The attainment of a better understanding and improvement of electrical properties of ternary blend is a task of particular scientific and economic importance. Ternary films of Poly (methylmethacrylate), Poly (ethlymat...The attainment of a better understanding and improvement of electrical properties of ternary blend is a task of particular scientific and economic importance. Ternary films of Poly (methylmethacrylate), Poly (ethlymathacrylate) and poly (vinlylidenefluoride) were prepared using solution cast technique. Thereafter, to study the hetro charges, homo-charges and interfacial charge formation in ternary system, the short circuit thermally stimulated discharge current (SC-TSDC) measurements were carried out on bilaterally metallized electrets. The ternary blend samples taken for the present investigations are hetrogeneous system involving three polymers differing in their conduction behaviour and dielectric property. Thus, unequal ohmic conduction currents arriving at the interface are expected to result in accumulation of charges at the interface or the Maxwell-Wagner effect. Clearly the Maxwell Wagner effect is expected to contribute discernibly to the observed TSDC’s of the ternary blends. The PMMA: PEMA: PVDF:: 100:100:50 blend exhibits highest tendency while 100:50:100 the least, towards the anomalous current flow. Moreover, the conductivity of 100: 100: 50 is found to be more and, therefore, a large amount of homocharge is injected leading to anomalous current.展开更多
Polymer based on (polyethyl-methacrylate) (PEMA) were exposed to different doses of gamma radiation up to 100 kGy and the physical properties have been studied. The effects of gamma irradiation on the optical spectrum...Polymer based on (polyethyl-methacrylate) (PEMA) were exposed to different doses of gamma radiation up to 100 kGy and the physical properties have been studied. The effects of gamma irradiation on the optical spectrum of PEMA films have been investigated using spectrophotometric measurements of reflectance and transmittance in the wavelength range 200-1100 nm. The structure of the sample is analyzed by X-ray diffraction technique and is found to be amorphous and partially crystalline. TGA studies revealed that the thermal stability of polyethyl methacrylate, improved after irradiation doses up to 100 kGy. On other hand driving absorption coefficient α(ω), consequently the band tail width Ee and optical band gap estimated. This behavior is believed to be associated with the generation of excess of electronic localized states. Also, Optical constants such as refractive index (n), extinction coefficient (K) have been determined using Swanepole method. Optical dispersion parameters and the dispersion parameters, such as Eo (single–oscillator energy), Ed (dispersive energy) are discussed in terms of the single-oscillator Wemple-DiDomenico model.展开更多
Jinpa, the sixth feature film by Tibetan director Pema Tseden, hit the screen on April 26, two days after U.S. superhero film Avengers: Endgame premiered in China. It bagged a box office income of over 10 million yuan...Jinpa, the sixth feature film by Tibetan director Pema Tseden, hit the screen on April 26, two days after U.S. superhero film Avengers: Endgame premiered in China. It bagged a box office income of over 10 million yuan ($1.47 million) as of May 8 with an audience of 300,000.展开更多
Pema from Nyilok Village is one of the many undergraduates since the beginning of China’s reform and opening up who comes from a mountainous area within Shangri-la.Although his grandmother passed away many years ago,...Pema from Nyilok Village is one of the many undergraduates since the beginning of China’s reform and opening up who comes from a mountainous area within Shangri-la.Although his grandmother passed away many years ago,Pema often thinks back to her telling him of the story of"eating books".When he was a child,he did not like to study and was quite the neighborhood troublemaker.展开更多
文摘The attainment of a better understanding and improvement of electrical properties of ternary blend is a task of particular scientific and economic importance. Ternary films of Poly (methylmethacrylate), Poly (ethlymathacrylate) and poly (vinlylidenefluoride) were prepared using solution cast technique. Thereafter, to study the hetro charges, homo-charges and interfacial charge formation in ternary system, the short circuit thermally stimulated discharge current (SC-TSDC) measurements were carried out on bilaterally metallized electrets. The ternary blend samples taken for the present investigations are hetrogeneous system involving three polymers differing in their conduction behaviour and dielectric property. Thus, unequal ohmic conduction currents arriving at the interface are expected to result in accumulation of charges at the interface or the Maxwell-Wagner effect. Clearly the Maxwell Wagner effect is expected to contribute discernibly to the observed TSDC’s of the ternary blends. The PMMA: PEMA: PVDF:: 100:100:50 blend exhibits highest tendency while 100:50:100 the least, towards the anomalous current flow. Moreover, the conductivity of 100: 100: 50 is found to be more and, therefore, a large amount of homocharge is injected leading to anomalous current.
文摘Polymer based on (polyethyl-methacrylate) (PEMA) were exposed to different doses of gamma radiation up to 100 kGy and the physical properties have been studied. The effects of gamma irradiation on the optical spectrum of PEMA films have been investigated using spectrophotometric measurements of reflectance and transmittance in the wavelength range 200-1100 nm. The structure of the sample is analyzed by X-ray diffraction technique and is found to be amorphous and partially crystalline. TGA studies revealed that the thermal stability of polyethyl methacrylate, improved after irradiation doses up to 100 kGy. On other hand driving absorption coefficient α(ω), consequently the band tail width Ee and optical band gap estimated. This behavior is believed to be associated with the generation of excess of electronic localized states. Also, Optical constants such as refractive index (n), extinction coefficient (K) have been determined using Swanepole method. Optical dispersion parameters and the dispersion parameters, such as Eo (single–oscillator energy), Ed (dispersive energy) are discussed in terms of the single-oscillator Wemple-DiDomenico model.
文摘Jinpa, the sixth feature film by Tibetan director Pema Tseden, hit the screen on April 26, two days after U.S. superhero film Avengers: Endgame premiered in China. It bagged a box office income of over 10 million yuan ($1.47 million) as of May 8 with an audience of 300,000.
文摘Pema from Nyilok Village is one of the many undergraduates since the beginning of China’s reform and opening up who comes from a mountainous area within Shangri-la.Although his grandmother passed away many years ago,Pema often thinks back to her telling him of the story of"eating books".When he was a child,he did not like to study and was quite the neighborhood troublemaker.
