Gel Point Research Articles

Self-compliant ionic skin by leveraging hierarchical hydrogen bond association

Robust interfacial compliance is essential for long-term physiological monitoring via skin-mountable ionic materials. Unfortunately, existing epidermal ionic skins are not compliant and durable enough to accommodate the time-varying deformations of convoluted skin surface, due to an imbalance in viscosity and elasticity. Here we introduce a self-compliant ionic skin that consistently works at the critical gel point state with almost equal viscosity and elasticity over a super-wide frequency range. The material is designed by leveraging hierarchical hydrogen bond association, allowing for the continuous release of polymer strands to create topological entanglements as complementary crosslinks. By embodying properties of rapid stress relaxation, softness, ionic conductivity, self-healability, flaw-insensitivity, self-adhesion, and water-resistance, this ionic skin fosters excellent interfacial compliance with cyclically deforming substrates, and facilitates the acquisition of high-fidelity electrophysiological signals with alleviated motion artifacts. The presented strategy is generalizable and could expand the applicability of epidermal ionic skins to more complex service conditions.

Modeling the cure shrinkage–induced warpage of epoxy molding compound

Product packaging processes often encounter issues, such as warping and deformation caused by the mismatch between the coefficients of thermal expansion of materials. Considerable amounts of epoxy molding compound (EMC) are used in packages. EMC exhibits viscoelastic properties and cure shrinkage, which can substantially affect the stress and warpage of packages. Mathematical models of cure shrinkage at isothermal and variable temperatures have not been comparatively discussed. Accordingly, this study aims to clarify the differences between the cure shrinkage during EMC curing estimated by the isothermal and modified two-domain Tait models. A fitting flow and calculation procedure for cure shrinkage was established to analyze the influence of these models on structural warpage. This study involved the experimental measurements of EMC material properties by using the cure reaction kinetics, isothermal and variable-temperature cure shrinkage, and generalized Maxwell models and degree of cure at gel point. Structural warpage was estimated by developing a process-oriented finite element method simulation and validating simulation results against experimental results. Analysis revealed good agreement between the warpage estimated by the two cure shrinkage models and experimental warpage. Compared with those of the other model, the results of the two-domain modified Tait model better matched the experimental results, with a deviation of approximately 1 %, because this model considered cure shrinkage that precisely corresponds to the actual process. Furthermore, the stress relaxation of viscoelastic behavior was validated through a parameterized post-curing process. Results indicated that although warpage occurrence reduced by extending the post-curing process time, it eventually converged to a certain value.

The kinetics of milk gel structure formation studies by electron microscopy

The aim of this study is to enhance the comprehension of the mechanism of enzymatic gelation in milk by visualizing the evolution of its microstructure through transmission electron microscopy. In order to minimize the potential for artifacts during the preparation process and eliminate any possible difficulties in interpreting the resulting images, three distinct methods were employed in the research: shading the surface topography with vacuum deposition of heavy metal, negative staining of the specimen with a heavy metal solution and replicating a cleavage of a quick-frozen sample. The selection of time intervals for sampling the gel during its evolution is determined by the most probable significant modifications in the resulting gel. Based on the research, it has been shown that natural milk is a nonequilibrium system from the perspective of statistical thermodynamics. A notable observation is that the glycomacropeptides forming the hair layer on the surface of casein micelles are unevenly distributed, leading to the formation of micelle dimers and trimers. It has been determind that during the initial stage of enzymatic gelation in milk, clusters of loosely bound micelles are formed in areas with the highest concentration. The formation of micelle chains is absent at this stage due to the non-anisometric nature of micelles and the energetic disadvantage of their formation. It has been found that under the influence of enzymatic gelation near the gel point, a hierarchical process involving the transformation of the milk’s protein component is activated. The trigger mechanism for this process is a cooperative conformational transition in clusters of casein micelles, which initiates a chain of more energy-intensive reactions in the following sequence: hydro­phobic interactions → hydrogen bridges → electrostatic interactions → calcium bridges. The result is the conversion of loosely bound micelle clusters into denser aggregates, predominantly contributing to the formation of milk curd. It is worth noting that gelation in milk can be regarded as a process that reduces the free energy of the dispersed system. Understanding the correlation between the decrease in the free energy value during gelation and the physical properties of the finished cheese and other dairy products continues to be a relevant area of research.

Effect of Hexagonal Boron Nitride on Morphology, crystallinity and internal Exfoliation properties of Polypropylene melt and solid phases

ABSTRACT Polypropylene (PP) is one of the most important polymers widely used in different industries due to its many superior properties. Hexagonal boron nitride (hBN) is generally used in the electronic packaging industry and insulator material production due to its high thermal conductivity and low electrical conductivity. However, the lubrication properties have not yet been examined in the polymer matrix. The main purpose of this study is to examine the lubricating properties of hBN in the PP matrix and to expand its application areas. In this research, hBN/PP composites have been produced and characterized by scanning electron microscopy with an energy dispersive X-ray detector (SEM-EDX) and the differential scanning calorimeter (DSC), respectively. The linear viscoelastic behaviors (LVBs) and rheological properties of the hBN/PP composites have been investigated at 190°C by hybrid rheometer which had high temperature plate-plate geometry system; furthermore, the SEM has been used for searching hBN particles deformation, which was mechanical deformation and distribution into the PP. The oscillation sweeps tests have shown that the critical strain values and the gelation point of composites decreased with the increasing of the hBN content into the composites. Over the 10%, hBN addition into the PP elevated internal lubrication by the exfoliation of hBN plaques. The Williamson model and the discrete retardation spectrum (DRS) equation has been applied on the hBN loaded PP composites and the PP.

Geometry-based cross-linking algorithm for modeling resorcinol resins through united-atom molecular dynamics simulations

The addition-condensation polymerization (ACP) of resorcinol with formaldehyde and the electrochemical polymerization (ECP) of resorcinol were desirable to improve the performances of resins. To achieve computational design, a new geometry-based cross-linking modeling algorithm for three-dimensional (3D) cross-linked network structures of resorcinol resins was developed for molecular dynamics (MD) simulations using a united-atom model. The ACP and ECP of resorcinol were successfully modeled using one algorithm by changing the parameters of the reaction rate constants of methylene, ether, and biphenyl bond formations. Furthermore, reaction judgment was performed under a reaction probability function comprising the Gaussian functions based on the interatomic distance of the reaction candidate atom pairs and interior angles regarding the spatial arrangement of two resorcinol rings. This geometry-based cross-linking algorithm successfully generated strainless 3D cross-linked network structures of the ACP and ECP resorcinol resins without the formation of highly bent unstable structures, such as U-shaped biphenyls. The MD simulation results indicated that the cross-linking of the ACP resin comprising methylene linkages proceeded with a network structure formation mechanism similar to that of phenolic resins, where the cross-linked network structure was determined at the gel point and the reactions after the gel point were to fix and freeze the network structure. For the ECP resins comprising ether and biphenyl linkages, the molar ratio of ether to biphenyl bonds affected the elastic property of the resins, and the incorporation of rigid biphenyl structures into ether-linkage networks increased the elastic modulus. Moreover, an increase in rigidity was observed as a decrease in the Poisson's ratio.

Determination of interaction parameters in a bottom-up approach employed in reactive dissipative particle dynamics simulations for thermosetting polymers.

The limitations in previous dissipative particle dynamics (DPD) studies confined simulations to a narrow resin range. This study refines DPD parameter calculation methodology, extending its application to diverse polymer materials. Using a bottom-up approach with molecular dynamics (MD) simulations, we evaluated solubility parameters and bead number density governing nonbonded interactions via the Flory-Huggins parameter and covalent-bonded interactions. Two solubility parameter methods, Hildebrand and Krevelen-Hoftyzer, were compared for DPD simulations. The Hildebrand method, utilizing MD simulations, demonstrates higher consistency and broader applicability in determining solubility parameters for all DPD particles. The DPD/MD curing reaction process was examined in three epoxy systems: DGEBA/4,4'-DDS, DGEBA/MPDA and DGEBA/DETA. Calculations for the curing profile, gelation point, radial distribution function and branch ratio were performed. Compared to MD data for DGEBA/4,4'-DDS, the maximum deviation in secondary reactions between epoxy and amine groups according to DPD simulations with Krevelen-Hoftyzer was 14.8%, while with the Hildebrand method, it was 1.7%. The accuracy of the DPD curing reaction in reproducing the structural properties verifies its expanded application to general polymeric material simulations. The proposed curing DPD simulations, with a short run time and minimal computational resources, contributes to high-throughput screening for optimal resins and investigates mesoscopic inhomogeneous structures in large resin systems.

Thermo-rheological and kinetic characterization and modeling of an epoxy vitrimer based on polyimine exchange.

The present study describes the development of cure kinetics and chemo-rheological models for an epoxy vitrimer based on polyimine exchange to elucidate the potential in terms of processing and accurate process selection. Reaction kinetics is investigated using differential scanning calorimetry. A good agreement between the model and data can be demonstrated for different stoichiometries by selecting a parallel reaction approach consisting of an nth-order and an autocatalytic approach. The suggested chemo-rheological model captures the intrinsically high viscosity of the resin over a broad temperature and curing range, even after the gelation point. The Di-Benedetto equation represents the glass transition temperature advancement with cure while combining the rheological Winter-Chambon criterion and the kinetic model determines the degree of cure at the gelation. These results give important advice for improved process modeling of vitrimeric resins, facilitate accurate process selection, and pave the way towards the development of composites based on the matrix system investigated in this work.

Aluminosilicate colloidal gels: from the early age to the precipitation of zeolites.

Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of mechanically homogeneous aluminosilicate gels enables the study of these materials through bulk rheology and observation of the aging dynamics until the precipitation of crystalline zeolites. The first part of this study deals with the establishment of ternary state diagrams, in order to identify the range of chemical formulations that enable preparation of single-phase homogeneous gels. Then, by studying the viscoelastic moduli during the gelation reaction, and by yielding the gel under large deformation, we propose an empirical law considering the partial order of reaction on each chemical element, to predict the gelation time according to the chemical formulation. The scaling behavior of the elastic properties of this colloidal gel shows a transition from a strong link behavior to a weak link regime. Long term aging results in the shrinkage of the gel, accompanied by syneresis of interstitial liquid at the surface. Zeolites precipitate through crystallisation by a particle attachment mechanism, when thermodynamic equilibrium is reached. The stoichiometry of the precipitated zeolites is not only consistent with the concentration of the remaining species in the supernatant but, surprisingly, it is also very close to the partial order of the reaction of the chemical elements involved in the determination of the critical gel point. This indicates a strong correlation between the morphology of the soft amorphous gel network that is formed at an early age and those of the final solid precipitated crystals.

A low-shrinkage-stress and anti-bacterial adherent dental resin composite: physicochemical properties and biocompatibility.

Polymerisation shrinkage and biofilm accumulation are the two main problems associated with dental resin composites (DRCs) that induce secondary caries, which can cause restoration failure. Polymerisation shrinkage can lead to microleakage gaps between the tooth and the DRCs, causing the aggregation of bacteria and development of secondary caries. Reducing the shrinkage stress (SS) and improving the resistance to bacterial adhesion have always been the focus of this field in modifying DRCs. A thiol-ene resin system can effectively reduce the polymerisation SS via its step-growth mechanism for delaying the gel point. Fluorinated compounds can reduce the surface free energies, thereby reducing bacterial adhesion. Thus, in this study, a range of mass fractions (0, 10, 20, 30, and 40 wt%) of a fluorinated thiol-ene resin system were added to a fluorinated dimethacrylate resin system/tricyclo decanedimethanol diacrylate to create a fluorinated methacrylate-thiol-ene ternary resin matrix. DRCs were prepared using the obtained ternary resin matrix, and their physical and chemical properties, effect on bacterial adhesion, and biocompatibility were investigated. The results demonstrated that the volumetric shrinkage and SS of the DRCs were reduced with no reduction in conversion degree even after the thiol-ene resin system was added. All DRC-based fluorinated resin systems exhibited an excellent anti-bacterial adhesion effect, as evidenced by the colony-forming unit counts, live/dead bacterial staining, and crystal violet staining tests against Streptococcus mutans (S. mutans). The genetic expressions associated with the bacterial adhesion of S. mutans were substantially affected after being cultured with fluorinated DRCs. All fluorinated DRCs demonstrated good biocompatibility through the in vitro cytotoxicity test and live/dead staining images of the L-929 cells. The above results illustrate that the DRCs based on the fluorinated methacrylate-thiol-ene resin matrix can be potentially applied in clinical practice due to their low SS and anti-bacterial adhesion effect.

Efficient reduction of photopolymerization shrinkage stress through microporous particles templated from Pickering emulsion droplets

Photopolymerization of acrylate based resin is a rapid, efficient and low-energy curing process that is achieving wide applications in many industrial fields. However, the volumetric shrinkage and the shrinkage stress of the cured resin have long been the major factor reduces adhesion strength of UV curable coatings onto the substrate. In this paper, the Pickering emulsion template method is employed to prepare elastic microporous particles with well-defined surface and internal structures and these microporous particles are thus added into the UV curable resin formulation to verify their capability to reduce polymerization stress through the microporous structure. The gel point time of UV-curable materials is delayed by 11 s with 1.5 wt% addition of the microporous particles and the double bond conversion at the gel point is subsequently increased. By real time MIR-photo-rheology and 3D line scanning laser confocal measurement, it is found that addition of microporous particles into the resin formulation can reduce the volume shrinkage of the resin by 61.2 % with only 1.5 wt% microporous particles, while the excellent mechanical and thermal properties of the cured resin is basically maintained.

Enhancing adhesive strength and durability: Exploring the benefits of upconversion particle-assisted near-infrared photopolymerization

Adhesives with exceptional strength and long-lasting durability are of paramount importance in various industries and applications by providing efficient bonding solutions, enabling the assembly of diverse materials. However, enhancing the adhesion strength of photocurable adhesives poses a significant challenge due to the presence of shrinkage stresses. In this work, upconversion particle-assisted near-infrared photopolymerization (UCAP) was used to cure adhesives, and the effects of curing condition, such as irradiation time and particles content, on adhesive properties were investigated. The adhesives cured through UCAP demonstrated a notable enhancement in shear strength, with an observed increase of approximately 25 % compared to the specimens cured by UV irradiation. Through a comprehensive analysis of the shrinkage deformation and rheological behavior during curing, this study successfully demonstrated the effects of UCAP in reducing shrinkage stress and alleviating the peeling tendency. Moreover, the reduced deformation of UCAP specimens compared to UV-cured specimens can be attributed to the increased gel point conversion in the UCAP process. The improved adhesive properties observed through UCAP indicates the potential for widespread utilization of UCAP technology.

Critical-Like Gelation Dynamics in Cellulose Nanocrystal Suspensions.

We use time-resolved mechanical spectroscopy to offer a detailed picture of the gelation dynamics of cellulose nanocrystal (CNC) suspensions following shear cessation in the presence of salt. CNCs are charged, rodlike colloids that self-assemble into various phases, including physical gels serving as soft precursors for biosourced composites. Here, a series of linear viscoelastic spectra acquired across the sol-gel transition of CNC suspensions are rescaled onto two master curves that correspond to a viscoelastic liquid state prior to gelation and to a soft solid state after gelation. These two states are separated by a critical gel point, where all rescaling parameters diverge in an asymmetric fashion yet with exponents that obey hyperscaling relations consistent with previous works on isotropic colloids and polymer gels. Upon varying the salt content, we further show that these critical-like dynamics result in both time-connectivity and time-concentration superposition principles.

Understanding the role of water in the lyotropic liquid crystalline mesophase of high-performance flexible supercapacitor electrolytes using a rheological approach

The effect of water on the structure, properties, and flexibility of lyotropic liquid crystalline (LLC) C12E23-LiCl-H2O gel electrolytes was explored. Structural techniques, such as X-ray Diffraction (XRD), Polarized Optical Microscopy (POM), and five dynamic measurements, were employed to examine the rheological properties of the LLC mesophase across various water contents. These analyses provided quantitative insights into the influence of water content and LiCl concentration on gel strength, gelation point, and structural recovery. The three-dimensional network of the gel encapsulates Li+ and Cl− ions within hydrophilic domains, showing significant performance in supercapacitor applications. The observed increase in storage modules with decreasing water content is attributed to variations in the quantity and average size of junction points owing to system entanglement. These research findings highlight that excess water molecules, which break down micellar connections, are responsible for the weakening of the gel. Conversely, at low water concentrations, the micellar domains entangle, displaying viscoelastic behavior akin to that of a transitory polymer network.

Photo-RDRP for everyone: Smartphone light-induced oxygen-tolerant reversible deactivation radical polymerization

Oxygen-tolerant reversible deactivation radical polymerization (RDRP) was carried out utilizing a smartphone flashlight. Well-controlled poly(oligo(ethylene oxide) monomethyl ether methacrylate) (POEOMA500) with relatively low dispersity (Đ = 1.16–1.35) was obtained employing dual catalysis atom transfer radical polymerization (ATRP) with CuBr2/tris(2-pyridylmethyl)amine (TPMA) and three different organic photocatalytic dyes (i.e. eosin Y (EY), fluorescein (FL), and riboflavin (RF)). The smartphone flashlight was also used for carrying out oxygen-tolerant photoinduced electron/energy transfer (PET) reversible addition–fragmentation chain transfer (RAFT) polymerization with EY and dithioesters RAFT agents , and photoiniferter (PI) RAFT polymerization with trithiocarbonate RAFT agent. The formation of crosslinked gels and facile measurement of gel points via recording the gelation process by in-built smartphone camera was also demonstrated.

Characterization of a low-methoxyl pectin extracted from red radish (Raphanus sativus L.) pomace and its gelation induced by NaCl

There is an increasing demand for obtaining pectin from new sources. Red radish (Raphanus sativus L.) pomace pectin extracted by alkali was low-methoxyl pectin with esterification degree of 10.17 %, galacturonic acid content of 69.71 % (wt), and average molar weight of 78.59 kDa. The pectin primarily consisted of rhamnogalacturonan I and homogalacturonan domains. The predominant monosaccharides of the pectin were galacturonic acid (46.32 mol%), arabinose (16.03 mol%), galactose (10.46 mol%), and rhamnose (10.28 mol%), respectively. The red radish pomace pectin solution exhibited a shear-thinning behavior. NaCl could induce gelation of red radish pomace pectin, and the gel properties of red radish pomace pectin were considerably affected by the NaCl concentration. As the NaCl concentration (0.25–0.50 mol/L) increased, the rate of gelation accelerated, and the time to gelation point appeared earlier. There was an optimal NaCl concentration (0.50 mol/L) for the pectin to form a gel with the greatest solid-like properties, gel hardness (33.84 g) and water-holding capacity (62.41 %). Gelation force analysis indicated gel formation mainly caused by electrostatic shielding effect of Na+ and hydrogen bonding. This research could facilitate the applications of the red radish pomace pectin in the realm of edible hydrocolloids.

Fabrication and Actuation of Magnetic Shape-Memory Materials.

Soft actuators are deformable materials that change their dimensions or shape in response to external stimuli. Among the various stimuli, remote magnetic fields are one of the most attractive forms of actuation, due to their ease of use, fast response, and safety in biological systems. Composites of magnetic particles with polymer matrices are the most common materials for magnetic soft actuators. In this paper, we demonstrate the fabrication and actuation of magnetic shape-memory materials based on hydrogels containing field-structured magnetic particles. These actuators are formed by placing the pregel dispersion into a mold of the desired on-field shape and exposing it to a homogeneous magnetic field until the gel point is reached. At this point, the material may be removed from the mold and fully gelled in the desired off-field shape. The resultant magnetic shape-memory material then transitions between these two shapes when it is subjected to successive cycles of a homogeneous magnetic field, acting as a large deformation actuator. For actuators that are planar in the off-field state, this can result in significant bending to return to the on-field state. In addition, it is possible to make shape-memory materials that twist under the application of a magnetic field. For these torsional actuators, both experimental and theoretical results are given.

Stimuli‐responsive properties of double network hydrogels derived from κ‐carrageenan and poly (acrylamide)

AbstractThe utilization of stretchable, antifreezing hydrogels is imperative when using them as electrolyte membranes and ionic conductors for flexible energy storage devices or electronic skin. However, a problem still persists in the formation of a functional hydrogel with comprehensive performance including antifreezing, temperature‐sensitive, favorable reusability, and self‐healing properties. Herein, through anionic κ‐carrageenan (κ‐CG) as the physical noncovalent crosslinking network of the hydrogel, and acrylamide (AM) as monomers forming the second network through chemical crosslinking, κ‐CG‐Li+/PAM double‐network (DM) hydrogels were obtained by one‐pot thermally initiated polymerization. The DM structure showed excellent fracture strain and strong breaking stress, and lithium ions ensure its good electrical conductivity. The transparency of the hydrogel could reach above 91.0%, and the freezing point of the resultant gel was −34.9°C, which was measured by differential scanning calorimetry at low temperature. The as‐synthesized DM gel exhibited robust tensile properties with tensile elongation of 1840% and fracture energy of 967.3 kJ/m3. The response sensitivity of the hydrogel as a wearable sensor in different environments was explored. κ‐CG‐Li+/PAM could not only respond in the large strain range of 100%–400% but also capture the change in 0.1% strain. The deformation sensitivity was GF = 1.83 at 200% compressive strain range, and the hydrogel had a pressure sensitivity of 2.71 kPa−1 over the pressure range of 0–5 kPa. In addition to the properties of ionic conductive hydrogels, the hydrogel demonstrated outstanding temperature sensitivity in the human body temperature range of 35°C–40°C or in the range of 20°C–60°C (TCR = 1.628/°C).

Rheological percolation, gel‐like behavior and electrical conductivity of multi‐walled carbon nanotubes filled ethylene‐vinyl acetate copolymer/acrylonitrile‐butadiene rubber nanocomposites

AbstractReasonable studies on the composite systems containing conductive nanoparticles are very important to manufacture the materials with physico‐mechanical tailor‐made properties. In this work, rheological percolation, gel‐like behavior and electrical properties of multi‐walled carbon nanotubes (MWCNTs) filled ethylene‐co‐vinyl acetate/acrylonitrile‐butadiene copolymer blends containing 0–7 wt% MWCNTs were studied. The Winter‐Chambon criterion validity was evaluated for physical gelation of the system. The rheological and electrical percolation threshold, gel point (Pg), relaxation exponent (n), gel strength (Sg), and the fractal dimension (df) at the gel point were calculated. The formation of physical gel and rheological percolation threshold were both found to occur at 1 wt% MWCNTs concentration. Based on the df value determined, it was revealed that the system behaved similar to the one in which the excluded volume interactions were nearly screened. It was also found that the storage modulus (G′) near the Pg followed a power‐law scaling relationship in the form where is the distance from Pg. The electrical conductivity of the nanocomposites increased with the increase in MWCNTs loading after the nanofillers content surpassed a certain value. A schematic model was proposed to demonstrate the variation of electrical conduction with the increase in MWCNTs concentration. The excluded volume and hard‐core models were also employed to estimate the average aspect ratio of the nanofillers embedded in the system.Highlights Morphology and gel‐like behavior of EVA/NBR/MWCNTs system were studied Winter‐Chambon criterion was found to be valid for the gelation of the system Rheological percolation and gel point were occurred at the same MWCNTs loading It was found excluded volume interactions were nearly screened at gel point A schematic model for microstructure development was suggested for the system

Exploring Gel-Point Identification in Epoxy Resin Using Rheology and Unsupervised Learning.

Any thermoset resin's processing properties and end-use performance are heavily influenced by the gel time. The complicated viscosity of resin as a function of temperature is investigated in this work, with a particular emphasis on identifying the gel point and comprehending polymerization. Rheology studies carried out using a plate-plate controlled stress rheometer under isothermal conditions were used to compare three experimental techniques for figuring out an epoxy resin's gel point. We also look at the basic modifications that take place during polymerization. We verify the reliability of the three strategies by including Principal Component Analysis (PCA), an unsupervised machine learning methodology. PCA assists in uncovering hidden connections between these methods and various affecting factors. PCA serves a dual role in our study, confirming method validity and identifying patterns. It sheds light on the intricate relationships between experimental techniques and material properties. This concise study expands our understanding of resin behavior and provides insights that are essential for optimizing resin-based processes in a variety of industrial applications.

Molecular simulation on the rheological properties of phenolic resins during crosslinking

In this paper, the variations in the viscosity and molecular weight of phenol–formaldehyde resin (PF) before gelation were simulated by the molecular dynamics simulation (MD) method, and a new mathematical model was developed to describe the rheological properties of PF. The modeling of PFs with different degrees of crosslinking was developed by using a new crosslinking program. The simulation results show that the gel point for the PF model is at 54% degree of crosslinking. The mathematical model shows that the higher the temperature of the system is, the lower the initial viscosity of the model. This study provides a new rheological model for controlling the curing process and the final performance of thermosetting resins.