Electrospun poly(vinylidene fluoride) (PVDF)/sulfonated poly(1,4‐phenylene sulfide) (sPPS) blend nanofiber webs are prepared to investigate the changes in piezoelectric behavior of PVDF as a function of sPPS content using spectral and electrical measurements. Initial fourier transform infrared (FTIR) spectral analysis carried out using PVDF/sPPS as‐cast films provides useful information about the preferential formation of the β‐crystalline phase in PVDF. Even with the addition of 10 wt% of sPPS, β‐crystalline absorbance increases significantly in as‐cast PVDF film at the expense of a corresponding decrease in α‐crystalline absorbance. Cyclic–voltammetric analysis confirms the redox behavior of sPPS and its influence on improving the performance of PVDF/sPPS blend‐based piezoelectric sensor through hydrogen bonding and ion‐dipole interactions. The piezoelectric output signal recorded using PVDF/sPPS blend (95:5) nanofiber web shows ~4.4 times increase in output signal amplitude compared to that of neat PVDF based sensor, which is an evidence that the PVDF/sPPS nanofiber web material can be used as a commercially viable flexible pressure sensor.
Poly(vinylidene fluoride) (PVDF) based water purification membranes exhibit excellent thermal stability and chemical resistance, but also possess inherent drawbacks such as severe membrane fouling, lower separation efficiency and water flux due to its hydrophobic nature. In the present study, we attempted to enhance the hydrophilicity of PVDF membranes by treating with varying content (0 to 3 wt%) of partially sulfonated poly(1,4-phenylene sulfide) (sPPS) component using phase-inversion process. Compared to neat PVDF membrane, the PVDF/sPPS blend membranes exhibited typical asymmetric morphology with larger finger-like pores, efficient distribution of hydrophilic SO 3 -groups and decreasing water contact angle (WCA) upto 62 o (77 o for neat PVDF) as confirmed from scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and contact-angle measurements, respectively. Studies carried out for pure water flux (880 L/m 2 h) and blood serum albumin (BSA) solution flux (185 L/m 2 h) confirmed the enhanced permeability and higher fouling resistance for PVDF-sPPS (3 wt% sPPS) membranes compared to neat PVDF membrane (175 L/m 2 h and 63 L/m 2 h, respectively), though the BSA flux decreased with an increase in the filtration time due to membrane fouling. Compared to the total organic carbon (TOC) values of poly(ethylene oxide) (PEO) aqueous solutions before permeation (189.9 mg/L for M w =100,000 and 75.68 mg/L for M w =300,000), TOC of neat PVDF membrane decreased to 15 mg/L for M w = 100,000 and 5 mg/L for M w =300,000. With increasing sPPS content, the TOC values showed an increasing trend due to their increasing pore size. Overall, the incorporation of sPPS in PVDF membrane lowered the WCA, enhanced fouling resistance and improved its permeability and selectivity, which exemplifies the importance of this study.
Hessian cloth (jute fabrics) samples were soaked in the alcoholic shellac solution and dried at 333 K for 4 hours. Six layers of shellac treated hessian cloth were heat pressed (373 K for 10 min at 5 MT pressure) to fabricate biocomposite and then its mechanical properties were evaluated. To improve the mechanical properties of the biocomposite, a series of formulations was prepared using varying percentages of urea (0.25 to 30 %) with shellac in methanol; then the composite was fabricated using same parameters. Mechanical properties such as tensile strength (TS), bending strength (BS), tensile modulus (TM), bending modulus (BM), elongation at break (Eb), impact strength (IS) of the biocomposite were determined. Percentage of urea and soaking time of hessian cloth for the composites were optimized over mechanical properties. The biocomposite prepared with 0.5 % urea at 2 min soaking time showed the highest mechanical properties (TS – 79 MPa, BS – 74 MPa, BM – 7 GPa, IS – 13 kJ/m2 and Eb – 11.3 %). Scanning electron microscopic images of the fracture surface of the composites were suggested.
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