Binder Film Research Articles

Back Cover: Synthesis and Characterization of Novel Azido Polymers: Hyperbranched Poly-3-azidomethyl-3-hydroxymethyl Oxetane (Prop., Explos., Pyrotech. 9/2017)

The back cover picture shows that we synthesized a series of novel hyperbranched azido polymers namely poly-3-azidomethyl-3-hydroxymethyl oxetanes (HBPAMHMOs) using cationic ring opening polymerization. GPC, 13C NMR and MALDI-TOF results indicate these polymers have controllable molecular weight and degree of branching, with narrow molecular weight distributions. To take a step forward, we prepared HBPAMHMO-based energetic binder film. Compared to its linear analogues, HBPAMHMO shows lower glass transition temperature, sensitivity, higher combustion heat and mechanical properties, suggesting a great prospect for numerous applications. More details can be found in the Full Paper by Dr. Chi Zhang et al. on page 1037.

Comparative impact of different binder addition methods, binders and diluents on resulting granule and tablet attributes via high shear wet granulation

This study investigated comparative impact of different binder addition methods (pouring, dripping, spraying), binders and diluents on resulting granule and tablet attributes via high shear wet granulation. Lactose monohydrate and mannitol as diluents, and hydroxypropyl methylcellulose (HPMC E5) and polyvinylpyrrolidone (PVP K30) as binders were used. Granules were characterized for morphology, bulk-density, tapped-density, flow, size, segregation-potential and friability. To determine granule friability, procedure described in European Pharmacopoeia was slightly modified to reduce manual-variations and obtain appreciable discrimination between the formulations. Binder-diluent affinity was assessed by measuring contact angles of diluent-dispersion droplets on binder films over a period of time. All blends were pressed at the same compression force and resulting tablets were characterized for pharmacotechnical properties. Results revealed that the binder addition methods altered granule-shape, which predominantly governed the granule flow. The binder addition by spraying increased fines, blend segregation-potential, granule friability, tablet tensile-strength and tablet disintegration-time; binder addition by pouring showed an opposite impact. Mannitol granules exhibited lower bulk density, superior flow, lower segregation-potential and higher friability than their lactose counterparts. Amongst binders, PVP produced more friable granules compared to HPMC. The high polydispersity-index of polymer-binder induced non-homogeneity facilitating the blend segregation-potential. Due to higher affinity, HPMC was suitable binder for mannitol, and PVP for lactose to promote granule growth. The binder-diluent affinity dominated viscosity and surface tension of binder solution to improve granule size. Increase in granule size decreased granule-friability, which subsequently decreased tablet hardness, tensile-strength and disintegration-time. Mannitol produced harder tablets, and lactose tablets disintegrated faster by all binders and binder addition methods.

EVALUATING THE RELATIONSHIP BETWEEN DYNAMIC SHEAR MODULUS AND NANO SCALE MODULUS OF ASPHALT BINDERS AT DIFFERENT AGING CONDITIONS

Traditionally, asphalt binder is characterized by a dynamic shear rheometer, which applies a shearload on a bulk volume of liquid asphalt binder to determine shear modulus (G*). Recently, a nanoindentation testcan characterize an asphalt binder film in the form of a coating around roadway aggregates, which is more practical.In a nanoindentation test, a sharp tip is used to indent an asphalt film while residing on an aggregate surface todetermine nanoindentation modulus (E). This study evaluates whether there is a relation between G* and E. Forboth tests, replicate samples were conditioned in three ways: unaged, rolling thin film oven aged, and pressurevessel aging. Results show that the E-value is approximately 2 to 6 times larger than the G*-value based on allsamples/conditioning.

Binder and carbon-free SbSn-P nanocomposite thin films as anode materials for sodium-ion batteries

Tin-antimony/phosphorus nanocomposite thin films have been successfully prepared by pulsed laser deposition and are studied as anode materials for sodium ion batteries. The thin films exhibit a specific capacity of about 252 mAh g−1 over 100 cycles at a rate of 250 mA g−1, which is much higher than those for tin-antimony alloy, antimony or tin thin films. The improved electrochemical performance is attributed to the introduced phosphorus, which plays a key role in forming a stable solid electrolyte interface layer, thus enhances the reversibility. Phase separation is revealed after the initial cycle by forming the metallic tin and antimony nanoparticles. In addition, introducing phosphorus into tin-antimony alloy film can reduce the interfacial resistance between the electrode and electrolyte, as well as facilitate sodium-ion diffusion in the electrode.

Measuring the binder film residues on black rock in mixtures with high amounts of reclaimed asphalt

Reclaimed asphalt pavement (RAP) and virgin materials were mixed and analysed using electron microscopy and image analysis techniques. Titanium dioxide was added as a tracer in the virgin bitumen to detect the effect of mixing temperature on the “RAP binder film thickness” which is the stiffer binder in the mixture in comparison to the virgin binder. The analysis conducted with the environmental scanning electron microscopy and X-Ray spectroscopy has shown that the RAP binder, instead of completely blending with the new binder, forms a layered structure coating the RAP aggregates. This structure is composed of an inner layer of RAP binder that is not blended with the virgin bitumen indicating the existence of the “black rock”. The RAP binder film thickness is a function of mixing temperature, local aggregate curvature and size of aggregates. The higher the mixing temperature, the thinner the layer of RAP binder tends to be. RAP binder film thickness was measured at micro-scale and subsequently statistically analysed showing that along the surface of the aggregate it is not homogenous; it depends on the local curvature of the aggregate, with positive curvature resulting in a smaller film thickness and negative curvature in larger film thickness.

Evaluation of Stiffness, Strength, and Ductility of Asphalt Binders at an Intermediate Temperature

The search for a test and parameter that can effectively describe the fatigue cracking resistance of an asphalt binder has led to many approaches. Of these, researchers have used stiffness, strength, and ductility-based criteria to screen binders on the basis of inherent resistance to cracking. In this study, poker chip testing on thin films of asphalt binder was used at intermediate temperatures to obtain both stress and ductility-based properties of eight binders. In addition, a dynamic shear rheometer frequency sweep at an intermediate temperature was conducted to obtain stiffnesses of the binders and a surrogate parameter for ductility. The results showed no relationship between strength and stiffness. In most cases, binders that were rated to have high ductility on the basis of the dynamic shear rheometer parameter also had high toughness on the basis of the poker chip test. However, some binders clearly departed from this trend, with at least one binder exhibiting both ideally desired high stiffness and toughness. Examination of failure surfaces from the poker chip test provided additional information about the mechanisms that drove failure.

Low temperature rheological properties of asphalt mixtures containing different recycled asphalt materials

Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) are valuable materials commonly reused in asphalt mixtures due to their economic and environmental benefits. However, the aged binder contained in these materials may negatively affect the low temperature performance of asphalt mixtures. In this paper, the effect of RAP and RAS on low temperature properties of asphalt mixtures is investigated through Bending Beam Rheometer (BBR) tests and rheological modeling. First, a set of fourteen asphalt mixtures containing RAP and RAS is prepared and creep stiffness and m-value are experimentally measured. Then, thermal stress is calculated and graphically and statistically compared. The Huet model and the Shift-Homothety-Shift in time-Shift (SHStS) transformation, developed at the École Nationale des Travaux Publics de l'État (ENTPE), are used to back calculate the asphalt binder creep stiffness from mixture experimental data. Finally, the model predictions are compared to the creep stiffness of the asphalt binders extracted from each mixture, and the results are analyzed and discussed. It is found that an addition of RAP and RAS beyond 15% and 3%, respectively, significantly change the low temperature properties of asphalt mixture. Differences between back-calculated results and experimental data suggest that blending between new and old binder occurs only partially. Based on the recent finding on diffusion studies, this effect may be associated to mixing and blending processes, to the effective contact between virgin and recycled materials and to the variation of the total virgin-recycled thickness of the binder film which may significantly influence the diffusion process.

Polyurethane Binder Mechanical Properties under Different Crosslinking Conditions

Mechanical properties of polyurethane type polymer binder with selected reactivity, used for production of the composite material based on scrap tires, were investigated under different crosslinking conditions: temperature, relative air humidity, hardening time. Shore C hardness, tensile strength and elongation at break were selected as main parameters, reflecting crosslinking degree of the prepared polymer binder films. DMA investigation of the samples in tensile mode of loading were realized to clear up influence of deformation circumstances on storage and loss components of the elasticity modulus. Strong correlation between mentioned above mechanical properties of the polymer binder and selected crosslinking conditions of the polymer were obtained. It was affirmed previously, that crosslinking degree of the polymer binder in the same time has direct influence also on mechanical properties of the composite material.

Nondestructive Low-Temperature Cracking Characterization of Asphalt Materials

AbstractAn acoustic-emission approach to evaluate the low-temperature cracking performance of asphalt binders is presented. The acoustic activity of a thin film of asphalt binder bonded to a granit...

Conceptualizing the asphalt film thickness to investigate the Superpave VMA criteria

Asphalt binder film thickness (FTb) is the key factor that is responsible for durability of asphalt mixtures. Mixtures with coarse aggregate gradations have difficulty meeting the Superpave minimum voids in mineral aggregate (VMA) criteria even though they tend to have thick asphalt films. In this study, the concept of asphalt binder film thickness (FTb) was used to investigate the Superpave VMA criteria. Superpave aggregate gradations of three nominal maximum aggregate sizes (NMAS): 9.5, 12.5 and 19.0 mm, were used. Aggregate gradations passing above, below, crossover through, humped, and through restricted zone were all considered. Superpave Gyratory Compactor test data of 126 compacted asphalt mixtures were used in the study. The current Superpave VMA criteria relate the mixture durability with VMA and set the same VMA value for mixtures with the same NMAS regardless of other parameters. However, a poor relationship was found between VMA and FTb (a durability measure) with an R2 ≅ 0.01, and yet a relatively good relationship (R2 ≅ 0.38) was found between voids filled with asphalt (VFA) and FTb although the VFA volumetric phase is part of the VMA volumetric phase in the mixture. This result was justified by the poor relationship between VFA and VMA (R2 ≅ 0.13). Despite that the effective binder content (Pbe) as a volumetric phase represents the VFA in the mixture, the relationship between FTb and Pbe was found to be more significant (higher R2) than the relationship between FTb and VFA. In this study, asphalt mixtures that did fail the Superpave VMA criteria in some cases had adequate asphalt FTb, and mixtures that passed the criteria did not necessarily have adequate FTb. In conclusion, although the current Superpave VMA criteria are significant, findings of this study support the tendency to modify the current criteria.

Time-dependent deformation behavior of polyvinylidene fluoride binder: Implications on the mechanics of composite electrodes

Abstract The majority of existing battery models that simulate composite electrode behavior assume the binder as a linear elastic material due to lack of a thorough understanding of time-dependent mechanical behavior of binders. Here, thin films of polyvinylidene fluoride binder, prepared according to commercial battery manufacturing method, are subjected to standard monotonic, load-unload, and relaxation tests to characterize the time-dependent mechanical behavior. The strain in the binder samples is measured with the digital image correlation technique to eliminate experimental errors. The experimental data showed that for (charging/discharging) time scales of practical importance, polyvinylidene fluoride behaves more like an elastic-viscoplastic material as opposed to a visco-elastic material; based on this observation, a simple elastic-viscoplastic model, calibrated against the data is adopted to represent the deformation behavior of binder in a Si-based composite electrode; the lithiation/delithiation process of this composite was simulated at different C rates and the stress/strain behavior was monitored. It is observed that the linear elastic assumption of the binder leads to inaccurate results and the time-dependent constitutive behavior of the binder not only leads to accurate prediction of the mechanics but is an essential step towards developing advanced multi-physics models for simulating the degradation behavior of batteries.

Evaluating the Effect of Mix Design and Thermodynamic Parameters on Moisture Sensitivity of Hot Mix Asphalt

AbstractThis study is an attempt to identify the effective mix design and thermodynamic parameters for the moisture damage of hot mix asphalt. In the present study, 24 different combinations of asphalt mixtures were made and evaluated using three types of aggregates with different mineralogical composition, two types of asphalt binders, and three types of additives. The components of surface-free energy of asphalt binders and aggregates are measured to provide thermodynamic parameters using the Wilhelmy Plate and Universal Sorption Device, respectively. To determine the performance of moisture sensitivity, environmental conditions simulation according to the modified Lottman test was used, and an indirect tensile strength test has been conducted on asphalt mixtures. The results of statistical analysis presented show that the free energy of cohesion, free energy of asphalt binder-aggregate adhesion, specific surface area of aggregates, and asphalt binder film thickness on the aggregate surface have a direc...

EXPERIMENTAL EVALUATION OF ANTI-STRIPPING ADDITIVES ON POROUS ASPHALT MIXTURES

The open structure of porous asphalt mix influences its strength and durability against air, water and clogging materials. These factors cause loss of adhesion between binder-aggregate interface and loss of cohesion within the binder film. This could lead to stripping problem which contribute to premature failures as well as deterioration in the performance and service life of porous asphalt. Therefore, this study is aimed to evaluate the potential of diatomite as anti-stripping additives in porous asphalt and compared with hydrated lime and Ordinary Portland Cement (OPC). Field Emission Scanning Electron Microscopy (SEM) test and Energy Dispersive X-ray Spectroscopy analysis (EDX) were conducted to investigate the microstructure and chemical composition of the anti-stripping additives. A number of gyratory compacted samples of porous asphalt mixture with Malaysian gradation were prepared. Each sample was incorporated with 2% of anti-stripping additives as filler then mixed with polymer modified bitumen of PG76. The samples were measured for air voids content, permeability rate, resilient modulus and abrasion loss. The results indicate that samples prepared with hydrated lime show higher permeability rate and lower abrasion loss compared to samples with OPC and diatomite. However, the samples prepared with diatomite show enhanced resilient modulus compared to those with hydrated lime and OPC.

Investigating the interaction between asphalt binder and fresh and simulated RAP aggregate

Although the role of individual ingredients of hot mix asphalt (HMA) such as asphalt binder and aggregates on its performance is readily recognized, there is only limited understanding about the interactions between these components and the properties of binder-aggregate interface. In order to study the interactions between asphalt binder and mineral aggregates, an interfacial test method was developed and its effectiveness was evaluated. Interfacial interactions were evaluated by testing thin films of an asphalt binder interfaced with the surface of aggregates under two different modes of loading in shear: sinusoidal oscillation and monotonically increasing. An Interaction Parameter (IP) was proposed to quantify the binder-aggregate interfacial effects. The results show that the methodology used in this study can quantify the effects of interaction between the asphalt binder and mineral aggregates. Furthermore, this research also investigated the interaction of an asphalt binder with the surface of simulated reclaimed asphalt pavement (RAP) aggregates. The results from this research not only provide an insight to the effects of binder-aggregate interaction, but can also help practitioners to better understand the effect of mixing conditions on the properties of mixtures produced using different materials.

Multiscale imaging and characterization of the effect of mixing temperature on asphalt concrete containing recycled components.

When producing asphalt concrete mixture with high amounts of reclaimed asphalt pavement (RAP), the mixing temperature plays a significant role in the resulting spatial distribution of the components as well as on the quality of the resulting mixture, in terms of workability during mixing and compaction as well as in service mechanical properties. Asphalt concrete containing 50% RAP was investigated at mixing temperatures of 140, 160 and 180°C, using a multiscale approach. At the microscale, using energy dispersive X-ray spectroscopy the RAP binder film thickness was visualized and measured. It was shown that at higher mixing temperatures this film thickness was reduced. The reduction in film thickness can be attributed to the loss of volatiles as well as the mixing of RAP binder with virgin binder at higher temperatures. X-ray computer tomography was used to characterize statistically the distribution of the RAP and virgin aggregates geometric features: volume, width and shape anisotropy. In addition using X-ray computer tomography, the packing and spatial distribution of the RAP and virgin aggregates was characterized using the nearest neighbour metric. It was shown that mixing temperature may have a positive effect on the spatial distribution of the aggregates but did not affect the packing. The study shows a tendency for the RAP aggregates to be more likely distributed in clusters at lower mixing temperatures. At higher temperatures, they were more homogeneously distributed. This indicates a higher degree of blending both at microscale (binder film) and macroscale (spatial distribution) between RAP and virgin aggregates as a result of increasing mixing temperatures and the ability to quantify this using various imaging techniques.

Inelastic shape changes of silicon particles and stress evolution at binder/particle interface in a composite electrode during lithiation/delithiation cycling

Inelastic shape changes of Si particles and stress evolution at binder/particle interface was modeled using coupled diffusion–stress framework available in finite element software. A simple model that contains two spherical Si particles with and without the polymer binder film was used to represent the composite electrode. The particles were lithiated and delithiated at two different rates: one representing a slow charging case which results in a uniform Li concentration throughout the Si particles and the other representing a fast charging condition which results in non-uniform lithium concentration within the spherical Si particles. The inelastic shape changes and associated contact forces predicted by the model are qualitatively consistent with experimental data. Further, the effect of binder mechanical properties and the binder fraction on the stress evolution in Si particles and at the binder/particle interface was calculated. The proposed model, although simple, can guide a battery design engineer to choose a proper binder, charge/discharge strategy, and binder fraction for a durable electrode design.

Fusion bonding of thermosets composite structures with thermoplastic binder co-cure and prepreg interlayer in electrical resistance welding

A new concept combining both thermoplastic binder co-cure and prepreg interlayer is proposed and investigated for fusion bonding of thermosets composite structures. Three different thermoplastic binders were co-cured respectively onto the surface of the carbon fiber reinforced epoxy (CF/Epoxy) composite laminates to form an auxiliary medium for electrical resistance welding. The carbon fiber reinforced binder (CF/Binder) prepreg interlayer, which is compression molded with a single layer of carbon fiber fabric sandwiched between two binder films, was designed as the heating element. Double cantilever beam (DCB) specimens were fabricated by fusion bonding of the CF/Epoxy composite laminates. The influence of the thermoplastic binders and the CF/Binder prepreg interlayers on the mode I interlaminar fracture toughness (GIC) and the morphology of the fracture surface were studied respectively by double cantilever beam test and scanning electron microscope. The results indicate that a maximum average delamination strength GIC of 1879.6J/m2 was obtained in the case of the AX8900 binder welded specimens using twill weave fabric heating element. Three types of failure pattern can be visually and microscopically observed, i.e. interfacial-type failure, cohesive-type failure and interlaminar-type failure.

Rolling Thin Film Oven Test and Pressure Aging Vessel Conditioning Parameters: Effect on Viscoelastic Behavior and Binder Performance Grade

This paper presents a sensitivity analysis of two parameters applied for the rolling thin film oven test (RTFOT) and pressure aging vessel (PAV) aging on the viscoelastic behavior and performance grade of asphalt binder PG 58-22. For the RTFOT, the temperature was varied from the default temperature of 163°C to 143°C and to 183°C. For the PAV, the binder film thickness was varied from the default 3.2 mm to 1.0 and 5.0 mm. Dynamic shear rheometer (DSR) tests were run with a temperature sweep from 46°C to 82°C at a frequency of 1.59 Hz on the virgin binder, as well as on the RTFOT and RTFOT+PAV-aged samples. Bending beam rheometer (BBR) tests were carried out at −12°C, −18°C and −24°C on the RTFOT+PAV-aged samples. The effect of the mentioned conditioning parameters on | G*| and δ—as well as on the upper and lower performance grade—was investigated. Results show that the effect of RTFOT temperature on the | G*| and δ is more distinct for lower DSR temperatures. In general, the effect of a change in the RTFOT temperature on the viscoelastic parameters can be considered as small. At 46°C DSR, a change of 1°C in the RTFOT temperature shifts | G*| by 2.2% and δ by 0.08°. The PAV binder film thickness has an exponential effect on | G*| and δ. A reduced RTFOT temperature leads to reduced long-term aging after PAV. Reduced short-term aging owing to reduced production temperatures results in significantly reduced long-term aging. The effect of RTFOT temperature and PAV binder film thickness on upper and lower performance grade was found to be insignificant.

Quantitative evaluation of blending and diffusion in high RAP and RAS mixtures

Due to variable aging of recycled asphalt pavement (RAP) and recycled asphalt shingle (RAS), the concerns arise over old-new binder blending during mixture production and subsequent diffusion process. In this study, a modified staged-extraction method was validated and employed to extract binder in approximately equal layers from retrieved virgin and RAP/RAS aggregates after mixing and subsequent diffusion treatment. Quantitative analysis was done on extracted binders in terms of large molecule size percentage LMS (%) from gel permeation chromatography (GPC). The results indicated that a well-blended binder film coated virgin aggregates from 50% RAP mix, while a non-homogeneous binder film was observed on RAP aggregates. The system of binder blend coating the virgin and RAP aggregates with un-mobilized RAP binder was validated. A possible composite binder system was found coating the virgin aggregates in 10% RAS mix. The diffusion study showed that within the mixture silo storage time, binder diffusion could be accomplished in both warm and hot mixes containing 50% RAP, indicating that binder homogeneity may not be an issue in high RAP mix. The binder diffusion in RAS mix was captured in a very slow rate. It was suggested that binder homogeneity can still be critical for high RAS mix.

Organic-free Anatase TiO₂ Paste for Efficient Plastic Dye-Sensitized Solar Cells and Low Temperature Processed Perovskite Solar Cells.

Recently, the synthesis of fine TiO2 paste with organic-free binder emerged as an indispensable technique for plastic photovoltaics due to the low temperature processing requirement. In this study, pure anatase TiO2 nanoparticles and organic-free TiO2-sol were successfully synthesized individually in organic-free solution. By mixing the pure anatase TiO2 with the newly developed TiO2-sol binder, mechanically robust and well-interconnected TiO2 films were prepared via UV-irradiation at low temperature for applications in plastic dye-sensitized solar cells (p-DSSCs). The structural, electrical, and photovoltaic properties of the films as well as the devices were investigated by various techniques. The dye-loading amount of the obtained film is 2.6 times that of the P25 electrodes. As revealed by electrochemical impedance spectroscopy results, the film derived from the as-prepared anatase TiO2 paste (A-TiO2) exhibits much smaller charge transport resistance and lower electron recombination rate than the P25 film, while the introduction of TiO2-sol into the paste can further remarkably decrease the resistance of the produced film (AS-TiO2). The p-DSSCs employing AS-TiO2 photoanode yield a high efficiency up to 7.51%, which is 86% higher than the P25 reference cells and also 31% higher than the A-TiO2 cell. As a proof of concept, the newly developed AS-TiO2 paste was also applied to low temperature processed perovskite solar cells (PSCs), and a promising high efficiency up to 9.95% was achieved.