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The preparation and characterization of composite materials composed of polypropylene (PP) as the base mixed with halloysite nanotubes (HNT) at various weight percentages (0.5, 1.5, and 3 wt.%) using a melt extrusion method operated at a temperature between 190 °C and 200 °C is described. The impact of the addition of the HNT filler on the PP nanocomposites was investigated based on the thermal and mechanical properties. The thermal characterization was conducted by differential scanning calorimetry (DSC). Significant increases in the rheological properties were observed with the addition of a high content of HNTs. The water absorption decreased with increasing HNT. The SEM micrographs showed that the HNT fillers were homogeneously dispersed throughout the entire PP matrix. [ABSTRACT FROM AUTHOR]

This study examined the effects of silane-modified polyimide polymer (PIS) on cement mortar. The PIS was added to replace cement in a specified ratio. Obtained results revealed that the PIS caused retardation on setting time, and accelerated UPV mostly by encapsulating unhydrated cement particles, filling pores, or reacting with C–S–H and Ca(OH)2 with shifting to Si–O vibrations. SEM results showed a good compact interface without forming considerable agglomeration and voids on the microstructure, and this improved flexural and compressive strength properties. In conclusion, silane-modified polyimide as an admixture or cement replacement can be recommended for construction industries to enhance the properties of cement mortar. [ABSTRACT FROM AUTHOR]

In low-temperature environments, asphalt materials harden easily and become brittle, and the repeated action of traffic load further aggravates the cracking of and damage to the asphalt mixture. In order to explore high-performance asphalt pavement materials that are more suitable for cold climates, this paper selected four modifiers, namely SBS, rubber powder, SBR and TPS. With SBS as the main agent, combined with other modifiers, three types of base asphalts with grades of 70#, 90# and 110# were compositely modified to prepare 12 different combinations of composite-modified asphalt samples. The optimal dosage of the modifier was determined by the basic performance test of asphalt, and the compatibility, interaction energy and mechanical properties of the modifier and base asphalt at different temperatures were analyzed by molecular dynamics simulation. Subsequently, the high- and low-temperature rheological properties of various modified asphalts were systematically evaluated using a dynamic shear rheology test (DSR) and a bending beam rheology test (BBR), and the rheological properties and road performance indicators of each composite-modified asphalt were comprehensively compared so as to select the road materials most suitable for cold areas. The research results show that different grades of base asphalt and modifiers show good compatibility in the range of 160–175 °C. Among them, rubber powder and TPS modifier significantly improve the high-temperature mechanical properties of SBS-modified asphalt, while rubber powder and SBR modifier significantly improve its low-temperature mechanical properties. The DSR and BBR test results further show that SBS/rubber powder composite-modified asphalt exhibits excellent rheological properties under both high- and low-temperature conditions, and is the preferred solution for road materials in cold regions. [ABSTRACT FROM AUTHOR]

With the rapid development of the construction industry and higher requirements on the properties of materials, extensive studies have been made to improve the property of the concrete and cementitious materials. This paper mainly studies the mechanical property, anti-chlorine ion diffusion, anti-chlorine ion diffusion, anti-freezing performance, hydration process, microstructure and rheological property of the concrete and cementitious materials after adding cellulose nanofibers. Results showed that the compressive strength of C40 concrete with 0.15% cellulose nanofibers added was 75.72 MPa at 56 days of age, 23.11% higher than that of the control group. It was also higher than that of concrete with 0.20% cellulose nanofibers admixture added. When the content of cellulose nanofibers was 0.15%, the flexural strength reached the maximum value of 6.55 MPa, improving by 24% compared with the control group. Under the circumstances of 150 freeze-thaw cycles, the mass loss rate of C50 concrete with 0.15% CNFs admixture registered at 0.41%, reducing by 0.81% compared with the control group. However, when the cellulose nanofibers increased to 0.20%, the mass loss rate of the concrete reached 0.48%, indicating that adding an appropriate amount of cellulose nanofibers could improve the performance of the concrete. The study provides a strong scientific basis for modifying concrete and cementitious materials.

AbstractThe particle size of polybutadiene (PB) particles can be effectively controlled through polymer agglomeration. However, up to now, the impact of the particle size and concentration of agglomerated PB on the mechanical properties and rheological behavior of ABS terpolymer remains unclear. Our research described here studied the effect of the particle size and content of agglomerated PB on the mechanical and rheological properties of ABS. It was found that the impact strength of ABS with a bimodal size distribution of PB (67/452 nm) exceeded that of ABS with a unimodal PB size distribution within the PB content range studied. Furthermore, the impact strength of the ABS containing 319 nm PB above the brittle-toughness transition point was greater than that of other ABS containing unimodal PB at the same PB content. For ABS with a unimodal PB distribution, the PB contents of ABS containing 220, 319, and 415 nm PB at the brittle ductile transition point were 14%, 12%, and 16%, respectively. The tensile strength and melting index of the ABS containing different particle sizes of agglomerated PB decreased linearly with the increase of PB content. Rheological tests showed the viscosity and dynamic viscoelastic properties of the ABS blends. All ABS exhibited shear-thinning behavior, and the addition of PB content resulted in more elastic than viscous behavior in the ABS blends. At the same angular frequency (ω), higher PB content corresponded to greater complex viscosity in the ABS blends. In addition, as the PB content in ABS was increased, it exhibited more solid-like behavior. This study, we suggest, provides a good insight into the effect of agglomerated PB on the ABS/PB blend properties and explores practical applications for the polymer agglomeration of polybutadiene latex (PBL). [ABSTRACT FROM AUTHOR]

In this study, we successfully realized the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and lysine derivative. A novel antibacterial modified polyamide 6 with a branched structure was obtained after the quaternization of the co-polymers. The co-polymers exhibited a significant increase in zero shear viscosity, melt index and storage modulus at the low frequency region. The quaternized co-polymers displayed thermal properties different from pure PA6 and good mechanical (tensile) properties. The antibacterial activity of the quaternized co-polymers depends on the quaternary ammonium groups' incorporated content. At 6.2 mol% incorporation of quaternary ammonium groups, the strong antibacterial activity has been introduced to the co-polymers. As the quaternary ammonium groups approached 10.1 mol%, the antibacterial polymers demonstrated nearly complete killing of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The above research results provided a new approach for the study of high-performance nylon. [ABSTRACT FROM AUTHOR]

In this study, a novel branched polyamide 6 has been synthesized via the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and α-Amino-ε-caprolactam (ACL). The NMR characterization proves the existence of a branched chain structure. The rheological test determines that there is a remarkable increase in the melt index (MFR), zero shear rate viscosity, and storage modulus in the low-frequency region. The shear-thinning phenomenon becomes more obvious. The thermal properties tested by differential scanning calorimetry (DSC) show that the melting point and crystallinity of co-polymers decrease with the incorporation of ACL. However, the crystal structure of the samples only exhibits a slight change. When the ACL content in the feed is 1 wt%, the tensile strength and fracture elongation rate of the co-polymers show a significant enhancement. [ABSTRACT FROM AUTHOR]

The physical properties as well as thermal and electrical stability of copper particles can be improved by surface protection, which mainly depends on the coating material. Our study was, therefore, focused on the rheological, thermal, mechanical and electrical characterization of polymer composites by comparing uncoated (Cu), silver-coated (Cu@Ag) and silica-coated (Cu@Si) copper flakes in low-density polyethylene at various volume concentrations (up to 40%). Interactions among particles were investigated by rheological properties, as these indicate network formation (geometrical entanglement), which is important for mechanical reinforcement as well as establishing an electric pathway (electrical percolation). The results showed that geometrical and electrical percolation were the same for Cu and Cu@Si, ~15%, while, surprisingly, Cu@Ag exhibited much lower percolation, ~7.5%, indicating the fusion of the Ag coating material, which also decreased crystal growth (degree of crystallinity). Furthermore, the magnitude of the rheological and mechanical response remained the same for all investigated materials, indicating that the coating materials do not provide any load transfer capabilities. However, they profoundly affect electron transfer, in that, Cu@Ag exhibited superior conductivity (74.4 S/m) compared to Cu (1.7 × 10−4 S/m) and Cu@Si (1.5 × 10−10 S/m). The results obtained are important for the design of advanced polymer composites for various applications, particularly in electronics where enhanced electrical conductivity is desired. [ABSTRACT FROM AUTHOR]

In many food applications, the mechanical properties of fats play a critical role in determining the processing performance of fat-rich products. In fact, fat crystal networks form a particular class of soft materials that exhibit viscoelastic properties. The uniqueness of the mechanical response is intricately linked to the hierarchical nature of the system, as fats possess a complex architecture encompassing features at different scale levels (i.e., length scales). Since the discovery of crystalline nanoplatelets (CNPs), it has been hypothesized that CNPs are the basic building blocks of lipid networks and that CNPs are the responsible units for the mechanical properties of fats. This hypothesis, however, has only been partially tested. In this article, we examine which units could be responsible (e.g., lamellae, CNP, CNP aggregates) for the mechanical breakdown of fat crystal networks, through Rheo-USAXS in beamline ID02 (ESRF, Grenoble, France). Time-resolved USAXS profiles were acquired during the three steps of a three-interval thixotropy test (3iTT), namely, pre-shear, shear and recovery. The results were then utilized to evidence which specific length scale is arranged (i.e., orientated) during rheological breakdown. The findings suggest that, at the tested shear rates, orientation is only visible from 250 nm onwards, suggesting that the rheological breakdown of triglycerides is primarily driven by the orientation, and possible disruption, of CNP aggregates. These results reveal the critical role of CNP aggregates in the mechanical properties of fats. In the longer term, we believe this study will steer future research toward a more focused understanding of CNP aggregation and disaggregation dynamics. [ABSTRACT FROM AUTHOR]

This is an article in the field of ceramics and composites. Rheology and microstructure properties of iron-doped tailings 3D printing cementitious materials were studied in this paper. The results show that the particle size of tailings is small and can be used as aggregates for 3D printing materials. In the 3D printing process, it can smoothly pass through the pipeline for conveying the cementitious material. As the content of iron tailings continues to increase, the shear viscosity of 3D printing cementitious materials shows a trend that first decreases and then stabilizes in the region. However, the changing law of shear stress shows an increasing trend as the interval between layers increases. The compressive strength and flexural strength of 3D printing cementitious materials both show a decreasing trend. When the interval between layers is in between 20～30 min, the compressive strength and flexural strength decrease more slowly. As the interval between layers continues to increase, the interlayer bonding strength of 3D printing cementitious materials shows a decreasing trend. The 3D printing cementitious material with 30% iron tailings content is hydrated for 90 days after XRD diffraction test. The main material components of the cementitious material are quartz, ettringite, calcite, albite, perovskite, Ca2SiO4 and seven substances such as calcium silicate hydrate.

Abstract Because of their propensity to build micellar nanostructures, amphiphilic block copolymers (ABCs) are an appropriate and unique toughening agent for epoxy systems individually on their own and in grafted form. The presence of epoxiphilic and phobic ends in ABCs is responsible for the self-assembly and the micellar structure. Nanofiller-grafted ABCs can effectively enhance the toughness of epoxy via the synergistic interaction of nanofillers and the ABCs. Even though there is sound literature supporting the effect of ABCs in epoxy, the action of double hydrophilic block copolymers (DHBC) in the epoxy matrix is less handled. Hence, the grafting of nanofillers in DHBCs and their subsequent role in tuning the properties of epoxy is a new concept. Hence this paper tries to bridge the gap via studying the effect of grafted fillers based on DHBCs in epoxy matrix. As a result, the current study focuses on the synthesis of double hydrophilic graphene nanoplatelets (rGO-g-DHBC) via nitrogen oxide-mediated polymerization for epoxy toughening application. The prepared rGO-g-DHBC was effectively utilized for epoxy toughening applications, resulting in a 457% improvement in toughness without compromising its inherent tensile strength. The mechanism behind the improved toughness was elucidated with the help of a scanning electron microscope, and the thermal, and rheological characteristics were studied.

This study produced and characterized composites based on nitrile rubber reinforced with rockwool fiber (RW) and carbon black (CB). Ten formulations with dual‐filler loading amounts ranging from 0 to 40 phr of CB and RW were designed using a simplex‐centroid mixture. The composites were assessed regarding their rheometric, rheological, mechanical, and thermal properties. The use of the RW in the dual‐filler system contributed to overall improvements in Shore A hardness, tear strength, modulus at 50%, and resilience, as well as reducing the Payne effect. Instead of using 40 phr of CB alone, a dual‐filler system comprising 20 phr of CB and 20 phr of RW lowers the Payne effect by around 60%, improves resilience by 35%, modulus at 50% strain by 8%, and the residual stress at equilibrium (σ∞/σ0) by 7%. On the other hand, the tensile strength is reduced by 23%. The optimum cure time, crosslink density, and maximum decomposition rate temperature were not affected by the rockwool's presence in the dual‐filler system. In general, the use of RW in combination with CB is advantageous mainly because it reduces compressive stress relaxation, which is an important property for sealing applications. Highlights: Dual‐filler systems based on carbon black (CB) and rockwool fiber (RW) offer advantages.RW‐rich dual‐filler systems reduce stress relaxation.RW‐rich dual‐filler systems reduce the Payne effect.CB‐rich dual‐filler systems increase tensile strength. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The properties of recycled post-consumer rigid polyethylene packaging waste were studied, using sorted waste washed in the laboratory with water alone and with added detergent, and compared with large-scale high-intensity washed flakes. The washed flakes were compounded using three different temperature profiles in a twin-screw extruder and then injection molded. A higher compounding temperature reduced the thermo-oxidative stability, the average molecular mass, and the viscosity of the samples. Rheological measurements suggested that changes in chain branching occurred at different compounding temperatures. The strength and the elongation at break were also influenced by the compounding temperature in both the molten and solid states. Detergent washing maintained the thermo-oxidative stability in contrast to washing with water. The large-scale washed samples had a relatively high thermo-oxidative stability, a higher melt elasticity, and a lower elongation at break in both the molten and solid states than the laboratory-scale washed samples. The thermal properties, melt elasticity, Young's modulus, yield stress, and yield strain of the samples were not, however, significantly affected by either the compounding temperature or the washing medium and intensity. The results indicated that recycled post-consumer rigid polyethylene packaging waste has properties that can support further applications in new products. [ABSTRACT FROM AUTHOR]

The influence of surface modification and some processing parameters on the palygorskite (Pal) dispersion and the mechanical, thermal and rheological properties of the resulting Nylon 6 nanocomposites was investigated. Natural Pal was surface modified with hexadecyl tributyl phosphonium and 3‐aminopropyl trimethoxysilane to produce organoclays with different surface energy values. Nylon 6/Pal nanocomposites were produced by twin screw extrusion and then injection molded, Pal loading was 2 wt. % in all the cases. A screw configuration was designed to impose different level of shear stresses to the nanocomposites during processing, and nanocomposites were extruded at two different screw speeds. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations indicated that Pal was dispersed differently depending mainly on the degree of shear stress and surface modification of Pal. The best tensile mechanical properties were achieved with Pal exhibiting the lowest surface energy value dispersed with the screw having high shear configuration. The fatigue life of nylon 6 improved with addition of Pal. The experimental results give some guidelines for producing Nylon 6/Pal nanocomposites with improved properties. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Materials & Green Construction is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, for the first time, photopolymers were synthesized from glycerol acrylates with different numbers of functional groups, 2-hydroxy-3-phenoxypropyl acrylate, glycerol dimethacrylate or glycerol trimethacrylate, without and with the addition of vanillin styrene. The photocuring kinetics were monitored by real-time photorheometry. The mechanical, rheological, thermal, antimicrobial and shape-memory properties of the photopolymers were investigated. All polymers synthesized demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as antifungal activity against Aspergillus flavus and Aspergillus niger. 2-Hydroxy-3-phenoxypropyl acrylate-based polymers showed thermoresponsive shape-memory behavior. They were able to maintain their temporary shape below the glass transition temperature and return to their permanent shape above the glass transition temperature. Synthesized photopolymers have potential to be used as sustainable polymers in a wide range of applications such as biomedicine, photonics, electronics, robotics, etc. [ABSTRACT FROM AUTHOR]

Biochar, the solid sub-product of biomass pyrolysis, is widely considered an effective water retention material thanks to its porous microstructure and high specific surface area. This study investigates the possibility of improving both mechanical and rheological properties of cement pastes on a micro-scale. The results show that using biochar as a reinforcement at low percentages (1% to 5% by weight of cement) results in an increase in compressive strength of 13% and the flexural strength of 30%. A high fracture energy was demonstrated by the tortuous crack path of the sample at an early age of curing. A preliminary study on the rheological properties has indicated that the yield stress value is in line with that of self-compacting concrete. [ABSTRACT FROM AUTHOR]

Polyethylene glycol (PEG), polypropylene glycol (PPG), and poly(ethylene glycol‐co‐propylene glycol) (PEPG) of number average molar masses (Mn) of 6–20 kDa are used as macroinitiators in the ring‐opening polymerization (ROP) of l‐lactide to synthesize high molar mass (50 kDa < MnCopo < 120 kDa) PLLA‐b‐polyether‐b‐PLLA linear triblock and starblock copolymers. At the studied block lengths, PEG and PEPG blocks exhibit miscibility with the PLLA blocks in the amorphous domains leading to a plasticization effect. As the PEG or PEPG block content is increased to 18 %wt, the Tg (Tg ≈ 24 °C) and the elastic modulus (E ≈ 500 MPa) are reduced, while the elongation at break (εb ≈ 280%) and crystallization rate are increased. At the same time, small angle oscillatory shear (SAOS) rheometric measurements show that the plasticized copolymers have a reduced melt viscosity. In contrast, SAOS and DSC measurements of the PPG‐containing block copolymers reveal phase separation of the PPG and PLA blocks leading to microstructures in the melt. Tensile tests show that the phase‐separated PPG‐containing block copolymers are more ductile than PLA homopolymers, but more brittle than the PEG‐ or PEPG‐plasticized block copolymers. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Post‐industrial low‐density and linear low‐density polyethylene blown films are mechanically recycled for reutilizing in the production of blown films for packaging applications. This process enables the production of films with lower cost and similar properties while preserving the environment and lowering the amount of waste material disposed of. The mechanical recycling process results in the production of recycled pellets. This process includes chopping, washing, drying, and reprocessing. Mixtures of these recycled materials and their virgin form with various concentrations are shaped into blown films with inherent 70 and 30 wt% loadings for low‐density polyethylene and linear low‐density polyethylene components, respectively. Fourier transform infrared spectroscopy results of the recycled material show no contamination or chemical reaction with other materials. Gel permeation chromatography is carried out on the virgin and recycled low‐density polyethylene and linear low‐density polyethylene, and the results indicate the occurrence of chain session and crosslinking during the recycling process. The decline in the thermal properties of the samples, seen from the differential scanning calorimetry results, indicates the presence of crosslinks. The effect of structural changes caused by the recycling process on the rheological properties is studied. The miscibility of the blend components is evaluated by Cole–Cole plots and then further proved by Han and Van Gurp–Palman curves. Mechanical properties display an upturn following the presence of the crosslinkes. A decline in the optical properties in the films caused by the refraction of light by the crosslink structure in the film bulk and on the surface is evident. Highlights: LDPE and LLDPE were recycled according to the circular economy approachBlown films containing virgin and recycled LDPE and LLDPE were producedChain scission and crosslinking as a result of recycling were studiedRheological, thermal, mechanical, and optical properties were studied [ABSTRACT FROM AUTHOR]

The technological parameters of 3D printing have an influence on the mechanical properties of the manufactured components. The purpose of the article was to study the comparative influence of the technological parameter of the number of shells variable in two stages (2 and 10) on selected mechanical properties. The maximum tensile stress for the number of shells 10 was 39.80 MPa, which is higher compared to the number of shells 2: 30.98 MPa. In the case of the maximum bending stress for the number of shells 10, an average value of 61.02 MPa was obtained, which is higher compared to the number of shells of 2: 37.46 MPa. Furthermore strong fit of the Kelvin-Voight model was obtained, as confirmed by the values of the Cℎi2: 0.0001 and R2: 0.997 coefficients. [ABSTRACT FROM AUTHOR]

Tailings from gold mines gradually approach ultra-fine, making mine backfill costs higher and strength lower, which poses a serious threat to the safety of underground personnel and equipment. It is well known that suitable chemical admixtures can enhance the working properties of mortar materials. Therefore, in order to achieve the purpose of reducing the cost of ultra-fine tailings backfill and improving the working performance of ultra-fine tailings filling slurry, this paper provides a study on the effect of sodium silicate and calcium chloride on the properties of ultra-fine tailings cemented backfill materials. The results of experimental studies through rheology, strength, and microstructural tests, etc., showed that the optimal proportioning parameters of cementitious materials are 76.92% blast furnace slag, 19.24% carbide slag, and admixtures of 2.88% sodium silicate and 0.96% calcium chloride. The 3, 7, and 28-day uniaxial compressive strength of the ultra-fine tailings cemented paste backfill with the newly formulated blast furnace slag-based cementitious material increased by 124%, 142%, and 14%, respectively, compared to that of the ultra-fine tailings cemented paste backfill with the P. O42.5 cement. The setting time for ultra-fine tailings cemented backfill slurry is shortened by the addition of admixtures, and the shear stress of the slurry is correlated with the amount of hydration product generation and its formation of flocculating structure. Moreover, the cost of the newly prepared cementitious material is much lower than that of traditional cement, which lays a good foundation for the cemented filling of ultra-fine tailings. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, the use of low viscosity and in‐situ polymerizable thermoplastic acrylic resins for advanced fiber reinforced composites has grown, specially to address the difficulty of fiber impregnation with high‐melt viscosity thermoplastic polymers. The present work investigated the curing kinetics, chemo‐rheology of an acrylic resin system for in‐situ pultrusion, and proposed the corresponding constitutive models. First, the curing kinetics was studied with the differential scanning calorimetry experiments. The viscosity development was obtained by a rheometer as functions of the degree of cure (DOC) and temperatures. The gelation point was acquired from the intersection point of storage and loss modulus curves through dynamic mechanical analysis test, which occurs at DOC of 0.65 determined by the cure kinetics model. Through the dynamic mechanical analysis, a four step cure hardening modulus model (modified CHILE approach) was proposed. The aforementioned models were applied in a case study to evaluate the influence of process parameters on the DOC, viscosity and physical behavior of the acrylic resin system in the pultrusion die. Highlights: Material characterizations of an acrylic resin system are investigated.The cure kinetics and viscosity and elastic modulus models are proposed.A pultrusion case study is given. [ABSTRACT FROM AUTHOR]

The production of sustainable and green structural concrete is getting more popular nowadays. The incorporation of agricultural waste is actively advocated in construction industries, as it makes the environment more eco-friendly. This study uses coconut shells as agro-waste as a substitute for coarse aggregate. Most tropical countries produce coconut shells at a hefty volume, but the lack of utilisation results in almost inconsequential waste material. The conventional aggregates (CA, i.e. crushed stone chips) were replaced by coconut shell aggregate (CSA) at 10%, 20%, 30%, 40%, and 50% (by weight), respectively. The rheological characteristics are measured by performing slump, density, and compacting factor tests. Various mechanical characteristics such as compressive, tensile, and flexural strength were investigated after 7, 14, and 28 days of the curing period, and the results were compared with various statistical parameters. The experimental research revealed that the workability as slump values declined gradually as the percentages of CSA increased. The strength values of concrete specimens were slightly reduced for up to 20% of CSA replacements. However, incorporating CSA at 30%, 40%, and 50% replacement provides concrete a lightweight property, and 50% replacement of CSA can still achieve the strength required to be termed as structural concrete. As a result, the replacement of CA at a hefty volume of CSA characterises the green property of concrete production. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cemented backfill mining is a green mining method that enhances the coal mining rate and the safety of mined-out regions. To transport the cemented gangue backfill material (CGBM) into the mined-out regions, it is essential to ensure high flowability and adequate compressive strength after hardening. Based on the response surface methodology (RSM), 29 experiments were conducted in this paper to test the yield stress and plastic viscosity of CGBM slurry. Cubic specimens with dimensions of 100 mm were prepared and underwent uniaxial compression tests to obtain the compressive strength at a curing age of 28 days. Quadratic polynomial regression models were established for yield stress, plastic viscosity, and compressive strength to explore the effects of fly ash content, water-cement ratio, mass concentration, and superplasticizer dosage on the properties of CGBM. Multi-objective optimization was conducted to determine the optimal material proportion of CGBM. The research results indicate that (1) the mass concentration most profoundly affected the yield stress and plastic viscosity of CGBM, and it increased with an increase in mass concentration. Fly ash content had an inverse relationship with compressive strength. Superplasticizer was found to improve the flowability and strength of CGBM. (2) The established response surface model could reflect the relationship between CGBM's material proportion and rheological and mechanical properties, and predict relevant parameters. (3) Multi-objective optimization determined the optimal proportion of CGBM to be 80% fly ash content, 54% water-cement ratio, 79% mass concentration, and 3% superplasticizer dosage. The research findings offer valuable guidance to mining backfill engineering. [ABSTRACT FROM AUTHOR]

This research aims to assess the rheological and mechanical characteristics of Self-compacting concrete (SCC) incorporating waste tire rubber aggregates (WRTA) as an interim substitute for coarse aggregates. However, the standard experimental modeling approach has significant obstacles when it comes to overcoming the nonlinearity and environmental susceptibility of concrete parts. Therefore, linear regression (LR) and extreme gradient boosting (XGBoost) were used as two standard single machine learning (ML) models to predict the aforementioned rubberized SCC features. In this study, conventional coarse aggregates were supplanted with WRTA at 0%, 5%, 10%, and 20% to uncover the optimal proportion of coarse aggregates substituting rubber. To find the optimum amount of WRTA to use as a substitute, the study follows the impacts of rubber on the self-compacting rubberized concrete's (SCRC) rheological and mechanical characteristics. The consequences on fresh properties were investigated by the slump flow, J-ring, and V-funnel tests, while compressive and splitting tensile strengths tests were conducted to assess mechanical properties. Increasing WRTA test outputs indicated a deterioration in workability and hardened qualities. While a 10% swapping ratio is deemed feasible for producing SCRC, optimal results were achieved by reducing environmental impacts and efficiently managing a significant volume of rubber tire waste with a 5% substitution of rubber within the coarse aggregates. The research findings indicated a noticeable decrease in fresh properties as the WRTA content increased. Notably, after 28 days, a 10% WRTA substitution led to a 34% reduction in compressive strength and a 28% decrease in splitting tensile strength, satisfying ACI standards. Furthermore, XGBoost demonstrated superior predictive performance with the highest R2 values, outperforming the LR model and affirming its efficacy in delivering more accurate predictions.

Abstract Polyethylene glycol (PEG), polypropylene glycol (PPG), and poly(ethylene glycol‐co‐propylene glycol) (PEPG) of number average molar masses (Mn) of 6–20 kDa are used as macroinitiators in the ring‐opening polymerization (ROP) of l‐lactide to synthesize high molar mass (50 kDa < MnCopo < 120 kDa) PLLA‐b‐polyether‐b‐PLLA linear triblock and starblock copolymers. At the studied block lengths, PEG and PEPG blocks exhibit miscibility with the PLLA blocks in the amorphous domains leading to a plasticization effect. As the PEG or PEPG block content is increased to 18 %wt, the Tg (Tg ≈ 24 °C) and the elastic modulus (E ≈ 500 MPa) are reduced, while the elongation at break (εb ≈ 280%) and crystallization rate are increased. At the same time, small angle oscillatory shear (SAOS) rheometric measurements show that the plasticized copolymers have a reduced melt viscosity. In contrast, SAOS and DSC measurements of the PPG‐containing block copolymers reveal phase separation of the PPG and PLA blocks leading to microstructures in the melt. Tensile tests show that the phase‐separated PPG‐containing block copolymers are more ductile than PLA homopolymers, but more brittle than the PEG‐ or PEPG‐plasticized block copolymers.

In this study, we successfully realized the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and lysine derivative. A novel antibacterial modified polyamide 6 with a branched structure was obtained after the quaternization of the co-polymers. The co-polymers exhibited a significant increase in zero shear viscosity, melt index and storage modulus at the low frequency region. The quaternized co-polymers displayed thermal properties different from pure PA6 and good mechanical (tensile) properties. The antibacterial activity of the quaternized co-polymers depends on the quaternary ammonium groups’ incorporated content. At 6.2 mol% incorporation of quaternary ammonium groups, the strong antibacterial activity has been introduced to the co-polymers. As the quaternary ammonium groups approached 10.1 mol%, the antibacterial polymers demonstrated nearly complete killing of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The above research results provided a new approach for the study of high-performance nylon.

In many food applications, the mechanical properties of fats play a critical role in determining the processing performance of fat-rich products. In fact, fat crystal networks form a particular class of soft materials that exhibit viscoelastic properties. The uniqueness of the mechanical response is intricately linked to the hierarchical nature of the system, as fats possess a complex architecture encompassing features at different scale levels (i.e., length scales). Since the discovery of crystalline nanoplatelets (CNPs), it has been hypothesized that CNPs are the basic building blocks of lipid networks and that CNPs are the responsible units for the mechanical properties of fats. This hypothesis, however, has only been partially tested. In this article, we examine which units could be responsible (e.g., lamellae, CNP, CNP aggregates) for the mechanical breakdown of fat crystal networks, through Rheo-USAXS in beamline ID02 (ESRF, Grenoble, France). Time-resolved USAXS profiles were acquired during the three steps of a three-interval thixotropy test (3iTT), namely, pre-shear, shear and recovery. The results were then utilized to evidence which specific length scale is arranged (i.e., orientated) during rheological breakdown. The findings suggest that, at the tested shear rates, orientation is only visible from 250 nm onwards, suggesting that the rheological breakdown of triglycerides is primarily driven by the orientation, and possible disruption, of CNP aggregates. These results reveal the critical role of CNP aggregates in the mechanical properties of fats. In the longer term, we believe this study will steer future research toward a more focused understanding of CNP aggregation and disaggregation dynamics.

In this study, a novel branched polyamide 6 has been synthesized via the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and α-Amino-ε-caprolactam (ACL). The NMR characterization proves the existence of a branched chain structure. The rheological test determines that there is a remarkable increase in the melt index (MFR), zero shear rate viscosity, and storage modulus in the low-frequency region. The shear-thinning phenomenon becomes more obvious. The thermal properties tested by differential scanning calorimetry (DSC) show that the melting point and crystallinity of co-polymers decrease with the incorporation of ACL. However, the crystal structure of the samples only exhibits a slight change. When the ACL content in the feed is 1 wt%, the tensile strength and fracture elongation rate of the co-polymers show a significant enhancement.

Silicon carbide whiskers (SiCw) have presented great potential to improve the mechanical properties of Al2O3 ceramic. However, effective curing of SiCw/Al2O3 ceramic slurry during digital light processing (DLP) is still challenged due to the high refractive index of SiCw. This paper aims to investigate the effect of SiCw content on rheological properties and associated curing behaviors of ceramic slurry. A modified Beer-Lambert model is proposed to evaluate the curing depth as functions of SiCw content and exposure parameters. The SiCw/Al2O3 ceramic slurries with the whiskers content of 0–16 vol.% are prepared and characterized. The results indicate that the curing depth decreased from 158 to 19 μm at the given exposure energy of 100 mJ/cm2 with the increase of SiCw content. The scattering and absorbance of light result in the decrease of curing depth and the geometrical overgrowth. The rheological properties of ceramic slurry are affected by the agglomerated whiskers. Furthermore, SiCw/Al2O3 ceramics are fabricated by DLP method, based on which the relationships among mechanical properties, microstructures and whiskers contents are determined. Significant effect of reinforcement is obtained in SiCw/Al2O3 ceramic due to whiskers pullout consuming the external loading energy. The microhardness and flexural strength of the SiCw/Al2O3 ceramics with 8 vol.% SiCw are 16.72 GPa and 208.5 MPa, respectively.

A sustainable method to reduce the use of natural resources and the negative effects of the concrete industry on the environment is to use waste lateritic aggregate in self-compacting concrete and evaluate its fresh, mechanical and durability characteristics. Using RSM's central composite design (CCD), Thirteen different SCC mixtures have been designed with varying input factor combinations (LA: 0–100%, PPF: 0–2%) and tested for eight responses (rheological properties, like slump flow, V-funnel time, and T500; mechanical properties, like compressive, split-tensile, and flexural strengths, and durability properties like drying shrinkage and rapid chloride penetration test). The analysis of variance (ANOVA) test was performed to determine the accuracy of the mathematical models developed following the experimental results. ANOVA was used to verify eight response models (seven quadratic and one linear). The inclusion of laterite aggregate has been found to linearly reduce the workability of fresh concrete. Self-compacting concrete will have a lower V-funnel value if any combination of components falls below these two limit values (31% LA and 1.12% PPF). The area bounded by the 760-mm contour line and the graph axes recorded the highest slump flow at (28% LA and 1.26% PPF). Similarly, SCC with a lower T500 value will be produced by any combination of components below these two limit values (25% LA and 1.11% PPF). By replacing 28.5% of the granite aggregate with laterite aggregate and adding 1.24% polypropylene fiber, the compressive strength of M30 grade self-compacting concrete increased by 12.33% after 28 days. A similar strength gain of 7.89% was seen in the splitting tensile by replacing 28% of the granite aggregate with laterite aggregate and adding 1.46% polypropylene fiber over the control mix, and a flexural strength gain of 14.46% was seen by replacing 31.4% of laterite aggregate and adding 1.2% polypropylene fiber, respectively. The low drying shrinkage values are related to a combination of LA concentration (34.4% replacement) and PPF (1.31%) and minimum chloride ingress is located in the region with a LA concentration (30.5% replacement) and a PPF content (1.26%), The projected optimal data were verified experimentally with an error rate of less than 5%. Thus, it is highly recommended that the created model be adequate and capable of optimizing both the experimental and analytical values. It is recommended that the utilization of 25% LA and 1% PPF in lateritic self-compacting concrete provides optimum outcomes for the construction industry in the field of civil engineering.

The novel ultra-high molecular weight polypropylene (UHMWPP) as a dispersed component was melt blended with conventional high-density polyethylene (PE) and maleic anhydride grafted-polyethylene (mPE) in different proportions through a kneader. Ultra-high molecular weight polypropylene is a high-performance polymer material that has excellent mechanical properties and toughness compared to other polymers. Mechanical, thermal, and rheological properties were presented for various UHMWPP loadings, and correlations between mechanical and rheological properties were examined. Optimal comprehensive mechanical properties are achieved when the UHMWPP content reaches approximately 50 wt%, although the elongation properties do not match those of pure PE or mPE. However, it is worth noting that the elongation properties of these blends did not match those of PE or mPE. Particularly, for the PE/UHMWPP blends, a significant drop in tensile strength was observed as the UHMWPP content decreased (from 30.24 MPa for P50U50 to 13.12 MPa for P90U10). In contrast, the mPE/UHMWPP blends demonstrated only minimal changes in tensile strength (ranging from 29 MPa for mP50U50 to 24.64 MPa for mP90U10) as UHMWPP content varied. The storage modulus of the PE/UHMWPP blends increased drastically with the UHMWPP content due to the UHMWPP chain entanglements and rigidity. Additionally, we noted a substantial reduction in the melt index of the blend system when the UHMWPP content exceeded 10% by weight. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of recycled plastic content on the processability and physical properties of blended modified recycled materials, recycled polypropylene rubber head masterbatch (recycled material) was blended with pure polypropylene to prepare blend samples, and their rheological properties, crystallization properties and mechanical properties were characterized. The results show that the viscosity of blend samples decreases and the relaxation peak at 0.1 s shifts to lower frequency when the recycled material content increases from 0 to 50%. Relaxation peaks also appeared in the blend melt at 1 s due to the presence of higher molecular weight parts in the recycled material. The peak temperature of the main crystallization peak increases from 118. 2 °C to 120 °C when the recycled material content increases from 0 to 50%, but the crystallization behavior at low temperature also appears. When the recycled material content increases from 10% to 50%, the crystallinity of the sample decreases from 40% to 35%, and a crystalline structure with lower melting point also appears. The impact strength, tensile strength, flexural strength and flexural modulus of the blend decrease by 35%, 7%, 10% and 9%, respectively, when the recycled material content is 50%, which indicates that the mechanical properties of the blend decrease with the increase of recycled material. [ABSTRACT FROM AUTHOR]

Producing starch gels with superior mechanical attributes remains a challenging pursuit. This research sought to develop a simple method using ethanol exposure to produce robust starch gels. The gels' mechanical properties, rheology, structural characteristics, and digestion were assessed through textural, rheological, structural, and in vitro digestion analyses. Our investigation revealed an improvement in the gel's strength from 62.22 to178.82 g. The thermal transitions were accelerated when ethanol was elevated. The exposure to ethanol resulted in a reduction in syneresis from 11% to 9.5% over a period of 6 h, with noticeable changes in size and color. Rheologically, the dominating storage modulus and tan delta (<0.55) emphasized the gel's improved elasticity. X-ray analysis showed stable B- and V-type patterns after ethanol exposure, with relative crystallinity increasing to 7.9%. Digestibility revealed an ethanol-induced resistance, with resistant starch increasing from 1.87 to 8.73%. In general, the exposure to ethanol played a crucial role in enhancing the mechanical characteristics of kudzu starch gels while simultaneously preserving higher levels of resistant starch fractions. These findings have wide-ranging implications in the fields of confectioneries, desserts, beverages, and pharmaceuticals, underscoring the extensive academic and industrial importance of this study. [ABSTRACT FROM AUTHOR]

The inherent shortcomings of fully biodegradable poly(butylene adipate-co-terephthalate) (PBAT) copolyesters including low strength, modulus, and melt viscoelasticity were addressed by melt blending of PBAT with high-stiffness and biological poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB). An epoxy-based chain extender was used to increase interfacial adhesion of partially miscible PBAT/P34HB (70wt/30wt) blends. The addition of chain extender refined phase-separated morphology of blends from SEM and decreased the degree of crystallinity by DSC. Compared with neat PBAT, PBAT/P34HB blends with chain extender showed much higher melt viscosity and elasticity, as indicated by rheological properties analyses. Compared with the PBAT/P34HB blend without chain extender, the breaking strength and elongation at break of PBAT/P34HB blend with incorporation of 1 wt% ADR were increased by 91.8% and 58.7%, respectively. It could be concluded that the combination of blending and chain-extension reaction simultaneously improved the strength, elongation at break, and melt viscoelasticity, which contributed to the suitability of biodegradable polymer blends for a wider range of end-use applications. [ABSTRACT FROM AUTHOR]

By preparing fine tailings slurry with different mass concentration and fiber content, the rheological parameters of slurry with different fiber content and curing time were tested. In addition, the influence law of fiber content and curing time on compressive strength was analyzed through the prepared fine tailings backfill samples, and the microstructure characteristics of fine tailings backfill were further studied. The results show that when the fiber content is 0.2 ~ 1.2%, the yield stress and plastic viscosity of the slurry increase with the increase of fiber content, and the thixotropy of the slurry also shows the same change characteristics. The bridge effect of fiber makes it easier for forming network structure, which increase the slurry rheology. When the curing time ranges from 0 h to 2.5 h, the increasing of curing time leads to the increasing trend of rheological parameters, and also increases the thixotropy of slurry. However, the increase of rheological parameters will continuously decrease when the curing time exceeds 1 h, indicating that the influence of curing time on yield stress and thixotropy will gradually weaken with the continuous extension of curing time. When the curing age increases from 3 to 56 days, the compressive strength of the fine tailings backfill increases with the curing age, but the increasing range of compressive strength decreases gradually. When the fiber content ranges from 0.2 to 1.2%, the compressive strength of backfill increases first and then decreases with the increase of fiber content, and reaches the maximum value when the fiber content is 0.6%. The extension of curing time reduces the generation of large-scale pore structure, which promotes the formation of more compact microstructure of backfill. [ABSTRACT FROM AUTHOR]

To enhance the ease of processability of the ultra-high molecular weight polypropylene (UHMWPP), the various low molecular weight polypropylenes (LMWPPs) blended with the UHMWPP via a facile melt blending process. The effect of the LMWPPs component on the UHMWPP component on its rheological and mechanical properties was characterized using various measurement techniques. The processability of the UHMWPP was improved drastically with the introduction of LMWPP components as the melt index of the blend increased. As the LMWPP content increases, the mechanical properties of the blends tend to increase or decrease, depending on the type of LMWPP. [ABSTRACT FROM AUTHOR]

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One of the approaches to improve the properties of polymers is to use additives in them. In the last few years, nanoscale additives have received attention due to the favorable properties they give to polymers in low concentrations. POSS or polyhedral oligomeric silsesquioxane has unique properties due to its nanometer size and organic–inorganic nature. The rigid structure of POSS and its compatibility with all types of polymers make their use attractive in various polymer industries. The concentration, structure of the mineral core, and type of POSS organic groups can affect the final properties of polymers containing these nanostructures. Chemical mixing of POSS with polymer increases the viscosity of the system, while physical mixing decreases the viscosity of the polymer. These nanostructures can improve properties such as tensile strength, modulus, and toughness of the polymer. Polymers with low concentrations of POSS have the advantage of high thermal stability and low flammability, which makes them ideal for applications in the aerospace industry where materials must withstand extreme temperatures and harsh environments. In addition, the low dielectric constant of POSS-containing polymers makes them useful for use in electronic components. The high specific surface of POSS allows the use of these nanostructures as supports for various catalysts. POSS is used in a wide range of industries including aerospace, biomedical, electronics and chromatography columns, etc. [ABSTRACT FROM AUTHOR]

Biochar, the solid sub-product of biomass pyrolysis, is widely considered an effective water retention material thanks to its porous microstructure and high specific surface area. This study investigates the possibility of improving both mechanical and rheological properties of cement pastes on a micro-scale. The results show that using biochar as a reinforcement at low percentages (1% to 5% by weight of cement) results in an increase in compressive strength of 13% and the flexural strength of 30%. A high fracture energy was demonstrated by the tortuous crack path of the sample at an early age of curing. A preliminary study on the rheological properties has indicated that the yield stress value is in line with that of self-compacting concrete.