Impact of poly(ε‐caprolactone) on the thermal, dynamic‐mechanical and crystallization behavior of polyvinylidene fluoride/poly(ε‐caprolactone) blends in the presence of KIT ‐6 mesoporous particles

2021 ◽  
Author(s):  
Vafa Fakhri ◽  
Mohammad Monem ◽  
Gity Mir Mohamad Sadeghi ◽  
Hossein Ali Khonakdar ◽  
Vahabodin Goodarzi ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Crystallization Behavior ◽  
Dynamic Mechanical ◽  
Mesoporous Particles

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

Membranes ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 38 ◽  
Author(s):  
Yuanhui Tang ◽  
Yakai Lin ◽  
Hanhan Lin ◽  
Chunyu Li ◽  
Bo Zhou ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Pore Size ◽  
Hollow Fiber ◽  
Polyvinylidene Fluoride ◽  
Room Temperature ◽  
Crystallization Behavior ◽  
Hollow Fiber Membranes ◽  
The Mean ◽  
And Performance ◽  
Stretching Ratio

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.

Effect of the molecular weight and its distribution of polyvinylidene fluoride on the relationship between the spinning process, microstructure and properties of hollow fiber membranes via thermally induced phase separation

2018 ◽  
Vol 89 (7) ◽  
pp. 1311-1320 ◽  
Author(s):  
Nana Li ◽  
Zhe Chang ◽  
Qingchen Lu ◽  
Changfa Xiao ◽  
Junyi Wu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Polyvinylidene Fluoride ◽  
Crystallization Behavior ◽  
Water Flux ◽  
Thermally Induced Phase Separation ◽  
Thermally Induced ◽  
Molecular Weights ◽  
Spinning Process ◽  
The Relationship

Polyvinylidene fluoride (PVDF) is an important material in the preparation of ultrafiltration membranes via the thermally induced phase separation (TIPS) method. In this paper, four PVDF hollow fiber membranes with different molecular weights were prepared via the TIPS method by using dibutyl phthalate and dioctyl phthalate as a mixed diluent. The relationship between the molecular weight of PVDF and its distribution, phase separation, crystallization behavior and spinning process has been systematically studied. The effects of three factors on the microstructure and properties of the PVDF membrane have been analyzed. The flow behaviors of the PVDF/diluent and PVDF melt were tested by a capillary rheometer and a melt flow rate instrument, respectively. A phase diagram of the membrane solution was determined by thermal polarizing microscope and differential scanning calorimetry. The crystallization behavior and angle of orientation of the membrane were tested by using a differential scanning calorimeter and a sound velocity orientation measurement instrument. The microstructures, such as the pore structure and crystalline grain structure, were observed by field emission scanning electron microscopy. Meanwhile, the properties of the membrane were examined from the view of water flux, porosity and tensile testing. The results showed that changes in the polymer molecular weights affected not only the dynamics but also the thermodynamics of phase separation in membrane formation. As the PVDF molecular weight increased, the phase separation region increased, but the membrane structure became denser. A wide molecular weight distribution easily produced large pores. Then, the water flux decreased first and then increased.

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