# Fileset

[Manuscript_final_clear.docx](https://mdr.nims.go.jp/filesets/01b7880a-5328-4491-9c99-031111820f05/download)

## Creator

[Sadaki Samitsu](https://orcid.org/0000-0002-4139-1656), [Ryota Tamate](https://orcid.org/0000-0002-1704-1058), [Takeshi Ueki](https://orcid.org/0000-0001-9317-6280)

## Rights

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Rheological Properties of Dense Particle Suspensions of Starches: Shear Thickening, Shear Jamming, and Shock Absorption Properties, copyright ©  2024 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.langmuir.4c02920[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Rheological Properties of Dense Particle Suspensions of Starches: Shear Thickening, Shear Jamming, and Shock Absorption Properties](https://mdr.nims.go.jp/datasets/0f8ffa77-2d4a-44d1-8678-8203bdc5a712)

## Fulltext

Rheological Properties of Dense Particle Suspensions of Starches: Shear Thickening, Shear Jamming, and Shock Absorption PropertiesSadaki Samitsu,1 Ryota Tamate,1 Takeshi Ueki11National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan*To whom correspondence should be addressed.E-mail: SAMITSU.Sadaki@nims.go.jpABSTRACTConcentrated suspensions of Brownian and non-Brownian particles display distinctive rheological behavior highly dependent on shear rate and shear stress. Cornstarch suspensions, composed of starch particles from corn plants, served as a model for concentrated non-Brownian suspensions, demonstrating discontinuous shear thickening (DST) and dynamic shear jamming (SJ). However, starch particles from other plant sources have not yet been investigated, despite their different sizes and shapes. This study is focused on the evaluation of the effects of the structural parameters of starch particles by preparing concentrated suspensions of starch particles from 13 different plants at particle fractions of 25%–50% and their rheological behavior through steady shear, pull-out, and ball-drop tests. Starch particles can be roughly classified as polygonal and ellipsoidal. The DST and SJ behavior typically reported for concentrated cornstarch suspensions were confirmed for other starch particles in both particle groups. The ball-drop test demonstrated excellent shock absorption properties for 11 concentrated suspensions of starch particles, except for sago palms. In the case of concentrated suspensions of starch particles, the particle fraction and shear applied were the dominant factors that significantly affected the rheological behavior, whereas the particle shape was not a primary contributor. The findings of this study drive further investigation on the effect of liquid and particle surface properties in concentrated particle suspensions on DST and SJ behaviors.KEYWORDSConcentrated particle suspensions, dynamic shear jamming, discontinuous shear thickening, Brownian particles, starch particlesINTRODUCTIONThe significant changes in rheology induced by shear are useful for designing the mechanical responses of smart materials. Concentrated suspensions of both Brownian and non-Brownian particles exhibit outstanding rheology that is strongly dependent on the shear rate and shear stress.1–5 For example, the steady-state shear flow of concentrated suspensions abruptly increases their viscosity by one to two orders of magnitude above the critical shear rate; this phenomenon is referred to as discontinuous shear thickening (DST). Wagner et al.6–10 have extensively investigated the DST behavior of Brownian particle suspensions. Such non-Newtonian behavior has been extensively studied recently, particularly in physics, owing to the scientific interest in its analogy to the jamming transitions 11 that occur in granular systems under shear. Simultaneously, the material factors governing shear thickening must be elucidated to design superior rheological materials.Cornstarch aqueous suspensions serve as a model for non-Brownian particle systems in physical studies, revealing various intriguing behaviors. These suspensions exhibit distinct DST behavior,12–17 contrasting sharply with the continuous shear thickening (CST) observed in dilute suspensions as shear rate increases. When shear stress is applied to a suspension at a considerably high particle fraction, the suspension is no longer fluidic and shows a transient solid-like behavior referred to as dynamic shear jamming (SJ).18–20 SJ can be induced by impact forces and forms a solidification front owing to the solid-like behavior of the jammed particles. This phenomenon, called impact-activated solidification, results in superior shock absorption by the suspension.21–24 When a drop of the suspension impacts a solid surface, it deforms in a manner completely different from that of Newtonian liquids because of the viscous dissipation of the impact energy.25 Furthermore, the suspensions spontaneously form unique patterns under the processing conditions, such as polygonal crack patterns during the drying process,26 fingering patterns appearing at the interface with Newtonian fluids,27 and changes in gas invasion patterns due to flow-to-fracture transition of the suspensions.28 Applications utilizing these rheological properties have also been reported, such as bulletproof performances of soft armors,29,30 surface finishing and edge polishing media based on dynamic jamming properties,31 and walking on suspensions.32Experimental studies, numerical model analyses, and simulations suggest that the rheological behavior of Brownian and non-Brownian suspensions arises from the transient frictional contact between particles and/or hydrodynamic forces, contingent on shear stress.12,33–39 Additional research points to particle swelling or steric repulsion of solvated polymers as potential mechanisms for frictional particle-particle interaction.40–42 Consequently, the structural parameters of the particles are expected to influence their rheological behavior. The effects of the particle size,8,43 aspect ratio,44,45 particle shape,46 and particle surface roughness47,48 on the DST behavior have been examined using synthetic particles. However, these particles have regular shapes and smooth surfaces, in striking contrast to the irregular polygonal shape of cornstarch. The uniformity of the surface curvature, that is, the presence or absence of corners, is another structural parameter of particles that has not yet been discussed for synthetic particles. Simulation studies have demonstrated the effects of particle asperities. 49–51 Considering the differences in particle structure and surface chemistry, it would be meaningful to examine further the rheological behavior of concentrated suspensions using particles belonging to the same material category as cornstarch but having different sizes, shapes, and curvatures. The obtained results can be compared with the rheological behavior of synthetic particle suspensions to understand the rheological mechanism better and provide useful information for the design of material rheology.In addition to cornstarch, other starch particles can be obtained from various plants, including potatoes, sweet potatoes, tapioca, wheat, rice, mung beans, lotuses, and sago palms. Interestingly, the shapes of starch particles differ considerably depending on the plant used as the raw material.52,53 The rheological behavior of concentrated suspensions has not yet been investigated. In this study, the rheological behavior, including DST, SJ, and shock absorption on ball impact, were investigated for concentrated suspensions in aqueous glycerol using 13 types of starch particles of different sizes and shapes. The rheological properties of the concentrated suspensions of starch particles are discussed considering the effect of structural parameters of starch particles such as size distribution, shape anisotropy, and surface roughness. The experimental setup used in this study is shown in Scheme 1. The results obtained in this study confirms that DST and SJ behavior occur in 11 out of 13 starch particles with different shapes, similar to cornstarch, which has been investigated previously, and clarifies that particle structure is not a major factor. These results demonstrate the importance of elucidating the role of the liquid component of particle suspensions in future research to design materials for DST and SJ behaviors to achieve particle suspension materials with excellent shock absorption properties.Scheme 1. Experimental setup used in this study. Concentrated starch suspensions were prepared in an aqueous 50% glycerol solution at particle fractions of 25–50 wt% using 13 starch particles obtained from different plant resources. The rheological properties of the suspensions were characterized using steady-state shear flow to determine the shear-thickening behavior (CST or DST), a pull-out test to determine the dynamic SJ behavior, and a ball-drop test to measure the shock absorption properties.EXPERIMENTAL SECTIONThirteen starch particles obtained from different plant sources (food grade) were purchased from domestic suppliers in Japan (Table 1). Their physical properties are listed in Table S1, and the values determined in this study are summarized in Table S2. Because the as-received starch particles contained 9%–15% moisture (Table S2), they were dried under a vacuum at 80 ℃ overnight before use. Glycerol was purchased from Wako Chemical Industries (Japan). Milli-Q water was used in all experiments.Table 1. Details of the starch particles used in this study Particle Source plant Shape P1 Tapioca Polygonal P2 Sweet potato Polygonal P3 Kudzu Polygonal P4 Corn Polygonal P5 Waxy corn Polygonal E1 Mung bean Ellipsoidal E2 Potato Ellipsoidal E3 Potato Ellipsoidal E4 Lotus Ellipsoidal E5 Sago palm Ellipsoidal E6 Bracken Ellipsoidal Wheat Wheat Others Rice Rice OthersPreparation of starch suspensions in aqueous glycerol. Dried starch particles (~10 g) were added to aqueous 50 vol% glycerol (10–15 g) and were homogeneously dispersed by 30 s mixing with a planetary centrifugal mixer (AR-100, THINKY, Japan). The particle fraction ϕ is expressed in this paper in units of weight percent of the particle weight relative to the weight of the suspension (wt%). After preparation, the suspension samples were stored at 5 ℃ for a maximum of several days and redispersed with the mixer just before measurements. The suspensions are denoted in this paper by the combination of particle ID and ϕ XX.X as [particle ID]-[XXX]. For example, P1-400 is the suspension of the starch particle derived from tapioca suspended in aqueous glycerol at ϕ = 40.0 wt%.Characterization of starch particles. The particle morphology was observed using scanning electron microscopy (SEM; Miniscope TM3000, Hitachi Co., Japan). The SEM samples were prepared by fixing starch particles on a double-sided carbon tape in an isolated manner and then coating them with 1-ethyl-3-methylimidazolium bistrifluoromethylsulfonylimide ionic liquid (1 wt% in ethanol) to prevent charging. Approximately five images were recorded for each particle and analyzed using commercial image analysis software (WinROOF2021, Mitani Co., Japan). The eight structural parameters of the particles determined by image analysis are listed in Table S1. The true density of the vacuum-dried particles was measured with a helium-gas pycnometer (AccuPyc II 1340-10CC, Shimadzu Co., Japan) at a temperature of 26.0–26.5 ℃ using 4.0–5.0 g of each sample. The bulk density in the dry (ρdry) and wet (ρwet) states were determined from the weight and volume of the particle bed. Vacuum-dried particles of a certain weight W were placed in a graduated cylinder (30 mL) and densified using a vibrator. When the volume change almost completed after 1–2 min of vibration, the filled volume in thedry state (Vdry) was measured by visual inspection. ρdry (g/cm3) was calculated using ρdry = W/Vdry. Based on the accuracies of the measured weight (±0.01 g) and volume (±0.1 mL), the error in the bulk density was ±0.02 g/cm3. ρwet was calculated from the dry weight of the starch particles and apparent volume of the particle suspension in wet state (Vwet) after settling using the relationship: ρwet = W/Vwet. Starch particles with a dry weight of approximately 20 g were wetted with an excess of aqueous 50% glycerol solution for at least a day, agitated with a planetary mixer to remove any air bubbles, and the apparent volume of the suspension was measured using a graduated cylinder after sufficient time had elapsed and the particles had completely settled.Rheological measurements of suspensions: Steady-state shear flow measurements. Steady-state shear flow was tested at 20 ℃ using a high-performance rheometer (MCR102, Anton-Paar, GmbH, Austria) with a 25-mm-diameter parallel plate geometry using the true gap option. When setting the suspension, any suspension that was outside the geometry was wiped off as much as possible. A doughnut-shaped sponge filled with water was placed around the geometry to prevent the drying of water in the suspension during the measurement. The instrument was operated in stress-controlled mode. Although concentrated particle suspensions sometimes do not give uniform shear flow between the gap, the shear stress σ and shear rate γ in this study were calculated from macroscopic values recorded by the rheometer.12 The apparent shear viscosity η was evaluated by dividing the shear stress by the shear rate: η = σ / γ. Shear-thickening behavior is associated with a power law relationship between σ and γ (i.e., σ = γα, with α > 1); consequently, a power law with exponent αs can be used to describe the relationship between η and σ (i.e., η = σαs, where αs = 1 – 1/α), which can be determined from the slope of the fitted linear relationship between log η and log σ in the shear-thickening regime. According to the slope of the steady-state shear flow plot αs, the shear thickening behavior of dense suspensions can be categorized into Newtonian fluids, CST, and DST. The ideal behavior of DST expresses viscosity is expected to change discontinuously at a given shear rate, which corresponds to αs = 1 on η–σ plot. In this study, a threshold value of 0.5 as a criterion proposed by Brown et al.3 was used to distinguish between CST and DST for convenience because the ideal discontinuity was not observed probably due to the limitation of our experimental setup. The minimum viscosity ηmin were determined from the η–σ plot.Rheological measurements of suspensions: Pull-out test. The pull-out test was performed using a MCR102 rheometer equipped with an advanced lift-drive control option.20 The suspension sample was placed in a glass Petri dish (15 mm diameter) at a depth of approximately 10 mm. A cylindrical SUS rod (8 mm diameter) was inserted at a 3 mm depth and pulled out at a constant speed of 8 mm/s after waiting 1 min for equilibrium. A positive force value was recorded downward in the direction opposite to that of the geometric motion. The tests were performed in quintuplicate for each sample and the maximum values of the force recorded for each measurement were averaged. If particle sedimentation occurred over time, the suspension was occasionally mixed manually using a spatula to prevent particle segregation during measurement.Rheological measurements of suspensions:Ball drop test. A ball-drop test system was built by fixing a flat aluminum plate on top of a force gauge (ZTA-100N, IMADA, Japan) (Figure 1). The starch suspension was placed in an aluminum Petri dish (31 mm in diameter and 10 mm in depth) to a 5 mm depth and attached to the plate with thin double-sided tape. To ensure good reproducibility, an electro holding magnet was placed directly above the sample dish, and a steel ball was dropped by turning off the electricity. The transient force during impact (<10 ms) was detected by a force gauge as an analog voltage output and recorded as a time series using a digital oscilloscope. The steel ball weighed 13.7 g, and its diameter was 15.0 mm. The drop height (from the bottom of the magnet to the top of the plate) was adjusted to 170 mm, such that the maximum transient force of the test without a sample was less than the maximum load of the force gauge.Figure 1. (a) Schematic illustration and (b) photograph of the experimental setup for the ball-drop test.Results and DiscussionCharacterizations of starch particles. The morphologies of the 13 starch particles were observed by SEM (Figures 2a and 2b, Figure S1). Based on digital image analysis of the SEM images, the shape characteristics of the particles are summarized in Table S2. The Pearson correlation coefficients between the parameters were calculated to capture the particle characteristics with a small number of parameters (Table S3). Some parameters exhibited strong positive and negative correlations. Therefore, we focused on four parameters—the circular equivalent diameter Dav, aspect ratio, and roughness—the correlations of which were less than 0.50. The aspect ratio and roughness were plotted against the diameter (Figures 2c and 2d). The shapes of the 11 particles were roughly classified into two types: polygonal and ellipsoidal, in good agreement with the morphology of the SEM images. The polygonal type includes five particles, with the most typical being tapioca, whereas the ellipsoidal type includes the other six particles, which are represented by mung beans. Cornstarch, commonly used as a model non-Brownian particle for concentrated suspensions, belongs to the polygonal category. The polygonal particles present partially angular shapes with small aspect ratios of 1.15–1.3 and a narrow size distribution of 5–12 μm on average. In contrast, the smooth ellipsoidal particles have higher aspect ratios of 1.3–1.5 and a wide size distribution of 10–35 μm on average. A large aspect ratio indicates a more elongated shape of the ellipsoidal particles. The roughness ranges from 1.16 to 1.35 and is similar between the polygonal and ellipsoidal particles.Wheat is a mixture of convex lens-shaped and spherical particles (Figure S1c); however, its shape parameters, such as Dav, aspect ratio, and roughness, fall within the same ranges as those of the polygonal particles. Sago palm E5 is roughly ellipsoidal; its partially missing shape results in larger roughness than those of the other ellipsoidal particles. Rice exhibits Dav = 3.8 μm, which is the smallest among the examined starch particles. Furthermore, its sharply angled polygonal shape exhibits the largest roughness (Figure S1c). Its characteristic shape is distinct from those of the other starch particles, which are located in a different region and have neither polygonal nor ellipsoidal shapes.Figure 2. SEM images of starch particles of tapioca P1 (a) and mung bean E1 (b). The scale bar is 20 μm. Average aspect ratio (c) and roughness (d) of the particles as functions of the average circular equivalent diameter Dav. Blue squares: polygonal particles, red circles: ellipsoidal particles, orange diamond: sago palm, purple ×: rice, black +: wheat. Rice and wheat have different shapes from the polygonal and ellipsoidal particles.The true density of the starch particles was approximately 1.51 ± 0.02 g/cm3 and was almost independent of the plant sources (Table S4). This value was in close agreement with previously reported values (density of 1.50 ± 0.01 g/cm3) measured via the buoyancy method using organic liquids.20 Six dry density values were in the 0.60–0.65 g/cm3 range, and seven were in the 0.75–0.91 g/cm3 range, forming two major groups. Comparing these findings with the particle shapes shown in Table S1, the smaller dry densities correspond to polygonal particles because polygonal particles are less likely to be densely packed than ellipsoidal ones. Theoretical DST and SJ models use the volume fraction of particles in the suspension as the parameter that determines the rheological behavior.17 However, special characterization is needed to precisely evaluate the volume fractions of starch suspensions experimentally because starch particles have porous structures and absorb some water. Han et al. measured the sound velocity of a dilute aqueous solution of cornstarch particles and determined that these particles were 31% porous based on particle compressibility in solution.54 Representative values of ϕV calculated from the weight fractions ϕW used in this study are listed in Table S5.Preparation of starch suspensions and their stability over time. The starch suspensions exhibited characteristic rheological properties that were clearly different from those of the viscous liquids, both manually and visually. When the starch suspension was dropped from a spoon, it began to flow with a smooth curvature like a viscous liquid with small breaks appearing at the edges of the flow. The direction of the flow sometimes turned sharply and fell off, the flow became thicker or thinner in parts, and the thickness of the flow changed irregularly (Figure 3a, Supplementary Video S1). When the container was repeatedly tilted, the smoothness of the surface of the suspension increased and became uneven (Figure 3b a, Supplementary Video S2). When the spoon was moved quickly into the dispersion, a clear break appeared, partially breaking up into a solid, followed by a flow that closed the break and spontaneously restored the flat suspension surface (Figure 3c a, Supplementary Video S3).Starch suspensions alter hand sensation both immediately after preparation and with prolonged storage, posing stability issues. For example, the suspensions are fluid for a short time after preparation but gradually harden after storage, even in a sealed container at 5 ℃, with some suspensions hardening after approximately 1 month. This is not due to particle swelling because Kusina et al. studied the aging behavior of aqueous cornstarch suspensions by maintaining them at room temperature for several weeks, and revealed that particle size did not change over several weeks and that particle swelling had little effect on the aging behavior of aqueous cornstarch suspensions.55 Sealed stored suspensions exhibited obvious changes, indicating that water evaporation was not the cause of the changes over time. Aging of the starch particles in aqueous medium may cause such loss of fluidity. Starch particles are composed of partially crystallized hydrophilic polymers and contain amorphous polymer chains on their surfaces. Oyarte et al. reported the presence of dangling chains on the surfaces of cornstarch particles using AFM-based force-curve measurements.40 Because of their crystalline domains, they are insoluble in water at room temperature and retain their particle shape in aqueous suspensions. If the particles remain in partial contact with each other for a long time in wet state, the polymer chains on the particle surfaces can crystallize, and bonding occurs between the particles in contact. Qiao et al. studied the hydration-induced crystal transformation of starch and found that non-crystalline chains take up water molecules and form new crystalline units, thereby increasing the total crystallinity of the starch.56 The aging is thought to cause the suspension to lose fluidity and, to some extent, solidify. In this study, the suspensions were evaluated within five days of preparation to ensure the reproducibility of the experimental results.Figure 3. Photographs of starch suspension E2-450 (a) flowing down from a spoon, (b) flowing unevenly when the container is repeatedly tilted, and (c) returning flat by a slow flow after a quick incision with a spoon. The movies of the result can be supplied as Supplementary Videos S1-S3.Steady-state shear flow test. Steady-state shear tests were performed at different ϕ values using polygonal P1 and ellipsoidal E1. The apparent η value was plotted as a function of σ or the shear rate γ on both logarithmic scales (Figure 4 and Figure S2). Even though the plots of P1 and E1 present similar trends, the rheological behavior varies significantly depending on ϕ.17 At ϕ values below 35 wt%, η increases slowly with σ, indicating CST. As ϕ increases above 40 wt%, η markedly increased with σ, indicating DST. Depending on whether the slope αs is less than or greater than 0.5,3 the suspensions can be divided into CST for ϕ < 37 wt% and DST for ϕ between 37 wt% and 45 wt% (upper panel in Figure 7). While the 48 wt% suspension was visually confirmed to flow with a low γ value, η was too high to enable its value to be determined in a highly stable and reproducible manner via steady shear testing using our rheometer. The η–γ plots also confirm that the CST and DST correspond to slow and rapid rises in η, respectively (Figure S2). The ϕ ranges of CST and DST agree with those determined from the η–σ plot. DST characterized by a steady-state shear flow test appears over a narrow ϕ range of only 3 wt%. The results indicate that ϕ significantly affects the presence or absence of DST, which is consistent with previous studies on aqueous cornstarch suspensions.16,17 Previous studies have reported methodologies to quantify the magnitude of DST behavior by assessing its proximity to the maximum particle fraction at the onset of the jamming state in a disordered packing system (ϕmax).14,17,45,57 In our study, ϕmax was determined (Figure S3) using the method reported by Pradeep et al.57 The ϕmax for the tapioca particle P1 and mung bean particle E1 were 53.2 and 57.5 vol%, respectively, showing no significant difference. In the subsequent experiments, the effect of ϕ was comprehensively evaluated. Figure 4. η–σ plots in steady-state shear flow for aqueous suspensions of the (a) polygonal particle P1 and (b) ellipsoidal particle E1.Pull-out test. To analyze P1 and E1, the SJ of the suspensions was evaluated via a pull-out test (Figure 5). For both the polygonal and ellipsoidal particles, the force was almost zero at ϕ = 40 wt%, whereas a distinct peak was detected at 48 wt%. The force curve of the 48 wt% suspension increased rapidly within a displacement range of 0.5–1.0 mm and then remained nearly constant in the displacement range of 2–3 mm. Then, the force suddenly returned to zero, exhibiting a solid-like rupture behavior20. The SJ was quantitatively characterized by the peak force Fmax. When no peak appeared on the force curve, Fmax was set to zero, indicating a fluidic state. If an Fmax of 1 N or more was detected, it was considered to be in the SJ state. The Fmax in the SJ state was 5.9 N for P1-480, which is higher than the Fmax of E1-480 (2.5 N).Figure 5. Pull-out test results for concentrated suspensions of (a) P1 and (b) E1 (ϕ: upper, 48 wt%; lower, 40 wt%). Normal force versus of upward displacement of geometry. Ball-drop test. The ball-drop test was used to evaluate the shock absorption properties of the starch suspensions18. A steel ball was dropped from a height of 165 mm, and when it struck the suspension, the transient force was recorded as a time series of the oscilloscope signal (Figure 6). For both P1-350 and E1-350, which exhibited CST, the plot showed a maximum force peak fpeak of 96–97 N. fpeak was almost the same as that when the steel ball was dropped directly without a sample, indicating no shock absorption properties. Regarding P1-400 and E1-400, which have the smallest ϕ exhibiting DST, fpeak was 81–83 N, slightly smaller than that of the 35 wt% suspension. After impact with the steel ball, the plot oscillates between positive and negative values because the suspension is not sufficient to shock-absorb completely, and the plate violently oscillates up and down. For ϕ = 45 wt%, which is in the middle of the ϕ range exhibiting DST and at the lower limit for SJ, fpeak = 16–17 N is observed, which is significantly smaller than those of the 35 and 40 wt% suspensions. The small fpeak demonstrates the good shock absorption properties of P1-450 and E1-450. The depth of the suspension affects the quantitative behavior of the ball-drop test.58The ball-drop test results were further examined by finely tuning ϕ and plotting it against the fpeak value that characterizes the shock absorption properties (Figure 7c). At lower ϕ values, no shock absorption is observed, whereas at higher ϕ values, fpeak decreases rapidly from 45 wt% to 46.5 wt%. As ϕ increases further, fpeak slightly increases and becomes almost constant in the SJ range. The shock absorption is maximized at the lower end of the SJ range.Figure 6. Transient forces recorded during ball-drop tests (upper: P1, lower: E1) for the (a) 35 wt% and (b) 40 wt% suspensions, which show negligible shock absorption, and (c) 45 wt% suspensions, which exhibit excellent shock absorption. Comparison of particle fraction dependence among rheological behaviors. The results of the three types of rheological measurements (steady-state shear flow, pull-out, and ball- drop tests) for the P1 and E1 suspensions are summarized in Figure 7. Regardless of the particle shape, as ϕ increased, the fluidity changes from CST to DST at ϕ = 37 wt%, whereas at higher ϕ values of 44–46 wt%, SJ appears. The E1 particle exhibits SJ with a slightly lower critical particle fraction than the P1 particle. When ϕ becomes so high (> 48 wt%) that the suspension cannot completely fill the particle-particle voids with liquid, the particles lose their flowability and become an inhomogeneous aggregated solid. In particular, the shock absorption property improves markedly in a very narrow ϕ range that exhibits DST and corresponds to the lower part of the range for SJ. Furthermore, no qualitative difference is observed between the polygonal and ellipsoidal particles. Quantitative comparison showed slight differences in Fmax and the minimum ϕ value at which the SJ appears in the pull-out test. The Fmax values of polygonal particles are nearly twice those of the ellipsoidal particles. Figure 7. ϕ dependence on (a) steady-state share flow, (b) pull-out test, and (c) ball-drop test for P1 (left) and E1 (right) suspensions. Symbols: (a) Blue circles indicate the slope in the low shear-stress region, and purple squares indicate the slope in the high shear region. (b, c) Values marked with a cross are obtained from multiple measurements; red triangles indicate the average values; and the solid lines are drawn to guide the eyes.The rheology of particle suspensions has been studied intensively since the late 1990s, and rheology at low particle fractions and in low shear has been described by continuum formulations.2,34 When a low shear is applied to a particle suspension, the particles move in isolation with considerable gaps between each other and exhibit weak shear-rate dependent viscosity. If the particles are loosely agglomerated owing to nonhydrodynamic attractive particle–particle interactions, the applied shear dissociates the particle agglomeration, and shear thinning occurs. On the other hand, suspensions with high particle fractions near maximum close packing exhibit considerably different behavior. According to physical model studies of the rheological behavior of concentrated particle suspensions, CST, DST, and SJ are represented by the illustrations in Figure 8. In well-isolated particle suspensions with low particle fractions, as the shear rate increases, several particles begin to interact with each other and exhibit CST behavior, in which the viscosity increases continuously with increasing shear rate. As the particle fraction increases, more particles come into contact with the applied shear, and contact friction begins to occur between the particles. When particle contact occurs often, the stresses caused by the particle contact begin to propagate, forming a network.33,34,38 Consequently, DST appears, in which the viscosity increases rapidly and discontinuously with respect to the shear rate. In suspensions with high particle fractions, as shear increases, the transient stress network due to particle contact expands in three dimensions, resulting in a SJ behavior that is transiently rheologically similar to that of solids.18Thus, in concentrated particle dispersions, the particle fraction and frictional behavior between the particles are the main parameters governing the rheological behavior.4,34 The criterion for determining the particle fraction is the critical jamming fraction, which is determined by particle shape parameters, including the particle size,8,43 particle size distribution,59 and particle shape.46 Furthermore, the critical jamming fraction is also dependent on the frictional contact between particles.20,35 The ratio of the particle fraction to the critical jamming fraction is a quantitative criterion that determines significant changes in the rheological behavior of particle suspensions.Figure 8. Schematic illustrations of CST, DST, and SJ.Particle type dependence in steady-state shear flow test. As described in the previous sections, rheological evaluations were performed on the representative suspensions of P1 and E1 using different ϕ values. To gain a more detailed understanding of the effects of the particle size and shape, rheological evaluations of other starch particles were conducted using the same procedure. Steady shear tests of starch suspensions were performed for ϕ = 45 wt%, where DST was obtained for both P1 and E1 suspensions. Ten starch particles showed distinct DST in the high shear range, where η increased significantly with σ (Figure 9 and Figure S4, S5). These results indicate that the particle size, shape, and size distribution do not determine the presence or absence of DST in the starch particles examined in this study. Unlike the other starch particles, the rice suspension became paste-like and lost most of its flowability. In this study, most of the starch particles exhibited had hydrophilic surfaces and good wettability in water, whereas the rice starch particles were less hydrophilic and exhibited limited wettability. When sprinkled into water, the mung bean and corn starch particles immediately sank, whereas the rice starch particles floated (Figure S6). When water was dropped onto a starch particle bed, the mung bean and corn starch beds absorbed the water, in contrast, the rice starch particle bed did not show water absorption characteristics, and the dropped water remained on the surface (Figure S6). Owing to their insufficient hydrophilicity, the rice starch particles did not exhibit DST; instead, they formed weak aggregates in aqueous glycerol and behaved as a solid-like paste at higher particle fractions.Figure 9. η–σ plots in steady-state shear tests for starch suspensions at particle fraction of 45 wt%: (a) polygonal particles and (b) ellipsoidal particles.To evaluate the effects of the particle structural parameters on the steady-state shear flow behavior quantitatively, σmin, the onset stress of DST, and ηmin, the minimum viscosity, are plotted as functions of the particle structural parameters (Figure 10). σmin is detected within a narrow range of 0.10–0.20 Pa for the ellipsoidal particles except for bracken (E6). The polygonal particles have a wide σmin range of 0.20–0.79 Pa, and most of them are larger than the ellipsoidal particles. Furthermore, ηmin considerably varies between the particles in an ηmin range from 1.8×102 to 1.5×104 mPa∙s.While no correlation is observed between ηmin and Dav (Figure S7), σmin decreases with increasing Dav irrespective of the ellipsoidal or polygonal particles (Figure 10a). Guy et al.43 measured the steady-state shear flow of sterically stabilized poly(methyl methacrylate) particles suspended in organic liquids and investigated the correlation between particle size and σmin over a wide range from 268 nm to 45 μm. In conjunction with other reports, they proposed that σmin decreases with increasing particle size. Brown et al.12 theoretically explained that σmin follows a scaling law for particle–particle interactions that depends on particle and liquid properties, whereas osmotic pressure decreases σmin with increasing particle size.12These results are consistent with the trends observed in the present study.The correlation between ηmin and the aspect ratio is clearly positive for the ellipsoidal particles, but the correlation is not clear for the polygonal particles (Figure 10c). σmin decreases with increasing aspect ratio (Figure 10b). The effect of the aspect ratio on the DST behavior has been investigated in several studies using calcium carbonate colloids (200–300 nm in diameter, aspect ratios of 1.7, 4.3, and 6.7) suspended in poly(ethylene glycol) 44 and silica colloids (250 nm in diameter, aspect ratios of 1–11) suspended in 70 vol% aqueous ethylene glycol.45 These studies reported that the larger the aspect ratio of the particles, the lower the particle fraction at which DST appears. According to the results reported, the viscosity increases as the aspect ratio increases when comparing the same particle fraction, which is qualitatively consistent with the increase in viscosity of the ellipsoidal particles observed in this study. The large aspect ratio also contributes partially to the increase in ηmin. The lack of a clear trend for the polygonal particles is probably due to the narrow aspect ratio range examined in this study.ηmin shows a strong positive correlation with roughness independent of shape, except in the case of sago palm (Figure 10d). Although the starch particles of sago palm are relatively rougher because some of the ellipsoid shape is missing, this partial lack of shape negligibly affects ηmin. Theoretical model calculations by Blair et al.51 showed that ηmin increases with increasing particle surface protrusion size, which is consistent with the results of this study. Although the data are slightly scattered, no correlation is evident between σmin and the particle roughness (Figure S7). Lootens et al.47 synthesized micrometer-sized silica particles with rough surfaces by partially dissolving the surface and investigated the effects of particle roughness on the DST behavior of concentrated aqueous suspensions. When compared at the same particle fraction, particles with rough surfaces showed lower σmin than those with smooth surfaces. In this study, the roughness of the particles was calculated as the ratio of the perimeter (S) to the area (A), using the formula S2/(4πA). The results indicated that the roughness also increased upon increasing the aspect ratio of the particles. The apparent correlation between the aspect ratio and roughness may have masked the dependence of σmin on roughness.  Figure 10. (a, b) Shear stress at ηmin, σmin, determined from the η–σ plots in Figure 9 and (c, d) minimum viscosity ηmin plotted as functions of the particle structural parameters (circular equivalent diameter Dav, aspect ratio, roughness). Symbols: blue squares: polygonal particles, red circles: ellipsoidal particles, orange diamond: sago palm. The sago palm particles have different roughness compared to the other ellipsoidal particles.The characteristic rheological parameters obtained from steady-state shear tests included ηmin in the low shear range and the slope αs of the η–σ plot in the high shear range. ηmin represents the flowability of concentrated particle suspensions, and αs characterizes the steep η change over a narrow shear rate range, i.e., the response of η rise to shear rate or shear stress.The αs–ηmin plot in Figure 11 represents the trade-off relationship between αs and ηmin, where the soild line displays the upper bound of the trade-off for suspensions exhibiting DST.Figure 11. αs versus ηmin for various starch suspensions with different particles and ϕ values. The gray solid line represents the upper bound of the trade-off relationship.Particle type dependence in pull-out tests. Concentrated suspensions of the 10 starch particles were prepared at ϕ = 38–50 wt% and subjected to pull-out tests. Similarly to the P1 and E1 suspensions shown in Figure 5, large forces were clearly detected at high ϕ values, indicating solid-like SJ behavior. Fmax is plotted as a function of ϕ in Figure 12. The polygonal particles have larger Fmax of 5.0–6.0 N than the ellipsoidal ones (1.0–3.0 N). The ellipsoidal particles show SJ at ϕ = 40–43 wt%, whereas the polygonal particles exhibit similar behavior at ϕ ≥ 45 wt%. In general, polygonal particles have higher Fmax than ellipsoidal particles because of the greater particle–particle friction caused by particle shape effects. James et al.45 reported that a larger particle aspect ratio reduces the minimum packing fraction required for SJ as well as the frictionless jamming packing fraction. Due to their larger aspect ratios, ellipsoidal particles resulted in SJ at lower ϕ. Comparing cornstarch P4, the waxy cornstarch P5 exhibited an approximately five times higher viscosity in steady-state shear measurement and a stronger SJ behavior at lower particle fractions during the pull-out test. While cornstarch and waxy cornstarch possess similar particle sizes and shapes, they differ in their chemical structures. Cornstarch compromises both amylose and amylopectin, whereas waxy cornstarch is predominantly composed of amylopectin.52,53 Amylopectin features a branched glucose polymer, whereas amylose has a linear structure. Starch low in amylose swells in hot water and increases in viscosity upon gelatinization. This variation in surface chemistry might strengthen the interaction among the waxy cornstarch particles under shear.Figure 12. ϕ dependence on Fmax in pull-out tests for concentrated suspensions of various starch particles: (a) polygonal and (b) ellipsoidal particles.Comparison of particle types with respect to rheological behaviors. Figure 13 summarizes the three rheological properties of the concentrated suspensions of the 13 starch particle types. The η–σ plot obtained from the steady shear test shows that αs exceeds 0.5 in the high σ range, confirming DST for both the polygonal and ellipsoidal particles. In the pull-out test results, all particle suspensions with optimized ϕ exhibit Fmax during pull-out, confirming SJ. Fmax is greater for the polygonal particles than for the ellipsoidal particles. In the ball-drop test, fpeak is less than 30 N for the 10 starch particles, except for E5, confirming their excellent shock absorption properties. Sago palm in E5 has a considerably larger roughness compared to the other particles and shows SJ at larger ϕ than the other starch particles (48–50 wt%), explaining why it does not exhibit any shock absorption properties at 45 wt%. Because starch particles are naturally occurring, large variations in particle shape and size occur, limiting the ability to discuss the quantitative effect of structural parameters precisely and in detail. In addition, they cannot be stored for long periods of time due to aging, and their stability as materials is insufficient. For practical application, the material must be changed and the chemical stability of the suspension must be improved.Figure 13. Rheological characteristics for various starch suspensions determined by (a) steady-state shear flow test, (b) pull-out test, and (c) ball-drop test. (a) Slope αs in the higher stress range in the η–σ plot for a 45 wt% starch suspension. (b) Fmax obtained for various ϕ values of starch particles plotted in Figure 12. (c) fpeak obtained for a 45 wt% starch suspension.CONCLUSIONThirteen starch types obtained from different plant sources were classified into polygonal and ellipsoidal shapes according to their particle size, aspect ratio, and roughness. Using these starch particles, concentrated suspensions were prepared with ϕ values between 25% and 50% and rheological measurements were obtained via steady shear flow, pull-out tests, and ball-drop tests. The suspensions showed ϕ-dependent rheological behavior, which changed from CST to DST and SJ as ϕ increased. This study confirmed that the presence or absence of such rheological behavior does not depend on the particle size, aspect ratio, or roughness of the starch particles. On the other hand, the quantitative parameters for the rheological properties were somewhat dependent on the particle shape characteristics. σmin decreased with increasing particle size and aspect ratio, whereas ηmin increased with increasing roughness. For ellipsoidal particles, ηmin also increased with increasing aspect ratio. Whereas SJ occurred at lower ϕ values for ellipsoidal particles than for polygonal particles, polygonal particles exhibited higher Fmax than ellipsoidal particles due to larger friction between the particles. The ball-drop test confirmed that the particles exhibited excellent shock absorption properties independent of the particle shape.In previous studies, DST and SJ have been studied in relation to particle shape parameters such as particle size, aspect ratio, and particle shape. This research confirmed that DST and SJ also appear for starch particles with different shapes and that the particle structure parameters are not the decisive factors. Therefore, in the design of particle dispersion materials with excellent shock absorption properties, it will next be necessary to clarify the effects of the properties of the liquid, which is a component of the suspension, on the presence or absence of DST and SJ in the future. Jaeger et al. proposed particle–particle friction mediated by a liquid with hydrogen bonding acceptability, such as water, as a mechanism for SJ.20,60 Morris et al. noted that adhesive forces due to particle contact alone are not sufficient to explain these phenomena, and there is a need to elucidate these phenomena; knowledge of tribology is also required.4 Future investigations should be focused on the evaluation of the effects of liquids on particle interactions such as electrostatic forces, particle–particle friction, lubrication hydrodynamics, and elasto-hydrodynamic forces.61,62 In addition, as aqueous suspensions of starch particles are unstable for long periods of time, in the materials field aiming at practical applications, it will be necessary to replace starch particles with particles of other materials that are chemically stable and to develop particle suspension materials with shock absorption properties using non-volatile or non-flammable liquids.ASSOCIATED CONTENTSupporting Information.The Supporting Information is available free of charge.SEM images of starch particles. η–γ plots for aqueous suspensions of polygonal and ellipsoidal particles at various ϕ values. Properties of starch particles. Correlations between starch particle parameters. True densities of starch particles. Volume fraction values calculated from the weight fraction of particles in the suspensions. (PDF).Supplementary Video for rheological behavior of concentrated starch suspensions (MP4)AUTHOR INFORMATIONCorresponding AuthorSadaki Samitsu − National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JapanE-mail: SAMITSU.Sadaki@nims.go.jpAuthorsRyota Tamate − National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JapanTakeshi Ueki − National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, JapanAuthor ContributionsS.S.: Conceptualization, funding acquisition, investigation, methodology, validation, visualization, writing - original draft, and writing - review and editing. R.T.: Conceptualization, funding acquisition, investigation, methodology, validation, visualization, and writing - review and editing. T.U.: Conceptualization, funding acquisition, investigation, methodology, validation, visualization, and writing - review and editing.NotesThe authors declare no competing financial interest.AcknowledgementsThis study was financially supported by the Acquisition, Technology, and Logistics Agency (ATLA) of Japan. We thank Ms. Miwa Ohniwa, Ms. Misa Hazutani, Ms. Ayumi Murakami, and Ms. Mayumi Takenouchi for providing experimental and instrumental support on the NIMS Molecules & Material Synthesis Platform.ABBREVIATIONSDST,  discontinuous shear thickening; SEM; scanning electron microscopy; SJ, shear jammingReferences(1) Barnes, H. A. Shear‐thickening (“dilatancy”) in suspensions of nonaggregating solid particles dispersed in Newtonian liquids. J. Rheol. 1989, 33 (2), 329–366. (2) Wagner, N. J.; Brady, J. F. Shear thickening in colloidal dispersions, Phys. Today 2009, 62 (10), 27–32.(3) Brown, E.; Jaeger, H. M. Shear thickening in concentrated suspensions: Phenomenology, mechanisms and relations to jamming. Rep. Prog. Phys. 2014, 77 (4), 046602.(4) Morris, J. F. Shear thickening of concentrated suspensions: Recent developments and relation to other phenomena. Annu. Rev. Fluid Mech. 2020, 52, 121–144.(5) Denn, M. M.; Morris, J. F. Rheology of non-Brownian suspensions. Ann. Rev. Chem. Biomol. Eng. 2014, 5, 203–228.(6) Boersma, W. H.; Baets, P. J. M.; Laven, J.; Stein, H. N. Time‐dependent behavior and wall slip in concentrated shear thickening dispersions. J. Rheol. 1991, 35 (6), 1093–1120.(7) Bender, J.; Wagner, N. J. Reversible shear thickening in monodisperse and bidisperse colloidal dispersions. J. Rheol. 1996, 40 (5), 899–916.(8) Maranzano, B. J.; Wagner, N. J. The effects of particle size on reversible shear thickening of concentrated colloidal dispersions. J. Chem. Phys. 2001, 114 (23), 10514–10527.(9) Cwalina, C. D.; Wagner, N. J. Material properties of the shear-thickened state in concentrated near hard-sphere colloidal dispersions. J. Rheol. 2014, 58 (4), 949–967.(10) Mari, R.; Seto, R.; Morris, J. F.; Denn, M. M. Discontinuous shear thickening in Brownian suspensions by dynamic simulation. Proc. Natl. Acad. Sci. U. S. A. 2015, 112 (50), 15326–15330.(11) Bi, D.; Zhang, J.; Chakraborty, B.; Behringer, R. P. Jamming by Shear. Nature 2011, 48, 355–358.(12) Brown, E.; Jaeger, H. M. The role of dilation and confining stresses in shear thickening of dense suspensions. J. Rheol. 2012, 56 (4), 875–923.(13) Fall, A.; Huang, N.; Bertrand, F.; Ovarlez, G.; Bonn, D. Shear thickening of cornstarch suspensions as a reentrant jamming transition. Phys. Rev. Lett. 2008, 100 (1), 018301.(14) Brown, E.; Jaeger, H. M. Dynamic jamming point for shear thickening suspensions. Phys. Rev. Lett. 2009, 103 (8), 086001.(15) Jiang, W.; Xuan, S.; Gong, X. The role of shear in the transition from continuous shear thickening to discontinuous shear thickening. Appl. Phys. Lett. 2015, 106 (15), 151902.(16) Fall, A.; Bertrand, F.; Hautemayou, D.; Mezière, C.; Moucheront, P.; Lemaître, A.; Ovarlez, G. Macroscopic discontinuous shear thickening versus local shear jamming in cornstarch. Phys Rev. Lett. 2015, 114 (9), 098301.(17) Maharjan, R.; Brown, E. Effective packing fraction for better resolution near the critical point of shear thickening suspensions. Phys. Rev. E 2019, 99 (4), 042604.(18) Peters, I. R.; Majumdar, S.; Jaeger, H. M.  Direct observation of dynamic shear jamming in dense suspensions. Nature 2016, 532, 214–217.(19) Majumdar, S.; Peters, I. R.; Han, E.; Jaeger, H. M. Dynamic shear jamming in dense granular suspensions under extension. Phys. Rev. E 2017, 95 (1), 012603.(20) James, N. M.; Han, E.; de la Cruz, R. A. L.; Jureller, J.; Jaeger, H.M. Interparticle hydrogen bonding can elicit shear jamming in dense suspensions. Nat. Mater. 2018, 17, 965–970.(21) Waitukaitis, S. R.; Jaeger, H. M. Impact-activated solidification of dense suspensions via dynamic jamming fronts. Nature 2012, 487, 205–209.(22) Han, E.; Peters, I. R.; Jaeger, H. M. High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming. Nat. Commun. 2016, 7, 12243.(23) Allen, B.; Sokol, B.; Mukhopadhyay, S.; Maharjan, R.; Brown, E. System-spanning dynamically jammed region in response to impact of cornstarch and water suspensions. Phys.  Rev. E 2018, 97 (5), 052603.(24) Liu, B.; Shelley, M.; Zhang, J. Focused force transmission through an aqueous suspension of granules. Phys. Rev. Lett. 2010, 105 (18), 188301.(25) Boyer, F.; Sandoval-Nava, E.; Snoeijer, J. H.; Dijksman, J. F.; Lohse, D. Drop impact of shear thickening liquids. Phys. Rev. Fluids 2016, 1 (1), 013901.(26) Ma, X.; Lowensohn, J.; Burton, J. C. Universal scaling of polygonal desiccation crack patterns. Phys. Rev. E 2019, 99 (1), 012802.(27) Palak; Sathyanath, R.; Kalpathy, S. K.; Bandyopadhyay, R. Emergent patterns and stable interfaces during radial displacement of a viscoelastic fluid. Colloids Surf. A: Physicochem. Eng. Asp. 2021, 629, 127405.(28) Ozturk, D.; Morgan, M. L.; Sandnes, B. Flow-to-fracture transition and pattern formation in a discontinuous shear thickening fluid. Commun. Phys. 2020, 3 (1), 119.(29) Petel, O. E.; Ouellet, S.; Loiseau, J.; Frost, D. L.; Higgins, A. J. A comparison of the ballistic performance of shear thickening fluids based on particle strength and volume fraction. Int. J. Impact Eng. 2015, 85, 83–96.(30) Cho, H.; Lee, J.; Hong, S.; Kim, S. Bulletproof performance of composite plate fabricated using shear thickening fluid and natural fiber paper. Appl. Sci. 2020, 10 (1), 88.(31) Span, J.; Koshy, P.; Klocke, F.; Müller, S.; Coelho, R. Dynamic jamming in dense suspensions: surface finishing and edge honing applications. CIRP Annals 2017, 66 (1), 321–324.(32) Crawford, N. C.; Popp, L. B.; Johns, K. E.; Caire, L. M.; Peterson, B. N.; Liberatore, M. W. Shear thickening of corn starch suspensions: Does concentration matter? J. Colloid Interface Sci. 2013, 396, 83–89.(33) Seto, R.; Mari, R.; Morris, J.F.; Denn, M. M. Discontinuous shear thickening of frictional hard-sphere suspensions. Phys. Rev. Lett. 2013, 111 (21), 218301.(34) Mari, R.; Seto, R.; Morris, J. F.; Denn, M. M. Shear thickening, frictionless and frictional rheologies in non-Brownian suspensions. J. Rheol. 2014, 58 (6), 1693–1724.(35) Wyart, M.; Cates, M. E. Discontinuous shear thickening without inertia in dense non-Brownian suspensions. Phys. Rev. Lett. 2014, 112 (9), 098302.(36) Singh, A.; Mari, R.; Denn, M. M.; Morris, J. F. A constitutive model for simple shear of dense frictional suspensions. J. Rheol. 2018, 62 (2), 457–468.(37) Jamali, S.; Brady, J. F. Alternative frictional model for discontinuous shear thickening of dense suspensions: Hydrodynamics. Phys. Rev. Lett. 2019, 123 (13), 138002. (38) Gameiro, M.; Singh, A.; Kondic, L.; Mischaikow, K.; Morris, J.F. Interaction network analysis in shear thickening suspensions. Phys. Rev. Fluids 2020, 5 (3), 034307.(39) Singh, A.: Jackson, G. L.; Van Der Naald, M.; De Pablo, J.J.; Jaeger, H. M. Stress-activated constraints in dense suspension rheology. Phys Rev Fluids 2022, 7 (5), 054302.(40) Oyarte Gálvez, L.; De Beer, S.; Van Der Meer, D.; Pons, A. Dramatic effect of fluid chemistry on cornstarch suspensions: Linking particle interactions to macroscopic rheology. Phys. Rev. E 2017, 95 (3), 030602.(41) Comtet, J.; Chatté, G.; Niguès, A.; Bocquet, L.; Siria, A.; Colin, A. Pairwise frictional profile between particles determines discontinuous shear thickening transition in non-colloidal suspensions. Nat. Commun. 2017, 8, 15633.(42) Bourrianne, P.; Niggel, V.; Polly, G.; Divoux, T.; McKinley, G. H. Tuning the shear thickening of suspensions through surface roughness and physico-chemical interactions. Phys. Rev. Res. 2022, 4 (3), 033062.(43) Guy, B. E.; Hermes, M.; Poon, W. E. E. Towards a unified description of the rheology of hard-particle suspensions. Phys. Rev. Lett. 2015, 115 (8), 088304.(44) Egres, R. G.; Wagner, N. J. The rheology and microstructure of acicular precipitated calcium carbonate colloidal suspensions through the shear thickening transition. J. Rheol. 2005, 49 (3), 719–746.(45) James, N. M.; Xue, H.; Goyal, M.; Jaeger, H.M. Controlling shear jamming in dense suspensions via the particle aspect ratio. Soft Matter. 2019, 15 (18), 3649–3654.(46) Brown, E.; Zhang, H.; Forman, N. A.; Maynor, B. W.; Betts, D. E.; Desimone, J. M.; Jaeger, H. M. Shear thickening and jamming in densely packed suspensions of different particle shapes. Phys. Rev. E 2011, 84 (3), 031408.(47) Lootens, D.; Van Damme, H.; Hémar, Y.; Hébraud, P. Dilatant flow of concentrated suspensions of rough particles. Phys. Rev. Lett. 2005, 95 (26), 268302.(48) Hsiao, L. C.; Jamali, S.; Glynos, E.; Green, P. F.; Larson, R. G.; Solomon, M. J. Rheological state diagrams for rough colloids in shear flow. Phys. Rev. Lett. 2017, 119 (15), 158001.(49) Townsend, A. K.; Wilson, H. J. Frictional shear thickening in suspensions: The effect of rigid asperities. Phys. Fluids 2017, 29 (12), 121607.(50) Singh, A.; Ness, C.; Seto, R.; De Pablo, J. J.; Jaeger, H. M. Shear thickening and jamming of dense suspensions: The “roll” of friction. Phys. Rev. Lett. 2020, 124 (24), 248005.(51) Blair, M.; Ness, C. Shear thickening in dense suspensions driven by particle interlocking. J. Fluid Mech. 2022, 948, A48.(52) Buléon, A.; Perez, S. Physical characteristics of starch granules and susceptibility to enzymatic degradation. Eur. J. Clin. Nutr. 1992, 46, S3–S16.(53) Singh, N.; Singh, J.; Kaur, L.; Sodhi, N. S.; Gill, S. Morphological, thermal and rheological properties of starches from different botanical sources. Food Chem. 2003, 81 (2), 219–231.(54) Han, E.; Van Ha, N.; Jaeger, H. M. Measuring the porosity and compressibility of liquid-suspended porous particles using ultrasound. Soft Matter 2017, 13 (19), 3506–3513.(55) Kusina, C.; Smit, W.J.; Boitte, J.B.; Aubrun, O.; Colin, A. Aging of cornstarch particles suspended in aqueous solvents at room temperature. Phys. Rev. E 2021, 103 (5), 052609.(56) Qiao, D.; Zhang, B.; Huang, J.; Xie, F.; Wang, D. K.; Jiang, F.; Zhao, S.; Zhu, J. Hydration-induced crystalline transformation of starch polymer under ambient conditions. Int. J. Biol. Macromol. 2017, 103, 152–157.(57) Pradeep, S.; Nabizadeh, M.; Jacob, A. R.; Jamali, S.; Hsiao, L. C. Jamming distance dictates colloidal shear thickening. Phys. Rev. Lett. 2021, 127 (15), 158002.(58) Egawa, K.; Katsuragi, H. Bouncing of a projectile impacting a dense potato-starch suspension layer. Phys. Fluids 2019, 31 (5), 053304.(59) Boersma, W. H.; Laven, J.; Stein, H. N. Shear thickening (dilatancy) in concentrated dispersions. AIChE J. 1990, 36 (3), 321–332.(60) van der Naald, M.; Zhao, L.; Jackson, G. L.; Jaeger, H. M. The role of solvent molecular weight in shear thickening and shear jamming. Soft Matter. 2021, 17 (11), 3144–3152.(61) Boromand, A.; Jamali, S.; Grove, B.; Maia, J. M. A generalized frictional and hydrodynamic model of the dynamics and structure of dense colloidal suspensions. J. Rheol. 2018, 62 (4), 905–918.(62) Lee, Y.-F.; Luo, Y.; Brown, S. C.; Wagner, N. J. Experimental test of a frictional contact model for shear thickening in concentrated colloidal suspensions. J. Rheol. 2020, 64 (2), 267–282.For Table of Contents Only2image3.tiffimage4.tiffimage5.tiffimage6.tiffimage7.pngimage8.pngimage9.tiffimage10.tiffimage11.pngimage12.tiffimage13.tiffimage14.tiffimage15.pngimage1.tiffimage2.tiff