Viscoelastic Properties Of Polymers Research Articles

Polysquaramides.

Thermoplastics, while advantageous for their processability and recyclability, often compromise thermochemical stability and mechanical strength compared to thermosets. Addressing this limitation, we introduce an innovative approach employing reversibly cross-linked polymers, utilizing squaramide moieties to reconcile recyclability and robustness. Herein, we detail the synthesis of supramolecularly cross-linked polysquaramides through the condensation polymerization of diethyl squarate with primary and secondary diamines. This methodology embeds hydrogen-bonding squaramide motifs into the polymer chains, yielding materials with significantly enhanced storage moduli, reaching up to 1.2 GPa. Material characterization via dynamic mechanical analysis, creep-recovery, and stress relaxation experiments delineate a distinctive rubbery plateau across a broad temperature range, excellent creep resistance, and multimodal viscoelastic flow, respectively, attributable to the dynamic nature of the supramolecular cross-links. Additionally, the study showcases the modulation of glass transition temperature (Tg) by altering the monomer composition and stoichiometry, demonstrating the tunability of polymer viscoelastic properties through precise control over hydrogen bonding interactions. Overall, the incorporation of squaramide motifs not only provides the structural integrity and mechanical performance of these thermoplastics but also leads to engineering materials with tailored viscoelastic characteristics.

A Numerical Model to Predict the Relaxation Phenomena in Thermoset Polymers and Their Effects on Residual Stress during Curing-Part I: A Theoretical Formulation and Numerical Evaluation of Relaxation Phenomena.

This paper analyzes the effect of crosslinking reactions on a thermoset polymer's viscoelastic properties. In particular, a numerical model to predict the evolution of epoxy's mechanical properties during the curing process is proposed and implemented in an Ansys APDL environment. A linear viscoelastic behavior is assumed, and the scaling of viscoelastic properties in terms of the temperature and degree of conversion is modeled using a modified version of the TNM (Tool-Narayanaswamy-Mohynian) model. The effects of the degree of conversion and structural relaxation on epoxy's relaxation times are simultaneously examined for the first time. This formulation is based on the thermo-rheological and chemo-rheological simplicities hypothesis and can predict the evolution of epoxy's relaxation phenomena. The thermal-kinetic reactions of curing are implemented in a homemade routine written in APDL language, and the structural module of Ansys is used to predict the polymer's creep and stress relaxation curves at different temperatures and degrees of conversion.

On Applicability of the Relaxation Spectrum of Fractional Maxwell Model to Description of Unimodal Relaxation Spectra of Polymers.

The relaxation time and frequency spectra are vital for constitutive models and for insight into the viscoelastic properties of polymers, since, from the spectra, other material functions used to describe rheological properties of various polymers can be uniquely determined. In recent decades the non-integer order differential equations have attracted interest in the description of time-dependent processes concerning relaxation phenomena. The fractional Maxwell model (FMM) is probably the most known rheological model of non-integer order. However, the FMM spectrum has not yet been studied and used to describe rheological materials. Therefore, the goal of the present paper was to study the applicability of the relaxation spectrum of FMM to the description of the relaxation spectra of polymers. Based on the known integral representation of the Mittag-Leffler two-parameter function, analytical formulas describing relaxation time and frequency spectra of FMM model were derived. Monotonicity of the spectra was analyzed and asymptotic properties were established. Relaxation frequency spectrum grows for large frequencies with a positive power law, while the relaxation time spectrum decays for large times with a negative power of time. Necessary and sufficient conditions for the existence of the local extrema of the relaxation spectra were derived in the form of two trigonometric inequalities. A simple procedure for checking the existence or absence of the spectra extrema was developed. Direct analytical formulas for the local extrema, minima, and maxima are given in terms of model fractional and viscoelastic parameters. The fractional model parameters, non-integer orders of the stress and strain derivatives of FMM uniquely determine the existence of the spectrum extrema. However, the viscoelastic parameters of the FMM, elastic modulus, and relaxation time affect the maxima and minima of the relaxation spectra and the values of their local peaks. The influence of model parameters on their local extrema was examined. Next, the applicability of the continuous-discrete spectrum of FMM to describe Baumgaertel, Schausberger and Winter (BSW) and unimodal Gauss-like relaxation spectra, commonly used to describe rheological properties of various polymers, was examined. Numerical experiments have shown that by respective choice of the FMM parameters, in particular by respective choice of the orders of fractional derivatives of the stress and strain, a good fit for the relaxation modulus experiment data was obtained for polymers characterized both by BSW and Gauss-like relaxation spectra. As a result, a good approximation of the real spectra was reached. Thus, the viscoelastic relaxation spectrum of FMM, due to the availability of the two extra degrees of freedom (non-integer orders of the stress and strain derivatives), provides deep insights into the complex behavior of polymers and can be applied for a wide class of polymers with unimodal relaxation spectra.

Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

AbstractA high loading of high‐density and high‐atomic‐number fillers are necessary to obtain desirable X‐ray attenuation characteristics from radiation shields. However, at high filler loadings, the mechanical and viscoelastic properties of polymers are severely impaired, posing a long‐term threat to the mechanical integrity and radiation protection, and the radiation shield temperature may increase after prolonged exposure to ionizing radiation, accelerating the aging of the polymer matrix. In addition, inadequate thermal conduction can make the user uncomfortable while using radiation shields for personal protection. Unfortunately, little attention has been paid to the viscoelastic, stress relaxation, and thermal conductivity‐related features of these densely loaded systems, despite the significant effect of these parameters on long‐term applications and user compliance. In the present work, two different styrene butadiene styrene (SBS) copolymers were used to develop SBS‐tungsten (W) composites. At 500 phr W loading, significant attenuation of X‐rays was achieved along with good tensile strength and elongation at break. The results indicate that the concentration of styrene in the SBS and W loading substantially affected the attenuation, mechanical and rheological properties, and tensile stress relaxation rates. The thermal conductivity increased by >100%, and after gamma irradiation, faster cooling was observed in the W‐loaded composites beyond 300 phr of W loading. The 40% styrene composite demonstrated superior heat transfer at high W loadings owing to the better dispersion and distribution of the W filler in the SBS matrix. Rheological results showed that SBS‐W composites with 30% styrene had a more pronounced Payne effect than those with 40% styrene. Stress relaxation and morphological analyses also revealed changes in the W dispersion in the SBS matrix depending on the styrene content.

Influence of Molecular Architecture on the Viscoelastic Properties of Polymers with Phase-Separated Dynamic Bonds

Polymers with dynamic bonds attract significant attention due to their many unique properties, such as self-healing and recycling. However, understanding microscopic mechanisms controlling their dynamics and viscoelastic properties, especially in the case of phase-separated dynamic bonds, remains rather limited. We present analysis of model polymer systems with phase-separating dynamic bonds (stickers) placed along the chain (pendant stickers) or at the end of the chain (telechelic systems). We demonstrate that the bond rearrangement process in these systems is controlled by the pullout of a sticker from a cluster, with the characteristic time defined by structural relaxation in clusters and miscibility of stickers in the polymer matrix. This enables decoupling of terminal relaxation from segmental dynamics of the polymer. The analysis revealed the critical role of the total concentration of stickers that controls dynamics of the polymer in the broad time range from segmental relaxation up to the time of sticker pullout from a cluster, regardless of the sticker placement on the chain and the length of the chain. Only at longer time scales, the molecular length and sticker placement influence viscoelastic properties. Based on these results, we suggest a general scenario for mechanisms controlling the dynamics and viscoelasticity of polymers with phase-separated dynamic bonds. This scenario can be helpful in guiding the design of dynamic polymers with desired viscoelastic properties.

Long-term decay of the water pressure in the osmotic tensiometer

Matric suction is an important state variable required for the assessment of unsaturated soil properties. Tensiometers are commonly used for direct matric suction measurement but have a limited measuring range up to 90 kPa due to the cavitation problem. Osmotic tensiometer (OT) can improve the measuring range of tensiometers by increasing the osmotic pressure of water to avoid the cavitation. However, the long-term water pressure decay that appeared in OTs caused a gradual decrease in their measuring range. In this study, crosslinked poly(acrylamide-co-acrylic acid) potassium salt (PAM-co-PAAK) was used for the preparation of OTs (five in total) to explore the mechanism of water pressure decay of OTs. The maximum water pressure in the OT versus the volume fraction of polymer filled in the OT was described based on the Flory-Huggins polymer theories and validated using WP4C dewpoint hygrometer. The long-term pressure decay of OT-1, OT-2, and OT-3 was observed for 130 d and constant pressures were found for OT-1 and OT-2, indicating that the pressure decay of OT was mainly caused by the stress relaxation of the polymer hydrogels, and standard linear solid (SLS) rheological model was appropriate to fit the decay data. For OT-1, OT-2 and OT-3, the theoretical osmotic pressure that was calculated based on the mass of retrieved polymer from OTs after 130-d pressure observation was higher than the actual osmotic pressure as observed, indicating that polymer leakage cannot explain the pressure decay of the OT. The ultraviolet–visible (UV–visible) spectrophotometry examined the change in polymer concentrations in the water containers of OT-4 and OT-5 and demonstrated that there was no increase in polymer leakage during the period of pressure decay of OT-4 and OT-5. As a result, the pressure decay of OT was not caused by polymer leakage. The results of this research suggested that the viscoelastic properties of polymers should be taken into consideration in further OT development. • Water pressure versus volume fraction of the polymer filled in OT was validated. • Pressure decay in OTs was mainly due to stress relaxation of polymer hydrogels. • No increase in polymer leakage during the period of pressure decay of OTs. • Development of new OTs should consider rheological properties of polymers.

Anomalous temperature dependent stiffness evolution in hydrogels

• A water-filled cavity model simulates the mechanical response of a hydrogel. • The model predicts the temperature-dependent viscoelastic response accurately. • The polymer and water dominant behaviours result in an anomaly in elastic response. We investigate the anomalous stiffness evolution of a hydrogel with an increase in temperature and provide an insight into the underlying mechanism through a finite element model. The continuum model considers the interplay between the water-filled fluid cavity, the surrounding viscoelastic chitosan matrix, and the temperature. It is observed that in the low-temperature regime (30 °C to 70 °C), water cavity volume fractions play a dominant role, while at higher temperatures (70 °C to 200 °C), the polymer viscoelastic properties govern the macroscopic stiffness of the system.

Chemotactic response of Escherichia coli to polymer solutions

Polymers are important components of the complex fluid environment for microorganisms. The mechanical effects on bacterial motile behavior due to the viscous or viscoelastic properties of polymers were extensively studied, whereas possible chemical effects on bacterial motility through bacterial chemoreception of the polymers were unclear. Here we studied the chemotactic response of Escherichia coli to polymeric solutions by combining the bead assay and FRET measurements. We found that the wild-type E. coli strain exhibited an attractant response to widely used polymers such as Ficoll 400, polyethylene glycol (PEG) 20000 and polyvinyl pyrrolidone (PVP) 360000, and the response amplitude from chemoreception was much larger than that from the load-dependence of motor switching due to viscosity change. The chemotactic response depended on the type of receptors and the chain length of the polymers. Our findings here provided important new ingredients for further studies of bacterial motile behavior in complex fluids.

Self-Healing and Electrical Properties of Viscoelastic Polymer-Carbon Blends.

Self-healing polymer-carbon composites are seen as promising materials for future electronic devices, which must be able to restore not only their structural integrity but also electrical performance after cracking and wear. Despite multiple reports about self-healing conductive elements, there is a lack of a broad fundamental understanding of correlation between viscoelasticity of such composites, their electrical properties, and self-healing of their mechanical as well as electrical properties. Here, it is reported thorough investigation of electromechanical properties of blends of carbon black (CB) as conductive filler and viscoelastic polymers (polydimethylsiloxanes (PDMS) and polyborosiloxane (PBS)) with different relaxation times as matrices. It is shown that behavior of composites depends strongly on the viscoelastic properties of polymers. Low molecular polymer composite possesses high conductivity due to strong filler network formation, quick electrical, and mechanical properties restoration, but for this the ability is sacrificed to flow and ductility at large deformation (material is brittle). In contrary, high relaxation time polymer composite behaves elastically on small time and flows at large time scale due to weak filler network and can heal. However, the electrical properties are worse than that of carbon and viscous polymer and degrade with time.

Investigation of Brine pH Effect on the Rheological and Viscoelastic Properties of HPAM Polymer for an Optimized Enhanced Oil Recovery Design.

A novel approach to improve viscous and viscoelastic properties by exploiting the pH and salinity sensitivity of HPAM polymer is proposed in this paper. Polymer flooding is a well-developed and effective enhanced oil recovery technique. The design of the makeup brine is one of the most critical phases of a polymer flood project, since the brine composition, salinity, and pH directly influence the polymer viscosity and viscoelasticity. However, the viscoelastic properties of hydrolyzed polyacrylamide polymers have not been given much consideration during the design phase of polymer flood projects. Our experimental study focuses on the optimization of the makeup water design for polymer flooding by evaluating the optimum solution salinity and pH for better stability and improved viscoelastic behavior of the polymer. Initially, the brine salinity and ionic composition is adjusted and then hydrolyzed polyacrylamide (HPAM) polymer solutions of varying pH are prepared using the adjusted brine. Rheological experiments are conducted over a temperature range of 25–80 °C and at different aging times. Polymer thermal degradation as a function of pH is assessed by examining the solutions at 80 °C for 1 week. Amplitude sweep and frequency sweep tests are performed to determine the viscoelastic properties such as storage modulus, loss modulus, and relaxation time. A 15–40% increase in the polymer solution viscosity and a 20 times increase in relaxation time is observed in the pH range of 8–10 in comparison to the neutral solution. This can be attributed to the low-salinity ion-adjusted environment of the makeup brine and further hydrolysis and increased repulsion of polymer chains in an alkaline environment. These results indicate that the viscoelastic properties of a polymer are tunable and a basic pH is favorable for better synergy between the brine and the polymer. Alkaline low-salinity polymer solutions have exhibited 60% higher thermal stability in comparison to acidic solutions and thus can be successfully applied in high-temperature reservoirs. The results of this study show that polymer solutions with an optimum pH in the basic range exhibit a higher viscoelastic character and an increased resistance toward thermal degradation. Hence, the polymer solution salinity, ionic composition, and pH should be adjusted to obtain maximum oil recovery by the polymer flooding method. Finally, this study shows that more effective polymer solutions can be prepared by adjusting the pH and designing a low-salinity water/polymer recipe to get the additional benefit of polymer viscoelasticity. The optimized low-salinity alkaline conditions can reduce the residual oil saturation by stronger viscous and viscoelastic forces developed by more viscous polymers. The findings of this study can be employed to design an optimum polymer recipe by tuning the brine pH and salinity for maximum incremental oil recovery, particularly in high-temperature and high-salinity formations.

INFLUENCE OF THE DYNAMICS OF FORCED MOTION ON THE STATIC FRICTION IN METAL-POLYMER SLIDING PAIRS

The resistance during the frictional interaction of polymeric materials with metallic materials is characterized by a significant dependence on the dynamics of the motion inputs. In a metal-polymer friction pair, the static friction resistance during standstill under load depends on the rate of growth of the force causing the relative motion. Tribological tests of selected (polymer-metal) sliding pairs were carried out. The selected polymers were polyurethane (TPU), polysulfone (PSU), and silicone rubber (SI). They interacted with a pin made of normalized C45 steel under unitary pressure p = 0.5 MPa in dry friction conditions at different gradients of the force driving the relative motion (dF/dt = 0.1-20 [N/s]). The static friction coefficient of the selected sliding pairs was determined on the basis of the recorded static friction force values. The test results show a significant influence of the rate of increase in the motion driving force on the values of static friction resistance. This is mainly due to the viscoelastic properties of polymers.

An Elongational and Shear Evaluation of Polymer Viscoelasticity during Flow in Porous Media

This paper uses a combination of approaches to evaluate the viscoelastic phenomenon in high-molecular-weight polymers (24–28 M Daltons) used for enhanced oil recovery (EOR) applications. Rheological data were cross-analyzed with single- and two-phase polymer flooding experiments in outcrop cores and micromodels, respectively. First, the impact of semi-harsh conditions (salinity, hardness, and temperature) was evaluated. Second, the impact of polymer degradation (sand face flow), focusing on the viscoelastic properties, was investigated. Finally, polymer viscoelastic properties were characterized, proposing a threefold rheological approach of rotational, oscillatory, and elongational behavior. Data from the rheological approaches were cross-analyzed with core flooding experiments and performed at a room temperature of 22 °C and at a higher temperature of 55 °C. The change in polymer viscoelastic properties were analyzed by investigating the effluents from core flooding experiments. Oil recovery experiments in micromodel helped our understanding of whether salinity or hardness has a dominating impact on in situ viscoelastic polymer response. These approaches were used to study the impact of mechanical degradation on polymer viscoelasticity. The brines showed notable loss in polymer viscoelastic properties, specifically with the hard brine and at higher temperature. However, the same polymer solution diluted in deionized water exhibited stronger viscoelastic properties. Multiple flow-behaviors, such as Newtonian, shear thinning, and thickening dominated flow, were confirmed through pressure drop analysis against interstitial velocity as already reported by other peer researchers. Turbulence-dominated excessive pressure drop in porous media was calculated by comparing core flood pressure drop data against pressure data in extensional viscometer–rheometer on a chip (eVROC®). In addition, a significant reduction in elastic-dominated flow was confirmed through the mechanical degradation that happened during core flood experiments, using various approaches. Finally, reservoir harsh conditions (high temperature, hardness, and salinity) resulted in a significant reduction in polymer viscoelastic behavior for all approaches.

Chain conformation of polymer melts with associating groups

Molecular association has profound influences on the viscoelastic properties of polymers with associating side groups. The conventional wisdom is that interchain association dominates in the melt state, and the dynamics of the associative polymer network therefore might be understood by extending the classical molecular approaches such as the Rouse and reptation models for linear chains. Using small-angle neutron scattering and molecular dynamics simulation, here we show that while interchain association is important, intrachain association can not be neglected in determining the static structures of associating polymers in the melt state. Analyses of the radius of gyration, static structure factor, and intrachain mean-square distance of polymers with associating side groups have revealed a substantial deviation from the random walk structure at even moderate association strength and degree of functionality. This finding emphasizes the important role of intrachain loops in associative polymer networks.

The Connection Between the Parameters of WLF Equation and of Arrhenius Equation

AbstractThe description of the change in characteristic temperatures of thermomechanical and viscoelastic properties of polymers and elastomers with deformation frequency or of temperature dependence of polymer properties is widely achieved by two equations: (1) the Williams‐Landel‐Ferry (WLF) equation and (2) the Arrhenius equation. Mostly the WLF equation is used. Often the distinction between the two descriptions is based on the argument: if volume processes play the key role, then WLF equation is the right one, if thermally activated processes play the key role, then Arrhenius equation is the right one. Both equations are based on the activation of processes, and always the temperature is the variable, which activate the processes. Both descriptions are methods to parameterize the temperature dependence of properties or the change of characteristic temperatures, as glass‐rubber transition temperature, with deformation rate. Also, the so‐called ‘volume processes’ are controlled by temperature, but the thermal activation can be small in energy to initiate the change in spatial position from one site to another for a molecule. This means both descriptions should be congruent. In this article, the congruence is shown and the relation between WLF parameters and Arrhenius parameters will be established. For this, a slight modification of the usual Arrhenius equation is necessary. Also, other descriptions are discussed in short: Doolittle equation and Vogel‐Fulcher equation, they were or are used to describe the change of viscosity with temperature in melts or solutions.

Effect of Recycling on the Cellular Structure of Polylactide in a Batch Process

The aim of the work is to demonstrate the possibility of using recycled biodegradable material as a cellular material with a reduced weight. An experimental study on the influence of recycling on the properties and foam ability of polylactide (PLA) was carried out. The influence of recycling on the polymer crystallinity, thermal and viscoelastic properties was investigated. During the batch process the cellular structure in PLA and recycled PLA were created. A higher degree of crystallinity, a lower viscosity value and a lower melt strength for recycled PLA, as compared to original material, were observed. For the recycled PLA, a fine cellular structure and low density (0.60 g/cm3) were obtained.

Carbon foam based on epoxy/novolac precursor as porous micro-filler of epoxy composites

The concept of application of crumbled carbon foam obtained from polymer precursor as a filler in polymer/carbon composite was described. The carbon foam used as powdered reinforcement of composites was prepared from epoxy resin cross-linked with phenol–formaldehyde resin (novolac) in a self-foaming process followed by carbonization at not very high temperature and ambient pressure. The structure of the carbon foam filler and resultant composites was studied by microscopic and spectroscopic methods. In the final composites, there were observed good quality dispersion of micronized grains of carbon foam, with the sizes that preserve their specific porous structure, in epoxy matrix and excellent adhesion at interfacial areas. The influence of the CF filler on the properties of resultant composites were investigated. Due to valuable properties of carbon foam, resultant composites occurred to have interesting characteristics: densities similar to those of pure polymer matrix, advantageous thermal and viscoelastic properties and enhanced tribological features.

Rheological Measurement of Polymeric Composites before and after UV Degradation

The aim of this paper is the comparison of selected rheological properties of polymeric composites with glass fibers materials before and after exposure in UV box. Rate and depth of degradation induced by the environment were evaluated by Frequency Sweep Test, which monitors changes in viscoelastic properties of polymers with respect to their molecular structure and their behavior in thermoplastic processes. Degradation process resulted in changes of complex dynamic viscosity, storage and loss modulus, changes in molecular weight and its distribution. UV radiation is intense degradation factors affecting the change in the structure and properties of polymers - the polymer matrix gradually degrades by UV radiation, the viscosity of the composites decreases, the COP is moved to lower angular frequencies with increasing molar mass.

Stress relaxation in polymeric microlattice materials

Breakthroughs in fabrication techniques enabled the creation of microlattice materials, which are assembled from truss-like elements on the micro-scale. The mechanical properties of these materials can be controlled varying the geometry of their microstructure. Here, we study the effect of topology and effective density on the visco-elastic properties of microlattices fabricated by direct laser writing. We perform micro scale relaxation experiments using capacitive force sensing in compression. The experimental results are analyzed using a generalized Maxwell model and the viscoelastic properties are studied in terms of density scaling laws. We develop a finite element model that allows extracting the bulk polymer viscoelastic properties. The experimental results show that the stiffness of lattice materials can be adjusted independently from the loss factor in a wide range of frequencies. We find that the loss factor dramatically increases with applied strain due to the onset of nonlinear dissipation mechanism such as buckling and plasticity. We show that at effective densities around 50% the energy dissipation per cycle in a microlattice outperforms the dissipation in the bulk, giving rise to a “less is more” effect. The present research defines a first step in the application of microlattice materials in vibration absorption.

A Comprehensive Combination of Apparent and Shear Viscoelastic Data during Polymer Flooding for EOR Evaluations

We present a comprehensive workflow to obtain the best insights into the viscoelastic behavior of polymers. Viscoelasticity is depicted in most cases by the current commercially available polymers used for EOR applications. The phenomenon is debated to be one of the reasons for additional oil recovery during polymer flooding applications. It is somehow accepted that polymer increases volumetric sweep efficiency owing to improved mobility ratio. Recently researches have explained that flooding polymers in porous media with elastic characteristics could recover additional oil, due to the improved microscale oil displacement (pore-scale). This study focuses on the analysis of polymer viscoelasticity based on single-phase core, sand-pack and capillary tube (CT) experiments coupled with their detailed rheological characterization, in order to evaluate polymer behavior in porous media. A combination of hydrolyzed polyacrylamides (HPAM) polymers as well as a bio polymer is presented throughout this evaluation. The evaluation of the data is addressed on the basis of pressure drop across the pores, separating the shear associated pressure by the extensional thickening associated pressure. Apart from that, viscoelastic dependence of the converging-diverging geometry has been experimented. Based on the observed behavior through porous media, HPAM polymers are compared with bio polymers. Moreover, the behavior of solutions with induced mechanical degradation (pre-sheared) is compared with non-sheared solutions. Similarly, concentrations with different polymer solutions are evaluated. The results obtained in this work allow for additional understanding of polymer solutions behavior in flooding applications. Furthermore The results support the definition of optimized workflows to assess their behavior under flow through porous media. Finally this evaluation helps to describe the parameter that defines polymer viscoelastic properties.

Characterization of Thermoplastic Polyurethane (TPU) and Ag-Carbon Black TPU Nanocomposite for Potential Application in Additive Manufacturing.

Electromechanical, adhesion, and viscoelastic properties of polymers and polymer nanocomposites (PNCs) are of interest for additive manufacturing (AM) and flexible electronics. Development/optimization of inks for AM is complex, expensive, and substrate/interface dependent. This study investigates properties of free standing films of a thermoplastic polyurethane (TPU) polymer and an Ag–carbon black (Ag-CB) TPU PNC in a lightly loaded low strain compression contact as a rough measure of their suitability for AM. The TPU exhibited high hysteresis and a large viscoelastic response, and sufficient dwell time was needed for polymer chain relaxation and measurable adhesion. A new discovery is that large enough contact area is needed to allow longer time constant polymer ordering in the contact that led to higher adhesion and better performance/reliability. This has previously unknown implications for interface size relative to polymer chain length in AM design. The standard linear model was found to be a good fit for the viscoelastic behavior of the TPU. The PNC exhibited no adhesion (new result), low electrical resistance, and relatively small viscoelastic response. This implies potential for AM electrical trace as well as switch applications.