Small Amplitude Oscillatory Shear Tests Research Articles

Hemicellulose-bacterial cellulose ribbon interactions affect the anisotropic mechanical behaviour of bacterial cellulose hydrogels

The aim of this study is to investigate the effect of hemicellulose-cellulose interactions on the anisotropic structure of the bacterial cellulose (BC) ribbon network. BC-arabinoxylan (BC-AX) and BC-mixed linkage glucan (BC-MLG) composites were prepared. The mechanical/rheological behaviour was evaluated by compression combined with small amplitude oscillatory shear (SAOS) and stress-relaxation tests. Microscopy revealed that the BC ribbons tended to orient parallel to the liquid/air interface. AX and MLG gathered on the surface of cellulose ribbons but had limited influence on the crystallinity of BC. BC hydrogels showed direction-dependent mechanical properties in compression and stress-relaxation tests. The peak compressive modulus of the tangential BC sample (compressed towards the side of the sample) was over 1000 kPa, whereas for the normal sample (compressed towards the top of sample) the value was only 280 kPa. The relaxation ability of the tangential sample was 48% lower than the normal sample at 1% compression ratio. AX and MLG reduced the anisotropic behaviour of the native BC in normal/tangential compression and stress-relaxation tests, especially in the highly-compressed composites. However, the rheological behaviour of BC and the composites was comparatively isotropic in SAOS. This study is beneficial for further understanding of the contribution of hemicelluloses to the mechanical properties of BC hydrogels, and may promote the application of BC-based materials in food and medical industries.

Influence of Type and Concentration of Biopolymer on β-Carotene Encapsulation Efficiency in Nanoemulsions Based on Linseed Oil.

Many lipophilic active substances, such as β-carotene, are sensitive to chemical oxidation. A strategy to protect these ingredients is encapsulation using nanoemulsions. This work analyzes the relationship between the physical stability and encapsulation efficiency of nanoemulsions based on linseed oil. The role of two different polysaccharides, Advanced Performance xanthan gum (APXG) or guar gum (GG) as stabilizers at different concentrations were studied to reach the required physical stability of these systems. This was investigated by means of droplet size distributions, steady-state flow curves, small amplitude oscillatory shear tests, multiple light scattering, and electronic microscopy. The overall results obtained reveal a depletion flocculation mechanism in all the APXG nanoemulsions, regardless of the concentration, and above 0.3 wt.% for GG nanoemulsions. Moreover, it has been demonstrated that enhanced physical stability is directly related to higher values of encapsulation efficiency. Thus, the nanoemulsion formulated with 0.2 wt.% GG, which presented the lowest creaming degree conditioned by depletion flocculation, showed a relative β-carotene concentration even above 80% at 21 days of aging time. In conclusion, the adequate selection of polysaccharide type and its concentration is a key point for the application of stable nanoemulsions as vehicles for active ingredients.

Insights into the viscoelastic properties of cement paste based on SAOS technique

Understanding the viscoelastic properties of cement paste is beneficial to pumping, formwork casting and 3D printing of cement-based materials. This paper presents new insights into the viscoelastic properties of cement paste with various compositions. Several parameters, including critical strain, storage modulus and viscoelastic yield stress obtained from small amplitude oscillatory shear (SAOS) test, are selected to characterize the viscoelasticity of fresh cementitious paste. Results reveal that increasing water-to-cement (w/c) ratio reduces the storage modulus at linear viscoelastic region (LVER) and viscoelastic yield stress of cement paste, whereas higher w/c increases the critical strain. The replacement of cement by fly ash has no significant influence on the critical strain of cement paste. Due to the improvement of cohesive bonding between cement particles by nanoparticles, the incorporation of nano-Fe3O4 particles results in an increase in the storage modulus at LVER, critical strain and viscoelastic yield stress. The critical strain of cement paste gradually increases with the concentration of polycarboxylate ether (PCE) superplasticizer, which possibly can be attributed to the interactions and entanglement of PCE molecules adsorbed onto the solid particles. By contrast, cement pastes with low PCE additions exhibit an increase in the viscoelastic yield stress, while higher PCE additions significantly decrease the storage modulus at LVER and viscoelastic yield stress of cement paste.

Influence of protein ratios on the structure and gel properties of soybean-wheat co-precipitated proteins

Co-precipitation is a method of combining proteins that can improve the defects of a single protein while also improving its functional properties. The effect of protein ratios on the structure and gelation of co-precipitated prepared with soy protein isolate (SPI) and wheat protein (WP) was investigated in this study. Structural analysis revealed that co-precipitation triggered sheet-helix transitions of SPI and WP, exposing hydrophilic groups and embedding hydrophobic moieties. The water dispersibility of the soybean-wheat co-precipitated protein (SWCP) was significantly improved (p < 0.05). Furthermore, when compared to the protein blend, the effect of co-precipitation was more significant. Small amplitude oscillatory shear tests revealed that the interaction between SPI and WP altered the gel formation temperature and increased gel elasticity. Co-precipitated protein resulted in denser and more homogenous gel networks with very strong inter-floc links, as well as increased water holding capacity and gel strength. According to the findings, co-precipitation may be a simple and practical method for modifying proteins to improve their functional properties.

Development of soy protein isolate emulsion gels as extrusion-based 3D food printing inks: Effect of polysaccharides incorporation

Soy protein isolate (SPI) emulsion gel inks with polysaccharides of guar gum (GG) or xanthan gum (XG) for extrusion-based three-dimensional (3D) printing were investigated. The effects of the polysaccharide type and concentration on the printability, rheological properties, and microstructure of inks were discussed. Results indicated that the 3D printed products of SPI-GG0.5 inks demonstrated low dimensional printing deviation with great self-supporting capability and smooth and slightly flawed surface texture, while SPI-XG0.5 inks had the highest hardness and rough surface texture. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that SPI-XG0.5 inks exhibited the maximal gel strength, providing its 3D printed products with highest hardness. Secondary loops of Lissajous plots wouldn't emerge in SPI-XG0.5 inks, indicating decreased network flexibility and slightly larger dimensional printing deviation. The microstructure and fourier transform infrared (FTIR) analysis suggested the interaction of SPI with XG was stronger than that of GG due to hydrogen bonding and electrostatic interactions. When the XG concentration reached 0.5%, the network structure of the inks was changed, resulting in a rough surface texture of the 3D printed product. There are few studies on 3D printing of SPI emulsion gels, and this research offers more possibilities for the development of 3D printing inks.

Enhanced dispersion stability and interfacial damping of POSS-functionalized graphene oxide in PDMS nanocomposites

Polyhedral oligomeric silsesquioxane (POSS) functionalized graphene oxide (GO) is prepared to improve the dispersity of GO nanofillers in a polydimethylsiloxane matrix. Improved interfacial affinity of the GO-POSS with a polymer matrix is characterized by a small amplitude oscillatory shear test. We confirm that the POSS-functionalized GO induces better filler dispersibility and less filler aggregation in the matrix, resulting in enhanced elasticity in the solution. After curing, the POSS interface works as a soft and lubricating layer at the interface, which enhances interfacial damping within the nanocomposites.

Determination of linearity limit of bitumen and mastic using large-amplitude oscillatory shear

ABSTRACT The delineation of the linear/nonlinear response of bituminous material in the frequency domain is conducted using the small-amplitude oscillatory shear test, wherein only the peak stress and strain are available. In contrast, the large-amplitude oscillatory shear tests provide complete waveform data. Analysis of such data can help to unravel the linear/nonlinear response with greater accuracy. This investigation reports such an exercise. An experimental investigation is conducted on five different materials at different strain amplitudes, frequencies, and temperatures. The geometry-based parameters obtained from the Lissajous plot gave contradictory linear/nonlinear delineation. Analysis of the higher order harmonics did not show any appreciable presence of nonlinearity. However, the orientation of the Lissajous plots differed from the strain amplitude. The elastic and viscous stress could be predicted using the first-order Chebyshev coefficients indicating the linear response, but the coefficients differed with the strain amplitude. The scaling-superposition of the waveform revealed a clear demarcation of the linear/nonlinear response. This indicated that the response of the bituminous material needs to be analysed for a range of frequency and amplitude. The mere analysis of the waveform data at any test condition can help only to establish the necessary condition for linearity but not a sufficient condition.

Dual role of nanoclay in the improvement of the in-situ nanofibrillar morphology in polypropylene/polybutylene terephthalate nanocomposites

The present study has addressed the effects of nanoclay on the properties of polypropylene (PP)/polybutylene terephthalate (PBT) blend fibers such as their dyeability and, rheological and resiliency behaviors which are produced by melt spinning. The results of the differential scanning calorimetry (DSC) analysis indicated that the presence of both nanoclay and PBT significantly influenced the crystallinity of PP which also confirmed their nucleating effects on the nanocomposite fibers. Compared to neat PP fibers, the incorporation of 0.5–1wt.% of nanoclay and 10 wt.% of PBT nanocomposite fibers caused approximately 23% and 52% enhancements in the resiliency and dye uptake respectively without using toxic carriers. The rheological analysis was carried out for investigating the viscoelastic behavior, and microstructural and dispersion of nanoclay in the nanocomposite fibers. The rheological behavior in the small amplitude oscillatory shear (SAOS) test demonstrated the percolation threshold network of the structure of PBT fibrils in the PP matrix. When the PBT domains are fibrillated, the storage modulus (G′) and complex viscosity increase compared to neat PP. Also, the nonterminal behavior at low frequencies indicates the uniform dispersion of nanoclay in fiber nanocomposites. These all cause the improvement of the melt strength of the PP matrix. Transmission electron microscopy (TEM) was used to study the dispersion and localization of nanoclay. Nanoclay has also played a compatibilizing role in the immisible PP/PBT blend and was localized mainly in the PBT disperse and interface, and therefore prevented coalescence. The role of the compatibility of nanoparticles is to decrease the mean diameter of the nano-fibrils to 75 nm, for the hot-drawn nanocomposite fibers, as measured by scanning electron microscopy (SEM). All of the above lead to increasing the melt strength and elasticity of the nanocomposites in the fiber spinning process.

Rheology and structural build-up of sodium silicate- and sodium hydroxide-activated GGBFS mixtures

Alkali-activated slag cements (AAS) are considered as an alternative to portland cement (PC) in many studies. A significant number of studies have focused on their mechanical and durability properties, but very few studies have concentrated on their rheological behavior. In this study, the effects of sodium silicate and sodium hydroxide on the rheological properties and structural build-up of alkali-activated GGBFS mixtures have been investigated. The sodium silicate-activated GGBFS mixtures exhibited a lower yield stress and a higher plastic viscosity than sodium hydroxide-activated GGBFS mixtures. The small-amplitude oscillatory shear (SAOS) tests indicated a negligible colloidal interaction between GGBFS particles in sodium silicate-activated system; therefore, the early increase in structuration was associated with the formation of reaction products due to the interaction between the dissolved calcium ions and the silicates originated from the activator solution. On the other hand, the stiffness and the early increase in structural build-up of sodium hydroxide-activated GGBFS system were attributed to the formation of well-percolated network.

Concentration dependence of yield stress, thixotropy, and viscoelasticity rheological behavior of lithium-ion battery slurry

The rheological properties of electrode slurry are mainly influenced by the concentration, which further affects the Lithium-ion batteries (LIBs) quality and manufacturing processes. In this work, various methods including steady-state shear, creep, rheological model fitting, hysteresis loop, and small amplitude oscillatory shear (SAOS) measurement were employed to investigate the concentration-dependent rheological behaviors of slurry, in particular its yield stress, thixotropy, and viscoelasticity. Results show that the difference in yield stress obtained from varying methods is observed, in which the yield stresses measured by the SAOS test are closer to the steady-state value due to its advantage that non-destructive property at small deformations only causes minimum disturbance. The improvement of slurry concentration enhances the bonding strength between particles, thereby resulting in an increase of yield stress and thixotropy, and a decrease of the time scale of transient behavior during the creep process. In oscillatory shear measurement, both storage and loss modulus are concentration-dependent, while yielding and strain stiffening corresponding to critical strains exhibit concentration-independent. In addition, the increase in concentration leads to a more pronounced strain stiffening behavior and a lower characteristic frequency as well as a longer relaxation time. Understanding the relationship between concentration and rheological behaviors will be helpful for material design, preparation, and production in different stages.

Enhancing magnetorheology with precession magnetic fields

We demonstrate a new route to enhance magnetorheology using precession-like magnetic fields. This field configuration is generated by the superposition of a 2D rotational field applied orthogonal to a uniaxial DC field. Maintaining a columnar linear chain structure when applying a precession field was determined to be integral in increasing the average cluster size of the aggregates for low precession angles and a low Mason number. A yield stress increase was experimentally observed when reapplying a uniaxial DC field following the application of a controlled low-angle precession field indicating a favorable structural evolution had taken place under the unsteady field configuration. Experimental results of small-amplitude oscillatory shear tests and shear rheograms are supported by particle-level simulation 3D models and start-up tests.

Effect of viscoelasticity on the foaming behaviour of long-chain branched polypropylene with different branching degrees analysed by using bubble-growth modelling

Long-chain branched polypropylene (LCB-PP) was generated by a melt grafting reaction with trimethylolpropane triacrylate (TMPTA) as the grafting monomer and zinc dimethyldithiocarbamate (ZDMC) or styrene (St) as the co-monomers. High-temperature size exclusion chromatography (HT-SEC) was used to characterize the molecular mass, molecular mass distribution and branching degree of the modified PP. Subsequently, linear and nonlinear viscoelasticity data were obtained by a small amplitude oscillatory shear (SAOS) test and uniaxial extensional viscosity measurement. The pressure balanced bubble-growth (PBB) model was used to calculate the critical coalescence radius (CCR) curves for PP to quantitatively correlate the viscoelasticity and foamability and evaluate the foamability of PP combined with batch foaming. It is shown that with increasing branching degree, the foam shows a better resistance to bubble coalescence, resulting in a more regular bubble structure and a higher expansion ratio. Moreover, viscosity should be controlled over an appropriate range for realising good foamability; otherwise, excessive viscosity can suppress bubble growth and limit the expansion ratio. MPPZ4 modified with 4 wt% TMPTA and 0.4 wt% ZDMC showed the best foamability. A combination of the PBB model and batch foaming experiment is used to quantitatively explain the contribution of LCB to foaming.

Acid-induced gels from soy and whey protein thermally-induced mixed aggregates: Rheology and microstructure

In this study, we explored how substituting whey protein isolate (WPI) with soy protein isolate (SPI) affects the linear and non-linear rheological behavior of acid-induced gels, and their microstructures. Commercial SPI and WPI dispersions (pH 7.0, 3.0 mS/cm) were preheated (95 °C, 30 min) at different protein concentrations (2%, 4%, 6%, and 8% w/w) and SPI: WPI ratios (0: 4, 1: 3, 2: 2, 3: 1 and 4: 0). The resultant thermally-induced aggregates were characterized before gelation was induced by glucono-δ-lactone (GDL). Small and large amplitude oscillatory shear (SAOS and LAOS) tests showed that replacing WPI with SPI decreased the strength (lower G′) and stretchability (lower γc) of acid-induced gels in the linear viscoelastic (LVE) regime. Gels containing SPI behaved more similar to pure SPI gels in the non-linear viscoelastic (NLVE) regime: displaying a relatively elastic response at large strain and a gradual transition to plastic behavior. The changes in rheological properties were explained by the differences in the gel microstructures, via fractal scaling theory, multiphoton laser scanning microscopy (MLSM) and scanning electron microscopy (SEM). WPI gels formed denser and homogenous gel networks with very strong inter-floc links, while hybrid gels and pure SPI gels formed coarser and more porous networks with intermediate inter-floc links. The constituent flocs in the latter were larger, with rougher, more elongated and branched structures. The present results provide useful information for future attempts to replace WPI with SPI in food products based on acid-induced gelation.

Viscoelastic Rheological Behaviors of Polypropylene and LMPP Blends.

Dynamic oscillatory shear testing is used to investigate polymeric viscoelastic behaviors. Small and large amplitude oscillatory shear tests are the canonical method for characterizing the linear and nonlinear viscoelastic behaviors of any polymeric material. With prominent and abundant work on linear viscoelastic studies, the nonlinear behavior is evasive in terms of generating infinite higher harmonics in the nonlinear regime. For this reason, intrinsic nonlinearities from large amplitude oscillatory shear (LAOS) studies have recently been used for insights on microstructural behaviors. This study is carried out for linear and nonlinear viscoelastic behavior with a main focus on LAOS of isostatic polypropylene (iPP) and relatively new low molecular weight and low modulus polypropylene-based polyolefin (LMPP) blends. The morphological results showed reduced spherulitic crystal nucleus size and increased distribution in blends with increasing LMPP. The blends showed subtle linear viscoelastic responses with strong nonlinear mechanical responses to variant strain and stress compared to pure iPP. The intracycle strain thickening and intracycle strain stiffening of high-content LMPP blends were comparatively dominant at medium strain amplitudes.

Development of new eggplant spread product: A rheological and chemical characterization

Eggplant (Solanum melongena) is an important vegetable of the Nightshade family with high demand due to its nutritional value and medicinal properties. The principal objective of this work was to develop and standardize a spread eggplant paste (SEP) with the addition of guar gum and evaluate its physicochemical, bromatological, sensory, and rheological characteristics. A two-factor factorial design with three levels was used for the formulation, evaluating the percentage of guar gum and oil. Flow curves in steady-state and small-amplitude oscillatory shear tests were performed to evaluate the rheological properties of the pastes. Sensorial analysis was performed using descriptive analysis. The standardized eggplant showed no signs of phase separation being stable during storage. Samples presented a non-Newtonian shear-thinning behavior described by Ostwald de-Waele model (R2 > 0.969). The products exhibit more elastic than viscous behavior, with a higher storage modulus than loss modulus in the evaluated frequency range, where the modules could be well described by a power function of the oscillatory frequency. The sensory evaluation revealed that the product color, odor, taste, and spreadability were acceptable, being an alternative for the transformation and agro-industrial use of eggplant for production chain development.

On the Influence of Viscoelastic Modeling in Fluid Flow Simulations of Gum Acrylonitrile Butadiene Rubber.

Computational fluid dynamics (CFD) simulation is an important tool as it enables engineers to study different design options without a time-consuming experimental workload. However, the prediction accuracy of any CFD simulation depends upon the set boundary conditions and upon the applied rheological constitutive equation. In the present study the viscoelastic nature of an unfilled gum acrylonitrile butadiene rubber (NBR) is considered by applying the integral and time-dependent Kaye–Bernstein–Kearsley–Zapas (K-BKZ) rheological model. First, exhaustive testing is carried out in the linear viscoelastic (LVE) and non-LVE deformation range including small amplitude oscillatory shear (SAOS) as well as high pressure capillary rheometer (HPCR) tests. Next, three abrupt capillary dies and one tapered orifice die are modeled in Ansys POLYFLOW. The pressure prediction accuracy of the K-BKZ/Wagner model was found to be excellent and insensitive to the applied normal force in SAOS testing as well as to the relation of first and second normal stress differences, provided that damping parameters are fitted to steady-state rheological data. Moreover, the crucial importance of viscoelastic modeling is proven for rubber materials, as two generalized Newtonian fluid (GNF) flow models severely underestimate measured pressure data, especially in contraction flow-dominated geometries.

Electrohydrodynamic Processing of PVP-Doped Kraft Lignin Micro- and Nano-Structures and Application of Electrospun Nanofiber Templates to Produce Oleogels

The present work focuses on the development of lignin micro- and nano-structures obtained by means of electrohydrodynamic techniques aimed to be potentially applicable as thickening or structuring agents in vegetable oils. The micro- and nano-structures used were mainly composed of eucalyptus kraft lignin (EKL), which were doped to some extent with polyvinylpyrrolidone (PVP). EKL/PVP solutions were prepared at different concentrations (10–40 wt.%) and EKL:PVP ratios (95:5–100:0) in N, N-dimethylformamide (DMF) and further physico-chemically and rheologically characterized. Electrosprayed micro-sized particles were obtained from solutions with low EKL/PVP concentrations (10 and 20 wt.%) and/or high EKL:PVP ratios, whereas beaded nanofiber mats were produced by increasing the solution concentration and/or decreasing EKL:PVP ratio, as a consequence of improved extensional viscoelastic properties. EKL/PVP electrospun nanofibers were able to form oleogels by simply dispersing them into castor oil at nanofiber concentrations higher than 15 wt.%. The rheological properties of these oleogels were assessed by means of small-amplitude oscillatory shear (SAOS) and viscous flow tests. The values of SAOS functions and viscosity depended on both the nanofiber concentration and the morphology of nanofiber templates and resemble those exhibited by commercial lubricating greases made from traditional metallic soaps and mineral oils.

Linear and non-linear rheology of heat-set soy protein gels: Effects of selective proteolysis of β-conglycinin and glycinin

Soy protein is widely used in the food industry as a gelling agent in many food products. Selectively hydrolyzing one of the two main components (β-conglycinin and glycinin) of soy protein is expected to modify its gelling ability in a novel way. To explore these modifications, selective proteolysis was applied on native soy protein isolate (SPI). Degraded β-conglycinin hydrolysate (DβH) and degraded glycinin hydrolysate (DGH) were obtained with a similar degree of hydrolysis (DH), as verified by SDS-PAGE and pH-stat. Heat-set gels were formed by SPI, hydrolysates, and dialyzed hydrolysates at different protein concentrations (6%, 10%, 14%). Rheological properties of these gels in the linear regime were determined by small amplitude oscillatory shear (SAOS) tests, while their non-linear rheology was studied by large amplitude oscillatory shear (LAOS) tests. Scaling theory, CLSM, and SEM images were used to link the rheological behavior to differences in the gel microstructure.Our results showed that hydrolysates had a shorter gelling time and lower gelling temperature, but the non-network peptides made hydrolysate gels less elastic and resulted in a lower critical linear strain than SPI gels. At low concentration and DH, DβH not only had a shorter gelling time but also formed stiffer gels than SPI, which could be due to increased hydrophobic interactions and disulphide bonds, as well as the more homogeneous gel network. On the other hand, DGH formed weaker gels than SPI at every concentration, and their gel structure was coarse, consisting of small and branched flocs. With increased strain amplitude, all gels showed a transition from predominantly elastic to plastic behavior. DβH displayed intercycle strain softening, while DGH and SPI displayed a weak and strong strain overshoot, respectively. In the medium strain range, SPI showed stronger intracycle shear stiffening and DβH gels showed stronger intracycle shear thinning. At the large strain regime, SPI and DβH gels showed abrupt yielding behavior while DGH gels yielded more gradually. Overall, the “rheological fingerprint” of soy protein heat-set gels was established, and these rheological properties can be tailored by selectively hydrolyzing different components of soy protein, and varying the DH.

Rheological behavior of oil well cement pastes containing various types of dispersants at different hydration temperatures

This research discusses the effects of different types of oil well dispersants and hydration temperatures on the rheological properties of cement pastes through rheometer. A polycondensate dispersant, AFS and three polycarboxylate dispersants, APC, PCES and MHS, were used at dosages ranging from 0.1% to 0.3% by weight of cement, and three hydration temperatures of 30, 45 and 60 ℃ were selected. The yield stress was calculated by modelling the flow curve through Herschel-Bulkley and Modified Bingham models. Furthermore, the thixotropy of the cement paste involving different dispersants and hydration temperatures was analyzed by hysteresis loop methods. Besides, the small amplitude oscillatory shear (SAOS) test was applied to evaluate rigidification rate of cementitious material, offering useful information for structuration process of cement paste. The results show that the influences of dispersants on rheological behavior are closely related to the molecular structure and the dosage of dispersant, as well as the temperature of hydration. Increasing the dosage of dispersant decreases the yield stress and apparent viscosity, but increases the hysteresis loop area, especially at the lower hydration temperature of 30 ℃. During SAOS measurement, the critical strain of cement paste with dispersants is higher than without dispersant. The storage modulus (G’) continuously increases with hydration time and temperature.

Rheological and mechanical properties of dynamic covalent polymers based on imine bond

AbstractDynamic covalent polymers based on imine bond (FPIs), which are capable of reorganizing their constitution on the molecular level, are prepared from bio‐based dimer fatty acids. The irregular structure of carbon chains in dimer fatty acids leads to the amorphous nature of FPIs. The effect of imine bond on the glass transition temperature of FPIs is studied by differential scanning calorimetry. The linear viscoelasticity of FPIs is investigated by small amplitude oscillatory shear tests and analyzed by using the Likhtman‐McLeish theory. It is found that the rheological behavior of FPIs is similar with that of static, linear entangled polymers predicted by Likhtman‐McLeish theory, when the dynamic chain arrangements caused by imine‐bond exchange is not active enough. For FPIs, the temperature variation of viscosity is still following the Arrhenius law with an activation energy of ~50 kJ mol−1. Owing to the thermal adaptability, FPIs demonstrate great malleability, self‐healing capability and processing stability at elevated temperatures.