Studies on α to β phase transformations in mechanically deformed PVDF films

Vijayakumar, R.; Khakhar, D. V.; Misra, Ashok

doi:10.1002/app.32218

Cited by 104 publications

(4 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This trend can also be obtained from Figure 1B. The X-ray diffractograms of all the membrane surfaces are seen to have well-defined peaks at 2θ = 17.8 • , 18.3 • , 19.9 • , and 26.6 • , which correspond to (100), (020), (110), and (021) crystal plane of α-phase [25]. This phenomenon also demonstrates that α-phase holds a dominant position in the membranes before or after the stretching, although after the stretching and annealing, a shoulder peak at 2θ = 20.6 • that corresponds to (110/200) plane appears and gradually becomes obvious as the stretch ratio is increased from 50% to 100%.…”

Section: Resultssupporting

confidence: 68%

“…It should be noted that the intensity of the characteristic β phase is not obvious as the stretching ratio is lower than 50%, and becomes evident as the stretching ratio is getting higher, which agrees with the results of the literature [21] that "stretching the fibers up to 40% was not enough to induce any detectable β phase crystals". diffractograms of all the membrane surfaces are seen to have well-defined peaks at 2θ = 17.8°, 18.3°, 19.9°, and 26.6°, which correspond to (100), (020), (110), and (021) crystal plane of α-phase [25]. This phenomenon also demonstrates that α-phase holds a dominant position in the membranes before or after the stretching, although after the stretching and annealing, a shoulder peak at 2θ = 20.6° that corresponds to (110/200) plane appears and gradually becomes obvious as the stretch ratio is increased from 50% to 100%.…”

Section: Resultsmentioning

confidence: 98%

See 1 more Smart Citation

Effects of Room Temperature Stretching and Annealing on the Crystallization Behavior and Performance of Polyvinylidene Fluoride Hollow Fiber Membranes

Tang

Lin

et al. 2020

Membranes

View full text Add to dashboard Cite

A treatment consisting of room temperature stretching and subsequent annealing was utilized to regulate the morphology and performance of polyvinylidene fluoride (PVDF) hollow fiber membranes. The effects of stretching ratios and stretching rates on the crystallization behavior, morphology, and performance of the PVDF membranes were investigated. The results showed that the treatment resulted in generation of the β crystalline phase PVDF and increased the crystallinity of the membrane materials. The treatment also brought about the orientation of the membrane pores along the stretching direction and led to an increase in the mean pore size of the membranes. In addition, as the stretching ratio increased, the tensile strength and permeation flux were improved while the elongation at break was depressed. However, compared to the stretching ratio, the stretching rate had less influence on the membrane structure and performance. In general, as the stretching ratio was 50% and the stretching rate was 20 mm/min, the tensile strength was increased by 36% to 7.47 MPa, and the pure water flux was as high as 776.28 L/(m2·h·0.1bar), while the mean pore size was not changed significantly. This research proved that the room temperature stretching and subsequent annealing was a simple but effective method for regulating the structure and the performance of the PVDF porous membranes.

show abstract

Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 98%

Effects of Room Temperature Stretching and Annealing on the Crystallization Behavior and Performance of Polyvinylidene Fluoride Hollow Fiber Membranes

Tang

Lin

et al. 2020

Membranes

View full text Add to dashboard Cite

show abstract

“…A significant enhancement in the β-phase content of PVDF was observed after the addition of fillers in the PVDF polymer matrix, such as ceramics, carbon-based materials, metal oxides, and graphene [ 6 ]. Some of these methods to enhance the beta phase of PVDF are stretching [ 104 ], electric poling [ 48 ], solvent casting, the addition of nucleating fillers, phase transitions, or copolymer development [ 105 ].…”

Section: β-Phase Induction In Pvdfmentioning

confidence: 99%

PVDF-Based Piezo-Catalytic Membranes—A Net-Zero Emission Approach towards Textile Wastewater Purification

Siddique,

Nawaz,

Razzaque

et al. 2024

Polymers

View full text Add to dashboard Cite

Among the various water purification techniques, advancements in membrane technology, with better fabrication and analysis, are receiving the most research attention. The piezo-catalytic degradation of water pollutants is an emerging area of research in water purification technology. This review article focuses on piezoelectric polyvinylidene difluoride (PVDF) polymer-based membranes and their nanocomposites for textile wastewater remediation. At the beginning of this article, the classification of piezoelectric materials is discussed. Among the various membrane-forming polymers, PVDF is a piezoelectric polymer discussed in detail due to its exceptional piezoelectric properties. Polyvinylidene difluoride can show excellent piezoelectric properties in the beta phase. Therefore, various methods of β-phase enhancement within the PVDF polymer and various factors that have a critical impact on its piezo-catalytic activity are briefly explained. This review article also highlights the major aspects of piezoelectric membranes in the context of dye degradation and a net-zero approach. The β-phase of the PVDF piezoelectric material generates an electron–hole pair through external vibrations. The possibility of piezo-catalytic dye degradation via mechanical vibrations and the subsequent capture of the resulting CO2 and H2 gases open up the possibility of achieving the net-zero goal.

show abstract

“…The α-phase is nonpolar and adopts a trans - gauche - trans - gauche ’ (TGTG′) conformation, while the β- and γ-phases are polar and characterized by all- trans (TTTT) and trans - trans - trans - gauche (T 3 GT 3 G′) conformations, respectively. However, conventional melt solidification conditions kinetically favor the generation of the nonpolar α-phase, posing a challenge in obtaining the desired polar phases. − To address this, researchers have explored various solid-state processing techniques, such as solid-state drawing/compression, − electrical field treatment, , and annealing. , These methods rely on a solid phase transformation from α to β/γ using α-PVDF as the starting material but often involve time-consuming, energy-intensive, or complex processes. Despite the industry’s adoption of solid-state drawing, the resulting PVDF films do not possess a satisfactory level of electric activity or thermal stability, due to the tiny phase size and conformation defects. , In consideration of processing efficiency and costs, there is a substantial demand for the development of readily implementable melt processing strategies to directly fabricate PVDF filled with polar crystalline phases.…”

Section: Introductionmentioning

confidence: 99%

Chain Orientation-Dependent Polymorphic Crystallization of Poly(vinylidene fluoride): A Guide to Achieving Polar Phases

Ye,

Sun,

Huang

et al. 2024

Macromolecules

View full text Add to dashboard Cite

Utilizing flow fields to control the generation of polar phases holds great potential for the efficient fabrication of electroactive poly(vinylidene fluoride) (PVDF). Herein, we investigated the melt-stretch-induced polymorphic crystallization of PVDF and its underlying mechanism through various structural and morphological characterizations. Under controlled stretch conditions, we achieved rapid preparation of γ-PVDF with a 90% γphase fraction, reducing the processing time by over 2 orders of magnitude compared to standard static conditions. This improvement was attributed to the dominance of γ-phase nucleation and growth over αand β-phases in a favorable flow environment. Based on experimental findings, a nucleation ability diagram was constructed to elucidate the strong chain orientation dependency of polymorphic crystallization. The diagram revealed that the optimal chain orientation degree required for flow-induced γ-, α-, and β-nucleation sequentially increased from 30 and 90 to over 90%, assuming that the chain orientation at the onset of crystallization aligns with the final crystal orientation. Consequently, stimulating the formation of the polar γ-phase through flow is comparatively easier than promoting the polar β-phase, which necessitates extreme chain extension. The competition among multiple phases under flow can be explained by chain conformational selection, which was semiquantitatively validated using stretch-induced conformational transition theory. This work provides valuable insights into the polymorphic crystallization behavior of PVDF under flow and can guide the design of flow parameters to achieve desired crystalline phases, particularly the polar γand β-phases.

show abstract

Studies on α to β phase transformations in mechanically deformed PVDF films

Cited by 104 publications

References 19 publications

Effects of Room Temperature Stretching and Annealing on the Crystallization Behavior and Performance of Polyvinylidene Fluoride Hollow Fiber Membranes

Effects of Room Temperature Stretching and Annealing on the Crystallization Behavior and Performance of Polyvinylidene Fluoride Hollow Fiber Membranes

PVDF-Based Piezo-Catalytic Membranes—A Net-Zero Emission Approach towards Textile Wastewater Purification

Chain Orientation-Dependent Polymorphic Crystallization of Poly(vinylidene fluoride): A Guide to Achieving Polar Phases

Contact Info

Product

Resources

About