Loss Modulus Data Research Articles

Effect of resin coating on highly viscous glass ionomer cements: A dynamic analysis

ObjectivesThis study determined the effects of self-adhesive resin coatings on viscoelastic properties of highly viscous glass ionomer cements (HVGICs) using dynamic mechanical analysis. Materials and MethodsThe HVGICs evaluated were Zirconomer [ZR] (Shofu), Equia Forte [EQ] (GC) and Riva [RV] (SDI). Sixty specimens (12mm x 2mm x 2mm) of each material were fabricated using customized Teflon molds. After initial set, the specimens were removed from their molds, finished, measured and randomly divided into 3 groups of 20. Half the specimens in each group were left uncoated while the remaining half was covered with the respective manufacturers’ resin coating. The specimens were subsequently conditioned in distilled water, artificial saliva or citric acid at 37°C for 7 days. The uncoated and coated specimens (n=10) were then subjected to dynamic mechanical testing in flexure mode at 37°C with a frequency of 0.1 to 10Hz. Storage modulus, loss modulus and loss tangent data were subjected to normality testing and statistical analysis using one-way ANOVA/Scheffe’s post-hoc test and Ttest at significance level p<0.05. ResultsMean storage modulus ranged from 1.39 ± 0.36 to 10.80 ± 0.86 GPa while mean loss modulus varied from 0.13 ± 0.03 to 0.70 ± 0.14 GPa after conditioning in the different mediums. Values for loss tangent ranged from 39.4 ± 7.75 to 213.2 ± 20.11 (x10 -3 ). Significant differences in visco-elastic properties were observed between mediums and materials. When conditioned in distilled water and artificial saliva,storage modulus was significantly improved when ZR, EQ and RV were uncoated. Significantly higher values were, however, observed with resin coating when the materials were exposed to citric acid. ConclusionThe visco-elastic properties of HVGICs were influenced by both resin coating and chemical environment

Dynamic Viscoelastic Characterization of Bulk-fill Resin-based Composites and Their Conventional Counterparts.

This study compared the viscoelastic properties of restorative and flowable bulk-fill resin-based composites (RBCs) with their conventional counterparts and evaluated the impact of aqueous solutions on viscoelastic properties. The materials examined included three conventional RBCs (Filtek Z350, Tetric N Ceram, and Beautifil II), three restorative bulk-fill RBCs (Filtek Bulk-Fill Restorative, Tetric N Ceram Bulk-Fill, and Beautifil Bulk-Fill Restorative) in addition to three flowable bulk-fill RBCs (Filtek Bulk-Fill Flowable, Tetric N Flow Bulk-Fill, and Beautifil Bulk-Fill Flowable). Beam-shaped specimens (12×2×2 mm) were fabricated using customized stainless-steel molds, finished, and measured. The specimens were randomly divided into four groups and conditioned in air (control), artificial saliva, 0.02 N citric acid, and 50% ethanol-water solution for seven days at 37°C. They were then subjected to dynamic mechanical analysis (n = 10) in flexure mode at 37°C with a frequency of 0.1 to 10 Hz. Storage modulus, loss modulus, and loss tangent data were subjected to statistical analysis using one-way analysis of variance/Tukey post hoc test at a significance level of α = 0.05. Viscoelastic properties of the RBCs were found to be product and conditioning medium dependent. For most RBCs, exposure to aqueous solutions, particularly an ethanol-water solution, degraded viscoelastic properties. With the exception of Filtek Bulk-Fill Restorative, bulk-fill restorative and flowable RBCs generally had significantly lower storage and loss modulus than their conventional counterparts regardless of conditioning medium. Conventional RBCs are thus favored over their bulk-fill counterparts, particularly for high-stress-bearing areas.

Determining elastic modulus from dynamic mechanical analysis: A general model based on loss modulus data

Dynamic mechanical analysis (DMA) method is used to measure viscoelastic properties such as storage and loss moduli of materials. The present work is focused on developing a generalized model that allows transforming the storage and loss moduli obtained from DMA to time domain elastic modulus values. The model is capable of transforming the loss modulus data that may have multiple transition peaks in the test temperature range into elastic modulus over a wide range of temperatures and frequencies. In order to develop the model, the storage modulus is divided into frequency dependent and independent components, which are analyzed separately to build a general transform for strain rate sensitive and insensitive material properties. To test the accuracy of the model, the model is validated with experimental data obtained on ethylene-vinyl acetate (EVA). The secant moduli obtained from tensile tests and loss modulus transform are compared and the average error is found to be 1.1% in the strain rate range of 10−6/s to 10−2/s, which provides validation for the model. The proposed method eliminates the need for conducting numerous tensile tests to obtain modulus over various temperatures and strain rates and replaces them with a single DMA experiment.

Expression of normal stress difference and relaxation modulus for ternary nanocomposites containing biodegradable polymers and carbon nanotubes by storage and loss modulus data

In this paper, the first normal stress differences (N1) and the relaxation modulus (G (t)) are predicted for prepared poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO)/carbon nanotubes (CNT) nanocomposites using the experimental results of storage and loss moduli. N1 and G (t) are calculated for these samples as a function of shear rate. Moreover, the effects of various parameters on N1 and G (t) are revealed to validate the equations. N1 increases by shear rate, but it shows a plateau at low shear rates. The addition of nanoparticles to the blends increases N1 demonstrating that the nanoparticles enhance the elasticity. G (t) decreases upon increasing in the shear rate in all samples and the addition of CNT to polymer blends causes a high G (t). A high storage modulus and small loss modulus enhance N1 and G (t), whereas poor storage modulus lowers N1 and G (t). Additionally, G (t) improves significantly at small strain and high N1. This work presents useful guidelines for calculation of N1 and G (t) and understanding the origin of these terms in polymer systems.

Examining the nature of network formation during epoxy polymerisation initiated with ionic liquids

A commercial diglycidyl ether of bisphenol A monomer (Baxxores™ ER 2200, eew 182 g/mole, DGEBA) is thermally polymerized in the presence of an ionic liquid, 1-ethyl-3-methylimidazolium acetate at a variety of loadings (5–45 wt %). The loss modulus data for cured samples, containing 5 wt % initiator, display at least two thermal transitions and the highest storage modulus occurs in the sample that has been cured for the shortest time at the lowest temperature. Samples that are exposed to higher temperatures (140, 150 °C) yield more heterogenous networks, whereas following exposure to a much shorter/lower temperature cure schedule (80 °C) exhibits a considerably higher damping ability than the other samples, coupled with a lower glass transition temperature. Differential scanning calorimetry reveals that the latter sample achieves a conversion of 95%, while crosslink densities for the DGEBA samples containing 5 wt % and 15 wt % are respectively 9.5 × 10−3 mol. dm−3 and 1.2 × 10−3 mol. dm−3 (when cured to 80 °C) and 2.0 × 10−2 mol. dm−3 and 2.4 × 10−3 mol. dm−3 (when cured to 140 °C).

Viscoelastic Properties of Contemporary Bulk-fill Restoratives: A Dynamic-mechanical Analysis.

This study investigated the viscoelastic properties of contemporary bulk-fill restoratives in distilled water and artificial saliva using dynamic mechanical analysis. The materials evaluated included a conventional composite (Filtek Z350), two bulk-fill composites (Filtek Bulk-fill and Tetric N Ceram), a bulk-fill giomer (Beautifil-Bulk Restorative), and two novel reinforced glass ionomer cements (Zirconomer [ZR] and Equia Forte [EQ]). The glass ionomer materials were also assessed with and without resin coating (Equia Forte Coat). Test specimens 12 × 2 × 2 mm of the various materials were fabricated using customized stainless-steel molds. After light polymerization/initial set, the specimens were removed from the molds, finished, measured, and conditioned in distilled water or artificial saliva at 37°C for seven days. The materials (n=10) were then subjected to dynamic mechanical testing in flexure mode at 37°C and a frequency of 0.1 to 10 Hz. Storage modulus, loss modulus, and loss tangent data were subjected to normality testing and statistical analysis using one-way analysis of variance/Dunnett's test and t-test at a significance level of p < 0.05. Mean storage modulus ranged from 3.16 ± 0.25 to 8.98 ± 0.44 GPa, while mean loss modulus ranged from 0.24 ± 0.03 to 0.65 ± 0.12 GPa for distilled water and artificial saliva. Values for loss tangent ranged from 45.7 ± 7.33 to 134.2 ± 12.36 (10-3). Significant differences in storage/loss modulus and loss tangent were observed between the various bulk-fill restoratives and two conditioning mediums. Storage modulus was significantly improved when EQ and ZR was not coated with resin.

Cure kinetics of epoxy/MWCNTs nanocomposites: Nonisothermal calorimetric and rheokinetic techniques

ABSTRACTNonisothermal calorimetric and isothermal rheokinetic analyses were used to study cure kinetics of epoxy/anhydride systems containing very low concentration of pristine and amine‐functionalized multiwalled carbon nanotubes (MWCNTs). Isoconversional methods were applied in calorimetric modeling of cure kinetics. Eα vs. α dependency and autocatalytic nature of curing were identified for both types of nanocomposites by isoconversional models. Fall in Eα value from 90 to 82.5 kJ mol−1 thanks to amine functionalization (with Eα of blank epoxy/anhydride of 80.3 kJ mol−1) was indicative of high potential of nanocomposites to cure at low concentration of functionalized MWCNTs (0.1 g with respect to 100 g of resin). Times of gelation and vitrification of epoxy were measured using storage and loss modulus data provided by isothermal rheokinetic analysis, showing a drop upon attachment of amine groups to MWCNTs. In complete agreement with nonisothermal calorimetric studies, variation of storage and loss modulus of nanocomposites confirmed hindered/accelerated cure devoted to pristine/amine‐functionalized MWCNTs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45221.

Toughened Isotactic Polypropylene: Phase Behavior and Mechanical Properties of Blends with Strategically Designed Random Copolymer Modifiers

A series of poly(cyclohexylethylene-ran-ethylene) (CE) copolymers were synthesized with statistical segment lengths designed to match that of isotactic poly(propylene) (iPP). Melt blending the CE compounds containing 50–70 wt % cyclohexylethylene repeat units with iPP at loadings between 5 and 20 wt % resulted in a dispersion of CE droplets with number-average diameters between 150 and 500 nm as determined by scanning electron microscopy. Linear dynamic mechanical elastic (G′) and loss (G″) moduli data were fit to the Palierne model providing estimates for the interfacial tension between iPP and CE, which was interpreted based on enthalpic (χH) and entropic (χS) contributions to the overall segment–segment interaction parameter, χ = χH + χS, attributed to density and statistical segment length differences, respectively. The small particle sizes are explained by a reduced interfacial tension, driven by minimization of χS (≈0), counterbalanced by χH > 0, establishing an optimal balance between phase separat...

Relaxation Kinetic Study of Eudragit® NM30D Film Based on Complex Modulus Formalism.

This study is aimed at resolving and characterizing the primary (α) and secondary relaxations (β) in Eudragit® NM30D film based on apparent activation energies derived from complex modulus formalism using dielectric analysis (DEA). The glass transition (T g) of the film was determined using differential scanning calorimetry (DSC). The α relaxation corresponding to T g and the β relaxations occurring below T g were probed using DEA. The occurrence of α and β relaxations in Eudragit® NM30D film was elucidated using the complex modulus of the dielectric response employing loss modulus and permittivity data. Activation energies of these relaxations and the fundamental frequency so determined support the assignment of the relaxation pattern in the Eudragit® NM30D film. DEA methodology of the complex modulus formalism is a useful tool for differentiating the α and β relaxation kinetics in Eudragits® not easily studied using traditional thermal methods such as DSC. The kinetics associated with α and β relaxations so determined will provide formulation design support for solid orals that incorporate Eudragit® polymers. As mobility changes can affect stability and diffusion, the dipolar α and β relaxations revealed through DEA analysis may enable a better correlation to functionality of Eudragit® based pharmaceutical dosage forms.

Chemical Composition and Temperature Influence on the Rheological Behaviour of Honeys

The purpose of this work was to examine the viscoelastic properties of Spanish honeys with various sugar contents [fructose (32–42 g/100 g honey), glucose (24–35 g/100 g honey), sucrose (0.0–3.4 g/100 g honey)]; concentrations (79–83 °Brix), and moisture levels (16–19 g/100 g honey) at different temperatures (5, 10, 15, 20, 25, 30, and 40°C). Honey showed Newtonian behaviour, presenting a highly viscous part (loss modulus was much greater than the elastic modulus). The loss modulus (G″) and viscosity increased with moisture content and a decrease with temperature. Exponential and power law models were applied to fit loss modulus and viscosity data. Polynomial models were proposed to describe the combined effect of temperature, fructose, glucose, sucrose content, other sugars, non-sugar substance, and moisture content.

Characterization of starch films containing starch nanoparticles. Part 2: Viscoelasticity and creep properties

Starch films were successfully produced by incorporating spray dried and vacuum-freeze dried starch nanoparticles. The frequency sweep, creep-recovery behavior and time–temperature superposition (TTS) on these films were studied. All these films exhibited dominant elastic behavior (than viscous behavior) over the entire frequency range (0.1–100rad/s). The incorporation of both types of starch nanoparticles increased the storage and loss modulus, tanδ, creep strain, creep compliance and creep rate at long time frame and reduced the recovery rate of films while the effect of different kinds of starch nanoparticles on these parameters was similar both in magnitude and trend. TTS method was successfully used to predict long time (over 20days) creep behavior through the master curves. The addition of these nanoparticles could increase the activation energy parameter used in TTS master curves. Power law and Burger's models were capable of fitting storage and loss modulus (R2>0.79) and creep data (R2>0.96), respectively.

The shear rheology of bread dough: modeling

The mechanics and rheology of the two-regime shear flow behaviour of bread dough was explored. Small-strain oscillatory measurements revealed that storage and loss moduli data as a function of applied frequency fit power law relations, with the exponent p ∼ 0.31. A Lodge-type model with a power law memory function was then investigated for shear flow, where relaxation parameters were derived from small-strain oscillatory tests. The model implied the response to steady shear may be described as a product of shear rate to the exponent p and a function of strain, which is confirmed by experimental observations. The soft-solid rheological behaviour of bread dough under steady shear deformation was then analysed over a range of shear rates (0.1–20 s − 1). Initially, stress was over-predicted in the reconstruction of the data, and the application of a damage function to the model was considered since the material fractures under shear strains ∼20. The damage term was found to be a function of strain over the complete range of shear rates. The transition of dough from solid-like to liquid-like behaviour is discussed, following the damage reduction factors rapidly reducing to zero post material fracture, which suggested a loss of elasticity in the dough. A simple integral-type model resulted for the prediction of the shear rheology of bread dough in the solid-like regime, with generalised Newtonian viscous behaviour predicted for shear flows following material fracture. Further analysis on local strain behaviour in more complex shearing geometry, such as tube flow, is required.

Opposing effects of nanoclay on viscoelastic response of reactive phenoxy/poly (trimethylene terephthalate) blends: Clay‐induced transreactions versus percolated network formation

AbstractThe role of nanofillers in reactive blends, which are compatibilized via interchange/exchange reactions, in particular transesterification reactions, is still a challenge. In this study, effects of clay on viscoelastic response of reactive melt intercalated phenoxy/poly (trimethylene terephthalate) blends are investigated. Using rheological plots, it was found that at low clay contents, clay‐induced transreactions could cause an unexpectedly enhanced viscous response. But higher clay contents lead to an enhancement in elastic behavior by inducing the formation of a percolated network. The observed opposing effects of clay particles on viscoelastic response were further examined by stress relaxation analysis, which verified the enhanced viscous response at low clay contents. The effect of interaction between the silicate layers and the blend matrix is also probed by using two different organo‐modifiers. Viscoelastic behavior of samples was also studied by dynamic mechanical analysis, and the results corroborated our findings from rheological measurements. Based on loss modulus data, the improved dynamic homogeneity of nanocomposites is attributed to the enhanced transreactions and stronger hydrogen bonds between the blend components. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers

Rheological investigation of interactions between sorbitol and polyhedral oligomeric silsesquioxane in development of nanocomposites of isotactic polypropylene

Sorbitol-type nucleating agents can be used to aid dispersion of polyhedral oligomeric silsesquioxane (POSS) molecules in isotactic polypropylene (iPP) and to promote self-assembly of POSS molecules into nanoparticles. In this paper, the interactions between a sorbitol-type nucleating agent and POSS molecules were investigated using polarized optical microscopy and rotational rheometry. Dibenzylidene sorbitol (DBS), a nucleating agent of iPP, was used in conjunction with two non-reactive POSS—trisilanolphenyl-POSS (ph-TPOSS) and octaisobutyl-POSS (bu-MPOSS). DBS formed three-dimensional fibrillar networks in iPP upon cooling from a homogeneous state. These fibrillar networks were characterized as gels using oscillatory shear rheometry. Trisilanolphenyl-POSS was incompatible with iPP but offered strong hydrogen bonding possibility with DBS; bu-MPOSS, on the other hand, was compatible with iPP but did not produce significant interactions with DBS. It was found that as low as 0.5 wt % of ph-TPOSS molecules in a ternary compound with 0.7 wt % DBS subdued fibrillar network formation by DBS and altered the rheological properties of the compounds. No such effect was seen in compounds of bu-MPOSS, although viscosity showed strong reduction. The storage modulus vs loss modulus data provided much better indication of changes of morphology in iPP/POSS and iPP/DBS/POSS compounds than loss tangent vs oscillatory frequency plots.

A simple method for determination of discrete relaxation time spectrum

A simple method for determining the discrete relaxation time spectrum from loss modulus data was developed. The method is based on the wavelet transform, which is a kind of peak-sharpening processes. Although several methods have been developed, most cannot determine the number of relaxation times in a single step without an adjustable parameter. However, the method suggested here provides a way of determining the number of relaxation times as well as the arrangement of the relaxation times automatically in a single numerical operation.

Hot compaction of polyoxymethylene. II. Structural characterization

AbstractThe structural characterization of sintered polyoxymethylene was carried out to determine the mechanism of sintering. Thermal behavior and small‐angle X‐ray scattering (SAXS) of sintered samples reveal that an improvement in either crystal size or perfection, or both, takes place during the sintering process, in comparison with compression‐molding from the melt. The loss modulus data also give evidence of crystal reorganization during sintering that improves the continuity of the crystalline phase and enhances its mechanical contribution. These findings eliminate the occurrence of major melting during sintering. However, the high mobility of the chains in the crystalline phase in the temperature range of the melting onset suggests that short range rearrangements of the chains in the crystalline lamellae are likely to occur during the time of the process. The proposed mechanism of sintering is that of crystallographic welding of crystals from neighboring particles, as a result of the combined effect of plastic flow and temperature during the hot compaction operation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Application of Ultrasonic Shear Rheometer to Characterize Rheological Properties of High Protein Concentration Solutions at Microliter Volume

The purpose of this work was to conduct preliminary rheological analysis on high protein concentration solutions by using the technique of ultrasonic shear rheometry at megahertz frequencies. The work was aimed at establishing the viability of the technique for analyzing protein solution rheology as well as obtaining an initial understanding of the effect of solution conditions on solution rheology of a model protein. Bovine serum albumin (BSA) was used for this study, and rheological analysis was conducted at 20 microL sample volume between pH 2.0 and 9.0 at different ionic strengths at 25 degrees C using 5 and 10 MHz quartz crystals. Significant differences in storage modulus among solutions at pH 5.0, 7.0, and 9.0 could only be detected at 10 MHz, and the errors associated with measurements were smaller as compared to those at 5 MHz for all the solutions studied. Solutions at pH 2.0 and 3.0 showed a time-dependent change in solution rheology. For solutions at pH 5.0, 7.0, and 9.0, which did not show time dependence in solution rheology, loss modulus data at lower concentrations correlated well with the dilute solution data in the literature. At higher concentrations, pH 5.0 solutions exhibited a higher loss modulus than pH 7.0 and pH 9.0 solutions. Storage modulus decreased with increasing ionic strength, unlike loss modulus, which did not show any change, except at pI of protein when no effect was observed. The results show the potential of high frequency rheometry for analyzing subtle differences in rheology of pharmaceutically relevant protein solutions at microliter volume.

Miscibility and viscoelastic properties of acrylic polyhedral oligomeric silsesquioxane–poly(methyl methacrylate) blends

We investigate the miscibility of acrylic polyhedral oligomeric silsesquioxanes (POSS) [characteristic size d≈2 nm] and poly(methyl methacrylate)(PMMA) in order to determine the effect of well-dispersed POSS nanoparticles on the thermomechanical properties of PMMA. Two different acrylic POSS species (unmodified and hydrogenated) were blended separately with PMMA at volume fractions up to ϕ=0.30. Both POSS species have a plasticizing effect on PMMA by lowering the glass transition temperature T g and decreasing the melt-state linear viscoelastic moduli measured in small amplitude oscillatory shear flow. The unmodified acrylic-POSS has better miscibility with PMMA than the hydrogenated form, approaching complete miscibility for loadings ϕ<0.10. At a loading ϕ=0.05, the unmodified acrylic POSS induces a 4.9 °C decrease in the T g of PMMA, far less than the 17.4 °C decrease in the glass transition temperature observed in a blend of 5 vol% dioctyl phthalate (DOP) in PMMA; however, the decrease in the glass transition temperature per added plasticizer molecule is nearly the same in the unmodified acrylic-POSS–PMMA blend compared with the DOP–PMMA blend. Time-temperature superposition (TTS) was applied successfully to the storage and loss moduli data and the resulting shift factors were correlated with a significant increase in free volume of the blends. The fractional free volume f 0=0.046 for PMMA at T 0=170 °C while for a blend of 5 vol% unmodified acrylic-POSS in PMMA f 0=0.057, which corresponds to an addition of 0.47 nm 3 per added POSS molecule at ϕ=0.05. The degree of dispersion was characterized using both wide-angle X-ray diffraction (WAXD) and dynamic mechanical analysis (DMA). Diffraction patterns for both blend systems show clear evidence of phase separation at ϕ=0.20 and higher, but no significant phase separation is evident at ϕ=0.10 and lower. The storage modulus measured in DMA indicates appreciable phase separation for unmodified acrylic POSS loadings ϕ≥0.10, while no evidence of phase separation is present in the ϕ=0.05 blend in DMA.

Examination of the Dynamic Mechanical Properties of Tissue Engineering Scaffolds

AbstractScaffolds of both natural and synthetic materials have been widely utilized to provide a three dimensional environment for cell growth. The characteristics of these scaffolds play a vital, but sometimes ambiguous, role in tissue engineering constructs. Collagen-glycosaminoglycan matrices have been used clinically as artificial skin implants. Previous research in our laboratory on this model has shown that gene expression is regulated by mechanical stress applied to the matrix. In this work we begin the process of quantifying the effects of mechanical stress and preparation technique on a matrix comprised of type I collagen and chondroitin-6-sulfate. Compressive loads were applied to the matrices using a dynamic mechanical analyzer at 37 degrees Celsius and retrofitted with 5% carbon dioxide gas flow. All samples were tested hydrated in either simulated body fluid or PBS. Storage and loss modulus data are presented. Mechanical tests were performed on collagen-GAG meshes both seeded with humandermal fibroblasts and not seeded with cells. Continuing work includes gene expression analysis of the cells on the seeded matrices in order to identify differential gene expression induced by mechanicalloading.

Effect of Thermal History on Structural Changes in Melt‐Intercalated Poly(ε‐caprolactone)/Organoclay Nanocomposites Investigated by Dynamic Viscoelastic Relaxation Measurements

AbstractPoly(ε‐caprolactone) (PCL) nanocomposites were prepared using two different types of organically modified nanosilicates by melt intercalation with an internal mixer. Dynamic mechanical analysis revealed possible structural changes in the nanocomposites even during the small deformation occurring during shear oscillatory measurements, as evidenced by a V‐shaped modulus change in the plot of the dynamic storage modulus as a function of stepwise increased temperature. X‐ray diffraction patterns were recorded at different simulated temperatures during the various stages of dynamic measurements. The X‐ray data indicate that the structural changes can be ascribed to a further intercalation of the PCL matrix chains into the silicate layers. This further intercalation is a consequence of the heat treatment during the dynamic mechanical measurements. Furthermore, there is a considerable vertical shift in addition to the horizontal shift in the higher temperature regime, which allows the mapping of a master curve through the application of the time‐temperature superposition principle to the dynamic storage and the loss modulus data obtained at various isothermal temperatures. The present study is also concerned with the relative molecular mobility of both PCL nanocomposites in the given experimental conditions considering the Williams‐Landel‐Ferry (WLF) equation and the Arrhenius relationship between the horizontal shift factor and the activation energy of flow. Moreover, the extent of the vertical shift as a function of temperature made it possible to determine the apparent activation energy of the further intercalation of PCL into the silicate layers. This intercalation is caused by the additional exposure to heat during the dynamic mechanical measurements after mixing, which led to a comparison of the relative diffusivity of the PCL matrix in the two nanocomposites.Dynamic shear storage moduli G′ of PCLOC25A and PCLOC30B as a function of temperature with increase increments of 20 °C from 60 to 260 °C. The G′ data were obtained from isothermal frequency sweep G′(ω) data at ω = 1 rad · s−1 at the corresponding temperatures.magnified imageDynamic shear storage moduli G′ of PCLOC25A and PCLOC30B as a function of temperature with increase increments of 20 °C from 60 to 260 °C. The G′ data were obtained from isothermal frequency sweep G′(ω) data at ω = 1 rad · s−1 at the corresponding temperatures.