http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ponnan Sathiyanathan,Arun Anand Prabu,김갑진 한국고분자학회 2016 Macromolecular Research Vol.24 No.8
In this study, neat polyvinylidene fluoride (PVDF) and its blend with polyoctafluoropentyl acrylate (POFPA) were electrospun under controlled conditions, and studied for their physico-mechanical and piezo-responsive behaviours. Initial FTIR studies confirmed the effect of thermal annealing on the crystalline phase transformations and chaindipole orientation in PVDF as a function of POFPA content. SEM data exhibited “root-shaped” morphology in the blend sample. Higher tensile strength (65.2±0.4 kPa) for the blend compared to that of neat PVDF (1.5±0.03 kPa) confirmed the elastic nature of the blend nanoweb. Peak-to-peak piezoelectric output signal (Vp-p 0.976 V) and capacitance hysteresis showed reduced tendency, whereas the capacitance maxima is higher for the blend sample (Cmax 0.182 nF) compared to that of neat PVDF (Vp-p 1.195, Cmax 0.147 nF). Overall, even 10 wt% addition of POFPA in PVDF greatly enhanced the tensile strength of nanofiber web along with improved piezocapacitive characteristics, a combination of great potential for many commercial sensor applications.
Rengasamy, Tamilarasan,Arun, Anand Prabu,Muniswamy, Raajenthiren,Mahendradas, Dharmendira Kumar,Yoo, Chang Kyoo The Society of Chemical Engineers, Japan 2009 Journal of chemical engineering of Japan Vol.42 No.7
<P>This communication presents the effect of five dissolved inorganic salts (sodium chloride, NaCl; calcium chloride, CaCl<SUB>2</SUB>; zinc chloride, ZnCl<SUB>2</SUB>; cadmium chloride, CdCl<SUB>2</SUB>; ammonium chloride, NH<SUB>4</SUB>Cl) on the enthalpy of mixing (<I>H</I><SUP>E</SUP>) of ethyl acetate/benzene binary system at 303.15 K; enthalpy measurements were performed using an isothermal displacement calorimeter with vapor space. The excess enthalpy of mixing of this system is significantly reduced in the presence of NH<SUB>4</SUB>Cl and NaCl; however, changes in the excess enthalpy of mixing were insignificant in the presence of CaCl<SUB>2</SUB>, ZnCl<SUB>2</SUB>, and CdCl<SUB>2</SUB>. The experimental values of <I>H</I><SUP>E</SUP> were fitted into the Redlich–Kister equation, and deviations from the ideal value and binary parameters were calculated. The importance of solute–solvent interactions was demonstrated from the decrease in the excess enthalpy of mixing in the negative direction with an increase in the NaCl concentration.</P>
Shamim-Ara Pervin,Arun Anand Prabu,Kap-Jin Kim 한국섬유공학회 2022 Fibers and polymers Vol.23 No.4
Structural characterization of industrial-grade poly(1,4-phenylene sulfide) (PPS) batch samples (solution- andmelt-polymerized) can only be carried out using expensive and least available solid-state NMR/high-thermal viscometer dueto their insolubility in common organic solvents even at 200 oC. In the present study, we prepared sulfonated PPS (sPPS)which is soluble in common organic solvents even at ambient temperature conditions, thereby facilitating its easiercharacterization in the solution state at R.T. using FTIR, NMR, and solution-viscosity measurements. sPPS was synthesizedthrough the anionic modification of PPS using chlorosulfonic acid (ClSO3H) and dichloromethane as a function of varyingPPS:ClSO3H mole ratio (1:5 and 1:10) and sulfonation time (1 to 48 h). A previously unreported methodology to identify thebranching types (phenylene and sulfide branching) in PPS was carried out using 1H-NMR curve-fitting analysis withLorentzian equation. Melt-polymerized PPS samples were analyzed to contain about two times higher degree of branchingthan the solution-polymerized PPS ones.
가줄라 프라사드,Ponnan Sathiyanathan,Arun Anand Prabu,김갑진 한국고분자학회 2017 Macromolecular Research Vol.25 No.10
In this paper, the crystallinity changes in polyvinylidene fluoride (PVDF) as function of varying phase-separation temperatures (0 to 90 oC) and chloride salts (BaCl2, CaCl2, CoCl2, NaCl, SnCl2, N2H6Cl2) were investigated. FTIR quantitative analysis showed higher β-crystalline and lower α-crystalline content for 70oC phase-separated PVDF and 70 oC phase-separated PVDF-CaCl2 (15wt%) samples. XRD and DSC studies also confirmed the influence of 70 oC phase-separation temperature and CaCl2 salt in improving the β-crystallinity in PVDF compared to the neat PVDF sample. Since higher β-crystalline content is favoured for use in piezoelectric applications, these two sample preparation conditions were optimized for use in piezoelectric studies. Electrospun nanowebs of the selected samples were measured for their piezoelectric output signals under applied pressure of 1 kgf and released periodically at 0.5 Hz. From the peak-to-peak output voltage, 70 oC phase-separated PVDF-CaCl2 sample exhibited significantly higher output voltage (+0.89 V) compared to neat PVDF (+0.48 V) and 70 oC phase-separated PVDF (+0.53 V) samples. These results conclude that the combinative effect of phase-separation temperature and metal salt addition plays a vital role in improving the piezoelectric characteristics of PVDF, which signifies the importance of this study.
The Effect of an External Electric Field on Solid-State Phase Transition of P(VDF/TrFE)(72/28)
Lee, Jong-Soon,Prabu, Arun Anand,Kim, Kap-Jin,Park, Cheol-Min The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.5
The copolymers of vinylidene fluoride and trifluoroethylene (P(VDF/TrFE)) with VDF content of 50-80 mole % can be applied to the field of nonvolatile ferroelectric polymeric random access memory (FePoRAM) devices, since they exhibit stable ferroelectric ${\beta}-phase$ at room temperature with spontaneous polarization of the C-F dipoles towards an external electric field greater than the coercive field. Many researchers have already reported the molecular structures and dynamics of the ferroelectric (F) crystalline phase and the unique change in chain conformation between polar F phase and nonpolar paraelectric (P) phase near their Curie transition temperature ($T_c$) which is dependent on factors such as VDF content and annealing treatment conditions. The effect of external electric field strength on the $F{\Leftrightarrow}P$ crystalline phase transition in P(VDF/TrFE)(72/28) random copolymer samples of nanometer thickness was investigated. Capacitance of 250 nm thick sample measured as a function of heating-cooling under varying external electric field strength exhibited increasing $T_c#s$ during heating ($T_c^{\uparrow}$) and cooling ($T_c^{\downarrow}$) under an applied electric field of more than 0.03 MV/cm. Applying cyclic bias electric field (+1 to -1 MV/cm) for samples kept isothermally at just above their $T_c^{\downarrow}$ during cooling, we were able to observe the field-induced $P{\rightarrow}F$ phase transition. With increasing cycles of the applied electric field for sample maintained just above $T_c^{\downarrow}$, the bistable C-E hysteresis was observed and the phase change from $P{\rightarrow}F$ is irreversible even after the electric field is removed. However, for samples kept well above $T_c^{\downarrow}$ and near $T_m\;(100^{\circ}C\;and\;120^{\circ}C$ respectively) during cooling, the F-phase initially formed through the field-induced phase transition is reversibly transformed to the P-phase when the applied electric field is removed. Drastic changes were observed in both coercive field ($E_c$) and remanent polarization ($P_r$) values during heating and cooling near the $T_c$ range due to the $F{\Leftrightarrow}P$ phase transition and the results are reported in detail here.