Low Loss Tangent Research Articles

Controllable low-temperature flash sintering and giant dielectric performance of (Zn, Ta) co-doped TiO2 ceramics

In this study, the challenge of high-temperature and long-time sintering of (Zn, Ta) co-doped TiO 2 ceramics is solved successfully using flash sintering technology. Joule heating and a high heating rate make the sample compact rapidly at low temperatures (1050 °C in 24 min). When the electric field was equal to 200 V/cm, high permittivity (ε' ∼ 1.32 × 10 4 ), low dielectric loss tangent (tan δ ∼ 0.27), and nonlinear coefficient ( α ∼ 5.8) values were obtained. Flash sintered samples have more free electrons, resulting in a high dielectric constant. Further, the higher the electric field, the smaller the grain resistance of the sample; this condition is conducive to reducing dielectric loss. giant dielectric performance is explained by the combined action of the electron-pinned defect dipole theory and the internal barrier layer capacitance effect. Therefore, this study provides a promising prospect for the green preparation of co-doped TiO 2 giant dielectric ceramics.

Effects of Sintering Conditions on Giant Dielectric and Nonlinear Current-Voltage Properties of TiO2-Excessive Na1/2Y1/2Cu3Ti4.1O12 Ceramics.

The effects of the sintering conditions on the phase compositions, microstructure, electrical properties, and dielectric responses of TiO2-excessive Na1/2Y1/2Cu3Ti4.1O12 ceramics prepared by a solid-state reaction method were investigated. A pure phase of the Na1/2Y1/2Cu3Ti4.1O12 ceramic was achieved in all sintered ceramics. The mean grain size slightly increased with increasing sintering time (from 1 to 15 h after sintering at 1070 °C) and sintering temperature from 1070 to 1090 °C for 5 h. The primary elements were dispersed in the microstructure. Low dielectric loss tangents (tan δ~0.018–0.022) were obtained. Moreover, the dielectric constant increased from ε′~5396 to 25,565 upon changing the sintering conditions. The lowest tan δ of 0.009 at 1 kHz was obtained. The electrical responses of the semiconducting grain and insulating grain boundary were studied using impedance and admittance spectroscopies. The breakdown voltage and nonlinear coefficient decreased significantly as the sintering temperature and time increased. The presence of Cu+, Cu3+, and Ti3+ was examined using X-ray photoelectron spectroscopy, confirming the formation of semiconducting grains. The dielectric and electrical properties were described using Maxwell–Wagner relaxation, based on the internal barrier layer capacitor model.

Preparation, characterizations, dielectric properties and nonlinear behavior of (Na+1/3Ca2+1/3Yb3+1/3)Cu3Ti4O12 ceramics

We present the investigation of phase formation, microstructural, dielectric properties and nonlinear behaviors of (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 ceramics prepared by a modified sol-gel method under various sintering conditions. According to the Rietveld refinement analysis, the main phase CaCu3Ti4O12-like (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 structure with a lattice constant of ≈7.384 Å was observed in the studied samples. The surface microstructural changes for the ceramics at different conditions were examined by scanning electron microscopy. The dielectric response and nonlinear behaviors of the specimens were methodically explored. At 1 kHz, a high dielectric constant of 5.49 × 103 with a low dielectric loss tangent ≈0.075 was successfully achieved. The sintered (Na1/3Ca1/3Yb1/3)Cu3Ti4O12 ceramics exhibited good nonlinear behavior. The interfacial polarization at the grain boundaries based on the internal barrier layer capacitor structure could explain the dielectric behavior of the studied specimens. From the results of the X-ray photoelectron spectroscopy (XPS) analysis, the presence of Cu+, Cu2+, and Ti3+ ions might be the major cause of the n-type semiconductor nature inside the grains.

Integration of Ferroelectric K0.5Na0.5NbO3 films on Si at 400 ℃

In this work, polycrystalline K0.5Na0.5NbO3 (KNN) thin films were successfully integrated on Si at 400 ℃ via a RF magnetron sputtering process. These films showed a polycrystalline bulk-like orthorhombic phase with mixed (00l) and (110) orientations, as was supported by X-ray diffraction and piezoelectric force microscopy analyses. Without a post-deposition annealing process, these films already showed a clear ferroelectric polarization-electric field (P-E) hysteresis loop, characterized by a remnant polarization ~11μC/cm2 and a coercive field of ~280 kV/cm. This polarization response shows a good aging resistance (~2 years). A dielectric constant of ~230 and a low loss tangent of ~1.8 % (@1 kHz) were achieved in the KNN film. Lastly, large dielectric tunabilities of ~50 % (@ 1 MHz) was revealed for the KNN film, illustrating their good potential for applications in tunable dielectrics.

Modulation of dielectric properties in low-loss polypropylene-based composites at GHz frequencies: theory and experiment

Polymer composites with high dielectric constant and low loss tangent are highly regarded as substrates for modern high-speed electronics. In this work, we analyze the high-frequency dielectric properties of two types of composites based on polypropylene infused with high-dielectric-constant microparticles. Two types of fillers are used: commercial ceramics or titanium oxide (TiO2) with different concentrations. The key observation is that adding the fillers causes an increase of dielectric constants by around 100% (for highest loading) up to 4.2 and 3.4, for micro-ceramics and TiO2 based composites, respectively. Interestingly, for the TiO2 composite, the loss tangent depends on the filler loading volume, whereas the other composite has a slightly increasing tendency, however, being at the level ~ 10–3. To explain the experimental results, a theoretical model determined by microwave reflection and transmission through a representative volume element is proposed, which allows the investigation of the impact of volume ratio, grain shape, aggregation, and size on the loss tangent and permittivity evolution. This approach could be used for modeling other low dielectric loss materials with inclusions.

Ultra‐lightweight 3D woven spacer integrated composites with stabilization of dielectric and robust mechanical properties at room and elevated temperatures

AbstractPolymer matrix composites with lightweight, low dielectric constant (ε) and dielectric loss tangent (tan δ), high‐temperature resistance, and excellent mechanical properties are urgently needed in the fields of aviation, aerospace, transportation, and wireless communication services. In this work, 3D woven spacer Kevlar/polyimide composites (3DKPC) with excellent dielectric properties and robust mechanical properties were designed and obtained by combining 3D weaving technology and thermal imidization process. Results show that the volume density of the prepared composites is as low as 0.24 g·cm−3, but its compressive strength can be up to 6.24 MPa. The dielectric constant and loss tangent of 3DKPC at room temperature are extremely low, with the value of ~1.32 and 6.9 × 10−3, respectively. Moreover, the compressive strength retention rate is more than 96% and the dielectric constant can be consistently lower than 1.36 when the temperature increases from 25 to 300°C, demonstrating the outstanding mechanical and dielectric stability of 3DKPC. In addition, as an application example of resulting composites, a microstrip antenna with 3DKPC as the substrate material was designed, followed by the simulation of its electromagnetic properties via High Frequency Structural Simulator. The results display that the gain of the microstrip antenna is 6.2 dB, which is superior to those of many other reported microstrip antennas, indicating that the 3DKPC proposed here has great application potential in aerospace, wireless communication, and other fields.

Phase evolution and enhanced electrical properties in Ba0.85Ca0.15Zr0.10Ti0.90O3 lead-free ceramics prepared at different sintering temperatures

ABSTRACT Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) lead-free ceramics were prepared by sol–gel technique, and the influence of sintering temperature on phase evolution and electrical properties has been investigated. The X-ray diffraction patterns indicated that the BCZT ceramics sintered at 850°C do not well crystallized into perovskite phase and orthorhombic-tetragonal biphase coexists at higher sintering temperatures (1250–1350°C). The average grain size increases from 0.23 to 1.37 μm as the sintering temperature increases from 850 to 1400°C. The dielectric properties improve with increasing sintering temperature up to 1300°C. The BCZT ceramics sintered at 1300°C exhibit enhanced dielectric, ferroelectric and piezoelectric properties with high dielectric constant ϵ′ ∼ 3470, low loss tangent (tanδ) of 0.053, spontaneous polarization Ps ∼ 12 μC/cm2, remnant polarization Pr ∼ 2.35 μC/cm2 and coercive field Ec ∼ 1.13 kV/cm and high d 33 ∼ 367 pCN−1 while simultaneously maintaining a high Tc above 100°C.

Influence of the addition of CaTiO3 on the microwave dielectric properties of the BaMoO4 matrix

This work presents the study of the dielectric properties in the microwave region (MW) of BaMoO4 ceramic and composites with CaTiO3 (CTO). The BaMoO4 matrix was synthesized by solid state reaction and characterized by X-ray diffraction. Ceramic composites were obtained by adding 20–80 mol% of CTO in the BaMoO4 matrix. The Silva-Fernandes-Sombra method was used to measure the resonant frequency temperature coefficient (τf), and the BaMoO4 composite with 20% CTO showed an adequate value of relative dielectric permittivity (εr = 8.90), low dielectric loss tangent (tan δ = 9.89.10−4) and τf close to zero (τf = 3.48 ppm °C−1). BMO and its composites were applied as dielectric resonator antennas, and their far-field parameters were obtained through numerical simulation.

Influence of excess bismuth oxide on the structural and dielectric characteristics of textured Bi4Ti3O12 ceramics

Bismuth titanate (Bi4Ti3O12), an Aurivillius family of ferroelectric oxide, has been widely investigated due to its large remnant polarization, high Curie temperature, high dielectric constant and relatively low tangent for the application in information memory storage devices. In this work, polycrystalline bismuth titanate ceramics samples with different amounts of excess Bi2O3 (3 and 5 wt%) were prepared using a low temperature, cost-effective molten salt synthesis method. The structural, microstructural and dielectric properties depend on the addition of excess Bi2O3 and the sintering duration of Bi4Ti3O12 ceramics. Moreover, the X-ray diffraction studies revealed the effect of excess bismuth oxide on the formation of preferential orientation along the c-axis. It is also observed that the orientation factor along the c-axis increases with an increase in the sintering duration for different content of bismuth oxide. The morphological studies revealed the oriented plate-like structure of bismuth titanate ceramics associated with the enhanced growth of grains. It is noticed from the EDAX analysis that the addition of excess bismuth oxide compensated the volatilization of bismuth ions in the crystal lattice of Bi4Ti3O12 ceramics. The dielectric property studies have exhibited a high value of dielectric constant (εr ~ 190), and low tangent loss factor (tanδ ~ 0.08) for the optimum bismuth oxide content of 5 wt% added Bi4Ti3O12 ceramics. Hence, we suggest that these materials could be utilized for the high energy storage capacity of non-volatile memory devices.

Enhancing high-frequency dielectric and mechanical properties of SiO2/PTFE composites from the interface fluorination

To achieve polytetrafluoroethylene (PTFE)-based composites for high-frequency applications with low dielectric constant, low dielectric loss tangent and low coefficient of thermal expansion (CTE), a novel pentafluorostyrene (PFS) interface modifier was used to achieve excellent performance for SiO2/PTFE composite materials. The effects of PFS modification on the microstructure, dielectric properties and thermal properties of SiO2/PTFE composites were investigated. It is found that the use of PFS greatly improves the interfacial compatibility of the composites, on the one hand the dielectric properties are effectively improved, on the other hand the steric resistance of PTFE matrix is enhanced and the CTE is reduced. When the PFS content of 5 wt%, the CTE of SiO2/PTFE is reduced to 86 ppm/°C. The dielectric loss of the composites varies from 0.71 × 10−3 to 1.53 × 10−3 at frequencies from 5 to 40 GHz. The composites also show stable dielectric properties across the applied temperature (0–150 °C). Benefiting from the high density and uniform microstructure of the PFS-modified composite, enabling it to withstand higher frequency and temperature applications.

Dielectric properties with high dielectric permittivity and low loss tangent and nonlinear electrical response of sol-gel synthesized Na1/2Sm1/2Cu3Ti4O12 perovskite ceramic

Giant dielectric ceramic, Na1/2Sm1/2Cu3Ti4O12, was successfully prepared by a modified sol-gel method. X-ray diffraction experiments indicated that a body-centered cubic structure with a space group of Im3 was obtained. Our density functional theory calculations revealed that codoping Na and Sm in the CaCu3Ti4O12 structure resulted in charge compensation between Na and Sm ions in this structure, whereas the oxidation states of Cu and Ti were unaltered. Giant dielectric permittivity ∼7.21 × 103 - 8.04 × 103 and low dielectric loss tangent ∼0.045–0.049 were accomplished at a sintering temperature of 1050 °C for 12–18 h. Nonlinear J - E property with breakdown electric field ∼5.13 – 5.78 × 103 V/cm and nonlinear coefficient ∼6.08–6.82 were also achieved. The n-type semiconducting grain originated from short-range migrations of mixed Cu+/Cu2+ and Ti3+/Ti4+ charges. Finally, our charge analysis showed that the occurrence of Cu+ and Ti3+ was related to the existence of oxygen vacancy in these ceramics.

Influence of ionic liquid on rheological behaviors of candle soot and cellulose nanocrystal filled natural rubber nanocomposites

Carbonaceous soot nanoparticles are used as novel filler in combination with cellulose nanocrystal (CNC) to prepare natural rubber (NR) nanocomposites to which ionic liquid (IL) 1-allyl-3-methylimidazolium chloride is used to enhance the filler-rubber interaction. Nanocomposites of candle soot (CS) and CNC well dispersed in NR were prepared by latex mixing and mechanical mixing followed by vulcanization. The presence of IL causes a slight agglomeration of the fillers but it improves bound rubber content and crosslinking degree. Both the fillers and IL improve dynamic modulus and tensile stress while they lower loss tangent in the linear viscoelastic region, providing a perspective for manufacturing high–performance rubber materials using novel fillers and modifiers.

Acceptor-donor concentration dependent polaronic relaxation, pinned electron defect dipole characteristic and colossal permittivity in co-doped rutile (Zn1/3Nb2/3)xTi(1-x)O2 (x = 0.02, 0.04, 0.06 and 0,08) ceramics

Colossal permittivity with low loss tangent has been achieved by co-substitution of Zn and Nb in TiO2. Incorporation of the divalent and pentavalent ions has been confirmed by structural and Raman spectroscopic analysis. Specific ratio of acceptor-donor pairs led to observation of colossal permittivity (∼104) with a low loss tangent (<0.1). Evidence of localized donor electrons in the dielectric response shows the generation of electron pinned defect dipoles. Low-temperature dielectric relaxation has been observed which correspond to the polaronic conduction following Arrhenius law. As the acceptor-donor content increases, the polaronic relaxation dynamics occurs at higher temperatures. This also reveals that the defect complexes are strongly correlated. Permittivity values corresponding to the loss tangent minima have been compared as a function of acceptor-donor content. Finally, optimum sintering temperature, frequency, measurement temperature, and composition have been identified.

Electrochemical performance and large positive–negative magnetodielectric coupling in iron chromite spinels

• Current work is one of its kind study suggesting a material that can be used to fabricate a device that can simultaneously store memory and energy. • Low cost sol–gel method is used to synthesize iron chromite nanocrystals by varying Fe/Cr ratio. • Spinel phase i.e. FeCr 2 O 4 is observed at Fe/Cr ratios of 0.45, 0.6 and 0.65. • Magneto dielectric (MD) studies confirm positive MD constant at 0.45, 0.6 & 0.65 Fe/Cr ratios. • The galvanostatic charging/discharging behavior shows capacitive behavior of FeCr 2 O 4 samples. • The electrochemical results suggest that synthesized nanocrystals have potential for energy storage system. Spinel ferrites with remarkable electrochemical performance and magnetodielectric (MD) coupling are promising candidates for energy storage and spintronic devices. This study focuses on structural phases, dielectric and magnetic polarization along with magnetodielectric (MD) coupling and electrochemical response of Fe-Cr spinels. Low cost sol–gel method is used to synthesize iron chromite nanopowders. Iron to chromium (Fe/Cr) ratio is varied in the range of 0.2–0.65 (with interval of 0.05). XRD patterns confirm the formation of phase pure FeCr 2 O 4 at Fe/Cr ratios of 0.45, 0.6 & 0.65. Amorphous behavior is observed at Fe/Cr ratios of 0.2, 0.25, 0.5 & 0.55. Mixed phases are observed at 0.3, 0.35 & 0.4 Fe/Cr ratios. Formation of pure spinel phase at Fe/Cr ratio of 0.45 results in high saturation magnetization of 9.2 emu/g. High grain boundary resistance (189.62kΩ) and high dielectric constant (∼83.38 at log f = 5.0) along with low tangent loss (0.00423 at log f = 5) are observed at Fe/Cr ratio of 0.45. Magneto dielectric studies confirm positive magneto dielectric constant (MDC) of synthesized nanopowders at 0.45, 0.6 & 0.65 Fe/Cr ratios. Cyclic voltammetry is performed at constant potential window. Oxidation/reduction process leads to the pseudo-capacitive response of the material. The cyclic voltammetry curves show specific capacitance of 156 Fg −1 , 144 Fg −1 and 152 Fg −1 at scan rate of 25 mV/s at Fe/Cr ratios of 0.45, 0.6 & 0.65 of FeCr 2 O 4 nanopowders, respectively. The galvanostatic charging/discharging behavior shows capacitive behavior of FeCr 2 O 4 nanopowders. The electrochemical results suggest that synthesized nanopowders have potential for energy storage system.

Coexistence of high magnetic and dielectric properties in Ni-Zr co-doped barium hexaferrites

Increased demands for multifunction, integration and miniaturization of electronic devices lead to the investigation of M-type hexaferrite with more abundant properties. In this paper, Ni-Zr co-doped barium ferrite (BaFe 12–2 x Ni x Zr x O 19 , 0 ≤ x ≤ 1 with step of 0.2) with concurrent of considerable saturation magnetization and dielectric properties are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM) and LCR meter. Results reveal that pure M-type hexaferrite phase are obtained with expanded cell parameters by increasing Ni-Zr substitution content. The microstructure shows that Ni-Zr doping has small influence on the average grain size. Magnetic measurements indicate that a maximum saturation magnetization is obtained at x = 0.2 with considerable value of 71.5 emu/g. While the permittivity is substantially enhanced by Ni-Zr co-doping for barium hexaferrite with values reach up to ~10 3 at 100 kHz and dielectric tangent loss about 0.2. These results imply that Ni-Zr doped barium hexaferrites may have potential application in multifunctional and miniaturized electronic devices. • Considerable saturation magnetization with values of 50-71.5 emu/g are obtained for Ni-Zr co-doped BaFe 12 O 19 . • Enhanced dielectric constant up to 10 3 at high frequency with low dielectric tangent loss about 0.2 is obtained. • The mechanism for the influence of Ni-Zr doping on the magnetic and dielectric behaviors of BaFe 12 O 19 have been analyzed.

Experimental study and DFT calculations of improved giant dielectric properties of Ni2+/Ta5+ co-doped TiO2 by engineering defects and internal interfaces

High-performance ceramics with chemical formula (Ni1/3Ta2/3)xTi1−xO2 with excellent dielectric properties are demonstrated. The dopants of Ni2+ and Ta5+ in TiO2 caused the formation of oxygen vacancies and free electrons. The (Ni1/3Ta2/3)xTi1−xO2 exhibited low loss tangent of 0.046 and a high dielectric permittivity of 3.5–4.5 × 104 with a very weak dependence on temperature (−60 to 200 °C). Broadband dielectric spectroscopy shows at least four dominant sources in the dielectric relaxation response in the temperature range of − 253–210 °C. DFT calculations indicate the formation of defect clusters, which are the largest contributors to the dielectric response, and these are found to be dominant even at temperatures down to − 253 °C. Both grain boundary and surface layer mechanisms in the ceramics contribute to the dielectric response at the relatively high temperatures. The sample–electrode contact effect associated with oxygen vacancy diffusion is dominant at high temperatures above 150 °C.

Biophysical properties of hydrogels for mimicking tumor extracellular matrix.

The extracellular matrix (ECM) is an essential component of the tumor microenvironment. It plays a critical role in regulating cell-cell and cell-matrix interactions. However, there is lack of systematic and comparative studies on different widely-used ECM mimicking hydrogels and their properties, making the selection of suitable hydrogels for mimicking different in vivo conditions quite random. This study systematically evaluates the biophysical attributes of three widely used natural hydrogels (Matrigel, collagen gel and agarose gel) including complex modulus, loss tangent, diffusive permeability and pore size. A new and facile method was developed combining Critical Point Drying, Scanning Electron Microscopy imaging and a MATLAB image processing program (CSM method) for the characterization of hydrogel microstructures. This CSM method allows accurate measurement of the hydrogel pore size down to nanometer resolution. Furthermore, a microfluidic device was implemented to measure the hydrogel permeability (Pd) as a function of particle size and gel concentration. Among the three gels, collagen gel has the lowest complex modulus, medium pore size, and the highest loss tangent. Agarose gel exhibits the highest complex modulus, the lowest loss tangent and the smallest pore size. Collagen gel and Matrigel produced complex moduli close to that estimated for cancer ECM. The Pd of these hydrogels decreases significantly with the increase of particle size. By assessing different hydrogels' biophysical characteristics, this study provides valuable insights for tailoring their properties for various three-dimensional cancer models.

Ultra–low loss tangent and giant dielectric permittivity with excellent temperature stability of TiO2 co-doped with isovalent-Zr4+/pentavalent-Ta5+ ions

The excellent giant dielectric properties (ExGDPs) are represented in the isovalent–Zr4+/pentavalent–Ta5+ ions co–doped TiO2 with different co–doping percentages (x%ZrTTO). The dopants were dispersed homogeneously in a highly compact–grained ZrTTO microstructure. The mean grain size and cell parameters with bond lengths slightly enlarged as x% increased. The (1%–5%) ZrTTO oxides exhibited ultra–low tanδ values of 0.004–0.016 with the giant dielectric permittivity (ε′∼2.7–3.7 × 104); while the ε′ of the 5%ZrTTO was slightly dependent on the temperature ranging from −60 to 200 °C, following the temperature dependence requirement for application in the X7/8/9R capacitors. Impedance spectroscopy showed a very large resistance of the grain boundaries. The dielectric properties of the 1%ZrTTO were strongly dependent on the applied DC electric field, indicating the dominant internal barrier layer capacitor (IBLC) effect. However, the dielectric properties of the 5%ZrTTO were nearly independent on the applied DC electric field up to 30 V/mm, which was primarily resulted from electron localization in defect dipoles. Therefore, the ExGDPs of the x%ZrTTO were attributed to the combined effects of the IBLC and localized–electron defect–dipoles related to oxygen vacancies (Ti4+⋅e−−VO••−e−⋅Ti4+ and 3Ti4+⋅e−−VO••−TaTi•) and Ti4+⋅e−−TaTi•.

Electrical responses and dielectric properties of (Zn2+ + F−) co–doped CaCu3Ti4O12 ceramics

The effects of Zn2+ and F− ions on the ceramic microstructure, electrical properties, and colossal dielectric response of CaCu3Ti4O12 were investigated. The dopants influenced the microstructure of the CaCu3Ti4O12. The replacement of Zn2+ and F− ions reduced the low–frequency loss tangent while retaining the high dielectric constant of CaCu3Ti4O12. In co–doped ceramics, the high dielectric permittivity of around 5.76 – 7.59 × 104 and low loss tangent of 0.082 – 0.085 can be attained. The decrease in the loss tangent of the co–doped ceramic samples is commensurate with the significant increase in the grain boundary (GB) resistance and breakdown electric field. The Cu+ and Ti3+ ions in CaCu3Ti4O12 were identified using X–ray photoelectron spectroscopy and were found to be decreased by co–doping with Zn2+ and F−. The presence of these ions may play a crucial role in the semiconducting grains. The substitution of Zn2+ and F− ions can increase the electrostatic potential barriers at the GBs, resulting in improved GB resistance.

The Modification of Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by Melt Blending.

Crystalline and noncrystalline poly(3-hyroxybutylate-co-4-hyroxybutylate) (P(3HB-co-4HB)) were melt blended to obtain mixtures of P(3HB-co-4HB) copolymers. The mixtures and P(3HB-co-4HB) copolymers of different 4HB contents were compared to study the effect of 4HB content on the properties of the copolymers and mixtures. P(3HB-co-4HB) copolymer mixtures, having various 4HB content, have been successfully made by melt blending instead of bacterial biosynthesis. In the case of copolymers, they were noncrystalline when the 4HB content was over 16%, while the P(3HB-co-4HB) mixtures at the same 4HB content were crystalline. The mixtures had a higher glass transition temperature, suggesting that their chain mobility is relatively low compared with the copolymer having the same 4HB content. Due to this effect, the mixture is expected to have a higher melt viscosity and a lower loss tangent to exhibit better melt processing properties. The mechanical properties of the mixtures show a similar behavior to the copolymers in that the tensile strength and the modulus decreases and elongation at the break increases with an increase in the 4HB content.