests were conducted to evaluate the potential improvements in various properties of RAP binder. The results indicated that the physical, fractional composition, rheological, and aging resistance of RAP binder improved through the rejuvenation mechanism. Therefore, the rejuvenator improved the chemical structure through re-balancing the constituents in the colloidal system, even after long-term re-aging, which proves it to be an aging-resistant binder. Furthermore, it has been concluded that Cereclor has substantial rejuvenation potential even after applying artificial aging, and it can be utilized in pavement recycling to achieve long-life performance. Furthermore, the results depict good correlations between the physical, rheological, and chemical parameters of virgin and RAP binder.

Simple and effective modification of absorbed glass mat separator through atmospheric plasma treatment for practical use in AGM lead-acid battery applications

Simple and effective modification method of commercial AGM using atmospheric plasma etching was reported for practical use in AGM battery applications. In order to enhance electrical performance and durability by improving degree of absorption of AGM for electrolyte solution, plasma-treated AGMs, AGM-X-Y, were fabricated by adjusting RF power and treatment time. In general, BET surface area and the degree of adsorption for electrolyte solution of plasma-treated AGMs increased with increase of RF power and plasma treatment time. However, on the contrary, too high RF power and long treatment time disturbed improvement of various properties, which would stem from smoothing of fiber surface and hydrophobic change by etching gas. The AGM-200-10 separator, which was treated with RF power of 200 W for 10 min, showed outstanding BET specific surface area (1.96 m2/g) and adsorption property (1.27 g/cc) for electrolyte. Moreover, AGM battery single cell with the AGM-200-10 separator showed much better electrical performance and durability in charge-discharge operation test under accelerated conditions, which should indicate the feasibility of the AGM-200-10 separator for practical use.

Structural, mechanical, dielectric properties and magnetic interactions in Dy3+-substituted Co-Cu-Zn nanoferrites.

Sol–gel-synthesized Co–Cu–Zn ferrite nanoparticles diluted with Dy3+ ions were investigated in terms of their structural, morphological, elastic, magnetic and dielectric properties. X-ray diffraction patterns showed the formation of a single-phase cubic spinel structure. As the concentration of Dy3+ ions was increased, the lattice length gradually increased from 8.340 to 8.545 Å, obeying Vegard's law. The Williamson–Hall (W–H) method was employed to observe the change in the lattice strain. Crystallite size obtained from W–H plots followed a pattern similar to that observed using the Scherrer equation. The cation distribution suggested a strong preference of Dy3+ ions for the octahedral B site while Cu2+ and Fe3+ ions were distributed over both A and B sites. The microstructures of the samples were visualized using transmission electron microscopy. Mechanical properties such as stiffness constant, longitudinal and transverse wave velocities, Young's modulus, bulk modulus, rigidity modulus, Poisson's ratio and Debye temperature were investigated by acquiring infrared spectra recorded in the range of 300 to 800 cm−1. Replacement of Fe3+ ions with the strongly magnetic Dy3+ ions increased the saturation magnetization and coercivity. Dielectric constant increased with Dy3+ substitution but decreased with applied frequency.

Synthesis and Characterization of Polystyrene (PS)/Modified Ni‐Al LDH Nanocomposite: Role of Composition, Modifier and Synthesis Route of Layered Double Hydroxides (LDH)

Layered double hydroxides (LDH) are two‐dimensional nanostructured materials, which impart flame retardancy property and improvement in various properties on incorporation into the polymer matrix. In this study, Ni‐Al LDH with a molar ratio of 2:1 and 3:1 (2NiAl and 3NiAl) was prepared by co‐precipitation method and Ni‐Al LDH with a molar ratio of 2:1 (NiAl urea) was also synthesized by the urea hydrolysis method. As the d‐spacing of these as‐synthesized LDHs is very small (≈0.8 nm) as well as hydrophilic in nature, hence, the unmodified LDHs are unsuitable for polymer nanocomposite preparation. In order to enhance the d‐spacing of LDHs, a simple regeneration method was employed to organically modify LDHs using two anionic surfactants such as sodium dodecyl benzene sulfate (SDBS) and sodium dodecyl sulfate (SDS). The hydrophobic tail of these anionic surfactants replaced the nitrate ions present in the unmodified LDHs leading to higher d‐spacing value, which was evident from XRD analysis. The above prepared LDHs (3 wt%) were incorporated into PS matrix by the solvent blending method to make PS nanocomposites. The 003 peak of modified LDHs did not appear in the XRD pattern of PS nanocomposites due to the disorientation of LDH layers in the PS matrix that was confirmed by TEM analysis. The TGA results clearly demonstrated that the thermal stability of the PS nanocomposite samples was increased by 26, 22 and 22 °C (PS/2NiAl SDS, PS/3NiAl SDS, and PS/NiAl urea SDS) for SDS modified LDH fillers, while in the case of SDBS modified LDH fillers, the improvement was around 32 °C in comparison with PS, when 15% weight loss was taken as a reference. The degradation mechanism, thermal degradation kinetics, and integral procedural decomposition temperature (IPDT) for all the nanocomposite systems were also evaluated using Criado method, Coats‐Redfern method, and Doyle's method, respectively. The effect of dispersion of the modified LDH fillers into PS matrix was examined using melt rheological analysis.

Accelerating carbonation in lime-based mortar in high CO2 environments

To accelerate the carbonation of lime, mortar samples were cured in chambers with high CO2 concentration. Two types of lime mortar were prepared, which are similar to Roman mortar types: lime and standard sand (M1) and extra ceramic dust and fragments (M2). After demolding, half of the samples were placed in the climate chamber where conditions were constant (20 °C, 60%, 1600 ppm) for six months, and the rest were left in laboratory conditions (25 °C, 34%, 703 ppm). The carbonation of the samples was evaluated at 28, 90, 120 and 180 days as well as microstructural, physical, hydric and mechanical properties. CO2 curing had pronounced effects on both types of mortar. M2 mortar samples showed advanced calcite precipitation and early improvement in various properties. At later stages, cracks caused drops in those properties.

Exploring the Influence of Methylene Diphenyl Diisocyanate as a Modifier for Ethylene Vinyl Acetate/Thermoplastic Polyurethane Blends

ABSTRACTEthylene vinyl acetate (EVA)/thermoplastic polyurethane (TPU) blend at various blend ratios has been modified via reactive processing with 4,4′-methylene diphenyl diisocyanate (MDI). Modification of the blends with even small amount of MDI shows significant improvement in physico-mechanical properties for EVA/TPU 50/50 and 30/70 blends, and it is also supported by the superior melt rheological behavior and dramatic improvement in oil resistance property. After the treatment of electron beam (dose range: 50–150 kGy), radiation crosslinked EVA/TPU (30:70) blend reveals further improvement in various properties. This particular material can find potential application as cable sheathing component.