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).

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.

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.

Crystalline phase of inorganic montmorillonite/poly(vinylidene fluoride) nanocomposites: influence of dispersion of nanolayers

2017 ◽  
Vol 37 (1) ◽  
pp. 31-41 ◽  
Author(s):  
Chao Fu ◽  
Xuemei Wang ◽  
Xiang Shi ◽  
Xianghai Ran
Keyword(s):  
Thermal Treatment ◽  
Crystalline Phase ◽  
Crystallization Process ◽  
Vinylidene Fluoride ◽  
Polar Phase ◽  
Solution Casting ◽  
Casting Method ◽  
Poly Vinylidene Fluoride ◽  
Solution Casting Method ◽  
Co Precipitation

Abstract Inorganic montmorillonite (MMT)/poly(vinylidene fluoride) nanocomposites were prepared by two methods: co-precipitation and solution casting. The effect of preparation methods and thermal treatment on crystalline phase was investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry tests. The isothermal crystallization process was observed with polarized optical microscopy. It was found that the solution-casting method was more effective than the co-precipitation method in inducing the polar phase in the melt-isothermal crystallization process. The addition of inorganic MMT by the solution-casting method without further thermal treatment promoted the β-phase crystallization. The inorganic MMT significantly improved the γ phase of the solution-cast samples in the melt-recrystallization process. The degree of dispersion of inorganic MMT influenced the relative content of the polar phase and the crystallinity of the samples in the same crystallization conditions, i.e. the preparation method and the thermal treatment. The effect of dispersion on crystallization kinetics was also studied to verify the enhancement of finely dispersed nanolayer clusters on the γ phase.

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.

The Influence of Reinforcing Fibers on the Morphology and Crystallization of Thermoplastic Polymer Composites

1991 ◽  
Vol 255 ◽  
Author(s):  
Ludwig Rebenfeld ◽  
Glenn P. Desio ◽  
Veronika E. Reinsch
Keyword(s):  
High Performance ◽  
Crystallization Process ◽  
Polarized Light ◽  
Fiber Surface ◽  
Weight Fraction ◽  
Degree Of Crystallinity ◽  
Surface Finishes ◽  
Reinforcing Fibers ◽  
Glass Carbon ◽  
The Degree Of Crystallinity

AbstractSemi-crystalline thermoplastic polymers are being used increasingly as matrices in high performance fiber reinforced composites. The crystallization kinetics and morphology of these polymers have been studied extensively, but relatively little attention has been given to the effects of the reinforcing fibers on the crystallization process.We have studied the effects of glass, carbon and aramid fibers on the rates of crystallization, the degree of crystallinity, and the glass transition temperature of such typical thermoplastics as poly(phenylene sulfide) and poly(ethylene terephthalate). Based on the isothermal crystallization studies using DSC, we find that, in general, reinforcing fibers increase the rates of crystallization and decrease the degree of crystallinity, the extent of these effects being dependent on the weight fraction of fiber in the composite, the specific type of fiber, and the nature of surface finishes (sizes) that may have been applied.The spherulitic morphology that develops in these polymers during the crystallization process, as characterized by polarized light microscopy, is also affected by the reinforcing fibers. In many cases, transcrystalline regions develop near the fiber surface due to nucleation effects.

Investigating the Effect of Nanoclay Loadings and Re-Processing on the Melting and Crystallization Behavior of PP/Clay Nanocomposites

2019 ◽  
Vol 951 ◽  
pp. 21-25
Author(s):  
Achmad Chafidz ◽  
Sholeh Ma'mun ◽  
Haryanto ◽  
Wara Dyah Pita Rengga ◽  
Prima A. Handayani ◽  
...  
Keyword(s):  
Crystallization Behavior ◽  
Crystallization Process ◽  
The Other ◽  
Degree Of Crystallinity ◽  
Clay Nanocomposites ◽  
Scanning Calorimetry ◽  
Onset Crystallization Temperature ◽  
Significant Difference ◽  
The Degree Of Crystallinity ◽  
Melting And Crystallization

In this study, PP/clay nanocomposites have been fabricated at different nanoclay loadings, i.e. 0, 5, 10, and 5 wt% for the 1stcycle and 2ndcycle (re-processing). The prepared nanocomposites were then characterized by a Differential Scanning Calorimetry (DSC) to investigate the effects of nanoclay loadings and re-processing on the melting and crystallization of the nanocomposites. The DSC results showed that the melting temperature,Tmwas not significantly affected by the nanoclay loadings and re-processing. In the other hand, the degree of crystallinity,Xcof the nanocomposites was higher than that of neat PP, but only reached a maximum at nanoclay loading of 5 wt% (i.e. 51.2% for NC-5-I and 48.3% for NC-5-II). Thereafter, theXcdecreased at higher nanoclay loadings. There was no significant difference inXcbetween 1stcycle and 2ndcycle. Additionally, in all nanocomposites samples for both cycles, there were two crystallization temperatures, i.e.Tc1andTc2. In the overall crystallization process, theTcof nanocomposites increased by 11-12°C compared to that of neat PP. Whereas, the onset crystallization temperature,Tocalso increased by approx. 13°C. Apparently, there was no significant effect of nanoclay loadings and re-processing on theTcndTocof the nanocomposites.

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%.

Crystallization Behaviours of Poly(vinylidene fluoride) (PVDF) Nanocomposites with MoS2 Nanosheets with Different Surface Functional Groups

2020 ◽  
Vol 20 (12) ◽  
pp. 7535-7543
Author(s):  
Guihai Gan ◽  
Cheng Wang ◽  
Pengpeng Chen ◽  
Jichang Liu
Keyword(s):  
Thermal Stability ◽  
Crystallization Temperature ◽  
Vinylidene Fluoride ◽  
Crystallization Rate ◽  
Cold Crystallization ◽  
Degree Of Crystallinity ◽  
Mos2 Nanosheets ◽  
Surface Functional Groups ◽  
Poly Vinylidene Fluoride ◽  
Thermal Stability Of

The crystallization behaviours of amorphous poly(vinylidene fluoride) (PVDF) nanocompositesmodified with two different kinds of molybdenum disulfide (MoS2) at different filler loadings were investigated in detail in this work. The crystallinity, melting temperature and crystallization temperature of the PVDF/MoS2 nanocomposites were transformed from α-phase to β-phase with the addition of MoS2, MoS2-COOH and MoS2-NH2. During isothermal cold crystallization, the overall crystallization rate of PVDF was slowed with increased MoS2 loading relative to that of neat PVDF. Moreover, the crystallization temperature of the PVDF nanocomposites increased with the addition of MoS2 despite the cooling rate during nonisothermal cold crystallization. DMA tests showed that the storage modulus of PVDF was decreased with the addition of MoS2, while those of PVDF/MoS2-COOH and PVDF/MoS2-NH2 were enhanced to different degrees. The decomposition of the PVDF/MoS2 nanocomposites were also discussed. Relative to neat PVDF, the thermal stability of PVDF was obviously improved with the addition of MoS2, MoS2-COOH and MoS2-NH2, which could be ascribed to the increased degree of crystallinity.

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