scholarly journals Influence of film stretching on crystalline phases and dielectric properties of a 70/30 mol% poly(vinylidenefluoride-tetrafluoroethylene) copolymer

2020 ◽  
Vol 10 (05) ◽  
pp. 2050023
Author(s):  
Thulasinath Raman Venkatesan ◽  
Anna A. Gulyakova ◽  
Reimund Gerhard
Keyword(s):  
Dielectric Properties ◽  
Polyvinylidene Fluoride ◽  
Ferroelectric Phase ◽  
Mechanical Analysis ◽  
Dielectric Relaxation Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Crystalline Phases ◽  
The Stability ◽  
Dissipation Losses

Polyvinylidene fluoride (PVDF)-based copolymers with tetrafluoroethylene (P(VDF-TFE)), trifluoroethylene (P(VDF-TrFE)) or hexafluoropropylene (P(VDF-HFP)) are of strong interest due to the underlying fundamental mechanisms and the potential ferro-, pyro- and piezo-electrical applications. Their flexibility and their adaptability to various shapes are advantageous in comparison to inorganic ferroelectrics. Here, we study the influence of stretching temperature on the crystalline phases and the dielectric properties in P(VDF-TFE) films by means of Dielectric Relaxation Spectroscopy (DRS), Fourier-Transform InfraRed spectroscopy (FTIR), Wide-Angle X-ray Diffraction (WAXD), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). Especially, the effect of stretching and the influence of the temperature of stretching on the mid-temperature ([Formula: see text] transition are studied in detail. The results show that stretching has a similar effect as that on PVDF, and we observe an increase in the fraction of ferroelectric [Formula: see text]-phase with a simultaneous increment in both melting point ([Formula: see text] and crystallinity ([Formula: see text] of the copolymer. While an increase in the stretching temperature does not have a profound impact on the amount of ferroelectric phase, the stability of the ferroelectric phase seems to improve — as seen in the reduction of the Full Width at Half Maximum (FWHM) of the WAXD peaks in both parallel and perpendicular directions to the molecular chain axis. The observation is also supported by the reduction of dissipation losses with an increase in stretching temperature — as seen in DRS measurements. Finally, both stretching itself and the temperature of stretching affect the various molecular processes taking place in the temperature range of the [Formula: see text] transition.

scholarly journals Relationship between the Stereocomplex Crystallization Behavior and Mechanical Properties of PLLA/PDLA Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1851
Author(s):  
Hye-Seon Park ◽  
Chang-Kook Hong
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Crystallization Behavior ◽  
Mechanical Analysis ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
Scanning Calorimetry ◽  
Nucleation Sites ◽  
Wide Range ◽  
Degree Of Crystallization

Poly (l-lactic acid) (PLLA) is a promising biomedical polymer material with a wide range of applications. The diverse enantiomeric forms of PLLA provide great opportunities for thermal and mechanical enhancement through stereocomplex formation. The addition of poly (d-lactic acid) (PDLA) as a nucleation agent and the formation of stereocomplex crystallization (SC) have been proven to be an effective method to improve the crystallization and mechanical properties of the PLLA. In this study, PLLA was blended with different amounts of PDLA through a melt blending process and their properties were calculated. The effect of the PDLA on the crystallization behavior, thermal, and mechanical properties of PLLA were investigated systematically by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), polarized optical microscopy (POM), dynamic mechanical analysis (DMA), and tensile test. Based on our findings, SC formed easily when PDLA content was increased, and acts as nucleation sites. Both SC and homo crystals (HC) were observed in the PLLA/PDLA blends. As the content of PDLA increased, the degree of crystallization increased, and the mechanical strength also increased.

Preparation by solution mixing and characterization of condensation type poly(dimethyl siloxane)/graphene nanoplatelets composites

2021 ◽  
pp. 002199832110558
Author(s):  
Panayiotis Ketikis ◽  
Efthimios Damopoulos ◽  
Georgios Pilatos ◽  
Panagiotis Klonos ◽  
Apostolos Kyritsis ◽  
...  
Keyword(s):  
Graphene Nanoplatelets ◽  
Matrix Composites ◽  
Dielectric Relaxation Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Dimethyl Siloxane ◽  
Diffraction Patterns ◽  
The Impact

The impact of the incorporation of graphene nanoplatelets (GN) on the properties of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) matrices was investigated. The composites were prepared by solution mixing, using tetrahydrofuran (THF) as a solvent. Brookfield viscosimetry, implemented during the vulcanization process, revealed that GN increases the viscosity of the system, compared to pristine PDMS, proportionally to its concentration. X-ray diffraction patterns suggested an efficient dispersion of GN in the polysiloxane matrix. The D and G bands ratio (ID/IG) calculation, based on RAMAN spectra of GN/PDMS specimens, revealed more defects in graphene nanoplatelets when incorporated in the PDMS matrix. By differential scanning calorimetry (DSC), a marginal increase in crystallization, glass transition and melting temperatures of PDMS in GN/PDMS composites was observed. Improvement of the thermal stability of LMW PDMS composites, especially for higher GN concentrations (3 and 5 phr), was noticed by thermogravimetric analysis (TGA). Additionally, GN enhanced the tensile strength of composites, up to 73% for the 3 phr GN/LMW PDMS composite. A significant increase in the elongation at break was recorded, whereas no effect on the modulus of elasticity was recorded. The decrease in toluene-swelling, for the LMW PDMS matrix composites, was attributed to the increase in the tortuosity path because of the efficient dispersion of GN. A decrease in oxygen permeability of 55–65% and 44–58% was measured in membranes made of PDMS composites containing 0.5 phr and 1 phr GN, respectively. Dielectric relaxation spectroscopy (DRS) measurements recorded a significant increase in the conductivity of the higher graphene content composites.

scholarly journals Study on the Structure and Dielectric Properties of Zeolite/LDPE Nanocomposite under Thermal Aging

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2108
Author(s):  
Bai Han ◽  
Chuqi Yin ◽  
Jiaxin Chang ◽  
Yu Pang ◽  
Penghao Lv ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Aging Time ◽  
Thermal Aging ◽  
Aging Treatment ◽  
Dielectric Strength ◽  
Breakdown Field ◽  
Scanning Calorimetry ◽  
Aging Resistance ◽  
The Stability ◽  
Breakdown Field Strength

Nanodoping is an effective way to improve the dielectric properties and the aging resistance of polyethylene. Nano-zeolite has a nano-level porous structure and larger specific surface area than ordinary nano-inorganic oxide, which can be used to improve dielectric properties of low-density polyethylene (LDPE) nanocomposite. The zeolite/LDPE nanocomposites were prepared and subjected to thermal aging treatment to obtain samples with different aging time. Using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the differential scanning calorimetry (DSC) test to study the microscopic and structure characteristics, it was found that nano-zeolite doping can effectively reduce the thermal aging damage to the internal structure of the nanocomposite; carbonyl and hydroxyl decreased significantly during the thermal aging time, and the crystallinity effectively improved. Nano-zeolite doping significantly improved the morphology and strengthened the aging resistance of the nanocomposite. In the dielectric strength test, it was found that nanodoping can effectively improve the direct current (DC) and alternating current (AC) breakdown field strength and the stability after the thermal aging. The dielectric constant of nanocomposite can be reduced, and the dielectric loss had no obvious change during the aging process. Moreover, the zeolite/LDPE nanocomposite with the doping concentration of 1 wt % had the best performance, for the nano-zeolite was better dispersed.

scholarly journals Characterization of Polypropylene Modified by Blending Elastomer and Nano-Silica

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1321 ◽  
Author(s):  
Xiaohong Chi ◽  
Lu Cheng ◽  
Wenfeng Liu ◽  
Xiaohong Zhang ◽  
Shengtao Li
Keyword(s):  
Dielectric Properties ◽  
Space Charge ◽  
Power Transmission ◽  
Breakdown Strength ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Insulation Material ◽  
Nano Silica ◽  
Scanning Calorimetry ◽  
High Voltage Direct Current

Polypropylene (PP) contains promising application prospects in thermoplastic cables for high voltage direct current (HVDC) power transmission because of its outstanding thermal and dielectric properties. However, the problem of poor toughness and space charge has restricted the application of pure PP in HVDC cables. In this paper, polyolefin elastomer (POE) and nano-silica were blended thoroughly and added into a PP mixture by a melting method. Scanning electron microscopy (SEM) was employed to observe the dispersion of POE and nanoparticles. Thermal properties were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Mechanical properties were evaluated by tensile tests. The elastomeric properties of composites were improved as the dispersed POE could transfer and homogenize external mechanical forces. DC breakdown results showed that the fail strength of composite with 10 phr POE and 1 phr nano-silica was obviously enhanced. The pulsed electro-acoustic (PEA) results showed that the injection and accumulation of space charge was increased by the introduction of POE, while it was restrained by the collective effect caused by nano-silica filling. X-ray diffraction (XRD) spectrograms showed that secondary ordered structures existed in the composites of PP, POE, and nano-silica, and that the ordered structure around the nanoparticles contributed to the enhancement of breakdown strength. The mechanical and dielectric properties were modified synergistically, which made the modified PP a propitious insulation material for HVDC cables.

scholarly journals Effect of Sr2TiMnO6 fillers on mechanical, dielectric and thermal behaviour of PMMA polymer

2015 ◽  
Vol 05 (03) ◽  
pp. 1550018 ◽  
Author(s):  
P. Thomas ◽  
B. S. Dakshayini ◽  
H. S. Kushwaha ◽  
Rahul Vaish
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Thermo Gravimetric Analysis ◽  
Mechanical Analysis ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melt Mixing ◽  
Transition Formula ◽  
Thermal Stability Of ◽  
Pmma Polymer

Composites of poly(methyl methacrylate) (PMMA) and [Formula: see text] (STMO) were fabricated via melt mixing followed by hot pressing technique. These were characterized using X-ray diffraction (XRD), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), thermo mechanical analysis (TMA) and impedance analyser for their structural, thermal and dielectric properties. The coefficient of thermal expansion (CTE) was measured between 40°C and 100°C for pure PMMA is 115.2 ppm/°C, which was decreased to 78.58 ppm/°C when the STMO content was increased to 50 wt.% in PMMA. There was no difference in the glass transition ([Formula: see text]) temperature of the PMMA polymer and their composites. However, the FTIR analysis indicated possible interaction between the PMMA and STMO. The density and the hardness were increased as the STMO content increased in the PMMA matrix. Permittivity was found to be as high as 30.9 at 100 Hz for the PMMA+STMO-50 wt.% composites, indicating the possibility of using these materials for capacitor applications. The thermal stability of polymer was enhanced by incorporation of STMO fillers.

scholarly journals Dielectric properties and conductivity of PVdF-co-HFP/LiClO4 polymer electrolytes

2018 ◽  
Vol 96 (7) ◽  
pp. 786-791 ◽  
Author(s):  
Kemal Ulutaş ◽  
Ugur Yahsi ◽  
Hüseyin Deligöz ◽  
Cumali Tav ◽  
Serpil Yılmaztürk ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Polymer Electrolytes ◽  
Room Temperature ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Maximum Conductivity

In this study, it was aimed to prepare a series of PVdF-co-HFP based electrolytes with different LiClO4 loadings and to investigate their chemical and electrical properties in detail. For this purpose, PVdF-co-HFP based electrolytes with different LiClO4 loadings (1–20 weight %) were prepared using solution casting method. X-ray diffraction (XRD), differential scanning calorimetry, and thermogravimetric (TGA) –differential thermal and dielectric spectroscopy analysis of PVdF-co-HFP/LiClO4 were performed to characterize their structural, thermal, and dielectric properties, respectively. XRD results showed that the diffraction peaks of PVdF-co-HFP/LiClO4 electrolytes broadened and decreased with LiClO4. TGA patterns exhibited that PVdF-co-HFP/LiClO4 electrolytes with 20 wt % of LiClO4 had the lowest thermal stability and it degraded above 473 K, which is highly applicable for solid polymer electrolytes. Dielectric constant, dielectric loss, and conductivities were calculated by measuring capacitance and dielectric loss factor of PVdF-co-HFP/LiClO4 in the range from 10 mHz to 20 MHz frequencies at room temperature. In consequence, conductivities of PVdF-co-HFP/LiClO4 increased significantly with frequency for low loading of LiClO4 while they only slightly changed with higher LiClO4 addition. On the other hand, dielectric constant values of PVdF-co-HFP/LiClO4 films decreased with frequency whereas they rose with LiClO4 addition. The dielectric studies showed an increase in dielectric constant and dielectric loss with decreasing frequency. This result was attributed to high contribution of charge accumulation at the electrode–electrolyte interface. The electrolyte showed the maximum conductivity of 8 × 10−2 S/cm at room temperature.

Crystallization Kinetics of β-Spodumene/Cordierite-Based Glass-Ceramics

2016 ◽  
Vol 881 ◽  
pp. 83-88 ◽  
Author(s):  
Rafael Bianchini Nuernberg ◽  
Oscar Rubem Klegues Montedo
Keyword(s):  
Crystallization Kinetics ◽  
Glass Ceramics ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Kinetics Parameters ◽  
Crystalline Phases ◽  
Cordierite Glass ◽  
Thermal And Electrical Properties ◽  
Kinetics Of

This work aims to investigate the crystallization kinetics of β-spodumene/cordierite glass-ceramics. Thus, three glasses with compositions based predominantly on cordierite (C), β-spodumene (L) and in a molar ratio 1:1 of both phases (CL) were prepared. The kinetics parameters such as activation energy for crystallization (ranging from 160 to 358 kJ/mol) and Avrami exponent (ranging from 1.4 to 10.7) were determined by means of non-isothermal methods using differential scanning calorimetry (DSC). Additionally, the samples were crystalized according to DSC analyses and characterized by using x-ray diffraction (XRD). The main detected crystalline phases were β-spodumene to the glass L, cordierite to the glass C and β-quartz, mulite and spinel to the glass CL. Considering the thermal and electrical properties of these crystalline phases, these glass-ceramics have potential use for LTCC (Low Thermal Co-fired Ceramics) applications.

scholarly journals Tunable Structure and Properties of Segmented Thermoplastic Polyurethanes as a Function of Flexible Segment

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1910 ◽  
Author(s):  
Manuel Asensio ◽  
Victor Costa ◽  
Andrés Nohales ◽  
Otávio Bianchi ◽  
Clara M Gómez
Keyword(s):  
Tensile Properties ◽  
Microphase Separation ◽  
Mechanical Analysis ◽  
Phase Behaviour ◽  
Scanning Calorimetry ◽  
Thermoplastic Polyurethanes ◽  
Separation Degree ◽  
Tunable Structure ◽  
Flexible Segment ◽  
The Stability

Segmented thermoplastic polyurethanes (PUs) were synthetized using macrodiols with different functional groups (carbonate, ester, and /or ether) as a segment with a molar mass of 1000 and 2000 g/mol, and 4,4’-diphenylmethane diisocyanate (MDI) and 1,4-butanediol as a rigid segment. The polyurethanes obtained reveal a wide variation of microphase separation degree that is correlated with mechanical properties and retention of tensile properties under degradation by heat, oil, weather, and water. Different techniques such as differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR), and synchrotron small-angle X-ray scattering (SAXS) were used to determine rigid-flexible segments’ phase behaviour. Retention of tensile properties determines the stability of the samples under different external factors. This work reveals that pure polycarbonate-based macrodiols induce the highest degree of phase miscibility, better tensile properties, hardness shore A, and retention of tensile properties under external agents.

scholarly journals Lightweight and Durable PVDF–SSPF Composites for Photovoltaics Backsheet Applications: Thermal, Optical and Technical Properties

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2104 ◽  
Author(s):  
M. H. Alaaeddin ◽  
S. M. Sapuan ◽  
M. Y. M. Zuhri ◽  
E. S. Zainudin ◽  
Faris M. AL- Oqla
Keyword(s):  
Polyvinylidene Fluoride ◽  
Mechanical Analysis ◽  
Short Fiber ◽  
Photovoltaic Module ◽  
Scanning Calorimetry ◽  
Sugar Palm Fiber ◽  
Technical Properties ◽  
Critical Components ◽  
Thermal Mechanical Analysis

Photovoltaic module backsheets are characterized according to their thermal, optical, mechanical, and technical properties. This work introduces new fabricated backsheets for PV modules using polyvinylidene fluoride (PVDF) reinforced with short sugar palm fiber (SSPF) composites. The preparation of composites undergoes multiple phases of fabrication. Thermal, optical, and technical investigations of their properties were conducted. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, in-situ scanning probe microscopy (SPM), dynamic mechanical analysis (DMA), thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and prolonged technical testing were accomplished to expansively understand the complex behavior of composites under various conditions. The optical properties of PV backsheets are critical components in determining the reflectance, absorbance, and transmittance of light. The PVDF–SSPF composites exhibited exceptional compatibility and thermal stability, further revealing a homogenous composite structure with enhanced interfacial bonding between the short fiber and polymer matrix.

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