Influence of the Crystallisation Kinetics on the Microstructural Properties of α-PVDF

2006 ◽  
Vol 949 ◽  
Author(s):  
Marco Pinto Silva ◽  
Vitor Sencadas ◽  
Anabela G Rolo ◽  
Gabriela Botelho ◽  
Ana Vera Machado ◽  
...  
Keyword(s):  
Vinylidene Fluoride ◽  
Alpha Phase ◽  
Degree Of Crystallinity ◽  
Infrared Transmission ◽  
Crystallisation Kinetics ◽  
Poly Vinylidene Fluoride ◽  
Different Temperatures ◽  
Kinetics Of ◽  
The Degree Of Crystallinity ◽  
Crystallization From The Melt

ABSTRACTThe kinetics of the isothermal crystallization from the melt at different crystallisation temperatures and the melting behaviour of Poly(vinylidene fluoride) (PVDF) in the alpha phase has been investigated. The variation of the microstructure of the samples crystallized at different temperatures was monitored with time by Optical Microscopy. The correlation between microstructure and kinetic parameters allows the tailoring of the microstructure by choosing the crystallisation conditions of the samples. Raman and Infrared Transmission Spectroscopy also show the appearance of the γ-phase for higher crystallisation temperatures. The influence of the crystallisation kinetics on the degree of crystallinity of the samples will be also presented and discussed.

scholarly journals Effect of Poling on the Mechanical Properties of β-Poly(Vinylidene Fluoride)

2006 ◽  
Vol 514-516 ◽  
pp. 951-955 ◽  
Author(s):  
Carlos M. Costa ◽  
Vitor Sencadas ◽  
João F. Mano ◽  
Senentxu Lanceros-Méndez
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Vinylidene Fluoride ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Direction Parallel ◽  
Poly Vinylidene Fluoride ◽  
The Stability ◽  
Kinetics Of ◽  
The Degree Of Crystallinity

In this work, mechanical and thermal experimental techniques have been applied in order to relate the mechanical response with the microscopic variations of the material. Stress-strain results along the main directions of β-poly(vinylidene fluoride), β-PVDF, in poled and non-poled samples enables to investigate the influence of the poling process on the mechanical response of the material. Further, differential scanning calorimetry experiments allow the investigation of the effect of poling in the degree of crystallinity of the material as well as on the stability of the crystalline phase. Thermogravimetric analysis was used to investigate the kinetics of the thermal degradation of poled and non-poled β-PVDF samples. The differences observed between the two materials suggest that the poling affects the mechanical properties of the material especially in the direction parallel to the polymeric chains and originates changes at a molecular level that remain beyond the melting of the material.

scholarly journals Fluoroalkyl Pentacarbonylmanganese(I) Complexes as Initiators for the Radical (co)Polymerization of Fluoromonomers

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 384 ◽  
Author(s):  
Roberto Morales-Cerrada ◽  
Vincent Ladmiral ◽  
Florence Gayet ◽  
Christophe Fliedel ◽  
Rinaldo Poli ◽  
...  
Keyword(s):  
Visible Light ◽  
Polyvinylidene Fluoride ◽  
Vinylidene Fluoride ◽  
Degree Of Crystallinity ◽  
End Groups ◽  
Radical Initiators ◽  
Alternating Copolymerization ◽  
Kinetics Of ◽  
The Degree Of Crystallinity ◽  
Moderate Yield

The use of [Mn(RF)(CO)5] (RF = CF3, CHF2, CH2CF3, COCF2CH3) to initiate the radical polymerization of vinylidene fluoride (F2C=CH2, VDF) and the radical alternating copolymerization of vinyl acetate (CH2=CHOOCCH3, VAc) with tert-butyl 2-(trifluoromethyl)acrylate (MAF-TBE) by generating primary RF• radicals is presented. Three different initiating methods with [Mn(CF3)(CO)5] (thermal at ca. 100 °C, visible light and UV irradiations) are described and compared. Fair (60%) to satisfactory (74%) polyvinylidene fluoride (PVDF) yields were obtained from the visible light and UV activations, respectively. Molar masses of PVDF reaching 53,000 g·mol−1 were produced from the visible light initiation after 4 h. However, the use of [Mn(CHF2)(CO)5] and [Mn(CH2CF3)(CO)5] as radical initiators produced PVDF in a very low yield (0 to 7%) by both thermal and photochemical initiations, while [Mn(COCF2CH3)(CO)5] led to the formation of PVDF in a moderate yield (7% to 23%). Nevertheless, complexes [Mn(CH2CF3)(CO)5] and [Mn(COCHF2)(CO)5] efficiently initiated the alternating VAc/MAF-TBE copolymerization. All synthesized polymers were characterized by 1H and 19F NMR spectroscopy, which proves the formation of the expected PVDF or poly(VAc-alt-MAF-TBE) and showing the chaining defects and the end-groups in the case of PVDF. The kinetics of VDF homopolymerization showed a linear ln[M]0/[M] versus time relationship, but a decrease of molar masses vs. VDF conversion was noted in all cases, which shows the absence of control. These PVDFs were rather thermally stable in air (up to 410 °C), especially for those having the highest molar masses. The melting points ranged from 164 to 175 °C while the degree of crystallinity varied from 44% to 53%.

Influence of the Crystallization Kinetics on the Microstructural Properties of γ-PVDF

2008 ◽  
Vol 587-588 ◽  
pp. 534-537 ◽  
Author(s):  
M.P. Silva ◽  
Vitor Sencadas ◽  
A.G. Rolo ◽  
Gabriela Botelho ◽  
Ana Vera Machado ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Optical Microscopy ◽  
Kinetic Parameters ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Vinylidene Fluoride ◽  
Microstructural Properties ◽  
Infrared Transmission ◽  
Poly Vinylidene Fluoride ◽  
Kinetics Of

The kinetics of the isothermal crystallization of the γ-phase Poly(vinylidene fluoride) has been investigated. Samples were prepared from the melt at different crystallisation temperatures and the variation of the microstructure of the samples was monitored with time by optical microscopy. Raman and Infrared transmission spectroscopies also show the appearance of the γ-phase for higher crystallisation temperatures. Two types of γ-phase spherulites have been identified. These spherulites represents different ways to obtain the γ-phase and show different thermal stability. The correlation between microstructure and kinetic parameters allows the tailoring of the microstructure by choosing the crystallisation conditions of the samples.

Effects of LiCF3SO3 on PVDF-HFP/MG49 (70/30) Based Blend Polymer Electrolyte

2013 ◽  
Vol 313-314 ◽  
pp. 117-120 ◽  
Author(s):  
Narges Ataollahi ◽  
Azizan Ahmad ◽  
Harun Haji Hamzah ◽  
Mohd Yusri Rahman ◽  
Nor Sabirin Mohamed
Keyword(s):  
Polymer Electrolyte ◽  
Vinylidene Fluoride ◽  
Solid Polymer ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Poly Vinylidene Fluoride ◽  
Solution Casting Method ◽  
Blend Polymer Electrolyte ◽  
Blend Polymer ◽  
The Degree Of Crystallinity

Poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP), Poly (methyl methacrylate)-grafted natural rubber (MG49) (70/30) complexed with different compositions of lithium trifluoromethane sulfonate (LiCF3SO3) based solid polymer electrolyte has been prepared using solution casting method. This work has demonstrated that conductivity values were found to depend upon the concentration of LiCF3SO3. The highest ionic conductivity was 1.97×10ˉ4 S cm-1at 25 wt. % of LiCF3SO3 at room temperature. X-ray diffraction (XRD) indicates decrease in the degree of crystallinity by increasing of salt concentration.

Effects of initial crystallization process on piezoelectricity of PVDF-HFP films

2015 ◽  
Vol 35 (5) ◽  
pp. 451-461 ◽  
Author(s):  
Bin Hu ◽  
Ning Hu ◽  
Liangke Wu ◽  
Feng Liu ◽  
Yaolu Liu ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Vinylidene Fluoride ◽  
Degree Of Crystallinity ◽  
Slow Cooling ◽  
Poly Vinylidene Fluoride ◽  
Cooling Speed ◽  
Solution Casting Method ◽  
Heating Pattern ◽  
The Degree Of Crystallinity ◽  
Initial Crystallization Temperature

Abstract The effects of some important factors in the initial crystallization process of the solution casting method on the piezoelectricity of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films were extensively explored. The experimental results revealed that there is an optimal initial crystallization temperature at around 90°C. The slow cooling speed can moderately enhance the degree of crystallinity. The most important finding was that a bilayer crystalline structure caused by an asymmetrical heating pattern can enhance the formation of packed micro-fibrillar morphologies after drawing. These three points can increase the piezoelectricity of the PVDF-HFP films, indicating the increase of the extended-chain crystals (β-phase).

Simulations of High-Strain Electrostrictive Chlorinated Terpolymers

2003 ◽  
Vol 785 ◽  
Author(s):  
George J. Kavarnos ◽  
Thomas Ramotowski
Keyword(s):  
Vinylidene Fluoride ◽  
High Strain ◽  
Polymer Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lamellar Structures ◽  
Annealing Conditions ◽  
Poly Vinylidene Fluoride ◽  
Electromechanical Responses ◽  
Kinetics Of

ABSTRACTChlorinated poly(vinylidene fluoride/trifluoroethylene) terpolymers are remarkable examples of high strain electrostrictive materials. These polymers are synthesized by copolymerizing vinylidene fluoride and trifluoroethylene with small levels of a third chlorinated monomer. The electromechanical responses of these materials are believed to originate from the chlorine atom, which, by its presence in the polymer chains and by virtue of its large van der Waals radius, destroys the long-range crystalline polar macro-domains and transforms the polymer from a normal to a high-strain relaxor ferroelectric. To exploit the strain properties of the terpolymer, it is desirable to understand the structural implications resulting from the presence of the chlorinated monomer. To this end, computations have been performed on model superlattices of terpolymers using quantum-mechanical based force fields. The focus has been on determining the energetics and kinetics of crystallization of the various polymorphs that have been identified by x-ray diffraction and fourier transform infrared spectroscopy. The chlorinated monomer is shown to act as a defect that can be incorporated into the lamellar structures of annealed terpolymer without a high cost in energy. The degree of incorporation of the chlorinated monomer into the crystal lattice is controlled by annealing conditions and ultimately determines the ferroelectric behavior of the terpolymers.

Molecular weight dependent of the crystallization kinetics of poly(vinylidene fluoride)

1992 ◽  
Vol 32 (17) ◽  
pp. 1300-1308 ◽  
Author(s):  
Sophie Roussel ◽  
Kathy Lynn McElroy ◽  
Lawrence H. Judovits
Keyword(s):  
Molecular Weight ◽  
Crystallization Kinetics ◽  
Vinylidene Fluoride ◽  
Poly Vinylidene Fluoride ◽  
Kinetics Of
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