Binder Composition Research Articles

Stabilizing the Si/C blend anode by a multifunctional ternary composite binder

Si/C blend anodes hold great promise in commercialized high-energy-density (HED) Li-ion batteries but suffer from volumetric effects and electrode integrity deterioration. This study reports a ternary composite binder consisting of carboxymethyl cellulose (CMC), cationic polyacrylamide (CPAM), and styrene-butadiene rubber (SBR), which can significantly improve the cyclability of a Si@C/graphite blend anode. A high capacity retention of 92.9% after 100 cycles was achieved in a half cell. Moreover, the ternary binder proves suitable for a very high mass loading (4.9 mAh/g) electrode and is effective in a 2 Ah-level full cell, which delivers an excellent capacity retention of 80.6% after 500 cycles. The beneficial effects were ascribed to the multifunctional groups compatible with the surfaces of both Si and carbon, and the designed rigidness and elasticity which restricts and accommodates the volumetric effects of the Si/C blend anode simultaneously.

НЕКОТОРЫЕ ОСОБЕННОСТИ РАЗРАБОТКИ ФОРМОВОЧНЫХ И СТЕРЖНЕВЫХ СМЕСЕЙ С ПРИМЕНЕНИЕМ БОРАТФОСФАТНЫХ СВЯЗУЮЩИХ

In the practice of foundry production, it is known to use cores of phosphate cold-hardening mixtures (CMC), containing: aluminophosphate (APS), magnesium phosphate (MFS), aluminochrome phosphate (ACPS), magnesium aluminophosphate (MAPS), calcium magnesium phosphate (CMPS), chromophosphate (CPS) and boraluminophosphate (BAPS) and other binders [1-20]. The widespread use of metal phosphate binders (MPBs) is hampered by the fact that CBTs made on their basis have a number of disadvantages. In particular, cold-hardening mixtures prepared using an aluminophosphate binder (APB) and a magnesium phosphate binder (MPB) do not provide the mixtures with sufficient binding and strength properties. Regulation of such properties of molding and core mixtures as survivability, formability, crumbling, strength and some other properties occurs by changing the composition and content of binder compositions in the mixtures. It is known that boric acid and its salts exhibit adhesive-cohesive properties and the use of which as a modifier in the composition of thermal insulation, molding, and core mixtures improves their physical, mechanical and technological characteristics. It is also known that boric acid enters into chemical reactions with inorganic and organic substances to form complex compounds that exhibit more pronounced binding properties than boric acid. The purpose of the work is to improve the properties of aluminophosphate and magnesium phosphate cold-hardening mixtures using boric acid (H3BO3), borophosphoric acid (composition H3BO3•H3PO4) and borophosphorous acid (composition H3BO3•H3PO3) and their effect on the strength characteristics, crumbling and formability of the tested mixtures.

Binder System Composition on the Rheological and Magnetic Properties of Nd-Fe-B Feedstocks for Metal Injection Molding

The applications of Nd-Fe-B-based magnets are experiencing significant diversification to achieve efficiency and miniaturization in different technologies. Metal injection molding (MIM) provides new opportunities to manufacture Nd-Fe-B magnets with high geometrical complexity efficiently. In this study, the impacts of the binder system composition and powder loading on the rheological behavior, contamination, and magnetic properties of the Nd-Fe-B MIM parts were investigated. A high-pressure capillary rheometer was used to measure the apparent viscosity and pressure drops for feedstocks with different binder formulations and powder contents. Also, oxygen and carbon contamination, density, and magnetic properties were measured for different feedstock formulations and powder loadings. From the rheological, density, and magnetic properties points of view, the binder system consisting of 45 vol.% LLDPE as backbone was selected as the optimum formulation. The findings indicated that the sample with this binder system and 55 vol.% powder content had a high density (6.83 g/cm3), remanence (0.591 T), and coercivity (744.6 kA/m) compared to other binder compositions. By using 58 vol.% powder loading, the values of density (7.54 g/cm3), remanence (0.618 T), and carbon residue (982 ppm) improved, and a suitable rheological behavior was still observed. Thus, a suitable feedstock formulation was developed.

Effect of Dry Mix Alkali Activated Slag Binder Composite Properties Cured in Ambient Condition

<p>A dry mix (solution-free) alkali-activated slag (a primary cementitious material) and/or fly ash based binder composition is developed that can be cast in-site and consequently cured at ambient temperature. Mortar specimens were cast by mixing slag and or fly ash, river sand, powder form alkaline activators (NaOH 14M, varying solids percentage of Na2SiO3) and water were thoroughly mixed in fabricated equipment. The dry density (28 days) of all specimens showed greater than 2200 kg/m3. The compressive strength (28 days) of all mixes was resulted in higher than 40 N/mm2. Among all the four mixes, a mix F103 with 90% slag, 10% fly ash, 30% Na2SiO3 and 14M NaOH at 3, 7 and 28 days curing showed overall higher compressive strength. It is due to fewer solids content of Na2SiO3. The experimental results indicated that solution free studied binder composite can be developed under ambient conditions eliminating other curing types without compromising in the strength. The studied sustainable mixes require only 12-15 percent water which is less compared to regular used mixes. Thus reduced water quantities can be achieved thereby protects the reduction in volume of water bodies, environment hazards, reduces CO2 emissions due to use of industrial by-products as main binders.</p>

Influence of recycled rubber and glass aggregates on magnesium sulfate resistance of geopolymers: Physio-mechanical properties and mechanisms

Recycled rubber aggregates (RRA) and recycled glass aggregates (RGA) are sustainable alternatives to natural aggregates. However, the influences of RRA and RGA on the magnesium sulfate resistance of geopolymers remain unclear. Previous studies have focused on the influences of binder type and composition on magnesium sulfate resistance but have neglected the role of aggregates. This study bridges this gap and demonstrates the influences of RRA and RGA on the magnesium sulfate resistance of geopolymers. This study investigated the physical properties, mechanical properties and phases of FA and GBFS-based geopolymers containing 0:10 – 10:0 RRA and RGA after being exposed to 5 % MgSO4 solution for 90 days. The results showed that compared to 100 % RGA, the 90-day length and mass of 100 % RRA increased by 50.48 and 33.22 times, respectively, and the 90-day compressive, flexural and splitting tensile strengths of 100 % RRA decreased by 65 %, 43.28 % and 56.75 %, respectively. However, the changes in length and mass of 100 % RGA were very small, and the mechanical properties even slightly increased rather than decreased. RRA + RGA showed an interval performance between 100 % RRA and 100 % RGA. The different magnesium sulfate resistance of RRA and RGA were attributed to the following mechanisms. RRA caused much higher drying shrinkage of geopolymers than RGA because the soft nature of RRA increased uncoordinated deformation, leading to micro-cracks in the matrix before magnesium sulfate exposure. The pre-existing micro-cracks served as physical transportation paths for external ions to diffuse into the interior of specimens, leading to expansive gypsum crystals formed in these micro-cracks. The accumulation of expansive gypsum crystals enlarged these micro-cracks and facilitated their propagation, leading to the expansion, cracking and degraded mechanical properties. By contrast, RGA reduced drying shrinkage due to its hard nature, which limited the availability of micro-cracks as physical transportation paths for external ions and therefore reduced the formation of expansive gypsum crystals and improved the magnesium sulfate resistance of geopolymers.

ВЛИЯНИЕ ОСОБЕННОСТЕЙ СОСТАВА ШУНГИТА РАЗЛИЧНЫХ МЕСТОРОЖДЕНИЙ НА СТРУКТУРООБРАЗОВАНИЕ ПОЛИМЕРНО-БИТУМНОГО ВЯЖУЩЕГО

For reduction the amount of expensive polymers and improving the technological, physico-mechanical, thermophysical and other properties of road materials fillers are introduced into polymer modified bitumen binders (PBB). Therefore, in recent years the interest in natural materials that are similar in composition and have comparable characteristics to synthetic products has been increased. In relation to graphene structures used to modify bitumen and polymers, shungite is seems to be a good alternative, the rock that is essentially a composite material from mixture of shungite carbon and mineral phases. When shungite powder using as PBB modifier the distinctive features of the shungite composition should have a positive effect on the structuring of a bitumen matrix in the presence of a polymer. Since the most important structural component of the rock is carbon, the purpose of this work is to study the effect of shungite carbon from rocks of various deposits on the structure formation of the polymer modified bitumen binder. A set of studies (differential scanning calorimetry, Raman spectroscopy, energy dispersive spectroscopy based on a scanning electron microscope) has established that carbon from samples from seven deposits of Karelia is characterized by varying degree of ordering of graphite-like (sp2-carbon) structures depending on the sampling location. An increase in the amount of carbon in the composition of shungite powder and a decrease in the degree of ordering of its structure determine higher values of the specific surface area and a greater effect from modification when adding fillers into the polymer modified bitumen binder. Samples from the Zazhoginsky deposit are the most active fillers with a high modifying effect, which maximally improve the cohesive strength of the composite organic binder and structure the system by the best way. The powders from rocks from other deposits also have the positive effect relative to the base PBB, but with less efficiency. All this indicates the prospects of the proposed modification.

Fresh and hardened properties for a wide range of geopolymer binders – An optimization process

The objective of this study was to identify the optimal geopolymer binder compositions produced from local industrial by-products and compare them with commercially available materials. The first part investigated the optimal binder composition by studying 27 mixtures. In this part of the research, three series of binders were created: the first series of 18 mixtures was Na-based fly ash-slag, the second series consisted of 8 mixtures of K-based fly ash-slag, and the third series were a mixture of metakaolin-slag based geopolymer. The compressive strengths of the mixtures at the age of seven days ranged from 2.18 to 96.23 MPa. The strength development is clearly defined by the components and proportions of the blends. Geopolymers reach about 80% of their 28-day strength in seven days. The 25% water content was optimal for slag-fly ash geopolymers. The strength of the material increased from 68.08 to 96.23 MPa when the Blaine surface area of the slag increased from 3500 to 4500 cm2/g. The optimal proportions of the alkali solution were the intermediate ratios: SiO2/Na2O = 2.0 and SiO2/K2O = 1.5. In the case where Visonta fly ash is prepared for blending, the fly ash content can be maximized by 30%–50% in addition to the blast-furnace slag. In the second part of the research, mortars were prepared from the selected binders: 4 mixtures were prepared with two different binders. In one of these mortars, the solid part of the binder consisted of local raw materials originating from Hungary. This mixture was prepared with 43 m% fine aggregates. The optimal composition of the tested 27 binders tested was selected as the geopolymer matrix for the production of three further mortar mixtures. In these geopolymer mortars, 55, 65, and 75 m% of aggregate applied. The flowtable values of fresh mortars decreased when the proportion of sand increased. The lower the additive content was, the higher the strength of the geopolymer mortar. The 28-day compressive strengths of filtered fly ash-slag mortar sample with 55%, 65%, and 75% of fine aggregate (F–S-a55, F–S-a65, and F–S-a75) made with the selected optimised filtered fly ash-slag geopolymer binder of group A-I.3 (F–S-A-I.3) varied between 11.39 and 40.15 MPa, whereas the Visont fly ash-slag mortar sample with 43% of fine aggregate (V–S-a43) has been 25.05 MPa. For 28 days, the density ranged between 1870 and 2204 kg/m3. The V–S-a43 is found to be the lowest-density blend. The chloride migration test revealed that geopolymer mortars with higher slag content have higher resistance to Cl− ions.

Effect of binder and activator composition on the characteristics of alkali-activated slag-based concrete

Alkali Activated Slag Concrete (AASC) has been a sustained research activity over the past two decades. Its promising characteristics and being environmentally friendly compared to Ordinary Portland Cement made AASC of exceptional interest. However, there is still no firm mix design, for the AASC, that can provide desirable fresh and hardened properties based on the composition of the binder and activator. This research specifically aims to investigate the affecting parameters on the slump and compressive strength of alkali-activated slag/lime-based concrete and provide a better understanding of the potential reasons for these characteristics. The experimental program consisted of two stages; the first stage studied the effect of different binder and activator compositions, and the second stage studied the water-to-binder ratio and binder content effects on the slump and compressive strength of alkali-activated slag/lime-based concrete. The binder and activator compositions were defined through two main parameters, the hybrid factor (HF = CaO/Si2O + Al2O3) and the solution modulus (Ms = SiO2/Na2O). The compressive strength, initial slump, and slump loss were measured to evaluate the different mixes and specify the optimum range of compositions. Based on the studied parameters, the effective range to achieve desirable slump and concrete compressive strength is from HF 0.6 up to 0.8 at Ms 1.5, this would achieve a compressive strength of more than 30 MPa and a slump of 100 mm after 90 min.

Role of polyferric sulphate in hydration regulation of phosphogypsum-based excess-sulphate slag cement: A multiscale investigation

Current demand for waste recycling, phosphogypsum-based excess-sulphate slag cement (PESSC) as a sustainable cement prepared by solid wastes, urges enhancing its performance development based on microstructure optimisation. For the purpose of improving the performance and durability of PESSC used in normal or corrosive environments, it is deemed an efficient technique to produce iron-doped compounds with high thermodynamic stability. This paper presents a systematic study of the effect of iron modification on PESSC binders by introducing 0%–2% polyferric sulphate (PFS) from a multiscale viewpoint. XPS, 29Si and 27Al NMR, and TEM were used to characterise the nanostructure of solid particles firstly at Level I. Then, the chemical composition and phase assemblage of PESSC binders were revealed at Level II in terms of ICC, ICP, DTG-DSC, FTIR, BSE-EDS and XRD. Finally, setting time and strength development were determined at Level III. Results indicated that the soluble FeOH4− supplied by the hydrolysis of PFS promotes the generation of iron-doped ettringite with a greater length-to-diameter ratio and thermodynamic stability. Seeding effect of iron doping also promotes the production of spherical and retiform gels with a slight influence on the chemical components and polymerisation. Despite the fact that iron doping weakens the early strength of PESSC mortars, it promotes the persistent hydration rate by retarding precipitation and encapsulation of hydrates on the surface of the slag, showing excellent strength in the later stages. In view of microstructure evolution and performance development during each stage, PFS supplementation within 1.0% is considered a feasible modification of PESSC relying on the formation control of iron-doped hydrates.

Basics and new opportunities for chemical re-alkalisation of carbonated concrete, including alkali-activated binders

Steel corrosion is one of the main factors limiting the durability of existing reinforced concrete components. Based on the corrosive circumstances, different prevention and repair methods can be applied. In the case of carbonation-initiated corrosion, chemical re-alkalisation (CRA) is one of the standard measures to counteract alteration processes in the concrete that lead to reinforcement corrosion. The current state of research on the CRA of carbonated concrete and the various materials that have been investigated in terms of their applicability for this repair measure are summarised. The review summarises current research results in the field of carbonated concrete and the proven pozzolanic reactivity of the carbonation products in contact with portlandite, which suggests an inhibitory effect on CRA, although this has not yet been investigated. There are also initial attempts that deviate from the application of classic Portland cement as a repair material, but their applicability in practice must be questioned. The use of alternative binders and the associated different compositions of pore solutions and varying alkalinity of these binders (e.g. composite cements with a high substitution rate or alkali-activated binders), have not yet been investigated for repair processes such as CRA, although the chemical composition of binders is of the greatest importance for successful application of the repair measure.

Optimizing the manufacturing technology of high-strength fiber reinforced composites based on aluminophosphates

Phosphate copolymers show promise for composite materials, but using polymer binders for structural composites is limited by underdeveloped manufacturing processes, resulting in low strength. This work optimized the technological process for obtaining carbon fiber reinforced plastics (CFRPs) based on aluminophosphate (AP), aluminoborophosphate (ABP), and aluminochromophosphate (ACP) binders. Carbon fiber impregnation regimes were optimized considering inorganic binders’ rheological properties, density, surface tension, and wettability. A rotary rheometer evaluated phosphate binder tack to optimize molding modes. The compaction dependency of woven phosphate binder prepregs on pressure was evaluated, selecting optimal CFRP molding modes. TGA-DSC analysis optimized phosphate binder drying and curing processes. CFRP samples with 55–58 % volume AP, ACP, and ABP binders were obtained by vacuum molding, exhibiting high tensile, flexural strength and modulus. High heat resistance was shown by dynamic mechanical analysis, and thermal shock resistance evaluated by residual flexural strength change.

A Low-Carbon Composite Cementitious Material Manufactured by a Combined Process of Red Mud

In present study, the effects of varying dosages of combined red mud on the microstructure and hydration process of low-carbon composite cementitious material. The findings indicated a gradual decrease in the reactivity of RM, following a linear trend. The non-evaporable water content of the composite binder exhibited an initial increase followed by a subsequent decrease, with the optimal content identified at 10%, for RM content ranging from 10% to 90%, non-evaporable water decreases linearly. Optimal bending strength and compressive strength were achieved in the mortar when incorporating 10% of RM, reaching 8.56 MPa and 51.2 MPa at 28 days, respectively. The porosity was at its lowest when the RM content was added at 10%, but further increasing RM dosage was reversed. The pore size distribution aligned with the experimental findings on porosity. X-ray diffraction (XRD) analysis revealed the involvement of RM in the secondary hydration reaction, thereby enhancing the mechanical properties of low-carbon composite cementitious material. The optimal content of RM is suggested to be 10%, with a maximum recommended limit of 30%. The analysis has shown that red mud particles serve a dual purpose in low-carbon composite cementitious material. They enhance compactness by acting as fillers and promote cement hydration through surface activity, thereby enhancing mechanical properties, durability, and pore size distribution.

Особенности строительного контроля компонентов и конструкции полимерных зон деформационных швов мостовых сооружений

The article considers the construction control peculiarities of components and design of transition polymer zones of bridge structures expansion joints. The authors have examined the transition zones of expansion joints of in-use bridge structures constructed with polymer concrete. The study revealed the lack of regulatory requirements at the national standardization system documents level. The authors confirmed the possibility of binder composition identification at the organisation of construction control of supplied products in accordance with the requirements of design documentation. The authors also confirmed the possibility of determining the products of chemical reaction during curing of polymer concrete in the transition zone of bridge expansion joints. The authors used a low viscosity liquid epoxy resin based on bisphenol with the inclusion of an amine-type hardener to produce a polymer-concrete mixture. When the components are mixed, a composition is obtained that cures and, when bound to mineral aggregate, provides the product with high strength, water resistance, wear resistance and good adhesion to various substrates. The material obtained for bridge constructions is safe for the environment and does not react with various agents. The method of infrared spectroscopy allows identifying the initial substances and reaction products with the probability of coincidence from 70 to 97%.

Application of artificial intelligence to chronic kidney disease mineral bone disorder.

The global derangement of mineral metabolism that accompanies chronic kidney disease (CKD-MBD) is a major driver of the accelerated mortality for individuals with kidney disease. Advances in the delivery of dialysis, in the composition of phosphate binders, and in the therapies directed towards secondary hyperparathyroidism have failed to improve the cardiovascular event profile in this population. Many obstacles have prevented progress in this field including the incomplete understanding of pathophysiology, the lack of clinical targets for early stages of chronic kidney disease, and the remarkably wide diversity in clinical manifestations. We describe in this review a novel approach to CKD-MBD combining mathematical modelling of biologic processes with machine learning artificial intelligence techniques as a tool for the generation of new hypotheses and for the development of innovative therapeutic approaches to this syndrome. Clinicians need alternative targets of therapy, tools for risk profile assessment, and new therapies to address complications early in the course of disease and to personalize therapy to each individual. The complexity of CKD-MBD suggests that incorporating artificial intelligence techniques into the diagnostic, therapeutic, and research armamentarium could accelerate the achievement of these goals.

A novel powder sheet laser additive manufacturing method using irregular morphology feedstock

Irregular (i.e. non-spherical) morphology powder is more cost-efficient to produce than spherical shaped powder. However, its reduced levels of flowability limit the wide application ranges of laser beam powder bed fusion (LPBF). To address this issue, a novel powder sheet additive manufacturing concept (MAPS) is proposed. Herein, a pre-manufactured metal particle-polymer binder composite (i.e. powder sheet) feedstock is employed as a raw material. The printability of irregularly shaped powder particles in sheet (MAPS) format was physically investigated using a range of different process parameters. The manufacturing process was observed by high-speed imaging. Microstructural and chemical element characterisations of the irregularly shaped powder particle print were then compared against those prints which were conducted using sheet-based (MAPS) spherical powder morphologies. The results indicated that the geometric accuracy and density of irregular powder morphology sheet printing improved when using a negative defocus strategy of the laser beam. A negative defocusing strategy allowed for the melting mode of the material to be transformed from keyhole to a more favourable conduction state. High speed imaging revealed that more spatter and vapour plume were observed with the increase in the magnitude of the negative defocus. The multi-morphology 304 L stainless steel (SS304) samples were printed in a single printer using an efficient method for the first time, i.e. printing spherical SS304 material on top of irregular SS304. EDX results indicated an insignificant change of chemical elements between the spherical and irregular prints. EBSD results revealed that columnar grains could grow through the irregular-spherical transition zone and similar grain size can form between spherical and irregular prints. The results of this study provide insights into the optimum printing configurations for powder sheet additive manufacturing using a cost-effective solution of irregular morphology material.

Fused Filament Fabrication of WC-10Co Hardmetals: A Study on Binder Formulations and Printing Variables

This research explores the utilization of powder fused filament fabrication (PFFF) for producing tungsten carbide-cobalt (WC-10Co) hardmetals, focusing on binder formulations and their impact on extrusion force as well as the influence of printing variables on the green and sintered density of samples. By examining the interplay between various binder compositions and backbone contents, this study aims to enhance the mechanical properties of the sintered parts while reducing defects inherent in the printing process. Evidence suggests that formulated feedstocks affect the hardness of the sintered hardmetal—not due to microstructural changes but macrostructural responses such as macro defects introduced during printing, debinding, and sintering of samples. The results demonstrate the critical role of polypropylene grafted with maleic anhydride (PP-MA) content in improving part density and sintered hardness, indicating the need for tailored thermal debinding protocols tailored to each feedstock. This study provides insights into feedstock formulation for hardmetal PFFF, proposing a path toward refining manufacturing processes to achieve better quality and performance of 3D printed hardmetal components.

Development of Sustainable 3D Printable Ternary Composite

3D printing technology has the potential to reduce construction waste through its controlled manufacturing process and optimized material consumption, making it a promising sustainable construction approach with reduced environmental impact. However, current 3D printed structures often have a high carbon footprint due to the large amounts of fine-grained primary materials used in mortar composites. Most efforts to develop 3D printed structures are associated with concrete and Portland cement-based materials.This research presents an innovative approach for the reuse of gypsum to develop a material suitable for 3D printing, with the goal to industrialize the usage of waste gypsum in civil engineering. The objective of this study is to develop a sustainable gypsum-cement-pozzolanic (GCP) ternary binder composite, incorporating recycled industrial waste gypsum materials such as construction demolition waste gypsum (CDG), along with Portland cement and secondary pozzolanic materials. The GCP ternary composite combines the desired properties of gypsum, such as fast setting time, with those of Portland cement, which offers high final strength. The addition of a pozzolanic component is essential to ensure the chemical stability of this ternary system.As part of this study, ternary composites were designed and tested for their mechanical properties, durability, and suitability for 3D printing. Development and optimization of the ternary composite was carried out as a loop of procedures (Fig.1). Through these optimization procedures, a range of mixtures with necessary properties for 3D printing was found. To ensure sustainability and to assess the environmental impact of the mixtures, life cycle assessment (LCA) was performed.The LCA of GCP composites showed at least 1.5 times lower embodied energy and carbon dioxide emissions compared to Portland cement-based mortars. This is without considering avoided emissions from the end-of-life stage of gypsum waste, as well as higher technical properties that make GCP composites superior to regular cement composites. Considering these factors, GCP composites exhibit even lower emissions and are considered a viable alternative to Portland cement-based mortars.

Rheological Behavior Features of Feedstocks with a Two-Component Wax–Polyolefin Binder Compared to Analogs Based on Polyoxymethylene

Despite the large number of studies devoted to different compositions of polymer binders for PIM technology, the actual task is still a comparative analysis of the properties of different types of binders to determine their advantages and disadvantages and optimize the compositions used. In this regard, this study aims at the identification and comparative analysis of the rheological properties of the most demanded feedstocks with binders based on polyoxymethylene and a wax–polyolefin mixture under the condition of using identical steel powder filler. The rate of change in the volume fraction of the liquid phase of the binder in the compared feedstocks with temperature change was determined by the calculation–experimental method. As shown, the temperature dependence of the viscosity of feedstocks with a binder based on a polymer blend depends on factors with variable power, i.e., the viscosity change with temperature occurs by different mechanisms with their relaxation spectra. Thus, the principle of temperature–time superposition for feedstocks with multicomponent binders is not applicable, and the study of the viscosity of such materials should involve a wide range of shear rates and temperatures using experimental methods. Capillary rheometry was used to measure the flow curves of feedstocks based on polyoxymethylene and wax–polyolefin binders. The analysis of flow curves of feedstocks showed that feedstocks with a binder of solution–thermal type of debinding have significantly lower viscosity, which is an advantage for molding thin-walled products. However, their difference of 1.5 times sensitivity to the shear rate gradient leads to their lower resistance to “jets” and liquation of components because of shear rate gradients when molding products with elements of different cross-sectional areas.

Linking Chemical Structure to the Linear and Nonlinear Properties of Asphalt Binders

The study described in this paper aims to establish the relationship between the chemical composition and rheological properties of asphalt binders in both the linear viscoelastic (LVE) and nonlinear viscoelastic (NLVE) domains. Two asphalt binders with different penetration grades were subjected to four distinct aging treatments of varying severity, resulting in changes in their chemical fingerprints. Chemical characteristics of the asphalt binders were analyzed using thin-layer chromatography (TLC), Fourier Transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Frequency sweep tests were conducted to evaluate the LVE behavior of the asphalt binders, while multiple stress creep recovery (MSCR) tests were employed to assess their NLVE properties. With regard to the LVE properties, rheological index ( R) and zero shear viscosity (ZSV) derived from the Christensen-Anderson-Marasteanu (CAM) model exhibited high correlations with FTIR and molecular weight distribution (MWD) parameters. Additionally, the polydispersity index (PDI) displayed a stronger correlation with LVE-based parameters. Findings from the MSCR tests revealed that the sensitivity of the percentage recovery ( %R) to chemical composition, as opposed to nonrecoverable creep compliance ( Jnr), can be largely attributed to the degree of nonlinearity. Furthermore, it was observed that lower molecular weight molecules exert a greater influence on %R in the nonlinear domain. Finally, it was found that Jnrslope is a more reliable parameter than Jnrdiff for assessing the effects of chemical makeup on stress and temperature sensitivity.

Investigation of Polymer-Asphalt Compatibility Using Molecular Dynamics Simulation.

Polymer modification is a promising approach to enhancing the performance of asphalt binders. However, a major issue plaguing polymer mixing with asphalt is the phase separation of these two components post-mixing. In the field of polymer science, the Flory-Huggins theory has been long established as the way to describe the conditions under which a mixture is stable or unstable. This Flory-Huggins interaction parameter χ and the molecular weights of the components are required under this theory. This work uses molecular dynamics simulations to calculate χ between various polymers found in waste plastics and asphalt. The compatibility of these polymers with the asphalt binder is discussed as a function of binder composition, molecular weight, and temperature. Four common polymers (polyethylene, polystyrene, polypropylene, and polybutadiene) were tested. While none of the polymers showed good compatibility with asphalt, PE was the most compatible. Stable compatibilization of plastics with asphalt will require additives or chemical modification of the plastic.