Dielectric Relaxation Spectroscopy Research Articles

Electron Beam Modification on Dielectric, Thermal, and Thermo-mechanical Properties of Styrene Butadiene Rubber/ Clay Nanocomposites

The effect of the surface treatment of clay nanoparticles on the Styrene -butadiene Rubber (SBR) /clay nanocomposite was studied. The treatment process was done by coating the clay by trimethylolpropane tiracrylate (TMPTA) then irradiated by 100 kGy of an electron beam accelerator. Two distinct groups from SBR/ Nano treated and non-treated clay composites were prepared to be compared with each other. The effect of clay nanoparticles loading and treatment process on the rubber was investigated by Dielectric properties, Thermal gravimetric analysis (TGA), thermomechanical analysis (TMA), and volume fraction dependence. It is found that by the addition of clay, there is a decrease in the amorphous contents of the samples owing to the detectable increase in the relaxation time as observed from the dielectric relaxation spectroscopy measurements. The depolarizing factor, calculated by Tasangaris equation indicates the change of the shape of clay particles from oblate ellipsoids to the shape of a sphere with the applied frequency. The activation energy was calculated for all samples and show that it decreases with the treatment process while increased with the increase of the clay. Furthermore, the weight loss has an undulatory behavior with the clay increasing and treatment process.

Influence of Pore Surface Chemistry on the Rotational Dynamics of Nanoconfined Water

We have investigated the dynamics of water confined in mesostructured porous silicas (SBA-15, MCM-41) and four periodic mesoporous organosilicas (PMOs) by dielectric relaxation spectroscopy. The influence of water-surface interaction has been controlled by the carefully designed surface chemistry of PMOs that involved organic bridges connecting silica moieties with different repetition lengths, hydrophilicity and H-bonding capability. Relaxation processes attributed to the rotational motions of non-freezable water located in the vicinity of the pore surface were studied in the temperature range from 140 K to 225 K. Two distinct situations were achieved depending on the hydration level: at low relative humidity (33% RH), water formed a non-freezable layer adsorbed on the pore surface. At 75% RH, water formed an interfacial liquid layer sandwiched between the pore surface and the ice crystallized in the pore center. In the two cases, the study revealed different water dynamics and different dependence on the surface chemistry. We infer that these findings illustrate the respective importance of water-water and water-surface interactions in determining the dynamics of the interfacial liquid-like water and the adsorbed water molecules, as well as the nature of the different H-bonding sites present on the pore surface.

NaCl increases the dielectric constant of nanoconfined water in phospholipid multilamellar vesicle by enhancing intermolecular orientation correlation rather than rotational freedom of individual molecules

We investigate how the NaCl affects the dielectric constant of nanoconfined water in phospholipid multilamellar vesicles using dielectric relaxation spectroscopy. An anomalous increase in the dielectric constant is observed near the physiological NaCl concentration (0<c<0.3M), which has been consistently proposed in molecular dynamic simulations but is first confirmed by experiment. NaCl accelerates the reorientation motion of surface-bound water, which implies an increase of the rotational degree of freedom. However, for water beyond the hydration layer, retarded collective reorientation motion and increased dielectric strength are observed, suggesting NaCl enhances intermolecular orientation correlation rather than rotational freedom.

Molecular interaction studies of hydrogen-bonded N-Methyl-2-Pyrrolidone /Ethanol binary mixtures by dielectric relaxation spectroscopy and their temperature dependence

Complex permittivity of the binary mixtures of N-Methyl-2-Pyrrolidone (NMP) with Ethanol (ETH) has been studied in the microwave frequency range at various temperatures. The binary liquid system NMP-ETH is selected to interpret the effect of carbonyl (-CO) group of NMP and hydroxyl group (-OH) of ETH on the volumetric, thermal and dielectric properties. The dipole moment (μ) and relaxation time (τ) is evaluated from Higasi's method and Havriliak-Negami equation. The excess molar volume (VmE), excess permittivity (εE), excess refractive index (nDE), excess inverse relaxation time (1/τ)E are fitted with the Redlich-Kister equation. The results obtained from Polarizable Continuum Model (PCM) and Integral Equation Formalism Polarizable Continuum Model (IEFPCM) solvation theories using DFT methods are correlated with the experimentally determined parameters. The molecular association and chemical stability of the system is interpreted in terms of single-point energy, HOMO-LUMO calculations. The existence of a hydrogen bond within the NMP-ETH system is confirmed from the FT-IR, UV–Vis's spectra.

Broadband dielectric response of silk Fibroin/BaTiO3 composites: Influence of nanoparticle size and concentration

In order to advance towards more sustainable electronics generation, natural polymers with tailored dielectric response are essential. In this search, the combination of bio-based materials with active fillers in composite form, suppose one of the most viable alternatives. To achieve it, this work has explored the ability to control dielectric response of Silk Fibroin, a protein polymer by its combination with ceramic barium titanate (BaTiO3) nanoparticles. Both the effect of filler concentration (0, 5, 10, 20 and 40 wt%) and size (100 and 200 nm) has been studied in composites processed by easily scalable techniques. Samples with a homogeneous distribution of nanoparticles have been obtained. Dielectric relaxation processes assessed by broadband dielectric relaxation spectroscopy (BDS) in wide frequency (0.1 Hz–1 MHz) and temperature ranges (- 40 to 220 °C), revealed a dielectric constant increasing with filler content and decreasing with filler size, ranging from 4.4 for SF up to 142 for the SF/BaTiO3 composite with 40 wt %, at room temperature and 1 kHz. Two relaxations processes are observed, the β-relaxation and the conductivity relaxation, both with temperature-dependent behaviour. The activation energy of the conductivity process decreases with increasing nanoparticle content and decreasing size. A Maxwell-Wagner-Sillar process related to the interface between the silk fibroin matrix and the BaTiO3 nanoparticles was also identified.

Preparation and characterisation of silver nanoparticles/graphene oxide hybrid nanofiller reinforced-polyaniline

ABSTRACT The silver nanoparticle (AgNP) coated graphene oxide (GO) hybrid nanofiller (Ag@GO) reinforced polyaniline (PANI) nanocomposite via in situ polymerisation method is synthesised. Fourier transform infrared (FTIR) spectroscopy analysis revealed the existence of chemical interactions between the Ag@GO hybrid nanofiller and the PANI matrix. The ultraviolet–visible (UV–VIS) spectroscopy showed the presence of a silver nanoparticle peak. The nanostructure morphology of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) established the presence of AgNPs on the surface of the GO nanosheets that successfully reinforced into the PANI matrix. The thermogravimetric-differential scanning calorimetry (TG-DSC) thermograms revealed that the thermal stability of the PANI/Ag@GO nanocomposite was significantly enhanced due to the synergistic effect imparted by the AgNPs, GO, and PANI matrix. The dielectric relaxation spectroscopy (DRS) study indicated that the dielectric behaviour of the PANI/Ag@GO nanocomposite was enhanced because of the strong interfacial interactions existing between the Ag@GO hybrid nanofiller and PANI matrix. Polyaniline/Ag@GO nanocomposite has been prepared via in situ polymerisation method. The results showed that the thermal stability as well as the dielectric properties of the PANI/Ag@GO nanocomposite increases due to the synergistic effect imparted by the GO, AgNP, and PANI, which may be suitable for application in the energy storage devices.

Mechanical and scratch behaviors of polyrotaxane‐modified poly(methyl methacrylate)

AbstractThe mechanical and scratch behaviors of polyrotaxane (PR) modified poly(methyl methacrylate) (PMMA) were investigated. PR is a necklace‐like supramolecule with rings threaded onto a linear backbone chain that is capped by bulky end groups. Cyclodextrin (CD) serves as the ring structure and can be functionalized to induce specific interactions with the hosting polymer matrix. To systematically investigate the effect of CD functionalization on the mechanical properties of PMMA, PR with polycaprolactone (PCL) grafted chains on CD, and PR with methacrylate functional groups at the terminal of the PCL grafted chains on CD were chosen for this study. Tensile and compressive true stress–strain tests, ASTM scratch test, and coefficient of friction measurements were conducted to fundamentally understand how PR influences the mechanical and scratch behaviors of PMMA. Additionally, dielectric relaxation spectroscopy and dynamic mechanical analysis were conducted to explore how PR influences the relaxation dynamics of PMMA. The above findings suggest that the methacrylate functional group on PR induces favorable molecular interactions with PMMA matrix, leading to enhanced molecular cooperativity during deformation, which in turn improves tensile and compressive properties and achieves greatly improved scratch resistance.

The Dielectric Behavior of Human ex vivo Cochlear Perilymph

This work details the acquisition, handling, and measurement of microliters of perilymph, the fluid inside the human hearing organ, using dielectric relaxation spectroscopy and the correlation of the molecular relaxations to the physiological composition. Comparing between ex-vivo fresh, fresh-frozen and fixed sources reveals that dielectric absorption of the pulses is due to alpha- and beta-charge transfer relaxation related to the geometry of white blood cells, lymphocytes, in the perilymph. Interestingly, comparing the presence of molecular relaxations and the amplitude of dielectric absorption, perilymph obtained from fixed temporal bones matches fresh perilymph better than when obtained from fresh frozen source, due to the importance of well-preserved cell geometry.

Superior optical and dielectric properties of ultrasonic-assisted solution-cast prepared PMMA/MMT nanocomposite films

Poly(methyl methacrylate) (PMMA) and montmorillonite (MMT) nanoclay based PMMA/MMT nanocomposite films were prepared by solution-cast (SC) and ultrasonic-assisted SC (USA-SC) methods, and characterized for structural, thermal, optical, and dielectric properties. The x-ray diffraction patterns evidenced that the amount of MMT exfoliated nanoplatelets and tactoids in the nanocomposites are significantly affected by the preparation methods. Differential scanning calorimetry thermograms showed lowering of glass transition temperature of these nanocomposites as compared to the neat polymer matrix. The ultraviolet–visible spectroscopic measurements explained that the SC prepared PMMA/MMT films have high absorbance in comparison to host matrix which further enhanced when the film thickness was increased. However, in comparison to the SC prepared nanocomposite films, the USA-SC prepared films have low absorbance in the visible region which remained independent of the film thickness. Each nanocomposite film exhibited two different energy bandgaps which confirm their use as multifunctional bandgap tuner in optoelectronic devices. The dielectric relaxation spectroscopy in the frequency range from 20 Hz to 1 MHz revealed that the USA-SC prepared PMMA/MMT film has about nine per cent increase of dielectric permittivity at all the frequencies without alteration in dielectric loss when compared with the PMMA film, confirming its great potential as nanodielectric for advances in flexible microelectronic device technology.

Solvation, Speciation, and De-Solvation Penalties in Multivalent Battery Electrolytes

Although substantial effort has been applied to the development of new multivalent liquid electrolytes for next generation batteries, an improved understanding of how the solvation environment controls the properties of these electrolytes is needed. Most working electrolytes for Mg2+ and Ca2+ systems utilize low permittivity solvents, namely ethers, which enable the high charge density of the divalent cation to exert significant influence on the surrounding solvation environment. These effects lead to non-intuitive concentration-dependent speciation and significant ion correlations even when employing “weakly coordination” anions. In this presentation we describe the solvation environments of critical exemplar systems based on Ca2+, Mg2+, and Zn2+ working cations using complementary techniques, including dielectric relaxation spectroscopy and modeling. In select cases we connect these solvation details to electrochemical desolvation barriers through temperature-dependent impedance spectroscopy. Through these investigations we address critical questions regarding the magnitude and tunability of the dication desolvation penalty during metal deposition and/or cathode insertion.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Relaxation behavior of sandwich-structured fluorinated graphene/poly(vinylidene fluoride-hexafluoropropylene) composites by dielectric relaxation spectroscopy

The sandwich-structured fluorinated graphene (FGN)/poly(vinylidene fluoride-hexafluoro- propylene) [P(VDF-HFP)] composites with various FGN constituents were fabricated via a layer-by-layer solution casting technique, and their dielectric relaxation phenomenons of the trilayered composites were studied in a systematic way by dielectric relaxation spectroscopy (DRS) at various temperatures (25°C–200 °C) in the range of 20 Hz to 5 M Hz. The variations in dielectric parameters (ε′and ε") with frequency at each studied temperature show that ε′and ε" increase with the rise of temperature and ε" significantly decreases with the addition of FGN. Moreover, the asymmetric shapes of electric modulus spectra (M″) and Cole-Cole plots exhibit the relaxation process of non-Debye, especially in trilayered FGN/P(VDF-HFP) composites. AC conductivity is irrelevant to frequency and temperature under low frequency-high temperature, but frequency sensitive under high frequency region. Furthermore, the two activation energies (Eτ and Eσ) gradually increased with the addition of FGN, showing that the mobility of charge carriers is suppressed, thus they are unable to overcome the relaxing and conducing barrier.

Quantifying Species Populations in Multivalent Borohydride Electrolytes.

Multivalent batteries represent an important beyond Li-ion energy storage concept. The prospect of calcium batteries, in particular, has emerged recently due to novel electrolyte demonstrations, especially that of a ground-breaking combination of the borohydride salt Ca(BH4)2 dissolved in tetrahydrofuran. Recent analysis of magnesium and calcium versions of this electrolyte led to the identification of divergent speciation pathways for Mg2+ and Ca2+ despite identical anions and solvents, owing to differences in cation size and attendant flexibility of coordination. To test these proposed speciation equilibria and develop a more quantitative understanding thereof, we have applied pulsed-field-gradient nuclear magnetic resonance and dielectric relaxation spectroscopy to study these electrolytes. Concentration-dependent variation in anion diffusivities and solution dipole relaxations, interpreted with the aid of molecular dynamics simulations, confirms these divergent Mg2+ and Ca2+ speciation pathways. These results provide a more quantitative description of the electroactive species populations. We find that these species are present in relatively small quantities, even in the highly active Ca(BH4)2/tetrahydrofuran electrolyte. This finding helps interpret previous characterizations of metal deposition efficiency and morphology control and thus provides important fundamental insight into the dynamic properties of multivalent electrolytes for next-generation batteries.

Molecular dynamics, microstructures and mechanical properties of segmented polyurethane elastomers under gamma irradiation

The influence of gamma irradiation on molecular dynamics, microstructures and mechanical properties of polyurethane (PU) elastomers with polyether (poly(tetramethylene glycol), PTMG) and polyester (poly(butylene adipate), PBA) soft segments has been studied. Dynamical mechanical analysis and broadband dielectric relaxation spectroscopy were used to investigate the molecular dynamics of PU elastomers. Interestingly, the α-relaxation exhibited contrasting tendency with irradiation dose for PTMG-PU and PBA-PU, demonstrating that main chain scission took place for PTMG soft segments, but main chain crosslink for PBA soft segments. The results of small-angle scattering technique indicated that the volume fraction of hard microdomains increase rapidly with irradiation dose. The microstructures of PTMG-PU were more susceptible to gamma irradiation compared with PBA-PU. The deterioration of tensile properties was not only related to irradiation damage of soft segments, but also caused by the destruction of the microstructures of hard microdomains.

Effects of Ag, ZnO and TiO2 nanoparticles at low contents on the crystallization, semicrystalline morphology, interfacial phenomena and segmental dynamics of PLA

Polymer nanocomposites, PNCs, based on polylactide (PLA, molar mass 75 kg/mol) reinforced with metal and metal oxide nanoparticles, commercial silver (Ag, ∼10 nm in size), zinc oxide (ZnO, <10 nm) and titania (TiO2, 3−5 nm), at small fractions (0.5, 1 and 2.5 wt%), are comparatively studied here. The main scope is the evaluation of the direct and indirect effects of the fillers on the in general slow crystallization rate of PLA, the latter being wanted in processing of this widely used renewable polymer. In addition, we explore the impact of the polymer-filler interactions on polymer mobility in connection to crystallizability. The following sum of complementary techniques are employed, attenuated total reflection Fourier transform infra red spectroscopy, X-ray diffraction (XRD) spectroscopy, differential scanning calorimetry (DSC), polarized optical microscopy (POM) and dielectric relaxation spectroscopy (DRS). Opposite to most cases of PLA-based PNCs, the fillers do not act as nuclei here and their role is indirect. The polymer seems to interact with the fillers resulting in the formation of an interfacial rigid amorphous fraction. Due to the presence of fillers surrounded by bound PLA, there seems to be an acceleration of the bulk-like chains diffusion (Tg slightly drops), most probably due to free volume increase. Subsequently, the easier chains diffusion leads free volume holes (defects) toward the polymer/nanoparticle interfaces, based on previously proposed model [Polymer 53 (2012) 1362–1372]. This leads to, in general, faster hot crystallization rate and thicker crystal lamellae (XRD). In the PNCs, quite larger however fewer spherulites formed in the PNCs as monitored by POM. DRS enabled the recording of segmental dynamics, which exhibits faster time scale and weakly improved cooperativity. Next to that, an additional molecular dynamics process was revealed to possibly arise from the polymer located around the nanoparticles. Finally, the overall data demonstrate the possibility to tune semicrystalline morphology and, indirectly, the mechanical performance and the diffusion of small molecules over the PNC volume, which is wanted in both applications and processing.

Dielectric Relaxation Spectroscopy and Synergy Effects in Epoxy/MWCNT/Ni@C Composites

The dielectric/electric properties of the Ni@C (carbon-coated Ni)/epoxy composites and Ni@C/MWCNTs (multi-walled carbon nanotubes)/epoxy composites loaded with fixed MWCNTs amount just below the percolation threshold (0.09 vol.%) and Ni@C at different concentrations up to 1 vol.% were investigated in broad frequency (20 Hz–40 GHz) and temperature (30 K–500 K) regions. In composites with the only Ni@C nanoparticles, the electrical percolation threshold was determined between 10 and 15 vol.%. Above the percolation threshold the dielectric permittivity (ε’) and the electrical conductivity (σ) of the composites loaded with Ni@C only are high enough, i.e., ε’ = 105 and σ = 0.6 S/m at 100 Hz for composites with 30 vol.% Ni@C, to be used for electromagnetic shielding applications. The annealing to 500 K was proved to be an effective and simple tool to decrease the percolation threshold in epoxy/Ni@C composites. For hybrid composites series an optimal concentration of Ni@C (0.2 vol.%) was determined, leading to the conductivity absolute values several orders of magnitude higher than that of a composite filled with MWCNTs only. The synergy effects of using both fillers have been discussed. Below room temperature the electrical transport is mainly governed by epoxy resin compression in all composites, while the electron tunnelling was observed only in hybrid composites below 200 K. At higher temperatures (above 400 K), in addition to the nanoparticles redistribution effects, the electrical conductivity of epoxy resin makes a significant contribution to the total composite conductivity. The dielectric relaxation spectroscopy allows estimating the nanoparticles distributions in polymer matrix and could be used as the non-destructive and fast alternate to microscopy techniques for general polymer composite fabrication control.

Association Equilibria of Organo-Phosphoric Acids with Imines from a Combined Dielectric and Nuclear Magnetic Resonance Spectroscopy Approach.

Aggregates formed between organo-phosphoric acids and imine bases in aprotic solvents are the reactive intermediates in Brønsted acid organo-catalysis. Due to the strong hydrogen-bonding interaction of the acids in solution, multiple homo- and heteroaggregates are formed with profound effects on catalytic activity. Yet, due to the similar binding motifs—hydrogen-bonds—it is challenging to experimentally quantify the abundance of these aggregates in solution. Here we demonstrate that a combination of nuclear magnetic resonance (NMR) and dielectric relaxation spectroscopy (DRS) allows for accurate speciation of these aggregates in solution. We show that only by using the observables of both experiments heteroaggregates can be discriminated with simultaneously taking homoaggregation into account. Comparison of the association of diphenyl phosphoric acid and quinaldine or phenylquinaline in chloroform, dichloromethane, or tetrahydrofuran suggests that the basicity of the base largely determines the association of one acid and one base molecule to form an ion-pair. We find the ion-pair formation constants to be highest in chloroform, slightly lower in dichloromethane and lowest in tetrahydrofuran, which indicates that the hydrogen-bonding ability of the solvent also alters ion-pairing equilibria. We find evidence for the formation of multimers, consisting of one imine base and multiple diphenyl phosphoric acid molecules for both bases in all three solvents. This subsequent association of an acid to an ion-pair is however little affected by the nature of the base or the solvent. As such our findings provide routes to enhance the overall fraction of these multimers in solution, which have been reported to open new catalytic pathways.

Observation of the relaxation process in fluoroelastomers by dielectric relaxation spectroscopy

The complex dielectric permittivity of fluoroelastomers in response to both frequency and temperature variations was thoroughly investigated by dielectric relaxation spectroscopy. To characterize the various types of relaxation processes, the dispersion spectra of permittivity in the frequency domain were successively deconvoluted using a newly developed simulation program that uses the empirical Havriliak-Negami model based on the Debye dielectric model and conductivity contribution. At 233 K ≤ T ≤ 290 K, the α and β relaxation processes were independently observed; they merged at T ≥ 290 K. At T > 303 K, and both Maxwell-Wagner-Sillars (MWS) relaxation, known as interfacial polarization, and conductivity relaxation processes were observed. From the α relaxation process, which is related to the glass transition phenomenon, the glass transition temperature Tg was determined using the Vogel-Fulther-Tamman-Hesse (VFTH) temperature dependence law; the result was similar to the estimate of Tg obtained using differential scanning calorimetry. The temperature dependence of conductivity complies well with VFTH behaviors, whereas the β and MWS processes can be described using the Arrhenius temperature dependence law. The corresponding activation energies of the rotational side groups and DC conductivity were obtained.

Elastic composites with PDMS matrix and polysulfone-supported silver nanoparticles as filler

Polysulfone-supported silver nanoparticles (Ag@PSF) were obtained by a combination of polymer nanoprecipitation and redox synthesis of silver, in the presence of two siloxane-based stabilizing agents, and were incorporated into a PDMS matrix. Soft elastic composites (PDMS-Ag@PSF) were obtained and were investigated by dielectric relaxation spectroscopy and tensile measurements, in comparison with similar materials containing either PSF particles or AgNPs. The mechanical properties of the composites are tunable by composition, depending quasi-linearly on the Ag content. A PDMS-Ag@PSF film with 0.8 wt% Ag, having Y = 0.12 MPa, maximum strain 550% and EBD = 36 V μm−1 exhibited electrical actuation of 8% lateral strain at 22 V μm−1. Apparent piezoelectric coefficient d33 values of ~15 pm V−1 were measured by piezoresponse force microscopy for the composites with Ag@PSF, showing a synergistic effect of the fillers’ components. In addition, the materials exhibited antibacterial and antifungal activity and low bioadhesion. Based on their properties, the highly stretchable composites can be regarded as candidates for applications like actuators, sensors or micro/nanogenerators in biomedical field.

Synthesis, Crystallization, Structure Memory Effects, and Molecular Dynamics of Biobased and Renewable Poly(n-alkylene succinate)s with n from 2 to 10

In this article, we synthesize five poly(n-alkylene succinate)s, PnASs, with n = 2, 4, 6, 8, and 10 via multi-step polycondensation methods. Next, we comparatively investigate these renewable and biobased polyesters from the points of view of structure, crystallinity, and molecular mobility, employing 1H nuclear magnetic resonance spectroscopy, size-exclusion chromatography, viscometry, X-ray diffraction, differential scanning calorimetry (DSC, conventional and temperature modulation modes), polarized optical microscopy (POM), and broadband dielectric relaxation spectroscopy (BDS). Next to the successful synthesis of the materials, we evaluate the characteristics of crystallization (temperature and fraction); moreover, we explore for the first time, on the same type of succinic polyesters, the impact of n on the structure memory related to crystal nucleation as well as the changes in the semicrystalline morphology. We demonstrate that the structure/crystal memory is stronger for the lower n (shorter alkylene succinate monomers) because of more chain–chain associations, the result being independent from the overall length of the polymer chain (molar mass, Mn 13–80 kg/mass). The crystalline fraction (CF ∼ 12–34%) increases with n, also independently from Mn; however, the chain length affects directly the nucleation rate as Tc increases with Mn. The direct effects of n, in the inter-/intrachain interactions, as well as the indirect ones, on the CF and distribution of crystallites were found to be responsible for the alternations in the static glass transition temperature in DSC (lowering of Tg with n) and the dynamic glass transition (α, αc relaxations in BDS). For the sum of these PnASs, the molecular dynamics mapping is shown here, also for the first time. With increasing n, segmental dynamics accelerates, whereas, interestingly, the cooperativity drops (elimination for n = 10). Comparing these results with the recorded alternations in the semicrystalline morphology (POM), we conclude spatial confinement to be imposed on the mobile amorphous polymer by the tightly distributed crystallites when n increases. Overall, these data provide proofs for the potential for tuning of the final polymer properties connected with crystallization (mechanical performance and permeability), envisaging future biomedical, packaging, and other application for these PnASs.

Physico-Chemical and Molecular Interactions in Sodium Dodecyl Sulfate+Acetamide, Formamide Aqueous Mixtures According to Dielectric Relaxation Spectroscopy Data at 303 K

Investigation of sodium dodecyl sulfate+acetamide, formamide aqueous mixtures of various concentrations has been performed by dielectric relaxation spectroscopy (TDR-time domain reflectometry) technique 303 K. The relaxation times were determined through the Debye method and relative viscosities of solution. The linear increase of relative viscosity has the same increasing trend as dodecyl sulfate concentrations up to 80 mM. The superposition of relaxation time between water and micelle through the rotation phenomena, whereas inside the micelle by hydrophobic phenomena, is found and discussed in light of obtained results and justified.