Linear Elastic Modulus Research Articles

Nonlinear static behaviors of nonlocal nanobeams incorporating longitudinal linear temperature gradient

The elastic parameters and the coefficient of thermal expansion (CTE) of nanomaterials change with temperature. If the elastic modulus, the CTE, and the longitudinal linear temperature gradient are coupled, the longitudinal symmetry of the mechanical properties of nanobeams is broken. However, researchers have not yet to examine how this symmetry breaking affects the mechanical properties of nanobeams. This paper provides a new analysis of the modified thermoelastic beam model established by the nonlocal stress gradient theory. The present analysis incorporates the coupling of the longitudinal linear temperature gradient, elastic modulus, thermal expansion, and scale effect. Afterward, we apply the Galerkin method to explore the buckling, post-buckling, and transverse bending of a (10,10) single-walled carbon nanotube (SWCNT). The results show that the linear temperature gradient induces the breaking of the nanobeam's longitudinal symmetry and then results in the coupling of the symmetrical and antisymmetrical weight functions of the deformations. While the linear temperature gradient marginally affects the symmetry of nanobeams, it significantly raises the buckling temperature and introduces the complexity of the post-buckling and transverse force bending. In addition, the integration of the linear longitudinal temperature gradient, elastic modulus, and nonlocal effect more significantly affects nanobeams' mechanical properties than individual factors.

An improved YOLOv8 for fiber bundle segmentation in X-ray computed tomography images of 2.5D composites to build the finite element model

It is necessary to segment fiber bundles in the reconstruction of the mesoscopic model of ceramic matrix composites using XCT images. Existing methods have great subjectivity, poor recognition accuracy, and heavy workload. To solve this problem, an improved lightweight YOLOv8 was proposed, which is a deep learning approach. By adding Slim-neck and VanillaNet, the complexity of the model was greatly reduced. Additionally, by replacing the loss function of the model with the Wise-IoU loss function, the ability of feature extraction of the model was improved. The effectiveness of the improved YOLOv8 in fiber bundle identification was demonstrated. Finally, a mesoscopic model was reconstructed by XCT images where fiber bundles were segmented by using the improved YOLOv8. The linear elastic modulus of the material was predicted and the error was found to be small, indicating that the improved YOLOv8 can effectively segment fiber bundles and thus reconstruct a high-precision mesoscopic model.

Switchable microscale stress response of actin-vimentin composites emerges from scale-dependent interactions.

The mechanical properties of the mammalian cell regulate many cellular functions and are largely dictated by the cytoskeleton, a composite network of protein filaments, including actin, microtubules, and intermediate filaments. Interactions between these distinct filaments give rise to emergent mechanical properties that are difficult to generate synthetically, and recent studies have made great strides in advancing our understanding of the mechanical interplay between actin and microtubule filaments. While intermediate filaments play critical roles in the stress response of cells, their effect on the rheological properties of the composite cytoskeleton remains poorly understood. Here, we use optical tweezers microrheology to measure the linear viscoelastic properties and nonlinear stress response of composites of actin and vimentin with varying molar ratios of actin to vimentin. We reveal a surprising, nearly opposite effect of actin-vimentin network mechanics compared to single-component networks in the linear versus nonlinear regimes. Namely, the linear elastic plateau modulus and zero-shear viscosity are markedly reduced in composites compared to single-component networks of actin or vimentin, whereas the initial response force and stiffness are maximized in composites versus single-component networks in the nonlinear regime. While these emergent trends are indicative of distinct interactions between actin and vimentin, nonlinear stiffening and longtime stress response appear to both be dictated primarily by actin, at odds with previous bulk rheology studies. We demonstrate that these complex, scale-dependent effects arise from the varied contributions of network density, filament stiffness, non-specific interactions, and poroelasticity to the mechanical response at different spatiotemporal scales. Cells may harness this complex behavior to facilitate distinct stress responses at different scales and in response to different stimuli to allow for their hallmark multifunctionality.

Biopolymer networks packed with microgels combine strain stiffening and shape programmability

Biomaterials that can be reversibly stiffened and shaped could be useful in broad biomedical applications where form-fitting scaffolds are needed. Here we investigate the combination of strong non-linear elasticity in biopolymer networks with the reconfigurability of packed hydrogel particles within a composite biomaterial. By packing microgels into collagen-1 networks and characterizing their linear and non-linear material properties, we empirically determine a scaling relationship that describes the synergistic dependence of the material's linear elastic shear modulus on the concentration of both components. We perform high-strain rheological tests and find that the materials strain stiffen and also exhibit a form of programmability, where no applied stress is required to maintain stiffened states of deformation after large strains are applied. We demonstrate that this non-linear rheological behavior can be used to shape samples that do not spontaneously relax large-scale bends, holding their deformed shapes for days. Detailed analysis of the frequency-dependent rheology reveals an unexpected connection to the rheology of living cells, where models of soft glasses capture their low-frequency behaviors and polymer elasticity models capture their high-frequency behaviors.

Theoretical study of kinetic arrest, shear elastic modulus, and yielding in simple biphasic colloidal mixtures.

Based on integrating microscopic statistical mechanical theories for structure and ideal kinetic arrest at the naive mode coupling level, we study dynamic localization, the linear elastic shear modulus, applied stress induced modulus softening, and the absolute yielding of simple biphasic binary mixtures composed of equal diameter hard and attractive spheres. The kinetic arrest map is a rich function of total packing fraction, strength of attraction, and mixture composition. The gel to attractive ideal glass transition, the degree of glass melting re-entrancy, and the crossover boundary separating repulsive glasses from attractive glasses vary with the mixture composition. Exponential and/or apparent (high) power law dependences of the elastic shear modulus on the total packing fraction are predicted with effective exponents or exponential prefactors that are sensitive to mixture composition and location in the kinetic arrest map. An analysis of the effective mean square force on a tagged particle that induces dynamic localization reveals a compensation effect between structural correlations and degree of particle localization, resulting in the emergence of a weaker dependence of the shear modulus on mixture composition at very high attraction strengths. Based on a microrheologically inspired formulation of how external stress weakens particle localization and the shear modulus, we analyze mechanical-induced modulus softening and absolute yielding, defined as a discontinuous solid-to-fluid stress-induced transition that can occur in either one or two steps. Estimates of the corresponding yield strains predict that the binary mixture becomes more brittle with increasing sticky particle composition and/or attraction strength.

Lightweight honeycomb furniture panels with discreetly located strengthening blocks

Furniture manufacturers indicate they know the benefits of lightweight honeycomb panels but still expect their higher mechanical properties. This work presents a numerical and experimental approach to designing new tables manufactured of paper honeycomb panels with discreetly arranged reinforcing blocks in the core. The main goal was to determine whether the discrete arrangement of the blocks affects the strength and amount of energy absorbed by the newly designed tables and stiffness of honeycomb panels. Optimization reduced the weight of the panels by up to 30 %. At the same time, their linear elastic modulus was increased from 1579 MPa to 1771 MPa. After ten load cycles, tables with discrete reinforcements have a stiffness up 86.85–87.20 % of the stiffness of the reference table. After destructive tests up 89.96–91.16 %. Ultimately, the test results demonstrate the effectiveness of replacing wide slats with discreetly placed reinforcing blocks in the core structure.

Scale-dependent interactions enable emergent microrheological stress response of actin-vimentin composites.

The mechanical properties of the mammalian cell regulate many cellular functions and are largely dictated by the cytoskeleton, a composite network of protein filaments, including actin, microtubules, and intermediate filaments. Interactions between these distinct filaments give rise to emergent mechanical properties that are difficult to generate synthetically, and recent studies have made great strides in advancing our understanding of the mechanical interplay between actin and microtubule filaments. While intermediate filaments play critical roles in the stress response of cells, their effect on the rheological properties of the composite cytoskeleton remains poorly understood. Here, we use optical tweezers microrheology to measure the linear viscoelastic properties and nonlinear stress response of composites of actin and vimentin with varying molar ratios of actin to vimentin. We reveal a surprising, nearly opposite effect of actin-vimentin network mechanics compared to single-component networks in the linear versus nonlinear regimes. Namely, the linear elastic plateau modulus and zero-shear viscosity are markedly reduced in composites compared to single-component networks of actin or vimentin, whereas the initial response force and stiffness are maximized in composites versus single-component networks in the nonlinear regime. While these emergent trends are indicative of distinct interactions between actin and vimentin, nonlinear stiffening and long-time stress response appear to both be dictated primarily by actin, at odds with previous bulk rheology studies. We demonstrate that these complex, scale-dependent effects arise from the varied contributions of network density, filament stiffness, non-specific interactions, and poroelasticity to the mechanical response at different spatiotemporal scales. Cells may harness this complex behavior to facilitate distinct stress responses at different scales and in response to different stimuli to allow for their hallmark multifunctionality.

An increase in Wharton's jelly membrane osteocompatibility by a genipin-cross-link

Wharton's Jelly (WJ) has attracted significant interest in the field of tissue healing thanks to its biological properties, including antibacterial activity and immunomodulation. However, due to the fast degradation and poor mechanical behavior in biological environment, its application in bone regeneration is compromised. Here, we proposed to use genipin as an efficient cross-linking agent to significantly improve the elasticity and the enzymatical stability of the WJ matrix. The degree of cross-linking, linear elastic moduli, and collagenase resistance varied over a wide range depending on genipin concentration. Furthermore, our results highlighted that an increase in genipin concentration led to a decreased surface wettability, therefore impairing cell attachment and proliferation. The genipin cross-linking prevented rapid in vitro and in vivo degradation, but led to an adverse host reaction and calcification. When implanted in the parietal bone defect, a limited parietal bone regeneration to the dura was observed. We conclude that genipin-cross-linked WJ is a versatile medical device however, a careful selection is required with regards to the genipin concentration.

Impact of cooling rate and shear flow on crystallization and mechanical properties of wax-crystal networks

Wax oleogels are one of the most promising strategies to produce trans-fat free and low-saturate functional fats. Under quiescent isothermal conditions, waxes form strong space-filling networks where oil is embedded. Nevertheless, in industrial processes, crystallization conditions deviate significantly from being isothermal and quiescent, yet these far from equilibrium conditions have received limited attention in the literature. Cooling and shear rate gradients during crystallization can promote molecular alignment, crystal growth, and crystal network reorganization that hold the potential to tune the mechanical properties of oleogels. Therefore, this study aimed to investigate the impact of different controlled cooling and shear rates during the crystallization process of beeswax oleogels. An analysis of both small and large amplitude oscillatory shear was conducted to understand the linear and nonlinear mechanical properties of oleogels. Additionally, microscopic/macroscopic analyses, including oil-binding capacity, were performed. The results indicate that sheared oleogels display plastic-like behavior, lower linear elastic moduli, and a higher perfect plastic dissipation ratio than oleogels cooled under quiescent conditions, which displayed stiff, brittle-like characteristics. In addition, these oleogels displayed a microstructure with smaller crystals than oleogels cooled under quiescent conditions. This phenomenon can be attributed to a transition of oleogels from a strong, yet brittle interconnected particle network, to a dispersion of jammed crystal particles that align more easily along the direction of flow, resulting in minimal additional contribution from viscous stress after yielding. Therefore, a controlled cooling and shear rate application is an effective method to tune the mechanical properties of wax oleogels.

Cell encapsulation in gelatin methacryloyl bioinks impairs microscale diffusion properties.

Light-assisted bioprinted gelatin methacryloyl (GelMA) constructs have been used for cell-laden microtissues and organoids. GelMA can be loaded by desired cells, which can regulate the biophysical properties of bioprinted constructs. We study how the degree of methacrylation (MA degree), GelMA mass concentration, and cell density change mass transport properties. We introduce a fluorescent-microscopy-based method of biotransport testing with improved sensitivity compared to the traditional particle tracking methods. The diffusion capacity of GelMA with a higher MA significantly decreased compared to a lower MA. Opposed to a steady range of linear elastic moduli, the diffusion coefficient in GelMA varied when cell densities ranged from 0 to 10 × 106 cells/ml. A comparative study of different cell sizes showed a higher diffusivity coefficient for the case of larger cells. The results of this study can help bioengineers and scientists to better control the biotransport characteristics in light-assisted bioprinted microtissues and organoids.

Effect of mineral diets on the development of cartilage material properties

Vitamin D and minerals, including zinc (Zn) and manganese (Mn), are vital in the development of bones, but their roles in the development of articular cartilage material behavior are not well understood. In this study, articular cartilage material properties from a hypovitaminosis D porcine model were evaluated. Pigs were produced by sows fed vitamin D deficient diets during gestation and lactation, and the offspring were subsequently fed vitamin D deficient diets for 3 weeks during the nursery period. Pigs were then assigned to dietary treatment groups with inorganic minerals only or inorganic plus organic (chelated) minerals. Humeral heads were harvested from pigs at 24 weeks of age. Linear elastic modulus and dissipated energy were measured under compression to 15% engineering strain at 1 Hz. Anatomical location within the humeral head affected elastic modulus. Diet significantly affected linear modulus and dissipated energy. The largest modulus and highest energy dissipation was in the inorganic zinc and manganese group; the lowest modulus and the least energy dissipation was in the organic (chelated) zinc and manganese group. Pairwise results between the control group and all vitamin D deficient groups were not statistically significant. Overall, these results suggest that mineral availability during rapid growth subsequent to a vitamin-D deficiency during gestation and lactation had minimal effects on articular cartilage material properties in young growing pigs. Though not statistically significant, some of the numerical differences between mineral sources suggest the potential importance of mineral availability during cartilage formation and warrant further study.

Viscoelastic behavior of oral mucosa. A rheological study using small-amplitude oscillatory shear tests

The purpose of this work was to determine the viscoelastic behavior of porcine and human oral mucosa under physiological conditions of temperature, hydration and chewing. The linear elastic and viscous shear moduli of these soft tissues were determined by small-amplitude oscillatory shear (SAOS) tests at masticatory frequency using a stress-controlled rheometer equipped with an immersion cell on punched biopsies 8 mm in diameter. Non physiological conditions of temperature were also used to access other parameters such as the denaturation temperature of collagen.First, the different parameters such as normal force, frequency and maximal strain were adjusted to obtain reliable data on porcine mucosa. The optimal normal force was 0.1N and the linear viscoelastic limit was found for a strain amplitude of 0.5% for both 0.1 and 1 Hz. The storage moduli of porcine mucosa, ranging from 5 to 16 kPa, were in the same range as cutaneous tissues determined by SAOS at equivalent frequencies. The storage modulus, superior to the loss modulus G″, indicates a predominant elastic contribution to shear stress in chewing conditions.Second, this protocol evidenced an influence of the anatomic site of the mouth on the viscoelastic behavior of porcine mucosa, mandibular biopsies having higher storage moduli than maxillary biopsies. Temperature scans showed the mechanical manifestation of collagen denaturation in the 60–70 °C range as previous calorimetric analyses. Finally, this mechanical protocol was successfully adapted to characterize human mucosa in an elderly population. It was shown that the elastic modulus is impacted by local inflammation (gingivitis), decreasing significantly from 6 ± 1.4 kPa to 2.5 ± 0.3 kPa.

Large amplitude oscillatory shear stress (LAOStress) analysis for an acid-curd Spanish cheese: Afuega'l Pitu atroncau blancu and roxu (PDO)

Large amplitude oscillatory shear stress (LAOStress) was used to study the nonlinear rheological properties of Afuega'l Pitu (PDO) cheese atroncau blancu and roxu, a Spanish acid-curd cheese made from cow's milk, from nine manufacturers. Composition, physicochemical and lipolytic parameters were determined. The moisture content varied between (23.60 ± 0.75)% and (45.84 ± 0.01)% and the percentage of salt-in-moisture was <(8.17 ± 0.86)%. Stress amplitude sweeps were conducted at 20 °C, 50 °C and 75 °C at frequencies of 0.628 rad/s, 6.28 rad/s and 31.4 rad/s, for each temperature. Experiments were analyzed using the MITlaos software modified to extract LAOStress quantitative material functions. The large number of experiments and the high dimensionality of the LAOS signals were carefully analyzed and reduced to understand the material response and extract the relevant properties. All cheeses showed a distinct signature that motivates us to introduce the concept of “pseudo-linear LAOS” where nonlinear rheology is evident in only some measures while others minimally change from the linear regime. We geometrically interpret these different LAOS measures as rotation and distortion of Lissajous curves; all cheeses showed pseudo-linear LAOS regimes where rotation is strong and distortion is minimal, i.e. first-harmonics change dramatically in a regime where higher-harmonics are small enough that Lissajous curves are nearly elliptical. The pseudo-linear behavior enabled low-dimensional data reduction and three metrics were discovered to be the most relevant: linear elastic modulus (G′), critical stress (σcrit) and strain (γcrit) amplitudes. All Afuega'l Pitu cheese samples softened as stress amplitude increased while maintaining a solid-like behavior (tanδ^1∼ 0.3), regardless of frequency and temperature. Moreover, the difference between blancu and roxu was statistically insignificant compared to difference between manufacturers. Linear G′ and nonlinear σcrit decreased with increasing temperature, while the nonlinear γcrit maintained a constant value at 50 °C and 75 °C. Although G′, σcrit and γcrit metrics establish comparison between cheeses, more metrics are still required to fully connect rheology to cheese texture and sensory profiles.

Scaling relations in rheology of proteins present in meat analogs

In this paper, we investigate whether the rheology of plant proteins is following similar scaling rules, as recently found for maltodextrins. The aim is to construct master curves of the rheology measurements, such that in combination with the scaling rules, the rheology can also be extrapolated to relevant practical conditions, that are not accessible with rheometers. We have analysed 4 different plant proteins, which are currently used in the manufacturing of meat analogs, on which we have performed frequency and amplitude sweeps for a wide range of temperatures and moisture contents. The frequency sweeps show that for all investigated temperatures and moisture contents the protein doughs show elastic behaviour for small strains and low frequencies, which maps on to a single master curve. Yet, the linear elastic modulus is governed by the ratio of the (moisture-dependent) glass transition temperature and the actual processing temperature ( T g / T ). Furthermore, we have constructed master curves for the strain sweeps, characterized by a critical strain that is independent of moisture content and temperature. Beyond the critical strain, the protein dough is showing strain thinning behaviour. Also with the use of literature data, we have found for pea a similar scaling exponent for shear thinning, strain thinning, and the moduli in the transition zone. This seems to confirm that plant protein doughs adhere to the Cox-Merz and Rutgers-Delaware rule, allowing translation to practical steady flow conditions as occurring during manufacturing. • For small strains all protein doughs show elastic behaviour for all investigated temperatures and moisture contents. • The linear elastic modulus is a function of T g /T. • Beyond a critical strain, which is temperature and moisture independent, doughs exhibit strain thinning. • An identical scaling exponent is found for transition zone, strain and shear thinning.

Mechanical properties and two damage models of frozen-thawed rocks under triaxial compression

Freeze-thaw induced damage in rock engineering is common in cold regions. However, a damage model for capturing the whole failure process of frozen-thawed rocks is still lacking. In this paper, triaxial compression tests of red sandstone experienced with different freeze-thaw cycles (FTCs) were conducted. Subsequently, the variation of mechanical properties with the numbers of FTCs under different confining pressures were obtained, including peak deviator stress, peak strain, linear elastic modulus, residual strength, friction angle and cohesion. The completely compacted point on stress-strain curve of rock was determined by calculating the strain difference between the stress-strain curve and a reference line. On theses bases, two damage constitutive models considering the initial compaction phase and residual deformation phase were established by means of the continuum damage mechanics and statistical microelement strength theory together with the random exponential function of strain difference. The calculated data obtained from the two proposed models and measured data were then compared. The results shows that the proposed model I is suitable for all rocks samples experienced with FTCs, while the proposed model II is suitable for rocks with small residual strength or large stress difference between peak strength and residual strength. Meanwhile, the two proposed models were compared with the existing ones by evaluating the factor Ω . The influence of confining pressure and FTCs on damage evolution of rock was discussed, and the physical meanings of the parameters in the two models were analyzed in details. The findings are beneficial for providing a reference in developing a constitutive damage model for rocks in cold regions.

Linear and Nonlinear Elastic Properties of Polystyrene-Based Nanocomposites with Allotropic Carbon Fillers and Binary Mixtures.

We report measurements of linear and nonlinear elastic properties of polystyrene-based nanocomposites with six types of nanofillers, including single and binary mixtures of allotropic carbon nanoparticles. Composite samples were fabricated by the same technology and contained the same filler concentration (5% wt.), which allowed for a direct comparison of their properties. It was shown that the most significant variations of linear and nonlinear elastic properties occur in different nanocomposites. In particular, the most pronounced enhancements of linear elastic moduli (in about 50%) obtained in tensile and flexural tests and in dynamic mechanical analysis were recorded in the sample filled with spherical fullerene nanoparticles. While the most profound rise of absolute values of nonlinear elastic moduli (tens of times) was obtained in the sample filled with the mixture of carbon nanotubes and graphene. The observed tendencies demonstrated the synergistic effect of fillers of different dimensionality on the elastic properties of nanocomposites.

Dental Implant and Natural Tooth Micro-Movements during Mastication-In Vivo Study with 3D VIC Method.

In the paper, using the video image correlation method, a study of the micro-movement pattern of the dental implant and of a normal was performed. It is revealed that there are great differences between these two situations. The linear displacement type of the dental implant refers to the linear elastic modulus of bone tissue in the case of normal bite forces. It seems that the major influencing factor regarding the type and value of implant micro-movement is defined by the underlying bone tissue. It is to be considered that masticator force transmission inside a more stiff and dense bone could be attenuated by the antagonist teeth parodontium, dental implant and abutment connection type, and the elastic modulus of material of the dental crown. Because of the elasticity of the periodontal ligament system, during the loading of the dental implant, the natural tooth has been displaced slightly more, leaving the dental implant in an unfavorable position, having to bear the full amount of loading forces. When comparing the relative displacements in the case of the loaded tooth, it is shown that the dental implant has been moving almost symmetrically with the tooth. This could mean that large amounts of forces are transmitted towards the periimplant bone tissue, but in a more optimal, parabolic manner due to the action of the periodontal ligaments surrounding the natural tooth.

(Digital Presentation) A Constant Deformation Modulus for the Simulation of Gas Diffusion Layer

The deformation of gas diffusion layer(GDL) directly affects gas diffusion and electron transfer in the fuel cell. The modulus of stress-strain relationship is the basic parameter in the process of deformation. In this paper, based on beam bending theory and geometric probability analysis, a nonlinear analytic model of stress-strain with physical meaning is established, and a constant deformation modulus of GDL is given. Based on the deformation modulus, we further simulate the inhomogeneous deformation of GDL within a half channel-rib model. The results indicate that the uneven deformation with deformation modulus is more significant than that with linear elastic modulus in the same condition. Finally, a shape-dependent bending radius design for the rib edge is proposed, in which the inhomogeneous deformation of GDL becomes smoother as the radius increases, thereby improving the service condition of GDL and prolonging its service life.

Frequency Dependence of Nonlinear Elastic Moduli of Polystyrene‐Based Nanocomposites in the Range of 1.5–2.5 MHz

AbstractThe nonlinear elastic moduli of block samples of polystyrene (PS) nanocomposites with three types of fillers: SiO2 particles, halloysite nanotubules, and carbon black (CB) are measured by ultrasonic technique in the frequency range of 1.5–2.5 MHz. The linear elastic moduli of nanocomposite samples change not significantly over those of pure PS, while nonlinear moduli demonstrate considerable variations. All samples exhibit a well‐marked dependence of nonlinear elastic moduli on frequency, more pronounce at lower frequencies. The most profound changes are obtained in samples with CB inclusions.

Understanding the role of cross-link density in the segmental dynamics and elastic properties of cross-linked thermosets.

Cross-linking is known to play a pivotal role in the relaxation dynamics and mechanical properties of thermoset polymers, which are commonly used in structural applications because of their light weight and inherently strong nature. Here, we employ a coarse-grained (CG) polymer model to systematically explore the effect of cross-link density on basic thermodynamic properties as well as corresponding changes in the segmental dynamics and elastic properties of these network materials upon approaching their glass transition temperatures (Tg). Increasing the cross-link density unsurprisingly leads to a significant slowing down of the segmental dynamics, and the fragility K of glass formation shifts in lockstep with Tg, as often found in linear polymer melts when the polymer mass is varied. As a consequence, the segmental relaxation time τα becomes almost a universal function of reduced temperature, (T - Tg)/Tg, a phenomenon that underlies the applicability of the "universal" Williams-Landel-Ferry (WLF) relation to many polymer materials. We also test a mathematical model of the temperature dependence of the linear elastic moduli based on a simple rigidity percolation theory and quantify the fluctuations in the local stiffness of the network material. The moduli and distribution of the local stiffness likewise exhibit a universal scaling behavior for materials having different cross-link densities but fixed (T - Tg)/Tg. Evidently, Tg dominates both τα and the mechanical properties of our model cross-linked polymer materials. Our work provides physical insights into how the cross-link density affects glass formation, aiding in the design of cross-linked thermosets and other structurally complex glass-forming materials.